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Construction"},{"TextID":59743,"ResultID":176261,"Text1":"Brick Industry Association: Tuck-Pointing Mortar Joints"},{"TextID":59744,"ResultID":176262,"Text1":"Brick Industry Association: Requirements for Cores and Frogs"},{"TextID":59745,"ResultID":176263,"Text1":"Brick Industry Association: Brick Sizes (Nominal Dimensions)"},{"TextID":59746,"ResultID":176264,"Text1":"Brick Industry Association: Modular Unit Coordination"},{"TextID":59747,"ResultID":176265,"Text1":"brick industry association web pages www home internet"},{"TextID":59379,"ResultID":175897,"Text1":"Brick Industry Association: Jackson County Memorial Hospital, Altus, Oklahoma"},{"TextID":59380,"ResultID":175898,"Text1":"Brick Industry Association: Jackson County Memorial Hospital, Altus, Oklahoma"},{"TextID":59381,"ResultID":175899,"Text1":"Brick Industry Association: Jackson County Memorial Hospital, Altus, Oklahoma"},{"TextID":59382,"ResultID":175900,"Text1":"Brick Industry Association: Robert R. Herring Hall, Rice University, Houston, Texas"},{"TextID":59383,"ResultID":175901,"Text1":"Brick Industry Association: Robert R. Herring Hall, Rice University, Houston, Texas"},{"TextID":59384,"ResultID":175902,"Text1":"Brick Industry Association: Robert R. Herring Hall, Rice University, Houston, Texas"},{"TextID":59385,"ResultID":175903,"Text1":"Brick Industry Association: Robert R. Herring Hall, Rice University, Houston, Texas"},{"TextID":59386,"ResultID":175904,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59387,"ResultID":175905,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59388,"ResultID":175906,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59389,"ResultID":175907,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59390,"ResultID":175908,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59391,"ResultID":175909,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59392,"ResultID":175910,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59393,"ResultID":175911,"Text1":"Brick Industry Association: Washington Harbour, Washington, D.C."},{"TextID":59394,"ResultID":175912,"Text1":"Brick Industry Association: Moon Kiss, Mill Creek, Washington - Artists: Mara Smith && Kris K King"},{"TextID":59395,"ResultID":175913,"Text1":"Brick Industry Association: Old No. 17, Redevelopment Project, Lincoln, Nebraska, - Artist: Jay Tschetter"},{"TextID":59396,"ResultID":175914,"Text1":"Brick Industry Association: Cayman Reef, Cayman Islands, - Artist: Jack Curran"},{"TextID":59397,"ResultID":175915,"Text1":"Brick Industry Association: The Tree of Life, Christ the King Church, Acme, Michigan - Artist: John Carlance"},{"TextID":59398,"ResultID":175916,"Text1":"Brick Industry Association: The Tree of Life, Christ the King Church, Acme, Michigan - Artist: John Carlance"},{"TextID":59399,"ResultID":175917,"Text1":"Brick Industry Association: Mise-en-Scene, Johnson County Community College, Overland Park, Kansas - Artist: Donna Dobberfuhl"},{"TextID":59400,"ResultID":175918,"Text1":"Brick Industry Association: Mise-en-Scene, Johnson County Community College, Overland Park, Kansas - Artist: Donna Dobberfuhl"},{"TextID":59401,"ResultID":175919,"Text1":"Brick Industry Association: Court Jester, Richlands, Virginia - Artist: John Hagerman"},{"TextID":59402,"ResultID":175920,"Text1":"Brick Industry Association: Northern Crop Research Laboratory, North Dakota State University, North Fargo, North Dakota"},{"TextID":59403,"ResultID":175921,"Text1":"Brick Industry Association: Faith Lutheran Church, Des Moines, Iowa"},{"TextID":59404,"ResultID":175922,"Text1":"Brick Industry Association: Franklin W. Olin Humanities Building, Bard College, Annandale-on-Hudson, New York"},{"TextID":59405,"ResultID":175923,"Text1":"Brick Industry Association: Ballplayers Refreshment Stand, Central Park, New York, New York"},{"TextID":59406,"ResultID":175924,"Text1":"Brick Industry Association: 350 North La Salle, Chicago, Illinois"},{"TextID":59407,"ResultID":175925,"Text1":"Brick Industry Association: Oregon Convention Center, Portland, Oregon"},{"TextID":59408,"ResultID":175926,"Text1":"Brick Industry Association: Baltimore Arena Parking Garage, Baltimore, Maryland"},{"TextID":59409,"ResultID":175927,"Text1":"Brick Industry Association: Baltimore Arena Parking Garage, Baltimore, Maryland"},{"TextID":59410,"ResultID":175928,"Text1":"Brick Industry Association: Patriots Square, Phoenix, Arizona"},{"TextID":59411,"ResultID":175929,"Text1":"Brick Industry Association: Patriots Square, Phoenix, Arizona"},{"TextID":59412,"ResultID":175930,"Text1":"Brick Industry Association: Park Place, Vancouver, British Columbia"},{"TextID":59413,"ResultID":175931,"Text1":"Brick Industry Association: Transpotomac Canal Center, Alexandria, Virginia"},{"TextID":59414,"ResultID":175932,"Text1":"Brick Industry Association: University of Texas at Arlington"},{"TextID":59415,"ResultID":175933,"Text1":"Brick Industry Association: University of Texas at Arlington"},{"TextID":59416,"ResultID":175934,"Text1":"Brick Industry Association: Carnegie Hall Tower, New York, New York"},{"TextID":59417,"ResultID":175935,"Text1":"Brick Industry Association: Carnegie Hall Tower, New York, New York"},{"TextID":59418,"ResultID":175936,"Text1":"Brick Industry Association: Carnegie Hall Tower, New York, New York"},{"TextID":59419,"ResultID":175937,"Text1":"Brick Industry Association: The New York, Chicago, Illinois"},{"TextID":59420,"ResultID":175938,"Text1":"Brick Industry Association: 222 Riverside Drive, New York, New York"},{"TextID":59421,"ResultID":175939,"Text1":"Brick Industry Association: 222 Riverside Drive, New York, New York"},{"TextID":59422,"ResultID":175940,"Text1":"Brick Industry Association: Trump Palace, New York, New York"},{"TextID":59423,"ResultID":175941,"Text1":"Brick Industry Association: United Hebrew Congregational Synagogue, Chesterfield, Missouri"},{"TextID":59424,"ResultID":175942,"Text1":"Brick Industry Association: United Hebrew Congregational Synagogue, Chesterfield, Missouri"},{"TextID":59425,"ResultID":175943,"Text1":"Brick Industry Association: Annunciation Greek Orthodox Church, Brockton, Massachusetts"},{"TextID":59426,"ResultID":175944,"Text1":"Brick Industry Association: Annunciation Greek Orthodox Church, Brockton, Massachusetts"},{"TextID":59427,"ResultID":175945,"Text1":"Brick Industry Association: Annunciation Greek Orthodox Church, Brockton, Massachusetts"},{"TextID":59428,"ResultID":175946,"Text1":"Brick Industry Association: Hickory Grove Baptist Church, Charlotte, North Carolina"},{"TextID":59429,"ResultID":175947,"Text1":"Brick Industry Association: Hickory Grove Baptist Church, Charlotte, North Carolina"},{"TextID":59430,"ResultID":175948,"Text1":"Brick Industry Association: Hickory Grove Baptist Church, Charlotte, North Carolina"},{"TextID":59431,"ResultID":175949,"Text1":"Brick Industry Association: 800 North Capitol Street, Washington, D.C."},{"TextID":59432,"ResultID":175950,"Text1":"Brick Industry Association: Franklin School, Washington, D.C."},{"TextID":59433,"ResultID":175951,"Text1":"Brick Industry Association: Charlestown Navy Yard Rowhouses, Charlestown, Massachusetts"},{"TextID":59434,"ResultID":175952,"Text1":"Brick Industry Association: LeBow Engineering Building Center for Automation Technology, Drexel University, Philadelphia, Pennsylvania"},{"TextID":59435,"ResultID":175953,"Text1":"Brick Industry Association: Illinois Telephone Company, Remote Switching Unit, Gurnee, Illinois"},{"TextID":59436,"ResultID":175954,"Text1":"Brick Industry Association: La Estrella Ranch House, Roma, Texas"},{"TextID":59437,"ResultID":175955,"Text1":"Brick Industry Association: 518 C St., Washington, D.C."},{"TextID":59438,"ResultID":175956,"Text1":"Brick Industry Association: Congregation of the Sisters of Charity of the Incarnate Word Long-Term Care Facility, San Antonio, Texas"},{"TextID":59439,"ResultID":175957,"Text1":"Brick Industry Association: Congregation of the Sisters of Charity of the Incarnate Word Long-Term Care Facility, San Antonio, Texas"},{"TextID":59440,"ResultID":175958,"Text1":"Brick Industry Association: Congregation of the Sisters of Charity of the Incarnate Word Long-Term Care Facility, San Antonio, Texas"},{"TextID":59441,"ResultID":175959,"Text1":"Brick Industry Association: Hotel Dieu Hospital, Cornwall, Ontario, Canada"},{"TextID":59442,"ResultID":175960,"Text1":"Brick Industry Association: Wake County Public Health Center, Raleigh, North Carolina"},{"TextID":59443,"ResultID":175961,"Text1":"Brick Industry Association: Wake County Public Health Center, Raleigh, North Carolina"},{"TextID":59444,"ResultID":175962,"Text1":"Brick Industry Association: Hospital for Sick Children, Washington, D.C."},{"TextID":59445,"ResultID":175963,"Text1":"Brick Industry Association: Hospital for Sick Children, Washington, D.C."},{"TextID":59446,"ResultID":175964,"Text1":"Brick Industry Association: Westlake Senior High School, Charles County, Maryland"},{"TextID":59447,"ResultID":175965,"Text1":"Brick Industry Association: Westlake Senior High School, Charles County, Maryland"},{"TextID":59448,"ResultID":175966,"Text1":"Brick Industry Association: The University of Oregon Science Complex, Eugene, Oregon"},{"TextID":59449,"ResultID":175967,"Text1":"Brick Industry Association: The University of Oregon Science Complex, Eugene, Oregon"},{"TextID":59450,"ResultID":175968,"Text1":"Brick Industry Association: The University of Oregon Science Complex, Eugene, Oregon"},{"TextID":59451,"ResultID":175969,"Text1":"Brick Industry Association: Wolf Family - Artist: Brickstone Studios"},{"TextID":59452,"ResultID":175970,"Text1":"Brick Industry Association: Brick Mask, Paul Gutman Library, Philadelphia, Pennsylvania - Artist: Syma"},{"TextID":59453,"ResultID":175971,"Text1":"Brick Industry Association: Alphabet of Land and Sea Creatures, Cordova High School - Artist: Patricia Turlington"},{"TextID":59454,"ResultID":175972,"Text1":"Brick Industry Association: Heron - Artist: James Marshall"},{"TextID":59455,"ResultID":175973,"Text1":"Brick Industry Association: Whales - Artist: Mara Smith"},{"TextID":59456,"ResultID":175974,"Text1":"Brick Industry Association: Salmon Run - Artist: Jack Curran"},{"TextID":59457,"ResultID":175975,"Text1":"Brick Industry Association: Nature of the Pacific Northwest I and II - Artist: Mara Smith"},{"TextID":59458,"ResultID":175976,"Text1":"Brick Industry Association: Coors Field, Denver, Colorado"},{"TextID":59459,"ResultID":175977,"Text1":"Brick Industry Association: Coors Field, Denver, Colorado"},{"TextID":59460,"ResultID":175978,"Text1":"Brick Industry Association: Coors Field, Denver, Colorado"},{"TextID":59461,"ResultID":175979,"Text1":"Brick Industry Association: The Ballpark in Arlington, Arlington, Texas"},{"TextID":60039,"ResultID":176271,"Text1":" bia catalog cover next or back to thumbnail page --> catalogs pages"},{"TextID":60040,"ResultID":176272,"Text1":" bia catalog page 2 design next previous back to thumbnail page --> catalogs pages"},{"TextID":60041,"ResultID":176273,"Text1":" bia catalog page 3 design next previous back to thumbnail page --> - a - brick in architecture award-winning eight-page color pictorial publication designed specifically for architects. illustrates the aesthetics of brick, as employed in buildings around the country. issued five times a year. past issues are available as supplies last. topics include all types of buildings and uses of brick in both commercial and residential construction. initial distribution is through architecture magazine. $1.50 each, $.60 each for 100 or more - b - brick shapes guide a 24-page brochure packed with information on shapes such as the bullnose, watertable, the dogleg, and many others. includes photos, graphics, and instructions on ordering non-standard brick. (1986) $2.00 each, $1.50 each for 50 or more #831 - c - brick designers sketchbook features six new brick home designs by three leading architectural firms, with special attention to brick detailing on the houses and in the landscaping of the site. also included is a special bia section on residential brick details and landscaping. 20 pages, four-color. (1991) $2.00 each, $1.50 each for 50 or more #535 - d - passive solar design strategies: guidelines for home building the manual presents all the information to design passive solar homes. the guidelines are customized to more that 230 climate regions in the u.s. providing design and construction data and predicted performance for your area. includes computer program to automate design calculations. specify geographic area when ordering. up to two climate data files are included in purchase price. (1995) $50.00 each #504 - e - designing low energy buildings a design manual with accompanying pc based design tool (energy 10) that helps building designers quickly identify the most cost effective energy saving measures for small commercial and residential buildings. $225.00 each #505 - f - the fireplace book a comprehensive study of masonry fireplaces, including design data and style nomenclature. seventy pages with more than 100 full-color illustrations of fireplaces, chimneys and masonry heaters. (1992) #25.00 each, $15.00 each for 10 or more #822 case studies brick noise barriers four-page case study of one of the newest and most successful highway noise barrier projects in raleigh, north carolina. included is design information and cost data. (1992) $1.50 each, $.75 for 100 or more #82 loadbearing brick masonry residence case study of a residence in lexington, kentucky utilizing single wythe loadbearing brick masonry without traditional wood framing. includes design and cost data. (1995) $1.50 each, $.75 for 100 or more #840 brick masonry loadbearing cavity wall six-page case study of a junior high school in arkansas. the school was designed to house 800 seventh, eighth and ninth grade students. included are design information and cost data. (1993) $1.50 each, $.75 for 100 or more #824 - g - brick energy basics a color brochure providing a layman s guide to thermal mass and peak load shifting. various wall assemblies are shown with their respective r-values and heat capacities to show compliance with the new energy codes. (1996) $1.00 each, $.50 each for 100 or more #515 videos (not shown) brick masonry construction inspection procedures vhs format, color, 24 minutes intended to familiarize young design professionals and reacq uaint veteran architects with the proper practice of overseeing brick masonry construction. included topics are pre-inspection preparation, specification compliance, workmanship and site preparation. (1987) $15.00 each, $10.00 each for 10 or more #951 streetscape: a northern renaissance vhs format, color, 14 minutes describes how downtown duluth, minnesota was revitalized through the repaving of sidewalks and streets with brick. includes interviews with local civic leaders and a detailed description of how the project was developed and installed. the duluth project used more than 3 1/2 million brick pavers. (1987) $15.00 each, $10.00 each for 10 or more #954 brick sculpture vhs format, color, 14 minutes intended for architectural and general interest audiences. describes the technique of sculpting of brick and the method of manufacture and installing. shows outstanding examples of brick sculpture from across the country. (1987) $15.00 each, $10.00 each for 10 or more #953 brick: a pattern for living vhs format, color, 15 minutes designed for a general audience, this presentation looks at the variety of patterns found in nature, art, and other manmade items, and focuses on the many patterns possible in brick architecture. wythes, running bond, flemish bond, common bond, rowlocks, headers and stretchers and other masonry terms are explained. (1985) $15.00 each, $10.00 each for 10 or more #962 brick in community design vhs format, color, 15 minutesbrick in community design vhs format, color, 15 minutes shows how brick creates overall community appeal. the use of brick on small and large scale in entrance gates, privacy walls, patios, gardens, walkways, community centers and other public buildings, private homes, and as an art form, all show how brick creates beauty and cohesiveness in community design. (1985) $15.00 each, $10.00 each for 10 or more #961 computer program (not shown) arch this dos-based program is an interactive graphics program for the structural analysis of unreinforced brick masonry segmental, semicircular and jack arches. the program verifies the structural resistance of the arch or determines the cause or causes of failure of the arch. the program produces a dimensioned drawing and a hatched drawing of the wall elevations containing the arch, a comprehensive list of analysis results for the arch ring and the abutments, shear and moment diagrams for the arch, and a printout of the critical analysis results. requires an ibm-pc or compatible. (1995) $25.00 #904 next --> catalogs pages"},{"TextID":60042,"ResultID":176274,"Text1":" bia catalog cover technical next previous back to thumbnail page --> catalogs pages"},{"TextID":60043,"ResultID":176275,"Text1":" bia catalog page 5 next previous back to thumbnail page --> technical - a - principles of brick masonry this thoroughly up-to-date manual is an informative resource for both architectural students and practicing designers. 88 pages. (1989) $5.00 each, $3.00 each for 10 or more #607 - b - flexible brick paving: light duty applications a 16-page, 4-color design and installation guide for light duty flexible brick paving. covers applications such as drawings, plazas, walkways and patios. (1992) $2.00 each, $1.00 each for 100 or more #531 - c - flexible brick pavements: design and installation guide a comprehensive manual covering the design, materials and construction of heavy-duty brick flexible paving systems. included are 34 tables, drawings and photographs to illustrate the latest in brick paving technology. 40 pages. (1991) $3.00 each, $2.00 each for 10 or more #530 - d - masonry structures: behavior and design an invaluable reference work on brick, block and other types of masonry construction. the 782-page book has 442 illustrations that present the principles of masonry design and performance. it contains a thorough review of design principles for both reinforced and unreinforced masonry construction. (1994) $80.00 , $76.00 each for 10 or more #720 - e - architectural details in brick reprint of a special 16-page advertising supplement that appeared in architecture magazine in november 1990. four-color illustrations of outstanding design details created in brick through unit placement, sculpture and color. also includes drawings of proper flashing, weep holes and expansion joints. (1990) $1.50 each, $1.00 each for 100 or more #821 - f - walls to save dollars this eight-page booklet presents a reasonable and comprehensive method of anticipating the total life-cycle cost of erecting, operating, and maintaining the walls of a building. a comparison of six wall types is provided: brick/block cavity wall; brick veneer/steel stud; precast concrete panel; metal panel; double plate glass and exterior insulation and finish system (eifs). (1997) $2.00 each, $1.00 for 10 or more copies #845 building code requirements for masonry structures (aci 530/asce 5/tms 402-99) and specifications for masonry stuctures (aci 530.1/asce 6/tms 602-99) and commentaries the code for masonry design includes design requirements, the specifications cover construction requirements. both have their own commentary. this document is referenced by the national and standard building codes. a must for all designers of masonry. (1999) $65.00 #835 astm standard specifications for brick, mortar and applicable testing methods for units authorized reprint of the current american society for testing & materials standards for brick units, mortar and methods of tests. available as individual standards or as a complete set of all seven specifications. 8 1/2\" x 11\" format. $1.00 each, single specifications, $.75 for 10 or more c216....... #616 c62........... #662 c652....... #652 c1088....... #688 c902....... #602 c67............ #667 c270....... #670 $5.00 each, set of 7 specifications, $4.00 each for sets of 10 or more #600 engineering & research digests a series of short topical subject-oriented papers covering concepts on a more general basis than in technical notes. originally published in brick news. $.50 each, $.25 each for 25 or more dimensional tolerances of walls #653 curved brick walls #620 ivy on brickwork #621 repointing #622 leaky walls #624 radon #625 brick do not leak #626 movement joints #627 proper chimney crowns #628 support of brick masonry #629 arches in residential construction #633 flashing chimneys #635 brick veneer subject to seismic forces #636 quoins #637 vented walls #638 support on wood #639 brick masonry over garage openings #641 replacement brick #642 ul fire ratings #644 brick veneer/steel stud residential #645 lipped brick #646 detailistepped flashingng #647 environmental aspects of brick #649 pool copings #650 dimensional tolerances of brick #651 through wall flashing #654 air barriers and moisture barriers in residential construction #655 prices and shipping single unit prices include postage or shipping charges within continental united states. foreign orders must be prepaid in u.s. funds and include postage or shipping charges. quantity order prices do not include postage or shipping costs. shipment will be made \"best way\" unless otherwise specified . all orders must be prepaid with cash, visa or mastercard or shipped ups cod unless prior credit arrangements have been made. virginia residents add 4.5% sales tax. audio-visual library videos and slides are available on loan free of charge from our audio-visual library. call or write for more information. next --> catalogs pages"},{"TextID":60044,"ResultID":176276,"Text1":" bia catalog cover next previous back to thumbnail page --> technical notes continued technical notes on brick construction a series of bulletins that contain design, detailing and construction information based on the latest technical developments in brick masonry. drawings, photographs, tables and charts illustrate each topic. they are available individually, or as a set. the purchaser of a complete set will automatically receive all new and revised issues. complete set of technical notes (including index and 3-ring binder) with update service $75.00 each, $60.00 for 10 or more #tn100 $1.00 each for individual copies, $.50 for 50 or more of the same number $.25 for the most current technical notes index #01dx electronic technical notes (version 2.0) the complete set of technical notes on brick construction is also available on cd-rom. the digitized series contains text, graphics and cad files. a search engine allows users to quickly find information. over 100 color photos are included showing various brick applications. (1999) $75.00 each, $60.00 for 10 or more #905 subject number - a - aci 530/asce 5/tms 402 mm building code admixtures in mortar anchor boltsarches mm construction mm flashing mm semi-circular mm structural design astm standards mm brick mm mortar 3 1, 8 44 31-31c 31 31 31 c 31 a 9 a 8 - b - barrier walls beams bearing walls (see engineered brick mm masonry) bonds and patterns in brickwork mm paving patterns bond breaks bond - mortar mm reinforced brick masonry brick sizes 7 17b mm 30 14, 29 18a, 21b 8 17, 17a 10b - c- calculated fire resistance caps cavity walls mm construction mm detailing mm glazed brick mm materials mm passive solar heating mm roperties chimneys classification of brick cleaning mm floors mm efflorescence coatings for brick cold weather construction mm guide specifications color - reflectivity (heat gain) mm mortar columns and pilasters compressive strength brick masonry mm brick units mm mortar mm walls condensation mm analysis control joints (see expansion joints) copings corbels and racking corrosion mm metal ties mm shelf angles mm steel lintels coursing tables for brick cracking curtain and panel walls 16b 36a 21-21c 21c 21b 13 21a 43 21 19- 19c 9a 20 14b 23 6, 6a 1 11a 4a 8 3b 3a, 39a, 42 9a, 39 8 39a, 42 7c 7d 36 36a 7a , 44b 7a 7a , 31b 10b 18 17l - d- mm dampproofing differential movement mm bond breaks mm expansion joints in paving mm expansion joints in walls mm flexible anchorage mm material properties mm volume changes and effects direct gain, passive solar heating mm performance calculations drainage walls 7f 18, 18a 18a 14 18a 18a 18 18 43 43b 7 rev - e- mm efflorescence mm causes and mechanisms mm prevention and control mm removal empirical design of brick masonry energy codes mm heat transmission coefficients engineered brick masonry mm allowable design stresses mm bearing wall mm building code requirements mm construction mm detailing mm guide specifications mm series material properties mm quality control mm section properties mm shear wall design mm testing mm wall types and properties estimating material quantities expansion joints mm paving 23 23a 20 42 4b 4 3a, 24a, 39a 24 3, 16, 24a 24f 24g 11 3a 39b 3b 24c 39 series 3b 10 18a 14 - f- mm fasteners for brick masonry fences field panels fireplaces, residential mm contemporary, projected corner, mm rumford, multi-faced mm details and construction mm finnish style masonry heater mm russian style masonry heater fire resistance flashing, types and selection mm arches mm details flexible pavements floor-wall connections, bearing wall freezing, protection from 44a 29a 9b 19-19e 19c 19b 19e 19d 16, 16b 7a 31 7 14 24b, 26 1 - g- mm garden walls girders, reinforced brick masonry glazed brick walls glossary 2 grout mm properties 3a testing guide specifications 29a 17m 13 17, 17a 39 11 series - h- mm heat transmission coefficients high-lift grouting hollow brick masonry mm reinforced hot weather construction 4 17a 41 17 series 1 - i- mm initial rate of absorption inspection mm rbm 7a, 9a, 39 7f 17a - l- mm landscape architecture mm garden walls mm miscellaneaous applications mm pedestrian applications mm lateral forces, shear wall mm design lintels mm reinforced brick mm structural steel loadbearing brick homes 29-29b 29a 29b 29 24c 17b 31b 26 - m- mm maintenance mm cleaning mm floors manufacturing of brick material properties masonry heaters modular brick masonry moisture control barrier walls mm caps and copings mm condensation analysis mm corrosion mm drainage walls mm flashing mm glazed brick walls maintenance mortar bond mm rain screen wall mm repointing mm water repellent coatings mm weep holes moisture movements mortars for brick masonry mm cold weather construction mm efflorescence mm estimating quantities mm guide specifications mm joints materials mm pavements and floors mm reinforced masonry mm repointing mm selection and control mm specifications, bia standard movement (see differential movement) 7f 20 14a, 14b 9 3a 19d, 19e 10 series 7 7, 36a 7c, 7d 7a, 31b , 44b 7 7a 13 7f 8 27 7f 6a 7 18 8 series 1 23 series 10 11e 7b, 21c 8 14a 17a 7f 8b 8a - n- mm noise barrier walls mm structural design 45 45a - p- mm painting brick masonry parapets passive solar systems patterns paving mm bases mm drainage mm expansion joints mm installation mm material selection patterns mm snow removal mm traffic mm typical details piers and pilasters portland cement/lime mortar prefabricated brick masonry mm introduction mm thin brick pressure-equalized rain screen wall 6 7, 18 series, 36a 43, 43b, 43c, 43d, 43g 30 14-14b 14 14 14 14a, 14b 14a 14, 30 14a, 14b 14 14 3b 8a 40 28c 27 - r- mm rain penetration (see moisture control) rain screen wall reinforced brick masonry mm beams mm curtain and panel walls mm flexural design mm floors mm girders mm high-lift grouted mm history mm hollow brick masonry mm inspection mm lintel design mm materials mm mortar and grout mm specifications mm workmanship repointing rigid pavements rumford fireplaces r-values 27 17b 17l 17b 14b 17m 17a 17 26, 41 17a 17b 17a 17a 11 series 17a 7f 14 19c 4, 4b - s- mm salvaged brick 15 sealers (see water mm repellents) sealants section properties selection of brick serpentine walls shelf angles typical details mm corrosion resistance single-wythe bearing walls sills 36 sizes of brick slip/skid resistance soffits solar energy mm (see passive solar systems) sound barriers mm (see noise barrier walls) sound insulation spalling specifications, general series aci 530.1/asce 6/tms 602 3 mm cold weather construction mm mortars stains, removal steel studs steps and ramps sustainable development 18a, 28 3b 9b 29a 7, 28b 7a 26 9b, 10b 14 36 5a 7f 11 1 8a, 11e 20 28b 29 29 - t- mm terminology terraces testing of brick and mortar allowable mm design stresses mm quality control thermal expansion of walls thermal storage capacity thermal storage walls, passive solar heating thermal transmission coefficients thin brick ties and reinforcement mm adjustable mm corrosion resistance mm joint reinforcement mm specifications tolerances tooling tuckpointing (see repointing) 2 29 39 series 3a, 39a 39b 18 series 4a 43 4 28c 44b 7a, 44b 44b 11a 11c 7b 7f - u- mm used brick u-values 15 4, 4b - v- mm veneer construction mm existing construction mm steel studs mm thin brick veneer mm wood studs 28a 28b 28c 28 - w- mm wall ties water penetration (see moisture control) water repellent coatings weep holes winter construction (see cold weather mm construction) workmanship mm reinforced brick masonry mm specifications 44b 6a 7 7b, 21c 17a 11 series next --> catalogs pages"},{"TextID":60045,"ResultID":176277,"Text1":" bia catalog cover next previous back to thumbnail page --> technical notes technical notes which carry the designation rev (revised) have been rewritten to include new technical information and replace any previous issues of that specific technical notes . the designation reissued indicates that the technical notes has been thoroughly reviewed and found to be technically accurate. previous editions dated on or after the bracketed [ ] date are still valid; only minor editorial changes have been made. the reissued date appears in parentheses( ). *numbers with an asterisk have been discontinued and are not included in the technical notes set, but are available from bia by special request for $3.00 each. missing numbers have been discontinued. 1 rev [mar. 1992] all-weather construction 2 rev [jan./feb. 1975] (reissued sept. 1988) glossary of terms relating to brick masonry 3 rev [oct. 1995] overview of building code requirements for masonry structures aci 530/asce 5/tms 402 and specifications for masonry structures aci 530.1/asce6/ tms 602 3a [dec. 1992] brick masonry material properties 3b [may 1993] brick masonry section properties 4 rev [jan. 1982](reissued sept. 1997) heat transmission coefficients of brick masonry walls *4a rev [feb. 1982] (reissued sept. 1988) heat gain through opaque walls 4b rev. [dec. 1992] energy code compliance of brick masonry walls 5a [june 1970] (reissued sept. 1988) sound insulation - clay masonry walls 6 rev [may 1972] (reissued daec. 1985) painting brick masonry 6a [april 1995] colorless coatings for brick masonry 7 rev [feb. 1985](reissued feb. 1998) water resistance of brick masonry - design and detailing, part i 7a rev [march 1985](reissued dec. 1995) water resistance of brick masonry - materials, part ii 7b rev [april 1985](reissued apr. 1998) water resistance of brick masonry - construction and workmanship, part iii 7c [feb. 1965] (reissued sept. 1988) moisture control in brick and tile walls - condensation 7d rev [may 1988] (reissued feb. 1993) moisture resistance of brick masonry walls condensation analysis 7f [feb. 1986] (reissued oct. 1998) moisture resistance of brick masonry - maintenance 8 rev [aug. 1995] mortars for brick masonry 8a rev [sept. 1988] standard specification for portland cement - lime mortar for brick masonry 8b [july/aug. 1976] (reissued sept. 1988) mortar for brick masonry - selection and controls 9 rev [march 1986] manufacturing, classification and selection of brick - manufacturing, part i 9a [june 1989] manufacturing, classification and selection of brick - classification, part ii 9b [jan. 1989] (reissued dec. 1995) manufacturing, classification and selection of brick - selection, part iii 10 rev [jan. 1971] (reissued may 1997) estimating brick masonry 10a rev [june/july 1973] (reissued july 1986) modular brick masonry 10b rev [june 1993] brick sizes and related information 11 rev [dec. 1971] (reissued apr. 1986) guide specifications for brick masonry, part i 11a rev [june 1978] (reissued sept. 1988) guide specifications for brick masonry, part ii 11b rev [feb. 1972] (reissued sept. 1988) guide specifications for brick masonry, part iii 11c rev [july 1972] (reissued may 1998) guide specifications for brick masonry, part iv 11d [aug. 1972] (reissued sept. 1988) guide specifications for brick masonry, part iv continued 11e rev [sept. 1991] guide specifications for brick masonry, part v, mortar and grout 13 [may 1962] (reissued march 1982) ceramic glazed brick facing for exterior walls 14 rev [sept. 1992] brick floors and pavements, design and detailing part 1 14a rev [jan. 1993] brick floors and pavements, materials and installation part ii 14b [nov./dec. 1975] (reissued sept. 1988) brick floors and pavements part iii 15 rev [may 1988] salvaged brick 16 rev [oct. 1974] (reissued oct. 1996) fire resistance 16b [june 1991] (reissued aug. 1991) calculated fire resistance 17 rev [oct. 1996] reinforced brick masonry, introduction 17a rev [aug. 1997) reinforced brick masonry - materials and construction, part ii 17b rev [mar. 1999] reinforced brick masonry beams 17l rev [feb./mar. 1973] (reissued sept. 1988) four-inch rbm curtain and panel walls 17m [july 1968] (reissued sept. 1988) reinforced brick masonry girders - examples 18 rev [jan. 1991] volume changes and effect of movement- part i 18a rev [dec. 1991] design and detailing of movement joints - part ii 19 rev [jan. 1993] residential fireplace design 19a rev [may 1980] (reissued jan. 1988) residential fireplaces, details and construction 19b rev [june 1980] (reissued apr. 1998) residential chimneys, design and construction 19c rev [april 1988] contemporary brick masonry fireplaces 19d [jan. 1983] (reissued june 1987) brick masonry fireplaces, part i, russian-style heaters 19e [1983] (reissued feb. 1998) brick masonry fireplaces, part ii fountain and contemporary style heaters 20 rev ii [nov. 1990] cleaning brick masonry 21 rev [aug. 1998] brick masonry cavity walls introduction 21a rev [feb. 1999] brick masonry cavity walls -selection of materials 21b [jan./feb. 1978] (reissued jan. 1987) brick masonry cavity walls - detailing 21c rev [oct. 1989] brick masonry cavity walls - construction 23 rev [may 1985](reissued feb. 1997) efflorescence, causes and mechanisms- part i 23a rev [june 1985] efflorescence, prevention and control-part ii 24 rev [feb. 1970] (reissued dec. 1986) the contemporary bearing wall *24a rev [may 1970] (reissued may 1985) building code requirements for the contemporary bearing wall *24b rev [july/aug. 1970] (reissued may 1985) design examples of contemporary bearing walls 24c rev [sept./oct. 1970] (reissued may 1988) the contemporary bearing wall - introduction to shear wall design *24d rev [dec. 1970] (reissued dec. 1987) the contemporary bearing wall - example of shear wall design *24e rev [nov. 1970] (reissued may 1987) the contemporary bearing wall - design tables for columns and walls 24f rev [nov./dec. 1974] (reissued sept. 1988) the contemporary bearing wall - construction 24g [dec. 1968] (reissued feb. 1987) the contemporary bearing wall - detailing *24h rev [jan. 1969] (reissued feb. 1987) the contemporary bearing walls - wall types and properties 26 rev [sept. 1994] single wythe bearing walls 27 rev [aug. 1994] brick masonry rain screen walls 28 rev [aug. 1991] anchored brick veneer, wood frame construction 28a [sept./oct. 1978] (reissued sept. 1988) brick veneer, existing construction 28b rev ii [feb. 1987] brick veneer, steel stud panel walls 28c [jan. 1986] (reissued feb. 1990) thin brick veneer - introduction 29 rev [july 1994] brick in landscape architecture - applications 29a rev [nov. 1968] (reissued jan. 1999) brick in landscape architecture - garden walls 29b [apr. 1967] (reissued may 1988) brick in landscape architecture - miscellaneous applications 30 [july 1967] (reissued sept. 1988) bonds and patterns in brickwork 31 rev [jan. 1995] brick masonry arches 31a [oct. 1967] (reissued july 1986) structural design of brick masonry arches 31b rev [nov./dec. 1981] (reissued may 1987) structural steel lintels 31c rev [feb. 1971] (reissued aug. 1986) structural design of semicircular brick masonry arches 36 rev [july/aug. 1981] (reissued jan. 1988) brick masonry details, sills and soffits 36a rev [sept./oct. 1981] (reissued jan. 1988) brick masonry details, caps and copings, corbels and racking 39 rev [jan. 1987] testing for engineered brick masonry - brick and mortar 39a [july/aug. 1975] (reissued dec. 1987) testing for engineered brick masonry - determination of allowable design stresses 39b rev [march 1988] testing for engineered brick masonry - quality control 40 [oct./nov. 1973] (reissued jan. 1987) prefabricated brick masonry - introduction 41 rev [feb. 1996] hollow brick masonry 42 rev [nov. 1991] empirical design of brick masonry 43 rev [may/june 1981] passive solar heating with brick masonry, part i - introduction *43b [sept./oct. 1979] (reissued jan. 1988) brick passive solar heating systems, part iii - performance calculations 43c [march 1980] passive solar cooling with brick masonry, part i - introduction 43d [sept./oct. 1980] (reissued sept. 1988) brick passive solar heating systems, part iv - material properties 43g [mar./apr. 1981] (reissued sept. 1986) brick passive solar heating systems, part vii - details and construction 44 [apr. 1986] anchor bolts for brick masonry 44a [may 1986](reissued aug. 1997) fasteners for brick masonry 44b [mar. 1987] (reissued sept. 1988) wall ties for brick masonry 45 [feb. 1991] brick masonry noise barrier walls - introduction 45a [apr. 1992] brick masonry noise barrier walls - structural design next --> catalogs pages"},{"TextID":60046,"ResultID":176278,"Text1":" bia catalog page 8 builder next previous back to thumbnail page --> - a - hot and cold weather masonry construction comprehensive introduction to, and explanation of, hot and cold weather construction techniques. (1999) $2.50 each, $2.00 each for 10 or more #606 - b - pocket guide to brick construction (ninth edition) handy pocket-sized (4ΓÇ¥ x 7ΓÇ¥) compilation of technical data on brick including more than 100 illustrations and 50 charts and tables. topics are referenced to bia technical notes and astm specifications. (1990) $5.00 each, $2.50 each 10 or more. #508 - c - brick masonry estimator a slide rule for estimating the amount of brick and mortar needed, for either modular or non-modular brick. (1972) $1.50 each, $1.00 each for 10 or more #711 the real thing fireplace plan (not shown) plans and template to construct ΓÇ£real thingΓÇ¥ fireplaces. designed for builders to use to compete with pre-fab fireplaces. (1991) $2.00 each, $1.00 for 10 or more #709 brick builder notes an informative, semi-technical series designed for the builder. explains in detail various aspects of brick construction. illustrated with tables and drawings. 4 pages each. $1.00 each, $.25 each for 100 or more (same item number) how big is a brick #201 estimating brick masonry #203 exterior brick paving #207 loadbearing brick houses #208 brick walls for housing #209 brick flooring #210 energy efficient fireplaces #211 cavity walls #212 veneering new construction #213 veneering existing construction #214 brick amenities #215 brick for passive solar heating #216 cold weather construction #217 residential fireplaces #218 brick in landscape architecture #219 residential details #220 building sales with brick fences #221 entranceways #222 sculpture #223 brick shapes #224 videos (not shown) flexible brick paving (an installation guide) vhs format, color, 25 minutes complete installation procedures for flexible brick paving. includes preparation of site, laying of base materials, choice of edge restraints and the laying and finishing of brick pavers. (1995) $15.00 each, $10.00 each for 10 or more #965 (english) | #968 (spanish) grout and methods of grouting masonry vhs format, color, 20 minutes covers why and how grout is specified and used. types of grout, use requirements, methods of placement, construction procedures are given. includes placing grout in both clay and concrete masonry. (1989) $15.00 each, $10.00 each for 10 or more #956 building a classic brick driveway vhs format, color, 32 minutes developed in cooperation with hometime, this video shows homeowners and paving contractors how a brick driveway is planned and constructed. it includes professional tips and techniques to produce an attractive, low maintenance driveway. (1998) $15.00 each, $10.00 each for 10 or more #967 residential brick construction vhs format, color, 30 minutes shows the proper construction techniques and the reasons behind them for the bricklaying used in home building. includes segments on mortar, wall types and moisture resistance, flashing and weep holes, wall ties, expansion joints, arch design and detailing and the support of brick. (1994) next --> catalogs pages"},{"TextID":60047,"ResultID":176279,"Text1":" bia catalog page 9 homeowner next previous back to thumbnail page --> - a - new home buyersΓÇÖ guide to brick a full-color booklet showing the home builder, buyer or owner ways to enhance the beauty of the home through the use of brick outside, inside and around the house. 16 pages. (1991) $1.50 each, $1.00 each for 100 or more #841 - b - the beauty of brick a 12-page color brochure that talks about the qualities of brick as a building material and the advantages of owning a brick home. (1999) $1.00 each, $.50 each for 100 or more #806 - c - seven easy steps to installing your own walkway, driveway or patio without mortar or concrete this full-color brochure describes in seven steps the proper procedures for installing a flexible (mortarless) brick pavement. includes material quantities and equipment needs with easy-to-follow directions. no. 10 size fold-out brochure. (1998) $1.00 each, $0.50 for 100 or more copies #886 - d - fireplaces & chimneys four-page, full color brochure for builders and consumers showing outstanding examples of brick fireplaces in a variety of styles and sizes. (1990) $1.00 each, $.50 each for 100 or more #818 - e - 16 outdoor projects step-by-step directions for building home projects. a patio, barbecue, paving, steps, screens and planters are several of the projects shown. (1974) $1.50 each, $.75 each for 100 or more #507 - f - build with the sun live with the sun provides concise explanation, in laymanΓÇÖs language, of passive solar principles and operation. no. 10 envelope stuffer. (1979) $.50 each, $.25 each for 100 or more #503v - g - warm beauty eight-page, full-color publication for builders and consumers, which provides ideas for fireplaces and chimney design. (1990) $1.25 each, $.80 each for 100 or more #820 barbeque plans plans include step-by-step instructions for constructing a concrete base and laying brick. lists tools needed and how to use them. explains and lists quantity and type of materials needed for making the concrete and the mortar. (1973) $.50 each, $.25 each for 100 or more small brick barbeque #521 large brick barbeque #522 next --> catalogs pages"},{"TextID":60048,"ResultID":176280,"Text1":" bia catalog cover education next previous back to thumbnail page --> catalogs pages"},{"TextID":60049,"ResultID":176281,"Text1":" bia catalog page 11 education next previous back to thumbnail page --> - a - playing in the big leagues as a brick mason a four-color career brochure. includes photos showing bricklayers at work on typical residential and commercial projects. text outlines the benefits and advantages of a career as a mason and advises how to get started. (1993) $1.00 each, $.50 each for 10 or more #707 - b - building your business designed to help the smaller (residential) mason contractor, building your business addresses the problems and issues that face their businesses including record keeping, cost control, managing employees, company growth, taxes and supplier relationships. based upon a series of articles that appeared in the magazine of masonry construction. (1994) $2.50 each, $1.50 each for 10 or more #833 - c - career poster 17ΓÇ¥ x 22ΓÇ¥ eye-catching, four-color poster designed to raise visibility of bricklaying as a career opportunity. ideal for guidance counselorΓÇÖs office or vocational education bulletin board. $1.00 each, $.50 each for 10 or more #718 - d - plan reading for brickmasons presents typical plans used by bricklayers and discusses their content, technical aspects and methods of incorporating their instructions into on-the-job performance. 70 pages. (1968) $5.00 each, $2.00 each for 10 or more #705 - e - fireplace details poster illustrates simple rules of thumb that will produce a safe, efficient fireplace that will draw properly. 17ΓÇ¥ x 22ΓÇ¥ two-color poster intended for classroom use. $.50 each, $.30 each for 50 or more #717 - f - bricklaying vocational training trade projects a package of learning projects that the students can construct themselves. 35 projects. (1989) $5.00 each, $2.00 each for 10 or more #703 bricklaying-brick and block masonry textbook designed specifically for secondary and post-secondary bricklaying programs. includes latest methods and techniques for teaching students to lay brick and block. (1988) $15.00 each, $10.00 each for 10 or more #870 studentΓÇÖs study guide/workbook tests the studentΓÇÖs comprehension of the material presented in the textbook. (1989) $5.00 each, $2.50 for 10 or more #871 instructorΓÇÖs guide included free with order of ten or more textbooks. (1989) $5.00 each #872 package one an introduction of our masonry curriculum for school administrators and instructors. includes one copy of each of the following: bricklaying - brick and block masonry (#870) studentΓÇÖs study guide/workbook (#871) instructorΓÇÖs guide (#872) recommended high school curriculum $12.50 for each package package two designed for the masonry instructor to enhance his or her curriculum. this package includes one of each of the following: bricklaying vocational trade projects (#703) plan reading for brickmasons (#705) fireplace details poster (#717) 4 videos: basic brick masonry skills (#959) bricklaying tools - choosing the right ones for you (#958) brick veneering (#950) residential brick construction (#964) $40.00 for each package videos (not shown) basic brick masonry skills vhs format, color, 30 minutes a comprehensive description of the basics of laying brick. includes defining masonry terms with examples, a description of the common trowels used in bricklaying and their use, as well as sections on mixing mortar by hand and machine, laying to the line and picking, spreading and furrowing mortar. (1992) $15.00 each, $10.00 for 10 or more #959 brick veneering vhs format, color, 20 minutes shows step-by step techniques of usual bricklaying procedures involved in veneering a single-family house. includes coursing layout, establishing corner leads, flashing, weep holes, facia, window and door openings, as well as proper clean-up procedures. (1985) $15.00 each, $10.00 for 10 or more #950 bricklaying ΓÇô master the craft and make your mark vhs format, color, 12 minutes recruiting video designed to give the young person considering a masonry career an idea of what life is like on the job. information on how to get into bricklaying, and on advancement opportunities. (1988) $15.00 each, $10.00 for 10 or more #957 bricklaying tools ΓÇô choosing the right ones for you vhs format, color, 20 minutes instructional video that gives the young mason, as well as the experienced mason, solid information on the selection, use, and care of basic bricklaying tools. (1989) $15.00 each, $10.00 for 10 or more #958 the making of brick-video vhs format, color, 22 minutes designed for a general audience including architects, builders and community groups, this presentation gives a brief historical introduction to the manufacture of brick and describes the modern methods of manufacture of brick step-by-step from the mining of clays to the finished product. (1995) $15.00 each, $10.00 for 10 or more #963 next --> catalogs pages"},{"TextID":60050,"ResultID":176282,"Text1":" bia catalog cover the industry previous back to thumbnail page --> - a - brick news a monthly news magazine covering items of interest to the brick industry. annual subscription rate: $30/year ($40/year outside u.s.). back issues $1 each, subject to availability. - b - brick manufacturing report a comprehensive report on practices in the brick industry including data on corporate structure, employment, manufacturing techniques, fuels, kiln types, transportation and computer use. based on a 1994 survey. $25.00 each #587 - c - u.s. brick sales and marketing report annual statistical report on the brick industry. includes data on shipments, production, capacity, types and quality of units produced and state-by-state destination of shipments reports. includes multi-year brick industry trend section. 22 pages. $25.00 (back copies available) #586 - d - bia membership directory a convenient geographical and alphabetical listing of all bia member brick manufacturers, distributors and suppliers to the industry. a listing of each member s products and services is also included. revised annually. $10.00 each #585 brick industry shipping guide (not shown) pocket-sized guide to shipping brick, including a discussion of responsibilities of the various parties, methods of containing the brick load and diagrams on how to tie down a load of brick. developed to promote highway safety by the bia-nabd liaison committee. (1989) $1.00 each #875 paving training seminar (not shown) describes selling techniques and technical information needed by salespeople for the proper promotion of clay brick pavers. broken into two parts, this video covers the size of the paving market, techniques for selling pavers and an in-depth look at the design and specification of brick pavements. (1998) video $30.00 #966 slides $100.00, part i ΓÇô selling techniques #925 $100.00, part ii ΓÇô technical information brick industry association 11490 commerce park drive reston, virginia 20191 (phone) 703-620-0010 (fax) 703-620-3928 catalogs pages"},{"TextID":60051,"ResultID":176283,"Text1":" \r\n \r\n \r\n Technical Notes 1 - All-Weather Construction \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 1 - All-Weather Construction \r\n \r\n March 1992 \r\n Abstract: This Technical Notes \r\n describes how extremes of cold and hot weather can influence brick \r\n masonry construction. Information on weather prediction necessary for \r\n construction planning is provided. Cold and hot weather are defined, and \r\n the reaction of clay brick masonry materials to these extreme conditions \r\n is described. Recommendations are provided for continuing construction \r\n in these severe exposure conditions. \r\n Key Words: absorption, brick, climatology, \r\n cold weather, evaporation, freezing, grout, hot weather, meteorology, \r\n mortar. \r\n INTRODUCTION \r\n Periods of cold and hot weather have a \r\n tremendous impact on the construction industry and the national economy. \r\n This is reflected in several ways. Cold weather can cause temporary delays \r\n and work stoppages on construction sites. Productivity and the quality \r\n of construction on job sites may be reduced if workers become too attentive \r\n to personal comfort during extremes in temperature. Proper material protection \r\n and handling can increase construction costs, although contractors and \r\n owners alike may benefit in the long run. Completed work not properly \r\n constructed during, or protected from, cold and sometimes hot weather \r\n may have to be removed and rebuilt. Investigations to evaluate the performance \r\n of suspect construction are an added expense which may be necessary. Owners \r\n and businessmen can suffer from lost rentals and business revenue when \r\n buildings are not completed on time. Furthermore, the seasonal influence \r\n on construction results in idle production facilities, large material \r\n inventories and high rates of unemployment during the winter months. Stopping \r\n work on a project due to extremes in weather conditions is not economically \r\n desirable. \r\n The purpose of this Technical Notes \r\n is to describe how masonry materials react to cold and hot weather \r\n conditions. It also describes provisions which should be made to ensure \r\n that construction does not decrease in quality and can continue without \r\n interruption. Although \"normal\", \"cold\", and \"hot\" are relative terms, \r\n normal, used in this Technical Notes, will be considered to be \r\n any temperature between 40 ° F and 90 ° F (4 ° C \r\n and 32 ° C). Cold will be considered to be any temperature below 40 ° F (4 ° C), and hot any temperature above 90 ° F (32 ° C). \r\n WEATHER PREDICTION \r\n To successfully build during periods of \r\n abnormal weather conditions, designers and contractors must have advance \r\n knowledge of local meteorological conditions as well as knowledge of historic \r\n climatological information for a given area. Meteorology may be \r\n defined as current state atmospheric conditions, while climatology \r\n may be defined as the historic record of the averages and extremes \r\n of weather representative of an area. When in the planning stages for \r\n a project, designers are usually concerned with climatological data such \r\n as the average and extreme daytime and nighttime temperatures or average \r\n wind velocity for use in designing mechanical or structural systems. Contractors, \r\n however, are more concerned with meteorological conditions during construction, \r\n such as hourly temperatures and mean daily temperature, as well as the \r\n predicted temperatures and wind velocities for the next few days. Mean \r\n daily temperature is determined by adding together the maximum temperature \r\n for each day (24 hours, midnight to midnight) and the minimum temperature \r\n for the same day and dividing by two. Ambient temperature as used in this \r\n Technical Note s is the outdoor temperature at the time considered. \r\n Meteorological information can be obtained \r\n from the National Weather Service, a branch of the National Oceanographic \r\n and Atmospheric Administration (NOAA). The National Weather Service has \r\n information centers located at major airports in cities throughout the \r\n country. These centers provide current weather information and regularly \r\n scheduled weather forecasts for the region under consideration. Climatological \r\n information can be obtained from the National Climatic Data Center, also \r\n a branch of NOAA. The National Climatic Data Center usually provides climatic \r\n information in the form of maps as shown in Figure 1. These maps contain \r\n daily, monthly and annual data for a region and may be obtained for a \r\n nominal fee by contacting the Center [5]. \r\n \r\n \r\n Examples of Climatic Data Available \r\n \r\n FIG. 1a \r\n \r\n Examples of Climatic Data Available \r\n FIG. 1b \r\n \r\n EFFECTS OF COLD WEATHER \r\n Cold weather during masonry construction \r\n affects the materials and labor used. Successful construction will consider \r\n both in the planning, scheduling and set up of the masonry work. In addition \r\n to anticipating the specific weather conditions, the contractor must determine \r\n what the probable effects of the weather will be on the materials and \r\n the workers, how to protect materials and workers, how to store the materials, \r\n and what procedures should be used to meet the requirements specified \r\n in the construction documents. \r\n In the United States, all model building \r\n codes have requirements relating to the construction of masonry during \r\n cold weather. While not identical, each of the building codes have similar \r\n general requirements regarding material protection, heating of materials, \r\n use of frozen materials and protection of completed work. \r\n Masonry Units \r\n Masonry units are the material in masonry \r\n construction least affected by below-normal temperatures. The physical \r\n properties of masonry units are essentially the same in cold weather except \r\n that a cold unit will have a slightly smaller volume than one at normal \r\n temperatures. However, the absorption characteristics of the masonry unit \r\n and its temperature contribute to the rate of freezing of masonry during \r\n cold weather. Under normal conditions of construction, using masonry units \r\n with initial rates of absorption (IRA) less than or equal to 30 g/min/30 \r\n in. 2 (30 g/min/194 cm 2 ) at the time of laying improves the bond between the brick and mortar \r\n which leads to increased moisture resistance of the wall assembly. In \r\n cold weather, brick having an initial rate of absorption of 25 g to 30 \r\n g/min/30 in. 2 (25 g to 30 g/min/194 cm 2 ) may be desirable. \r\n Using brick with a higher IRA reduces \r\n the risk of freezing by more rapidly absorbing water from the mortar or \r\n grout. If a brick with a low IRA is used, then the water content of the \r\n mortar should be the minimum necessary for workability. If suction or \r\n other measures reduce the water content to less than 6 percent of the \r\n total mortar volume prior to freezing, the mortar will not experience \r\n disruptive expansive forces upon freezing. Further, significant reductions \r\n in transverse or compressive strength of the masonry assemblage will not \r\n occur. \r\n The temperature of the masonry unit also \r\n contributes to the rate of freezing of masonry. A cold unit will more \r\n rapidly withdraw the heat of hydration from the mortar and thus increase \r\n the rate of freezing. Masonry units preheated prior to laying minimize \r\n cold weather effects on the hydration process of the mortar by maintaining \r\n the heat within the mortar. Masonry units should be heated to a temperature \r\n of approximately 40 0 F (4 ° C) prior to laying when ambient temperatures are below \r\n 20 ° F ( -7 ° C). Heating units to temperatures above 40 ° F (4 ° C) is seldom necessary. It may be advantageous to heat \r\n units even when ambient temperatures are above 20 ° F \r\n ( -7 ° C). Preheated units will exhibit the same absorption characteristics as \r\n units laid during normal weather conditions. \r\n Units which are frozen should be thawed \r\n and dried completely before use. Frozen masonry should not be built upon. \r\n Completed masonry which is frozen may be moistened after thawing to reactivate \r\n the hydration process and continue to develop strength [7,10]. \r\n Mortar \r\n Mortar mixed with cold materials have \r\n properties quite different from those at normal temperatures. Cold weather \r\n retards the hydration of the cement in the mortar mix. Mortar mixed during \r\n cold weather often has lower water content, increased air content, and \r\n reduced early strength compared with those mixed during normal temperatures. \r\n For these reasons, mortar is often mixed with heated materials to produce \r\n performance characteristics associated with mortar mixed at normal temperatures, \r\n or with admixtures which may improve the early strength and plasticity \r\n of the mix. Water, sand, or both may be heated for use in mortar. Heating \r\n prepackaged materials such as portland cement and hydrated lime can be \r\n difficult. Specific recommendations are a function of temperature and \r\n are found in later sections of this Technical Notes . \r\n Mortar materials and the proportion of \r\n ingredients, within the permissible ranges, can also be modified for cold \r\n weather conditions. A higher sand content provides a stiffer mortar which \r\n will better support the weight of subsequently laid masonry. A lower lime \r\n content will allow the water content of the mortar to decrease more rapidly, \r\n just as a brick with a higher IRA. High-early-strength (Type III) portland \r\n cement may be used to increase the rate of early strength gain. Admixtures, \r\n although not recommended, may be used to accelerate the rate of set. \r\n Freezing of the mortar should be avoided \r\n in all cases. Mortar which freezes is not as weather-resistant or as watertight \r\n as mortar that has not been frozen [6]. Furthermore, significant reductions \r\n in compressive and bond strength may occur. Mortar having a water content \r\n over 6 to 8 percent of the total volume will experience disruptive expansive \r\n forces if frozen due to the increase in volume of water when it is converted \r\n to ice. Thus, the bond between the unit and the mortar may be damaged \r\n or destroyed. Mortar in newly completed masonry should be protected from \r\n freezing. Specific requirements are found in Table 1. \r\n \r\n \r\n \r\n Note: Construction requirements, \r\n while work is in progress, are based on ambient temperatures. \r\n Protection requirements, after masonry is placed, are based on mean \r\n daily temperatures . \r\n Grout \r\n Grout, although made from similar materials, \r\n should not be confused with concrete. Typically smaller aggregate is used \r\n in grout for easier placement and consolidation. Concrete uses a minimum \r\n amount of water, whereas the water-cement ratio for grout is high, because \r\n grout is placed in absorptive molds of brick. Furthermore, high water \r\n content is necessary in grout for ease of flow, but it greatly increases \r\n the amount of volumetric expansion which can occur upon freezing. Thus \r\n grout, like mortar, should be mixed with heated materials to prevent the \r\n damaging effects of freezing. High-early-strength (Type III) portland \r\n cement may be used to increase the rate of early strength gain of the \r\n grout. Admixtures may also be used, but protection of the grouted masonry \r\n is still required. \r\n MATERIALS IN COLD WEATHER CONSTRUCTION \r\n Protection \r\n Although the temperature of the materials \r\n used in masonry construction is one of the factors which should be adjusted \r\n for cold weather construction, adjustments in construction practices may \r\n also be necessary. ACI 530.1/ ASCE 6/TMS 602 , Specifications for Masonry \r\n Structures , addresses material heating as well as requirements for \r\n protection of masonry constructed in cold weather [3]. Protection is one \r\n of the most necessary adjustments to make in construction practices. Construction \r\n materials should be carefully covered to remain dry. ACI 530.1/ASCE 6/TMS \r\n 602 requires protection such as the use of insulating blankets and forced \r\n air heaters. However, protection may also include special light-weight, \r\n warm work clothes worn by laborers or standard construction equipment \r\n adapted to unique cold weather protection uses. This approach is common \r\n in northern Europe where cold weather may last up to six months. \r\n All masonry materials should be kept dry \r\n and free from ice and snow by covering with tarpaulins or clear polyethylene \r\n sheets. Sand and masonry units should be covered and stored on raised \r\n platforms to avoid contact with the ground. Careless material storage \r\n increases the cost of laying masonry because removal of ice and snow and \r\n thawing of masonry units are necessary before construction may begin. \r\n Partially completed or exposed walls should be covered at the end of each \r\n days work with a weighted tarpaulin which extends a minimum of 2 ft (1 \r\n m) down each side of the wall to prevent contamination by water, ice, \r\n or snow (Fig. 2). \r\n \r\n \r\n Brick Noise Barrier Wall with Cold Weather Protection \r\n \r\n FIG. 2 \r\n \r\n Workers should also be protected from \r\n the cold weather to maintain their productivity. Recommended protection \r\n will vary with weather conditions from warmer clothes to complete enclosure \r\n of the work site. Masons may work in the open with forced air heaters \r\n as a heat source at mean daily temperatures no less than 20 \r\n 0 F ( -7 ° C). Heated enclosures should be provided at temperatures below 20 0 F ( -7 ° C). By providing wind breaks or temporary shelters, workers \r\n can remain productive at outside temperatures well below freezing. If \r\n a shelter or enclosure is used both the workers and the materials benefit \r\n from a warmer environment. The masons comfort and productivity are improved, \r\n and the materials need less preparation prior to laying (i.e. heating). \r\n There are many types of equipment which \r\n are available as sources of heat for cold weather construction. The type \r\n selected will depend upon availability of equipment, fuel source and economics, \r\n size of project and severity of exposure. Salamanders are widely used \r\n as a source of heat on scaffolds. Commercial electric blankets may be \r\n used to cover walls during the curing period. When complete enclosure \r\n of the work area is provided, space heaters are recommended. The enclosure \r\n should allow circulation of warm air on both sides of the masonry wall. \r\n Contractors have used several different \r\n methods for complete and partial enclosures of buildings. Large tents, \r\n temporary wood structures covered with clear plastic, and shelters built \r\n of prefabricated panels covered with clear plastic sheets are examples \r\n of complete enclosures (Figs. 3 and 4). Partial enclosures often consist \r\n of enclosed swinging scaffolds which may be moved from floor to floor \r\n when necessary (Figs. 5 and 6). \r\n \r\n \r\n Enclosure in Place \r\n FIG. 3 \r\n \r\n \r\n Interior of Enclosure \r\n FIG. 4 \r\n \r\n \r\n Scaffold Enclosure \r\n \r\n FIG. 5 \r\n \r\n \r\n Tubular Scaffold Enclosure \r\n \r\n FIG. 6 \r\n \r\n Mortar and Grout Admixtures \r\n Accelerators. Accelerators are \r\n admixtures used to speed the setting time of mortar and grout. By increasing \r\n the rate of hydration of the cement, accelerators increase the rate of \r\n early strength gain. The most common accelerators are inorganic salts \r\n such as calcium chloride, calcium nitrate, soluble carbonates and some \r\n organic compounds. Any accelerator should be evaluated for deleterious \r\n effects on masonry strength and materials. Admixtures must not contribute \r\n to staining or efflorescence or cause corrosion of metal accessories used \r\n in construction of the masonry. Indiscriminate use of accelerators can \r\n adversely affect the in-place performance of the completed masonry. Accelerators \r\n alone are not suggested treatment for cold weather construction problems. \r\n Mortar and grout containing accelerators must still be protected from \r\n freezing. \r\n Calcium chloride, while highly effective \r\n as an accelerator and widely used in the past, causes corrosion of metals \r\n used in masonry due to the chloride content. For this reason, chlorides \r\n should not be used in mortar or grout in contact with metals (i.e. ties, \r\n anchors and reinforcement). Also, the incidence of efflorescence may be \r\n increased when excessive salts are present. If a chloride accelerator \r\n is used, it is recommended that it be limited to amounts not to exceed \r\n two percent of the weight of Portland used in the mortar mix or one percent \r\n of the weight of masonry cement. \r\n Calcium nitrite and calcium nitrate are \r\n inorganic nonchloride compounds also used as accelerators. These compounds \r\n require higher dosage by weight and are more costly than calcium chloride, \r\n but will not corrode metals or contribute to efflorescence. \r\n Antifreeze. An antifreeze lowers \r\n the freezing point of the substance to which it is added. Most commercial \r\n mortar \"antifreeze\" admixtures do not do this, but are instead accelerators. \r\n However, some true antifreeze admixtures are available. These admixtures \r\n are alcohols or combinations of salts. If used in the quantities required \r\n to be effective, significant reductions in mortar compressive and bond \r\n strengths usually result. For this reason, use of antifreeze compounds \r\n is not recommended. \r\n Heating \r\n In freezing weather, ice may be present \r\n in mixing water and moisture in the sand may turn to ice. Ice in the mixing \r\n water must be melted before it can be added to the mixer. Sand which contains \r\n frozen particles or frost cannot be used. It must first be thawed by heating \r\n in an appropriate manner. Further heating may also be beneficial. \r\n As \r\n stated earlier, both water and sand used in the mortar and grout may be \r\n heated to provide proper temperatures for construction. Water is the \r\n easiest method to heat. It is also the best material to heat because of \r\n its high specific heat. Sand may also be heated. This may be done by placing \r\n an electric heating pad on top of the sandpile and covering with a weather-resistant \r\n tarpaulin (Fig. 7). The electric pad can safely heat the sand overnight \r\n without exceeding a temperature of 100┬░F (38 ┬░C). A more labor intensive \r\n method of heating the sand is to place the sand over a heated pipe or \r\n to pile the sand around a horizontal metal culvert or smoke stack section, \r\n in which a slow fire is built (Fig. 8). Other methods for heating sand \r\n involve the use of a steam lance or other steam heaters. Careful attention \r\n to the fire or other heat source and the sand is required. Sand should \r\n be heated slowly to avoid scorching. \r\n In \r\n an alternate approach, an electric rod can be used to heat mixing water \r\n and sand simultaneously. The electric heating rod is placed in a drum \r\n of water in the center of a sandpile. The rod heats the water over several \r\n hours. The sand surrounding the drum slowly absorbs heat from the drum \r\n and insulates the drum from further heat losses. \r\n Materials \r\n heated for use in mortar should have a minimum temperature of 70┬░F (21┬░C) \r\n and a maximum temperature of 160┬░F (71┬░C) to avoid flash set. Scorched \r\n sand (with a reddish cast) must not be used in mortar. \r\n In \r\n cold weather, mortar should be mixed in smaller amounts so it can be used \r\n before it cools. In any case, mortar must be used within 2 1/2 hours from \r\n the time of initial mixing. After combining all ingredients, the temperature \r\n of the mortar should be between 40┬░F and 120┬░F (4 ┬░C to 49┬░C). Mortar \r\n temperatures over 120┬░F (49┬░C) may lead to flash set, resulting in lower \r\n compressive strength and reduced bond strength. Once a mortar temperature \r\n is selected, steps should be taken to mix successive batches to the same \r\n temperature. Mortar may be placed on electrically heated mortar boards \r\n to help maintain proper temperature. However, use caution to avoid excessive \r\n drying of the mortar with the heater. \r\n Grout \r\n should be placed at a minimum temperature of 40┬░F (4┬░C) and a maximum \r\n temperature of 120┬░F (49┬░C) and a maximum temperature of 120┬░F (49┬░C) \r\n within 1.5 hours of mixing. As with mortar, water or aggregate may be \r\n heated to produce a heated mixture. Water temperature should not exceed \r\n 160┬░F (71┬░C). The sand may be heated following recommendations for heating \r\n sand used in mortar. Masonry receiving grout should have a minimum temperature \r\n of 40┬░F (4┬░C). \r\n \r\n Heating of a Sandpile with an Electric Blanket \r\n FIG. 7 \r\n \r\n \r\n Heating \r\n of a Sandpile with a Metal Pipe \r\n FIG. 8 \r\n COLD \r\n WEATHER CONSTRUCTION RECOMMENDATIONS \r\n Special \r\n Precautions \r\n There are two reasons why masonry should never be placed on a snow or \r\n ice-covered base or bed. There is danger of movement when the base thaws, \r\n and bond cannot be developed between the mortar bed and frozen supporting \r\n surfaces. \r\n If \r\n the walls are properly covered when work is halted, ice or snow removal \r\n from walls should not be necessary. However, in the event that the covering \r\n is displaced, the top course may be thawed with steam or a portable blow-torch, \r\n carefully applied. The heat should be sustained long enough to thoroughly \r\n dry out the masonry. If \r\n portions of the masonry are frozen or damaged, defective parts should \r\n be replaced before progressing with new work. \r\n General \r\n Requirements—Cold Weather \r\n The \r\n following items are suggested in addition to the construction and protection \r\n requirements for cold weather masonry construction found in Table 1. These \r\n items can be incorporated in the specifications of the project where applicable. \r\n \r\n 1. \r\n Protect masonry units, cementitious materials and sand so that they are \r\n not contaminated by rain, snow or ground water. \r\n \r\n 2. \r\n Cover tops of masonry at all times when work is not in progress. Cover \r\n shall extend a minimum of 2 ft (1 m) down the masonry, and shall be securely \r\n held in place. \r\n \r\n 3. \r\n Units with higher initial rates of absorption (up to 40 g/min/30 in. 2 \r\n (40 g/min/194 cm 2 )) may be used to resist mortar freezing. However, \r\n units with suctions in excess of 30 g/min/30 in. 2 (30 g/min/194 cm 2 \r\n ) shall be sprinkled, but not saturated, with heated water just prior \r\n to laying. Water temperature shall be above 70┬░F (21┬░C) when units are \r\n above 32┬░F (0 ┬░C). If units are 32┬░F (0┬░C) or below, water temperature \r\n shall be above 120┬░F (49┬░C). \r\n \r\n 4. Use a mortar with a higher sand content and a lower water retention, \r\n especially with brick units having a low IRA. If Type III portland cement \r\n is used, the protection period listed in Table 1 may be reduced from 48 \r\n to 24 hours. \r\n \r\n 5. Heat sand and water used in mortar and grout mixtures to a minimum \r\n temperature of 70┬░F (21┬░C) and a maximum temperature of 160┬░F (71┬░C). \r\n Keep mortar temperature less than 120┬░F (49┬░C) to avoid flash set. \r\n \r\n 6. Maintain temperature of masonry units above 20┬░F (-7┬░C) when laid. \r\n \r\n 7. \r\n Place grout at a minimum temperature of 40┬░F (4┬░C) and a maximum temperature \r\n of 120┬░F (49┬░C). Maintain masonry receiving grout above 40┬░F (4┬░C). Maintain \r\n grouted masonry above 32┬░F (0┬░C) for 48 hours following placement of grout. \r\n EFFECTS \r\n OF HOT WEATHER \r\n Periods of hot weather may also adversely affect the construction of masonry. \r\n The contractor must take measures to ensure that the quality of masonry \r\n construction does not suffer from high temperatures. While hot weather \r\n has been defined to be temperatures above 90┬░F (32┬░C), temperature, wind \r\n speed, relative humidity and solar radiation all influence the absorption \r\n of masonry units, the rate of set, and the drying rate of mortar. The \r\n primary concern in controlling these properties in hot weather is evaporation \r\n of water from the mortar. If sufficient water is not present, bond between \r\n the brick and mortar will be sacrificed. \r\n \r\n The \r\n effects of high temperature and high humidity are not as damaging to the \r\n performance of the masonry as are low temperatures and low humidity. The \r\n increased rate of hydration of the cement and favorable curing conditions \r\n in hot, humid weather will help develop masonry strength if sufficient \r\n water is present at the time of construction. \r\n Temperature \r\n of the materials may be the easiest factor to adjust to produce performance \r\n characteristics associated with construction at normal temperatures. \r\n Adjustments in construction practices further aid the construction of \r\n quality masonry in hot weather conditions. ACI 530.1/ASCE 6/TMS 602 specifies \r\n construction methods to produce quality masonry in hot weather conditions. \r\n Masonry \r\n Units \r\n Masonry units are the material in masonry construction least affected \r\n by hot weather. However, the interaction between the masonry units and \r\n the mortar or grout is critical. Warmer units will absorb more water from \r\n the mortar. In hot weather conditions this is usually not a problem unless \r\n high suction brick are used (IRA over 30 g/min/30 in. 2 (30 g/min/194 \r\n cm 2 )). If high suction brick are used, they should be properly wetted \r\n prior to laying. Wetting may take place immediately before laying the \r\n units, but the preferred method is to wet the whole pallet 3 to 24 hours \r\n before use. The brick must be surface dry at the time of laying and should \r\n have an IRA less than 30 g/min/30 in. 2 (30 g/min/194 cm 2 ). Lower bond \r\n strength results if not enough water is present in the mortar when the \r\n units are laid. Thus, lower absorption units may be desirable because \r\n they allow more complete hydration of the mortar. \r\n Mortar \r\n Mortar in hot weather will tend to lose its plasticity rapidly due to \r\n evaporation of the water from the mix and the increased rate of hydration \r\n of the cement. The use of admixtures to increase plasticity is not recommended \r\n unless their full effect on the mortar is known. Mortar with a high lime \r\n content and high water retention should be used. Retempering of the mortar \r\n should be permitted. Mortar mixed at high temperatures often has higher \r\n water content, lower air content, and a shorter board life than those \r\n mixed at normal temperatures. Temperature of the mortar should be maintained \r\n between 70 ┬░F and 120┬░F (21┬░C and 49┬░C). Temperatures above 120┬░F (49┬░C) \r\n may cause flash set of the cement. Cold water may be used to help control \r\n the temperature of the mortar. Ice is highly effective in reducing the \r\n temperature of the mix water. When used, ice should be completely melted \r\n before combining the water with any other ingredients. In any case, mortar \r\n should be used within two hours of initial mixing. \r\n Grout \r\n Grout reacts to hot weather in a manner similar to mortar. Water more \r\n easily evaporates and thereby reduces the water-cement ratio. Grout requires \r\n a high slump, at least 8 in. (203 mm), for placement into the absorptive \r\n brick molds. Therefore, a high water-cement ratio should be maintained \r\n by reducing evaporation and initially mixing grout with adequate water. \r\n Furthermore, ACI 530.1/ASCE 6/TMS 602 specifies grout shall be used within \r\n 1 1/2 hours of mixing. As with mortar, ice may be used to lower the mix \r\n water temperature. \r\n HOT \r\n WEATHER CONSTRUCTION RECOMMENDATIONS \r\n Special Precautions \r\n During periods of hot weather the temperature of the materials should \r\n be controlled for best results. Storing brick and sand under cover of \r\n shade will help control heat gain of the materials. Sand should be stored \r\n on a raised platform and not in contact with a cover during the hot part \r\n of the day. This prevents ground moisture from rising, then condensing \r\n on the cover after temperatures cool down, thus contaminating the materials. \r\n When possible, shade should also be provided for laborers, whose productivity \r\n decreases with increasing temperature and humidity. Starting work earlier \r\n in the day and scheduling masonry construction to avoid the hot, mid-day \r\n periods can reduce the effects of high temperatures on laborers and materials. \r\n \r\n Adjusting \r\n masonry construction practices may effectively control hot weather problems. \r\n ACI 530.1/ASCE 6/TMS 602 limits the length that mortar may be spread to \r\n 4 ft (1.2 m) and requires masonry units to be placed within one minute \r\n of spreading the mortar. Wind breaks may prevent rapid drying of mortar \r\n during and after placement, and covering walls with a weather resistant \r\n membrane at the end of the work day will prevent rapid loss of moisture \r\n from the masonry assemblage. Wet curing or fog spraying may further improve \r\n masonry strength development dur-ing periods of high temperatures and \r\n low relative humidity. \r\n General \r\n Requirements—Hot Weather \r\n The following items are suggested in addition to the construction and \r\n protection requirements for hot weather masonry construction found in \r\n Table 2. These items can be incorporated in the specifications of the \r\n project where applicable. \r\n 1. \r\n Maintain temperature of mortar and grout between 70┬░F and 120┬░F (21┬░C \r\n and 49┬░C). \r\n 2. \r\n Cold water may be used when mixing mortar and grout. Ice used to lower \r\n the mix water temperature must be completely melted before adding the \r\n water to the other ingredients. \r\n 3. \r\n Masonry units with high suctions (IRA over 30 g/min/30 in. 2 (30 g/min/194 \r\n cm 2 )) should be properly wetted prior to use. Units with lower rates \r\n of absorption may be desirable. \r\n 4. \r\n Mortar with a high water retention is desirable. \r\n 5. \r\n Limit the spread of mortar beds to 4 ft (1.2 m) when temperatures are \r\n 100┬░F (38┬░C) or above, or 90┬░F (32┬░C) with a 8 mph (3.6 m/s) wind. \r\n 6. \r\n Place masonry units within one minute of spreading mortar. \r\n 7. \r\n Partially completed walls may be fog sprayed at the end of the work day \r\n to control moisture evaporation. \r\n TABLE \r\n 2 \r\n Requirements for Brick Masonry Construction in Hot Weather \r\n \r\n \r\n \r\n Note : \r\n Construction requirements, while work is in progress, are based on ambient \r\n temperatures. \r\n Protection requirements, after masonry is placed, are based on mean daily \r\n temperatures. \r\n SUMMARY \r\n This Technical Notes describes how masonry materials react to extremes \r\n in weather conditions. Construction requirements and protection requirements \r\n are recommended for construction in both cold and hot weather to ensure \r\n that construction can continue without a decrease in quality. Performance \r\n characteristics associated with materials mixed and constructed during \r\n normal temperatures can be achieved by following the appropriate construction \r\n and protection recommendations addressed in this Technical Notes . \r\n Tables 1 and 2 summarize these recommendations for cold Note: Construction \r\n requirements, while work is in progress, are based on ambient temperatures. \r\n Protection requirements, after masonry is placed, are based on and hot \r\n weather construction. \r\n The \r\n information and suggestions contained in this Technical Notes are \r\n based on the available data and the experience of the engineering staff \r\n of the Brick Institute of America. The information contained herein must \r\n be used in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonry. Final decisions on the use of the \r\n information contained in this Technical Notes are not within the \r\n purview of the Brick Institute of America and must rest with the project \r\n architect, engineer and owner. \r\n REFERENCES \r\n 1. All-Weather Masonry Construction State of the Art Report , Technical \r\n Task Committee, International Masonry All-Weather Council, December 1968. \r\n 2. \r\n Brown, M.L., \"Speeding Mortar Setting in Cold Weather\", The Magazine \r\n of Masonry Construction , Vol. 2, No. 10 October 1989. \r\n 3. \r\n Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS \r\n 402) and Specifications for Masonry Structures (ACI 530.1/ASCE \r\n 6/TMS 602), American Concrete Institute, American Society of Civil Engineers, \r\n and The Masonry Society, 1992. \r\n 4. \r\n Cold Weather Concreting (ACI 306R), American Concrete Institute, \r\n 1988. \r\n 5. \r\n National Climatic Data Center, Federal Building, Asheville, NC 28801-2696, \r\n phone (704) 259-0682. \r\n 6. \r\n Randall, Jr., F.A., and Panarese, W.C., Concrete Masonry Handbook , \r\n Portland Cement Association, 1991. \r\n 7. \r\n Recommended Practices & Guide Specifications for Cold Weather Masonry \r\n Construction , International Masonry Industry All-Weather Council, \r\n December 1970. \r\n 8. \r\n Standard Specification for Cold Weather Concreting (ACI 306.1), \r\n American Concrete Institute, 1990. \r\n 9. \r\n Suprenant, B.A., \"Laying Masonry in Cold Weather\", The Magazine of Masonry \r\n Construction, Vol. 1, No. 9, \r\n December 1988. \r\n 10. \r\n Van der Klugt, L.J.A.R., \"Frost Damage to the Pointing and Laying Mortar \r\n of Clay Brick Masonry\", TNO Building Construction and Research, Rijswijk, \r\n The Netherlands, 9th International Brick/Block Masonry Conference, October \r\n 1991. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n"},{"TextID":60052,"ResultID":176284,"Text1":" \r\n \r\n Technical Notes 10 - Estimating Brick Masonry \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 10 - Estimating Brick Masonry \r\n Reissued May 1997 \r\n INTRODUCTION \r\n Except for the non-modular \"Standard Brick\" \r\n (3 3/4 by 2 1/4 by 8 in.) and some oversize brick (3 3/4 by 2 3/4 by 8 \r\n in.), virtually 100 per cent of the brick produced and used in the United \r\n States are sized to fit the modular system. Even the \"standard\" brick \r\n is available also in a modular size (nominal dimensions 4 by 2 2/3 by \r\n 8 in.). Since there is still a considerable production of non-modular \r\n brick, this revised Technical Notes includes estimating information \r\n for that size of unit in addition to modular units. \r\n ESTIMATING PROCEDURE \r\n Because of its simplicity and accuracy, the \r\n most widely used estimating procedure is the \"wall-area\" method. It consists \r\n simply of multiplying known quantities of material required per square \r\n foot by the net wall area (gross areas less areas of all openings). \r\n Estimating material quantities is greatly \r\n simplified under the modular system. For a given nominal size, the number \r\n of modular masonry units per square foot of wall will be the same regardless \r\n of mortar joint thickness - \r\n assuming, of course, that the units are to be laid with the thickness \r\n of joint for which they are designed. There are only three standard \r\n modular joint thicknesses: 1/4 in., 3/8 in. and 1/2 in. \r\n \r\n In contrast, the number of non-modular standard \r\n brick required per square foot of wall will vary with the thickness of \r\n the mortar joint. \r\n In the estimating procedure, determine the \r\n net quantities of all material before adding any allowances for \r\n waste. Allowances for waste and breakage vary, but, as a general rule, \r\n at least 5 per cent should be added to the net brick quantities and 10 \r\n to 25 per cent to the net mortar quantities. Particular job conditions, \r\n or experience, may dictate different factors. \r\n \r\n \r\n \r\n \r\n ESTIMATING TABLES \r\n Table 1 gives net quantities of brick and \r\n mortar required to construct walls one wythe in thickness with various \r\n modular brick sizes and the two most common joint thicknesses ( 3/8 in. \r\n and 1/2 in.). Mortar quantities are for full bed and head joints. \r\n \r\n \r\n \r\n \r\n Table 2 provides similar information for walls \r\n constructed only with non-modular brick. \r\n \r\n \r\n \r\n \r\n 1Note: Correction factors are applicable only \r\n to those brick which have lengths of twice their bed depths. \r\n The brick and mortar quantities in Tables \r\n 1 and 2 are for running (or stack) bond which contains no headers. For \r\n bonds requiring full headers, the correction factors given in Table 3 \r\n must be applied. Also, when estimating quantities for multiwythe walls, \r\n the mortar quantities for interior vertical and/or longitudinal collar \r\n joints given in Table 4 must be added. \r\n \r\n \r\n \r\n \r\n \r\n Table 5 contains the quantities of portland \r\n cement, hydrated lime and sand required for 1 cu ft of four types of mortar. \r\n Although ASTM Standard Specifications for Mortar for Unit Masonry (ASTM \r\n Designation C 270) permits a range of proportions for each mortar type, \r\n the quantities in Table 5 have been based on a single set of proportions \r\n for each of these types. For convenience in estimating, quantities based \r\n on both weight and volume are included in the table. Mortar is generally \r\n proportioned by volume on the job, although proportioning by weight is \r\n the more accurate method. For more complete information on mortar ingredients, \r\n proportions, properties and uses, see Technical Notes 8 \r\n Revised, \"Portland Cement-Lime Mortars for Brick Masonry\". \r\n MORTAR YIELD \r\n General . For given volumes of materials, mortar yield depends upon \r\n proportions, water content and air content. Water content will vary with \r\n sand gradation, lime and cement content, and, quite often, the judgment \r\n of the brick mason. \r\n Mortar yield calculations are based on absolute \r\n volume. To determine yield, first obtain: \r\n 1. Unit weights and specific quantities of \r\n all materials (see Table 6). \r\n 2. Total volume of water used in mortar mix, \r\n including mixing water and the water present in the sand. \r\n \r\n \r\n \r\n \r\n 1Values for sand are not listed because they \r\n vary considerably. Obtain precise values from laboratory tests (or from \r\n supplier). \r\n Sand . When a relatively small amount of water (4 to 10 per cent) \r\n is added to dry sand, it bulks, that is, it increases in volume \r\n far in excess of the volume of water added. This increase can be as much \r\n as 50 per cent, depending largely upon the gradation of the sand. Because \r\n of bulking, volumetric measurement of sand is not very accurate. \r\n Although weighing sand is a more accurate \r\n method of measurement, it is, perhaps, not nearly so convenient as measuring \r\n volume. For proportion specifications, ASTM C 270 assumes that 1 cu ft \r\n of damp, loose sand (bulked sand) is equal to 80 lb of dry sand (and that \r\n it has bulked approximately 38 per cent). \r\n Specific Gravity of Sand . Obtain \r\n the specific gravity of sand from the supplier. Procedure for determining \r\n specific gravities of sands is given in ASTM C 128, Standard Method of \r\n Test for Specific Gravity and Absorption of Fine Aggregate. An average \r\n value for silica sands is 2.65. \r\n Moisture Content of Sand . In \r\n any given sand, the moisture content may vary from day to day or even \r\n from hour to hour. While this variation exists, it is not as critical \r\n in mortars as it is in portland cement concrete. Most damp loose sands \r\n contain approximately 1/2 to 1 gal of water per cu ft of sand. For many \r\n yield calculations, an assumption of this amount of water may be sufficient. \r\n Where greater accuracy is desired, determine moisture content according \r\n to the procedure given in ASTM C 70, Standard Method of Test for Surface \r\n Moisture in Fine Aggregate. \r\n Weight of Sand . To \r\n accurately determine mortar yield requires knowledge of the sands moisture \r\n content, specific gravity and unit weight (bulked and dry). To determine \r\n bulked unit weight, weigh 1 cu ft of bulked sand. The standard method \r\n for determining unit weight of aggregate is given in ASTM C 29, Standard \r\n Method of Test for Unit Weight of Aggregate. When moisture content and \r\n bulked weight are known, the weights of water and dry sand are easily \r\n computed. \r\n Water . Use the total weight of water in yield calculations; i.e., \r\n sum of the weights of mixing water and water present in the sand. If the \r\n moisture content of the sand is known, it is a simple matter to calculate \r\n the weight of water in the sand. Add the weight of water present in the \r\n sand to the weight of mixing water added to the batch at the mixer. To \r\n convert gallons of mixing water to pounds, multiply by 8.33. \r\n Absolute Volume . The \r\n absolute solid volume of a material is the volume of its solid portion \r\n only; voids are not included. Thus: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n In Eq (1): \r\n \r\n \r\n V m = absolute solid volume of any given material in cubic feet \r\n W m = batch weight of the material in pounds \r\n G m = specific gravity of the material \r\n \r\n \r\n \r\n \r\n The absolute volume of mortar is the sum of the \r\n absolute volumes of all ingredients (cement, lime, sand and water): \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Mortar Yield . Mortar \r\n yield is equal to its absolute volume (V M ) plus the volume of entrapped air. When the air content of mortar is \r\n known, the yield may be found from the relationship: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n In Eq (3): \r\n Y = volume of mortar yield in cubic \r\n feet \r\n V M \r\n = absolute solid volume of mortar in cubic feet from Eq (2) \r\n \r\n a = air content of freshly mixed mortar \r\n in per cent \r\n \r\n \r\n Air contents of freshly mixed portland cement-lime \r\n mortars are in the order of 10 per cent. \r\n Mortar Yield by \"Rule-of-Thumb \". \r\n For jobs where mortar yield calculations \r\n are not critical, use the following \"rule-of-thumb\" to determine approximate \r\n mortar yield: \r\n For each 1 cu ft of damp loose sand, the mortar \r\n yield will be 1 cu ft. \r\n Illustrative Example . Determine \r\n the batch yield for the following mortar: \r\n Batch proportions by volume: 1 cu ft \r\n portland cement, 1 cu ft lime, 6 cu ft damp loose sand, and 8 1/3 , gal mixing water. For all materials except sand, \r\n specific gravities and unit weights are as shown in Table 6. Specific \r\n gravity of sand, G S = 2.65. \r\n Moisture content of sand, w = 8 per cent. Damp loose weight of sand, \r\n W = 87 lb per cu ft. Batch weight of sand = 6(87) = 522 lb. Assume mixed \r\n mortar contains 10 per cent air. \r\n \r\n Step1 . Determine the total weight of each material in the batch \r\n (see Table 6). \r\n \r\n \r\n Step 2 . Using the batch weights determined in Step 1, calculate \r\n the absolute solid volume for each material from Eq (1) and the total \r\n from Eq (2) \r\n \r\n . \r\n \r\n Step 3 . \r\n Determine mortar yield from Eq (3) \r\n \r\n \r\n Note: By the \"rule-of-thumb\" method the yield \r\n is 6 cu ft. However, had this mix required more or less mixing water, \r\n or had it varied in air content, the yield would have varied also. Conceivably, \r\n this difference may be significant for large quantity computations. \r\n \r\n \r\n \r\n \r\n \r\n \r\n"},{"TextID":60053,"ResultID":176285,"Text1":" \r\n \r\n \r\n Technical Notes 10A - Modular Brick Masonry June/July 1973 (Reissued July 1986) \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 10A - Modular Brick Masonry \r\n June/July 1973 (Reissued July 1986) \r\n \r\n INTRODUCTION \r\n \r\n \"Greater productive capacity in the construction industry \r\n to meet the demands of an expanding population must be provided \r\n by increases in efficiency in the processes and techniques \r\n of designing and building. An ultimate objective is the development \r\n of a system of construction in which all materials, components, \r\n products and equipment fit together simply and easily with \r\n minimum alterations required on the job.\" \r\n With this statement, the editors of Modular Practice, \r\n published in 1962 by John Wiley & Sons, Inc., introduced \r\n the concept of modular coordination to the reader. This statement \r\n is even more to the point today, since the use of modular \r\n coordination in the design and construction of buildings not \r\n only increases production but can also result in significant \r\n cost savings. \r\n This year marks the 35th anniversary of a meeting called \r\n by the American Standards Association (now the American National \r\n Standards Institute) in August 1938, from which the development \r\n of the principles of modular or dimensional coordination stem. \r\n This conference, called to explore the need for setting up \r\n a project on modular coordination, was attended by representatives \r\n of the various facets of the building industry, including \r\n the Brick Institute of America (then SCPI). Their unanimous \r\n recommendation to ASA was that such a project be initiated. \r\n This was effected in 1939 as ASA Sectional Committee A62 on \r\n the Coordination of Dimensions of Building Materials and Equipment, \r\n under the sponsorship of the American Institute of Architects \r\n and the Producers Council, Inc. This committee currently \r\n operates under the name of ANSI Standards Committee on Pre-Coordination \r\n of Building Components and Systems, although at present it \r\n is without sponsorship. \r\n During the past 35 years many organizations have contributed \r\n to both the technical and educational aspects of the project, \r\n including the Federal Government, American Institute of Architects, \r\n American Society of Civil Engineers, Associated General Contractors, \r\n Consulting Engineers Council, National Association of Home \r\n Builders, Prestressed Concrete Institute and many trade associations \r\n representing producers of building products and components \r\n manufactured to predetermined sizes. \r\n The Modular Building Standards Association was organized \r\n in 1957 by the American Institute of Architects, Associated \r\n General Contractors of America, National Association of Home \r\n Builders and the Producers Council, Inc. It was supported \r\n by those organizations plus individual memberships. MBSA worked \r\n with the Building Research Advisory Board (BRAB), National \r\n Academy of Sciences-National Research Council in the preparation \r\n of a manual on modular design. The project was carried on \r\n under a grant from the Ford Foundations Educational Facilities \r\n Laboratories, Inc. This manual, Modular Practice , is \r\n the one quoted at the beginning of this Technical Notes \r\n and is still the most comprehensive treatment of the subject \r\n available. \r\n \r\n AMERICAN MODULAR STANDARDS \r\n \r\n Since the organization of ANSI Standards Committee A62, BIA \r\n has been represented on the committee and has participated \r\n in the development of the following standards: (Copies of \r\n these standards available from American National Standards \r\n Institute, 1430 Broadway, New York, N.Y. 10018.) \r\n \r\n \r\n A62.1 - 1957 Basis \r\n for the Coordination of Dimensions of Building Materials \r\n and Equipment \r\n A62.2 - 1945 Basis \r\n for the Coordination of Masonry \r\n A62.3 - 1946 Sizes \r\n of Clay and Concrete Modular Masonry Units \r\n A62.4 - 1947 Sizes \r\n of Clay Flue Linings \r\n A62.5 - 1968 Basis \r\n for the Horizontal Dimensioning of Coordinated Building \r\n Components and Systems \r\n A62.6 - 1969 Classification for Properties and Performances of Coordinated Building \r\n Components and Systems \r\n A62.7 - 1969 Basis \r\n for the Vertical Dimensioning of Coordinated Building Components \r\n and Systems \r\n A62.8 - 1971 Numerical \r\n Designation of Modular Grid Coordinates \r\n \r\n \r\n SIZES OF MODULAR BRICK UNITS \r\n \r\n Currently, a large percentage of brick is produced in modular \r\n sizes and, consistent with its long established policy, BIA \r\n recommends modular design and the use of modular products \r\n as a means of reducing building costs. \r\n The sizes of modular brick listed in Table 1 are typical \r\n of those generally produced by the industry. However, as design \r\n requirements change, new sizes may be added and less popular \r\n sizes dropped. Also, few manufacturers produce all of \r\n the sizes listed. Therefore, it is recommended that the designer \r\n consult current manufacturer or regional catalogs for available \r\n sizes in any locality before proceeding with a design. \r\n \r\n Tables for use in estimating quantities of modular brick and \r\n mortar are given in Technical Notes 10 \r\n Revised, \"Estimating Brick Masonry\". \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n a Available as solid units conforming to ASTM C 216 or \r\n ASTM C 62, or, in some cases, as hollow brick conforming \r\n to ASTM C 652 \r\n b Refer to Technical Notes 10B , \r\n \"Brick Sizes and Related Information\" \r\n c Reg U.S. Pat. Off., BIA \r\n \r\n \r\n \r\n \r\n MODULAR UNIT DIMENSIONS \r\n \r\n The listed dimensions of modular masonry units are \"nominal, \r\n and are equal to the manufactured or specified dimension plus \r\n the thickness of the mortar joint with which the unit is designed \r\n to be laid, as indicated in Fig. 1. For example, the manufactured \r\n length of a unit whose nominal length is 12 in. would be 11 \r\n 1/2 in. if the unit were designed to be laid with 1/2 in. \r\n joints, or 11 5/8 in. for 3/8 - in. joints. \r\n \r\n \r\n \r\n \r\n Guideline for Modular Sizes of Brick \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Capital Letters Signify Nominal Dimensions. Lower Case \r\n Letter Signify Actual or Specified Dimensions. \r\n The Thickness of Mortar Joint is Shown as \"j\". Dimenstion \r\n Points on Grid Lines Are Shown with Arrows. \r\n Dimestion Points Not on Grid Lines Are Desingated with Dots. \r\n \r\n \r\n \r\n \r\n \r\n \r\n The manufactured dimensions of a single unit may vary from \r\n the specified dimensions by not more than the permissible \r\n tolerances for variation in dimensions included in the applicable \r\n ASTM specifications. \r\n In Table 1, all dimensions are nominal and the standard mortar \r\n joint thickness is determined by the type and quality of the \r\n product, particularly by the permissible variation in dimensions. \r\n In general, facing brick are laid in either 3 3/8 - in. or \r\n 1/2 - in. thick mortar joints, although some products, such \r\n as ceramic glazed brick or structural clay facing tile, are \r\n designed for 1/4 - in. thick mortar joints. \r\n \r\n MASONRY UNIT COORDINATION \r\n \r\n The manner in which the coordination of different modular \r\n masonry units is accomplished is shown in Fig. 2. The exterior \r\n facing brick are shown with 3/8 - in. joints and are backed \r\n up with units, such as structural clay tile, designed for \r\n use with 1/2-in. joints. The inside facing of ceramic glazed \r\n units are laid in 1/4-in. joints. The full coordination between \r\n units is apparent, as indicated in the enlargements. The thickness \r\n of the vertical joints between the different types of units \r\n is the average of the joint thicknesses used with each unit. \r\n \r\n \r\n \r\n \r\n Modular Unit Coordination \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n DESIGN \r\n \r\n The authors of Modular Practice emphasize the importance \r\n of establishing the 4-in. modular grid as a reference system \r\n for the three dimensional elements of plan and structure, \r\n but state that no part of the plan should be forced \r\n to fall on the grid, nor should any dimension be forced to \r\n be multiples of 4 in. However, they also point out economies \r\n that can be effected in construction costs through the use \r\n of modular dimensions, thus minimizing the altering of predimensioned \r\n components at the job site. \r\n \r\n GRID LOCATIONS OF MASONRY WALLS \r\n \r\n Figure 3 shows grid locations of mortar joints in walls constructed \r\n with various modular units when the walls are centered between \r\n grid lines. It can be seen that all grid lines coincide with \r\n horizontal mortar joints for only the 2 - in. and 4 - in. \r\n nominal heights, thus providing 4 - in. flexibility. \r\n \r\n \r\n \r\n \r\n Elevations Showing Grid Locations \r\n FIG. 3a \r\n \r\n \r\n \r\n \r\n \r\n \r\n Elevations Showing Grid Locations \r\n FIG. 3b \r\n \r\n \r\n \r\n \r\n \r\n \r\n Elevations Showing Grid Locations \r\n FIG. 3c \r\n \r\n \r\n \r\n \r\n \r\n \r\n Elevations Showing Grid Locations \r\n FIG. 3d \r\n \r\n With the 2 2/3 - in. high units (as well as 8 - in. high \r\n units), grid lines coincide with horizontal joints every 8 \r\n in. If 4 - in. flexibility is required, a course of 4 - in. \r\n high supplementary units (or a rowlock header course) must \r\n be used. \r\n The fact that alternate grid lines coincide with the mortar \r\n joints when the 2 2/3 - in. high brick is used provides a \r\n simple rule for determining the location of a grid line with \r\n respect to the masonry at any point above or below a given \r\n reference grid line. Any grid line which is an even multiple \r\n of 4 - in. from the reference line will have the same relative \r\n position with respect to the masonry coursing, while any grid \r\n line that is an odd multiple of 4 in. will have the alternate \r\n position. This simple rule greatly simplifies the checking \r\n of course heights, particularly for lintels, where it is usually \r\n essential that the head of the opening coincide with a horizontal \r\n mortar joint. \r\n A symmetrical grid location for walls is usually preferred \r\n to an unsymmetrical position. The correct symmetrical location \r\n (centered between grid lines or centered on a grid line) will \r\n often be influenced by the length of the masonry units to \r\n be used. \r\n With masonry units whose nominal lengths are 8 or 16 in., \r\n vertical (head) joints will occur on grid lines when 4 and \r\n 8 - in. thick walls are centered between grid lines, \r\n and they will occur at mid - grid points when these walls \r\n are centered on grid lines. \r\n The above conditions are also true for 12 - in. nominal length \r\n units when they are laid in one-third bond. However, when \r\n these units are laid in center (1/2) bond, vertical joints \r\n in alternate courses will occur on grid lines and be centered \r\n between grid lines. \r\n \r\n CONCLUSION \r\n \r\n As this is written (May 1973), it is anticipated that Congress \r\n will pass legislation which would create a National Metric \r\n Conversion Board to plan and coordinate a voluntary conversion \r\n process in which, over a period of some ten years, the United \r\n States will go metric\". It is highly probable that modular \r\n or dimensional coordination will be made an integral part \r\n of metrication in the construction industry, as it was in \r\n Great Britain when it made the decision to convert to metric \r\n about eight years ago. It is expected that, if this comes \r\n to pass, the acceptance and use of modular coordination will \r\n increase at a much more rapid pace than it has under the evolutionary \r\n process it has been permitted to follow for the past 35 years. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60054,"ResultID":176286,"Text1":" \r\n \r\n Technical Notes 10B - Brick Sizes and Related Information June 1993 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 10B - Brick Sizes and Related Information \r\n June 1993 \r\n \r\n Abstract: This Technical Notes provides information \r\n on brick sizes and nomenclature. Standard nomenclature for \r\n the twelve most common brick sizes is given. The differences \r\n between nominal, specified and actual dimensions are explained. \r\n Vertical and horizontal coursing tables for modular and non-modular \r\n sizes are provided. \r\n Key Words: actual dimension, \r\n brick, nominal dimension, size, specified dimension, standard \r\n nomenclature. \r\n INTRODUCTION \r\n Brick are available in many varied \r\n sizes and have been called by many different names. This proliferation \r\n of sizes and names can be confusing for the designer and specifier. \r\n The problem is further compounded by the need to distinguish \r\n between nominal, specified and actual dimensions. Recent efforts \r\n led jointly by the Brick Institute of America and the National \r\n Association of Brick Distributors have led to the development \r\n of standard nomenclature for brick which represent roughly \r\n 90 percent of all sizes currently manufactured. \r\n This Technical Notes lists \r\n the sizes of brick units generally available in the United \r\n States and presents the standard nomenclature for brick sizes. \r\n The differences between nominal, specified and actual dimensions \r\n are explained. Guidance is given on the recommended order \r\n in which brick dimensions should be listed. Vertical and horizontal \r\n coursing tables are presented as an aid to the reader. Other \r\n Technical Notes in this series provide tables for estimating \r\n brick masonry and information on modular brick masonry. \r\n BRICK SIZES AND NOMENCLATURE \r\n Brick sizes have varied over the \r\n centuries, but have always been similar to present day sizes. \r\n The size of a brick has historically been small enough to \r\n be held in the hand, and most brick have remained small. Brick \r\n is a building element with a human scale. The use of small \r\n scale elements, such as brick, tends to break down massive \r\n expanses of wall into visually pleasing parts. Furthermore, \r\n the use of oversized units alters the scale of the masonry \r\n unit in relation to the wall. Because people have a perceived \r\n size of brick, the use of oversize units makes the wall appear \r\n smaller. \r\n Over time new sizes have been developed \r\n to meet specific design, production or construction needs. \r\n New types of construction have required new sizes, such as \r\n hollow units for reinforced masonry and larger units for increased \r\n economy. Hollow units have varying coring patterns but typically \r\n are larger than standard or modular size and have larger cells \r\n to allow placement of vertical reinforcement. Units with larger \r\n face dimensions allow the bricklayer to lay more square foot \r\n of wall per day. Such units, compared to standard or modular \r\n size units, may increase the number of brick laid per day \r\n by over 50 percent. However, as units get larger and heavier, \r\n a point of diminishing return exists. Also, units with larger \r\n heights make filling the head joint with mortar more difficult. \r\n Until now, a given brick size may \r\n have been known by several names due to regional variations. \r\n A joint committee of the Brick Institute of America and the \r\n National Association of Brick Distributors recently developed \r\n standard nomenclature for brick which represent roughly 90 \r\n percent of all sizes currently manufactured. The standard \r\n nomenclature for brick sizes is presented in Table 1. These \r\n terms were developed by a consensus process involving companies \r\n across the country. The use of these standard terms when describing \r\n brick is strongly recommended. \r\n \r\n \r\n \r\n 1 1 in.=25.4mm; 1 ft=0.3m \r\n \r\n 2 Common joint sizes used \r\n with length and width dimensions. Joint thicknesses of bed joints \r\n vary based on vertical coursing and specified unit height. \r\n \r\n 3 Specified dimensions \r\n may vary within this range from manufacturer to manufacturer. \r\n Table 2 lists other brick sizes \r\n that are produced by a limited number of manufacturers. Since \r\n clay is such a flexible medium, manufacturers can make many \r\n different sizes. Also, modular and non-modular sizes are illustrated \r\n in Figs. 1 and 2, respectively. The coring patterns shown \r\n in these figures are for illustrative purposes only. Manufacturers \r\n incorporate cores and cells in solid and hollow brick in many \r\n different sizes and patterns. The brick manufacturer should \r\n be consulted for information on sizes and coring patterns. \r\n \r\n \r\n \r\n \r\n Modular Brick Sizes (Nominal Dimensions) \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Non-Modular Brick Sizes (Specified \r\n Dimensions) \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 1 in.=25.4mm; 1 \r\n ft=0.3m \r\n 2 Common joint sizes \r\n used with length and width dimensions. Joint thicknesses \r\n of bed joints vary based on vertical coursing and specified \r\n unit height. \r\n 3 Specified dimensions \r\n may vary within this range from manufacturer to manufacturer. \r\n \r\n \r\n BRICK DIMENSIONS \r\n Brick are identified by three dimensions: \r\n width, height and length. Height and length are sometimes \r\n called face dimensions for these are the dimensions showing \r\n when the brick is laid as a stretcher. The terms applied to \r\n brick positions as they are placed in a wall are shown in \r\n Fig. 3. The shaded areas indicate the surfaces of the brick \r\n that are exposed. Specifications and purchase orders should \r\n list brick dimensions in the standard order of width \r\n first, followed by height , then length . \r\n \r\n \r\n \r\n \r\n Brick Positions in a Wall \r\n FIG. 3 \r\n \r\n \r\n When specifying or designing with \r\n brick, it is important to understand the difference between \r\n nominal, specified and actual dimensions. Nominal dimensions \r\n are most often used by the architect in modular construction. \r\n In modular construction, all dimensions of the brick and other \r\n building elements are multiples of a given module. Such dimensions \r\n are known as nominal dimensions. For brick masonry the nominal \r\n dimension is equal to the specified unit dimension plus the \r\n intended mortar joint thickness. The intended mortar joint thickness \r\n is the thickness required so that the unit plus joint thickness \r\n match the coursing module. In the inch-pound system of measurement, \r\n nominal brick dimensions are based on multiples (or fractions) \r\n of 4 in. In the SI (metric) system, nominal brick dimensions \r\n are based on multiples of 100 mm. For more information on modular \r\n construction see Technical Notes 10A \r\n Revised. \r\n As the name implies, the specified \r\n dimension is the anticipated manufactured dimension. It should \r\n be stated in project specifications and purchase orders. Specified \r\n dimensions are used by the structural engineer in the rational \r\n design of brick masonry. In non-modular construction, only \r\n the specified dimension should be used. Tables 1 and 2 provide \r\n the specified and nominal dimensions, where applicable. \r\n The actual dimension of a \r\n unit is the dimension as manufactured. Actual dimensions may \r\n vary slightly from a specified size. The actual dimensions \r\n of a brick must fall within the range of sizes defined by \r\n the specified dimensions plus or minus the specified dimensional \r\n tolerances. Dimensional tolerances are found in the ASTM standard \r\n specifications for brick, such as ASTM C 216 Standard Specification \r\n for Facing Brick, or may be specified in the project documents. \r\n COURSING \r\n Although nominal dimensions are \r\n given only for modular brick, it should be noted that the \r\n heights of both modular and non-modular brick are the \r\n same. This is because when modular sizes were first introduced, \r\n brick manufacturers were faced with the problem of supplying \r\n matching brick to existing non-modular construction. From \r\n an appearance standpoint, most designers required that the \r\n vertical coursing of modular brick match the existing non-modular \r\n brick. Thus, all brick are modular in height. The vertical \r\n coursing information given in Tables 1 and 2 is a reflection \r\n of this fact. Table 3 provides vertical dimensions based on \r\n the modular vertical coursing given in Tables 1 and 2. For \r\n example, units with heights which course vertically 2 courses \r\n to 4 in. (2C = 4 in.) such as Roman size, should use column \r\n 1 of Table 3. The dimensions given in Table 3 include typical \r\n mortar joints of 3/8 in. to 1/2 in. The actual mortar joint \r\n size can be determined from the vertical coursing information \r\n and the specified unit size. For example, when coursing out \r\n with a modular height unit, the mortar bed joint is slightly \r\n larger than 3/8 in. and slightly less than 1/2 in., so that \r\n 3 courses of brick and mortar will equal the 8 in. module. \r\n For most brick sizes the mortar bed joint will not be exactly \r\n 3/8 in. nor 1/2 in. Table 3 is applicable to both modular \r\n and non-modular brick. In this table, the brick are assumed \r\n to be positioned in the wall as stretchers or headers. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 1 in.=25.4mm; \r\n 1 ft=0.3m \r\n 2 Brick positioned \r\n in wall as stretchers or headers. \r\n \r\n \r\n \r\n \r\n Horizontal coursing information \r\n is given in Table 4. The table includes coursing for both \r\n modular and non-modular brick. \r\n Another useful tool for designers \r\n is the brick scale. The brick scale is a coursing scale marked \r\n with multiples of common nominal brick sizes. They come in \r\n a set which matches the most common architectural scales, \r\n 1/4 in. = 1 ft-0 in., 1/2 in. = 1 ft-0 in., etc. Many brick \r\n manufacturers, brick distributors and masonry promotional \r\n groups provide brick scales to designer. \r\n \r\n \r\n \r\n 1 1in.=25.4 mm; 1ft \r\n = 0.3m \r\n \r\n CONCLUSION \r\n This Technical Notes presents \r\n the standard nomenclature for brick sizes. Information on \r\n brick sizes is given and the differences between nominal, \r\n specified and actual dimensions are explained. Coursing tables \r\n for both modular and non-modular brick are provided. \r\n The information and suggestions \r\n contained in this Technical Notes are based on the \r\n available data and the experience of the engineering staff \r\n of the Brick Institute of America. The information contained \r\n herein must be used in conjunction with good technical judgment \r\n and a basic understanding of the properties of brick masonry. \r\n Final decisions on the use of the information contained in \r\n this Technical Notes are not within the purview of \r\n the Brick Institute of America and must rest with the project \r\n architect, engineer and owner. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60055,"ResultID":176287,"Text1":" \r\n \r\n \r\n Technical Notes 11 - Guide Specifications for Brick Masonry,Part 1 Dec. 1971 (Reissued April 1986) INTRODUCTION \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11 - Guide Specifications for Brick Masonry, \r\n Part 1 \r\n Dec. 1971 (Reissued April 1986) \r\n \r\n INTRODUCTION \r\n \r\n Numerous methods are being explored to reduce constantly rising building \r\n costs. One means in which many segments of the construction industry \r\n believe holds promise of lowering these costs is the use of specific, \r\n definitive and concise specifications. They must convey to the contractor \r\n the exact requirements of the project and be organized to facilitate \r\n take-off and estimating. Many general contractors have testified that \r\n the use of such specifications results in lower contract bids. \r\n During recent years, organizations, such as the American Institute \r\n of Architects (AIA), Producers Council (PC), Associated General Contractors \r\n of America (AGC), and the Construction Specifications Institute (CSI), \r\n have made the improvement of construction specifications one of their \r\n major activities. \r\n In accordance with the work of these agencies, the guide specifications \r\n in this series of Technical Notes are written to follow the CSI \r\n format insofar as possible. \r\n Use of Standards. It is recommended that, where suitable standards \r\n exist, such as those developed by the American Society for Testing and \r\n Materials (ASTM), American National Standards Institute (ANSI), American \r\n Concrete Institute (ACI) and other similar nationally recognized organizations, \r\n they be used and included in the project specifications by reference. \r\n Use of Detailed Descriptive Requirements. While detailed descriptive \r\n requirements are generally necessary as a means of specifying installation \r\n or workmanship, it is recommended that they be used only as a last resort \r\n in specifying materials. \r\n Use of Performance Specifications. Performance specifications \r\n are not, in general, considered suitable for specifying architectural \r\n building products. It is recommended that, if performance specifications \r\n are used to specify building materials, they should state results desired \r\n or properties desired, but not both. \r\n Use of Trade Names. It is recommended that, if building products \r\n are specified by trade names, the \"special conditions\" contain a clause \r\n providing that substitutes will be considered on a quality and price \r\n basis, and that the phrase \"or equal\", frequently included in such specifications, \r\n be eliminated. \r\n The following paragraph is suggested for substitutions: \r\n Variation From Materials Specified: It is intended that materials or \r\n products specified by name of manufacturer, brand, trade name or by \r\n catalog reference shall be the basis of the bid and furnished under \r\n the contract, unless changed by mutual agreement. Where two or more \r\n materials are named, the choice of these shall be optional with the \r\n contractor. Should the contractor wish to use any materials or products \r\n other than those specified, he shall so state, naming the proposed substitutions \r\n and stating what difference, if any, will be made in the contract price \r\n for such substitution should it be accented. \r\n Use of Allowances. It is recommended that allowances be used \r\n only with discretion. In all cases of allowances, there should be sufficient \r\n description to indicate to the contractor the extent of labor required \r\n to install the items for which allowances are listed. Also, all allowances \r\n should be listed under special conditions or under a separate section \r\n with cross references to the individual trade sections involved. \r\n \r\n SPECIFICATIONS FOR STRUCTURAL CLAY PRODUCTS \r\n \r\n Standard specifications for the various types and grades of brick and \r\n tile have been developed by technical committees of the American Society \r\n for Testing and Materials. Membership of these committees is balanced \r\n among consumers, manufacturers and a general interest group made up \r\n of engineers, scientists, educators, testing experts and representatives \r\n of research organizations. Because of this balance of committee membership, \r\n ASTM specifications are widely accepted and it is recommended that the \r\n appropriate ASTM specifications be included by reference in all specifications \r\n for solid brick, hollow brick, structural facing tile (glazed or unglazed) \r\n and structural clay tile. \r\n ASTM standards are under continuous review by the stands committees \r\n having jurisdiction over them. From time to time these standards are \r\n revised as a result of new developments. The ASTM designation of a standard \r\n consists of a letter and a number permanently assigned to the standard, \r\n a dash and a number indicating the year the standard was approved: as \r\n for example, C 216-69 which designates the Standard Specifications for \r\n Facing Brick approved in 1969. If the letter T follows the year designation, \r\n it indicates a tentative standard. \r\n When ASTM specifications are included by reference in project specifications, \r\n the full designation, including the year of approval, should be given, \r\n since, obviously, after a contract has been awarded, a revision of specifications \r\n by ASTM does not alter the contract. Similarly, the dates of any other \r\n specifications or codes included by reference should be given. \r\n Solid Masonry Units. ASTM Specifications C 216, C 62, and C \r\n 126 cover solid building brick, facing brick and ceramic glazed units \r\n made from clay and/or shale. Under these specifications, a solid masonry \r\n unit may be cored not in excess of 25 per cent; consequently, the term \r\n \"solid brick\" is not confined to those units which have no cores, unless \r\n so stated in the project specifications. \r\n Hollow Masonry Units. ASTM Specification C 652 covers hollow \r\n building brick, facing brick or hollow masonry units made from clay, \r\n shale, fire clay or mixtures thereof, and fired. The term \"hollow\" in \r\n this specification is defined to mean any unit cored in excess of 25 \r\n per cent, but not more than 40 per cent, in every plane parallel to \r\n the bearing surface. \r\n Supplementary Requirements. ASTM specifications for brick and \r\n tile do not fix the size or color and texture of the units. They do, \r\n however, include requirements for several grades and types of products, \r\n and some of them contain optional requirements which are applicable \r\n to specific projects, if so specified. \r\n When ASTM specifications are included in project specifications by \r\n reference, it is essential that they be supplemented with project requirements \r\n covering size, color, grade, type, etc. Without these supplementary \r\n provisions, the specifications are incomplete and inadequate as a basis \r\n for estimating. \r\n Size. Size of units required should be included in the project \r\n specifications. Without this information, a contractor cannot accurately \r\n estimate quantity of materials or the labor required to construct the \r\n masonry. \r\n It is recommended that the specified size be the manufactured size. \r\n Individual unit dimensions may vary from the specified or manufactured \r\n size by the allowable tolerances included in the appropriate ASTM specifications \r\n for the particular type or grade. \r\n Specifying nominal sizes of clay masonry units is not recommended, \r\n due to the ambiguity of the term \"nominal\". In some fields, it is understood \r\n to mean approximate and actual dimensions may vary from the nominal \r\n only by permissible variations in dimensions included in the specifications. \r\n However, in modular design, the nominal dimension of a masonry unit \r\n is understood to mean the specified or manufactured dimension plus the \r\n thickness of the mortar joint with which the unit is designed to be \r\n laid; that is, modular brick, whose nominal length is 8 in., would have \r\n a specified (manufactured) length of 7 1/2 in. if designed to be laid \r\n with a 1/2 - in. joint, or 7 5/8 in. if designed to be laid with a 3/8 \r\n - in joint. \r\n Color and Texture. Generally, the color and texture of the brick \r\n or structural facing tile in a masonry wall vary slightly. These variations, \r\n which prevent monotony in the appearance of the finished wall, are one \r\n of the most attractive features of brick and tile. Because of these \r\n variations and of the wide variety of colors and textures produced by \r\n the industry, it is impossible to write descriptions of either color \r\n or texture which will accurately identify the products required. \r\n For this reason, ASTM specifications for brick and structural clay \r\n facing tile provide that texture and color shall conform to an approved \r\n sample showing the full range of color and texture that will be acceptable. \r\n The number of units required in the sample should be stated in the project \r\n specifications and will depend upon the range of color and texture. \r\n In general, it will be from three to five. \r\n Grade and Type. Most ASTM specifications for brick or structural \r\n clay tile cover two or more grades, and specifications for facing brick, \r\n hollow brick and ceramic glazed structural facing tile include requirements \r\n for two or more types. Specifications for structural clay facing tile \r\n cover two types and two classes. \r\n When these specifications are included in project specifications by \r\n reference, it is essential that the grade and type or type and class \r\n of product required be specified. Failure to do so makes it difficult \r\n for the contractor to estimate the project and frequently results in \r\n a demand for extras after the contract is awarded. \r\n Cell Arrangement. Structural clay tile are produced with either \r\n vertical cells or horizontal cells. Furring tile, nominal thickness \r\n 2 in., in ceramic glaze often referred to as \"soaps\", are produced with \r\n either solid backs or open (ribbed) backs. If either vertical-cell or \r\n horizontal-cell units are required for specific locations, this should \r\n be stated in the project specifications. Similarly, if solid-back soaps \r\n or furring are required, it should be so stated. Otherwise, product \r\n specifications make the selection optional with the supplier. \r\n Plaster Base Finish. Specifications for structural clay facing \r\n tile and structural clay tile contain requirements for the finish of \r\n surfaces suitable for the application of plaster. When such surfaces \r\n are required, they should be specified in the project specifications; \r\n otherwise, the finish of the unexposed (back) of the unit is optional \r\n with the supplier. \r\n Tests . Most ASTM specifications for structural clay products \r\n provide that the cost of tests of units furnished for any particular \r\n project \"shall be borne by the purchaser\", unless the tests indicate \r\n that the units do not conform to the requirements of the specifications, \r\n in which case \"the cost shall be borne by the seller\". Project specifications \r\n should state the number of tests that will be required and should indicate \r\n who is responsible for selecting the samples and who pays the cost of \r\n testing. \r\n \r\n PROJECT SPECIFICATIONS FOR STRUCTURAL CLAY PRODUCTS \r\n \r\n As previously indicated, it is recommended that ASTM specifications, \r\n supplemented to meet project requirements, be used in specifying brick \r\n and structural clay tile. These specifications are suitable for use \r\n in any of the following forms: \r\n Open Specifications. This type of specification, frequently \r\n required in public work, makes no reference to product trade names. \r\n In such a specification, ASTM specifications should be included by reference, \r\n supplemented with project requirements, and an \"approved sample\" of \r\n the required color and texture should be available for inspection by \r\n bidders prior to submission of bids. \r\n Trade Names. For private work, specifying facing brick and structural \r\n facing tile by trade or manufacturers names gives the contractor definite \r\n information as to the product required and provides the architect with \r\n assurance that the quality desired will be furnished. \r\n In general, when this method is used, three or more acceptable products \r\n are named and the contractor is given the option of selecting among \r\n them. \r\n When trade names are used for specifying brick or tile, it is recommended \r\n that the units be required to comply with applicable ASTM specifications \r\n and that samples of acceptable units be available for inspection of \r\n bidders prior to bidding; also, that a provision for substitution, similar \r\n to that previously recommended, be included in the specifications. \r\n Allowances. The use of allowances for cost of facing brick and \r\n facing tile has been used successfully for many years and, in general, \r\n this method is recommended by the Structural Clay Products Institute. \r\n Allowances place all contractors on an equal basis and permit the owner \r\n to select products that he considers most desirable. However, when this \r\n method is employed, the specifications should state the size and texture \r\n of the units that will be selected, the tests that will be required \r\n and the responsibility for payment of tests. \r\n \r\n GUIDE SPECIFICATIONS \r\n \r\n The guide specifications in Technical Notes 11A \r\n Revised and 11B Revised are written for \r\n both reinforced and non-reinforced brick masonry, designed to comply \r\n with ANSI A41.1-1953 (R1970), \"Building Code Requirements for Masonry\", \r\n ANSI A41.2-1960 (R 1970), \"Building Code Requirements for Reinforced \r\n Masonry\", or equivalent sections in the Model Building Codes. \r\n The guide specifications in these Technical Notes can be used \r\n for engineered brick masonry designed to comply with Building Code \r\n Requirements for Engineered Brick Masonry, BIA, August 1969, or \r\n equivalent sections in the Model Building Codes, when additional quality \r\n assurance requirements are incorporated into the specification. See \r\n Technical Notes 11C Revised. \r\n The specifications do not cover requirements for structural clay tile, \r\n concrete masonry units, glass block or stone. Where these materials \r\n and design procedures are included in the masonry section, the specifications \r\n should be supplemented or revised. It will be found, however, that many \r\n of the requirements pertaining to brick masonry are also applicable \r\n to other types of masonry construction. \r\n \"Guide Specifications for Masonry Mortar\" will be included as a separate \r\n Technical Notes 11E to comply \r\n with CSI format. \r\n Metric numbers listed are conversions from the current customary system \r\n and are not industry agreed-upon standards; i.e., a typical modular \r\n 3 1/2 x 2 1/4 x 7 1/2 - in.. (actual size) brick may be produced at \r\n some dimensions other than 89 x 57 x 191 mm when metric dimensions are \r\n adopted within the industry. \r\n The cold weather protection requirements contained in paragraph 1.05.C \r\n are those recommended by the International Masonry Industry All-Weather \r\n Council, published December 1, 1970. \r\n In using these specifications, the specification writer should cheek \r\n each section to insure compliance with project requirements and modify \r\n the paragraphs or delete those not needed. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Brick \r\n and Tile Engineering, Harry C. \r\n Plummer, Brick Institute of America (BIA), November 1967. \r\n 2. Building \r\n Code Requirements for Engineered Brick Masonry, BIA, August 1969. \r\n 3. Recommended \r\n Practice for Engineered Brick Masonry, \r\n J . G. Gross, R. D. Dikkers and J. C. Grogan, BIA, November \r\n 1969. \r\n 4. Specifications \r\n for Clay Masonry Construction, BIA, \r\n February 1962. \r\n 5. Technical \r\n Notes on Brick Construction, BIA, \r\n published monthly. \r\n 6. Building \r\n Code Requirements for Masonry, ANSI \r\n - A41.1-1953 (R 1970). \r\n 7. Building \r\n Code Requirements for Reinforced Masonry, \r\n ANSI - A41.2-1960 (R 1970). \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60056,"ResultID":176288,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11A - Guide Specifications for Brick Masonry, \r\n Part 2 \r\n June 1978 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes contains the guide specifications in CSI \r\n format for Division 4, Section 04210, Part I - General, and Part II \r\n - Products. Part III - Execution is in Technical Notes 11B \r\n Revised. \r\n The specifications are applicable to ANSI A41.1 - 1953 (R1970), Building \r\n Code Requirements for Masonry, ANSI A41.2 - 1960 (R 1970), \"Building \r\n Code Requirements for Reinforced Masonry, or equivalent sections in \r\n the Model Building Codes. \r\n The guide specifications in Technical Notes 11A \r\n Revised and 11B Revised can be used \r\n for engineered brick masonry designed to comply with Building Code \r\n Requirements for Engineered Brick Masonry, BIA, August 1969, or \r\n equivalent sections in the Model Building Codes, when additional quality \r\n assurance requirements are incorporated into the specifications. See \r\n Technical Notes 11C Revised. \r\n \r\n Guide Specification & Notes \r\n \r\n PART I - GENERAL \r\n \r\n 1.01 DESCRIPTION: \r\n \r\n A. Related Work Specified Elsewhere: \r\n \r\n 1. Concrete work: Section 03__________. \r\n 2. Rough carpentry: Section 06__________. \r\n 3. Structural steel and metals: Section 05__________. \r\n 4. Waterproofing: Section 07__________. \r\n \r\n B. Material Installed but Furnished by Others: \r\n \r\n 1. Bolts. \r\n 2. Anchors. \r\n 3. Nailing blocks. \r\n 4. Inserts. \r\n 5. Flashing. \r\n 6. Lintels. \r\n 7. Doors. \r\n 8. Window frames. \r\n 9. Vents. \r\n 10. Conduits. \r\n 11. Expansion joints. \r\n \r\n \r\n 1.02 QUALITY ASSURANCE: \r\n \r\n \r\n A. Brick Tests: \r\n \r\n \r\n 1. Test in accordance with ASTM C 67-__________with the following \r\n additional requirements: \r\n \r\n a. If the coefficient of variation of the compression samples \r\n tested exceeds 12%, obtain compressive strength by multiplying \r\n average compressive strength of specimens by \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where v is the coefficient of variation of sample tested. \r\n b. Cost of tests of units after delivery shall be borne by \r\n the purchaser, unless tests indicate that units do not conform \r\n to the requirements of the specifications, in which case cost \r\n shall be borne by the seller. \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.A This section can be deleted if Architect/Engineer has \r\n sufficient experience and confidence in the brick manufacturer \r\n to accept compliance with project specifications based on certification \r\n section 1.03.C. \r\n 1.02.A. 1.a. To be applied only for engineered brick masonry. \r\n 1.02.A. 1.b. To be used only in a case of dispute. \r\n \r\n \r\n \r\n B. Furnish Sample Panel: \r\n \r\n \r\n \r\n 1. Approximately 4 ft. (1.2 m) long by 3 ft. (1 m) high, showing \r\n the proposed color range, texture, bond, mortar and workmanship. \r\n All brick shipped for the sample shall be included in the panel. \r\n \r\n 2. Erect panel in the presence of the Architect/Engineer before \r\n installation of materials. \r\n 3. When required, provide a separate panel for each type of brick \r\n or mortar. \r\n 4. Do not start work until Architect/Engineer has accepted sample \r\n panel. \r\n 5. Use panel as standard of comparison for all masonry work built \r\n of same material. \r\n 6. Do not destroy or move panel until work is completed and accepted \r\n by Owner. \r\n \r\n NOTE: \r\n \r\n 1.02. B. 1. The sample panel, when accepted, shall become the \r\n project standard for: bond, mortar, workmanship and appearance. \r\n 1.02.B.3. Brick for sample panels are usually furnished at no \r\n cost. If additional panels are needed, care must be exercised \r\n not to burden the supplier with excessive costs. \r\n \r\n \r\n \r\n \r\n 1.03 SUBMITTALS: \r\n \r\n \r\n \r\n A. Samples: Furnish not less than five individual brick as samples, \r\n showing extreme variations in color and texture. \r\n \r\n B. Test Reports: \r\n \r\n \r\n \r\n 1. Test reports for each type of building and facing brick are \r\n to be submitted to the Architect Engineer for approval. \r\n 2. Testing and reports are to be completed by an independent \r\n laboratory. \r\n 3. Test reports shall show: \r\n a. Compressive strength. \r\n b. 24 - hr. cold water absorption. \r\n c. 5 - hr. boil absorption. \r\n d. Saturation coefficient. \r\n e. Initial rate of absorption (suction). \r\n \r\n C. Certificates: Prior to delivery, submit to Architect/Engineer \r\n certificates attesting compliance with the applicable specifications \r\n for grades, types or classes included in these specifications. \r\n \r\n \r\n NOTE: \r\n \r\n 1.03.A and B Sections can be deleted if Architect/Engineer has \r\n sufficient experience and confidence in the brick manufacturer \r\n to accept compliance with project specifications based on certification \r\n section 1.03.C. \r\n 1.03.B.3. This section should be altered to meet the requirements \r\n of the project. Brick are not required to meet the 5-hr boil absorption \r\n and/or saturation coefficient requirements of ASTM C 216, ASTM \r\n C 62 and ASTM C 652 if they meet the physical property requirements \r\n of Sections 5.1 and 5.2 of ASTM C 216, Sections 3A, 3.5 and 3.6 \r\n of ASTM C 62 and Sections 5.1 and 5.2 of ASTM C 652. \r\n No limit is placed on initial rate of absorption (suction). Units \r\n having initial rates of absorption exceeding 30 g./min./30 sq. \r\n in. (194 cm 2 ) should be wetted prior to laying. For \r\n cold weather masonry construction, higher suctions may be tolerated \r\n (up to 30-40 g.) than for normal construction. Note Sections 1.05.C.2.a \r\n and 3.01.A. 1. \r\n 1.03.C. List materials for which certificates of compliance are \r\n required. \r\n \r\n \r\n \r\n \r\n 1.04 PRODUCT DELIVERY, STORAGE AND HANDLING: \r\n \r\n \r\n A. Store brick off ground to prevent contamination by mud, dust \r\n or materials likely to cause staining or other defects. \r\n \r\n B. Cover materials when necessary to protect from elements. \r\n C. Protect reinforcement from elements \r\n \r\n 1.05 JOB CONDITIONS: \r\n \r\n \r\n A. Protection of Work: \r\n \r\n 1. Wall covering: \r\n \r\n \r\n a. During erection, cover top of wall with strong waterproof \r\n membrane at end of each day or shutdown. \r\n b. Cover partially completed walls when work is not in progress. \r\n c. Extend cover minimum of 24 in. (610 mm) down both sides. \r\n d. Hold cover securely in place. \r\n \r\n \r\n 2. Load application: \r\n \r\n \r\n a. Do not apply uniform floor or roof loading for at least \r\n 12 hr. after building masonry columns or walls. \r\n b. Do not apply concentrated loads for at least 3 days after \r\n building masonry columns or walls. \r\n \r\n \r\n \r\n B. Staining: \r\n \r\n \r\n 1. Prevent grout or mortar from staining the face of masonry \r\n to be left exposed or painted: \r\n \r\n a. Remove immediately grout or mortar in contact with face \r\n of such masonry. \r\n b. Protect all sills, ledges and projections from droppings \r\n of mortar, protect door jambs and corners from damage during \r\n construction. \r\n \r\n \r\n \r\n Protection: \r\n \r\n \r\n 1. Preparation: \r\n \r\n \r\n a. If ice or snow has formed on masonry bed, remove by carefully \r\n applying heat until top surface is dry to the touch. \r\n b. Remove all masonry deemed frozen or damaged. \r\n \r\n \r\n 2. Products: \r\n \r\n \r\n a. When brick suction exceeds recommendations of Section 1.03.B.3, \r\n sprinkle with heated water: \r\n \r\n (1) When units are above 32 o F. (0 o \r\n C.), heat water above 70 o F. (21 o C.). \r\n (2) When units are below 32 o F. (0 o \r\n C.), heat water above 130 o F. (54 o C.). \r\n \r\n b. Use dry masonry units. \r\n c. Do not use wet or frozen units. \r\n \r\n \r\n 3. Construction requirements while work is progressing: \r\n \r\n \r\n a. Air temperature 40 o F. (4 o C.) to \r\n 32 o F. (0 o C.): \r\n \r\n (1) Heat sand or mixing water to produce mortar temperatures \r\n between 40 o F. (4 o C.) and 120 o \r\n F. (49 o C.). \r\n \r\n b. Air temperature 32 o F. (0 o C.) to \r\n 25 o F. (-4 o C.): \r\n \r\n (1) Heat sand and mixing water to produce mortar temperatures \r\n between 40 o F. (4 o C.) and 120 o \r\n F. (49 o C.). \r\n (2) Maintain temperatures of mortar on boards above freezing. \r\n \r\n c. Air temperatures 25 o F. (-4 o C.) to \r\n 20 o F. (-7 o C.): \r\n \r\n (1) Heat sand and mixing water to produce mortar temperatures \r\n between 40 o F. (4 o C.) and 120 o \r\n F. (49 o C.). \r\n (2) Maintain mortar temperatures on boards above freezing. \r\n (3) Use salamanders or other heat sources on both sides of \r\n walls under construction. \r\n (4) Use windbreaks when wind is in excess of 15 mph. \r\n \r\n d. Air temperature 20 o F. (-7 o C.) and \r\n below: \r\n \r\n (1) Heat sand and mixing water to produce mortar temperatures \r\n between 40 o F. (4 o C.) and 120 o \r\n F. (49 o C.). \r\n (2) Provide enclosures and auxiliary heat to maintain air \r\n temperature above 32 o F. (0 o C.). \r\n (3) Minimum temperature of units when laid: 20 o \r\n F. (-7 o C.). \r\n \r\n \r\n \r\n 4. Protection requirements for completed masonry and masonry not \r\n being worked on: \r\n \r\n \r\n \r\n a. Mean daily air temperature 40 o F. (4 o \r\n C.) to 32 o F. (0 o C.): \r\n \r\n (1) Protect masonry from rain or snow for 24 hr. by covering \r\n with weather-resistive membrane. \r\n \r\n b. Mean daily air temperature 32 o F. (0 o \r\n C.) to 25 o F. (-4 o C.): \r\n (1) Completely cover masonry with weather-resistive membrane \r\n for 24 hr. \r\n \r\n c Mean daily air temperature 25 o F. (-4 o \r\n C.) to 20 o F. (-7 o C.): \r\n \r\n \r\n (1) Completely cover masonry with insulating blankets or \r\n equal protection for 24 hr. \r\n \r\n \r\n d. Mean daily air temperature 20 o F. (-7 o \r\n C.) and below: \r\n \r\n \r\n \r\n (1) Maintain \r\n masonry temperature above 32 o F. (0 o \r\n C.) for 24 hr. by: \r\n \r\n (a) Enclosure and supplementary heat. \r\n \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n \r\n \r\n (a) Electric heating blankets. \r\n \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n \r\n \r\n (a) Infrared lamps. \r\n \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n \r\n \r\n (a) Other approved methods. \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.05.C.3 Ideal mortar temperature is 70 o F. ┬▒ 10 o \r\n F. (21 o C. ┬▒ 6 o C.). The mixing temperature \r\n should be maintained within 10 o F. (6 o C.). \r\n 1.05.C.4 The following options may be used in cold weather construction: \r\n \r\n 1. Change to a higher type of mortar required in ASTM C 270. \r\n (Example: If ASTM type N mortar is specified for normal temperature, \r\n change to type S or type M.) \r\n 2. Increase the protection time where required in Section 1.05.C.4 \r\n to 48 hr. with no change being made in the type of mortar. \r\n 3. Without changing the mortar type and maintaining 24-hr. \r\n protection in Section 1.05.C.4, replace type I Portland cement \r\n in the mortar with type III, ASTM C 150. \r\n \r\n 1.05.C.4.d This section may be written to allow the contractor \r\n to select means of protection. \r\n \r\n \r\n \r\n \r\n PART II-PRODUCTS \r\n \r\n 2.01 BRICK: \r\n \r\n \r\n A. Facing Brick: \r\n \r\n \r\n 1. ASTM C 216-__________, Grade__________, Type__________. \r\n 2. Dimensions:__________ x __________ x __________. \r\n \r\n (t) (h) \r\n ( l ) \r\n \r\n 3. Minimum compressive strength: _____________. \r\n \r\n 4. Provide brick similar in texture and physical properties to \r\n those available for inspection at the Architect/Engineers office. \r\n 5. Do not exceed variations in color and texture of samples accepted \r\n by the Architect/Engineer. \r\n \r\n \r\n NOTE: \r\n \r\n \r\n 2.01.A.1 Grade: SW for brick in contact with earth or where weathering \r\n index is greater than 50, MW elsewhere. Type: FBS, FBX, FBA. \r\n \r\n 2.01.A.2 Determine availability. Typical \r\n actual sizes for use with 3/8 - in. mortar joints: 3 5/8 x \r\n 2 5/16 x 7 5/8 or 11 5/8 in. (92 x 59 x 194 or 295 mm); 3 5/8 \r\n x 2 13/16 \r\n x 7 5/8 \r\n or 11 5/8 \r\n in. (92 x 74 x 194 or 295 mm): 3 5/8 \r\n x 3 5/8 x \r\n 7 5/8 or \r\n 11 5/8 \r\n in. (92 x 92 x 194 or 295 mm);3 5/8 \r\n x 5 x 7 5/8 \r\n or 11 5/8 \r\n - in (92x 127x 194 or 295 mm);3 5/8 \r\n x 1 5/8 x 11 5/8 \r\n in. (92 x 41 x 295 mm); 5 5/8 x 2 5/16 x 11 5/8 in. (143 x 59 x 295 mm); 5 5/8 x 2 13/16 x 11 5/8 in. (l43 x 74 x 295 mm); 5 5/8 \r\n x 3 5/8 \r\n x 11 5/8 \r\n in. (143 x 92 x 295 mm). \r\n \r\n 2.01.A.3 Required only for structural masonry. Range: 2000 psi \r\n to 14,000 psi (13.8 MPa to 96.5 MPa). \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n A. Facing Brick: Provide a cash allowance of__________per thousand. \r\n B. Glazed Brick: \r\n \r\n \r\n 1. ASTM C 126-__________, Grade__________, Type__________. \r\n 2. Dimensions:__________ x __________ x __________. \r\n \r\n (t) (h) \r\n ( l ) \r\n \r\n 3. Minimum compressive strength:__________. \r\n \r\n NOTE: \r\n \r\n 2.01.B.1 Grade: S for narrow mortar joints; SS where face dimension \r\n variation must be very small. Type: I, II. \r\n 2.01.B.2 See 2.01.A.2. \r\n 2.01. B.3 See 2.01.A.3. \r\n \r\n \r\n C. Building Brick: \r\n \r\n \r\n 1. ASTM C 62-__________, Grade__________. \r\n 2. Dimensions:__________ x __________ x __________. \r\n \r\n (t) (h) \r\n ( l ) \r\n \r\n 3. Minimum compressive strength:__________. \r\n \r\n \r\n NOTE: \r\n \r\n 2.01.C.1 Grade: SW for brick in contact with earth or where weathering \r\n index is greater than 50, MW elsewhere, NW in interior and backup \r\n areas. \r\n 2.01.C.2 See 2.01.A.2. \r\n 2.01.C.3 See 2.01.A.3. \r\n \r\n \r\n \r\n D. Hollow Brick: \r\n \r\n \r\n 1. ASTM C 652-__________, Grade__________, Type__________. \r\n 2. Dimensions:__________ x __________ x __________. \r\n \r\n (t) (h) \r\n ( l ) \r\n \r\n 3. Minimum compressive strength:__________. \r\n \r\n \r\n 4. Provide brick similar in texture and physical properties to \r\n those available for inspection at the Architect/Engineers office. \r\n 5. Do not exceed variation in color and texture of samples accepted \r\n by the Architect/Engineer. \r\n \r\n NOTE: \r\n \r\n 2.01.D.1 Grade: SW for brick in contact with earth or where weathering \r\n index is greater than 50, MW elsewhere. Type: HBS, HBX, HBA, HBB. \r\n 2.01.D.2 See 2.01.A.2. \r\n 2.01.D.3 See 2.01.A.3. \r\n \r\n \r\n \r\n \r\n 2.02 REINFORCEMENT: \r\n \r\n \r\n A. Cold-drawn steel wire: ASTM A 82-__________. \r\n B. Welded steel wire fabric: ASTM A 185-__________. \r\n C. Billet steel deformed bars: ASTM A 615-_________, Grade__________. \r\n D. Rail steel deformed bars: ASTM A 616-__________, Grade_________. \r\n E. Axle steel deformed bars: ASTM A 617-__________, Grade__________. \r\n \r\n NOTE: \r\n \r\n 2.02.C Grade 40, 50, 60. \r\n 2.02.D Grade 50, 60. \r\n 2.02.E Grade 40, 60. \r\n \r\n \r\n 2.03 ANCHORS AND TIES: \r\n \r\n \r\n A. Coated or corrosion-resistant metal meeting or exceeding applicable \r\n standard: \r\n \r\n 1. Zinc-coating flat metal: ASTM A 153-__________, Class__________. \r\n 2. Zinc-coating of wire, ASTM A 116-__________, Class 3. \r\n 3. Copper-coated wire: ASTM B 227-__________ , Grade 30HS. \r\n 4. Stainless steel: ASTM A 167-__________, Type 304. \r\n \r\n \r\n NOTE: \r\n \r\n 2.03.A.1 Class B-1, B-2, B-3. \r\n \r\n B. Types: \r\n \r\n 1. Wire mesh: \r\n \r\n a. Minimum gage: 20. \r\n b. Mesh: 1/2 in. (12.7 mm). \r\n c. Galvanized wire. \r\n d. Width: 1 in. (25 mm) less than width of masonry. \r\n \r\n 2. Corrugated veneer ties: \r\n \r\n a. Minimum gage: 22. \r\n b. Minimum width: 7/8 in. (22 mm). \r\n c. Length: 6 in. (152 mm) \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n 2. Wire ties: Use two 10-gage. \r\n 3. Cavity wall ties: \r\n \r\n a. Wire diameter: 3/16 in. (4.7 mm). \r\n \r\n b. Shape: Rectangular, at least 2 in. (51 mm) wide with ends \r\n overlapped or \"Z\" with 2 - in. (51 mm) legs. \r\n c. Length: Select length to allow 1 - in. (25 mm) minimum mortar \r\n cover of ends or legs. \r\n \r\n \r\n 4. Multi-wythe wall ties: \r\n \r\n \r\n a. Prefabricated welded joint reinforcement. \r\n b. Longitudinal cross tie wire: \r\n \r\n (1) 9 gage. \r\n (2) Spaced 16 in. (406 mm) o.c. \r\n \r\n \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 2.03.B.4 Cavity wall ties may be used. \r\n \r\n \r\n 5. Dovetail flat bar or wire anchors: \r\n \r\n \r\n a. Flat bar: \r\n \r\n (1) Minimum gage: 16. \r\n (2) Minimum width: 7/8 in. (22 mm). \r\n (3) Fabrication: Corrugated, turned up 1/4 in. (6.4 mm) at \r\n end or with 1/2-in. (12.7 mm) hole within 1/2 in. (12.7 mm) \r\n of end of bar. \r\n \r\n \r\n b. Wire: \r\n \r\n (1) Wire gage: 6. \r\n (2) Minimum width: 7/8 in. (22 mm). \r\n (3) Fabrication: Wire looped and closed. \r\n \r\n \r\n 6. Rigid anchors for intersecting bearing walls: \r\n \r\n \r\n a. Dimensions: 1 1/2 in. (38 mm) wide by 1/4 in. (6.4 mm) thick \r\n by minimum 24 in. (610 mm) long. \r\n b. Fabrication: Turn up ends minimum 2 in. (51 mm) or provide \r\n cross pins. \r\n \r\n \r\n 7. Wire ties for high-lift grout reinforced brick masonry: \r\n \r\n \r\n a. Minimum gage: 9. \r\n b. Fabrication: \r\n \r\n (1) Bend into stirrups 4 in. (102 mm) wide and 2 in. (51 \r\n mm) shorter than overall wall thickness. \r\n (2) Form so that tie ends meet in center of one embedded \r\n end of stirrup. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 2.04 CLEANING AGENTS: \r\n \r\n \r\n \r\n A. Do not use cleaning agent other than water on brick, except \r\n with concurrence of Architect/Engineer. \r\n B. Acceptable cleaner for dark brick: _____________. \r\n \r\n C. Acceptable cleaner for light colored brick: _______________. \r\n \r\n NOTE: \r\n \r\n 2.04.B Specify cleaner recommended by brick manufacturer. \r\n 2.04.C Proper cleaning agent is more critical for light colored brick. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60057,"ResultID":176289,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11B - Guide Specifications \r\n for Brick Masonry, \r\n Part 3 \r\n Feb. 1972 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n This Technical Notes contains \r\n the guide specifications in CSI format for Part III - Execution. Part \r\n I - General, and Part II - Products are in Technical Notes 11A \r\n Revised. \r\n Guide Specification and Notes \r\n PART III - EXECUTION \r\n 3.01 PREPARATION: \r\n \r\n A. Wetting Brick: \r\n 1. Wet brick with absorption rates \r\n in excess of 30 g./30 sq. in./min. (30 g./194 cm 2 /min.) determined by \r\n ASTM C 67-__________, so that rate of absorption when laid does \r\n not exceed this amount. \r\n 2. Recommended procedure to insure \r\n that brick are nearly saturated, surface dry when laid is to place \r\n a hose on the pile of brick until the water runs from the pile. \r\n This should be done one day before brick are to be used. In extremely \r\n warm weather, place hose on pile several hours before brick are \r\n to be used. \r\n \r\n B. Cleaning Reinforcement: Before being placed, remove loose rust, ice \r\n and other coatings from reinforcement. \r\n \r\n NOTE: 3.01.A.1 \r\n Note requirements for cold weather, section 1.05.C.2.a, and section \r\n 1.03.B.3 for testing requirements. \r\n \r\n \r\n \r\n \r\n 3.02 GENERAL ERECTION REQUIREMENTS: \r\n A. Pattern Bond: \r\n 1. Lay exposed masonry in running \r\n bond. \r\n 2. Bond unexposed masonry units \r\n in a wythe by lapping at least 2 in. ( 51 mm). \r\n \r\n \r\n NOTE: 3.02.A.1 Alter \r\n if other than running bond required. \r\n B. Joining of Work: \r\n \r\n 1. Where fresh masonry joins partially \r\n set masonry: \r\n a. Remove loose brick and mortar. \r\n b. Clean and lightly wet exposed \r\n surface of set masonry. \r\n \r\n 2. Stop off horizontal run of masonry \r\n by racking back 1/2 length of unit in each course. \r\n 3. Toothing is not permitted except \r\n upon written acceptance of the Architect/Engineer. \r\n \r\n \r\n C. Tooling and Tuck Pointing: \r\n \r\n 1. Tooling: \r\n a. Tool exposed joints when \r\n \"thumb-print\" hard with a round jointer, slightly larger than \r\n width of joint. \r\n b. Trowel-point or concave-tool \r\n exterior joints below grade. \r\n c. Flush cut all joints not \r\n tooled. \r\n \r\n 2. Tuck pointing: \r\n a. Rake mortar joints to a depth \r\n of not less than 1/2 in.(12.7 mm) nor more than 3/4 in. (19 mm). \r\n b. Saturate joints with clean \r\n water. \r\n c. Fill solidly with ______________ \r\n pointing mortar. \r\n d. Tool joints. \r\n \r\n NOTE: \r\n 3.02.C Alter to allow other joints \r\n to meet architectural requirements. \r\n 3.02.C.2 Delete if not required. \r\n 3.02.C.2.c Specify proportions. \r\n Pointing mortar should be of same proportions as mortar in main \r\n part of wall, if known; if not, type N. \r\n \r\n \r\n D. Flashing: \r\n \r\n 1. Clean surface of masonry smooth \r\n and free from projections which might puncture flashing material. \r\n a. Place through-wall flashing \r\n on bed of mortar. \r\n b. Cover flashing with mortar. \r\n \r\n \r\n \r\n E. Weep Holes: \r\n \r\n 1. Provide weep holes in head \r\n joints in first course immediately above all flashing by: (a) Leaving \r\n head joint free and clean of mortar \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n (a) Placing and leaving sash \r\n cord in joint. \r\n \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n 2. Maximum spacing: 24 in. (610 \r\n mm) o.c. \r\n 3. Keep weep holes and area above \r\n flashing free of mortar droppings. \r\n \r\n F. Sealant Recesses: \r\n \r\n 1. Leave joints around outside \r\n perimeters of exterior doors, window frames and other wall openings: \r\n a. Depth: uniform 3/4 in. (19 \r\n mm). \r\n b. Width: 1/4 in. (6.4 mm) to \r\n 3/8 in. (9.5 mm). \r\n \r\n \r\n \r\n G. Movement Joints: \r\n 1. Keep clean from all mortar and \r\n debris. \r\n 2. Locate as shown on drawings. \r\n \r\n H. Cutting Brick: \r\n 1. Cut exposed brick with motor-driven \r\n saw. \r\n \r\n \r\n **OR** \r\n \r\n \r\n 1. By other methods which provide \r\n cuts that are straight and true. \r\n \r\n \r\n ******** \r\n \r\n I. Mortar Joint Thickness: \r\n 1. Lay all brick with__________in. \r\n joint. \r\n \r\n NOTE: 3.02.I Coordinate \r\n joint thickness with brick specified in 2.01.A.2. \r\n \r\n 3.03 NON-REINFORCED BRICK MASONRY \r\n A. Brick Installation: \r\n \r\n 1. Lay brick plumb and true to \r\n lines. \r\n 2. Lay with completely filled \r\n mortar joints. \r\n 3. Do not furrow bed joints. \r\n 4. Butter ends of brick with sufficient \r\n mortar to fill head joints. \r\n 5. Rock closures into place with \r\n head joints thrown against two adjacent brick in place. \r\n 6. Fill vertical, longitudinal \r\n joints, except in cavity walls: \r\n a. By parging either face of \r\n backing or back of facing. \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. By pouring the vertical joint \r\n full of grout. \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. Shoving alone. \r\n 7. Do not pound corners and jambs to fit stretcher units \r\n after they are set in position. Where an adjustment must be made \r\n after mortar has started to harden, remove mortar and replace with \r\n fresh mortar. \r\n \r\n \r\n NOTE: 3.03.A If hollow \r\n units are specified, alter to conform to requirements of the units. \r\n B. Cavity Walls: \r\n 1. Keep cavity in cavity walls clean \r\n by: \r\n a. Slightly beveling mortar bed \r\n to incline toward cavity. \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n a. Placing wood strips with attached \r\n wire pulls on metal ties. \r\n b. Before placing next row of \r\n metal ties, remove and clean wood strips. \r\n \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n \r\n 2. As work progresses, trowel \r\n protruding mortar fins in cavity flat on to inner face of wythe. \r\n \r\n C. Non-Bearing Partitions: \r\n \r\n 1. Extend from top of structural \r\n floor to bottom surface of floor construction above. \r\n 2. Wedge with small pieces of \r\n tile, slate or metal. \r\n 3. Fill topmost joint with mortar. \r\n \r\n \r\n NOTE: 3.03.C Alter to \r\n local code requirements if suspended ceilings are used. \r\n D. Structural Bonding: \r\n \r\n 1. Bond or anchor corners and \r\n intersections of loadbearing brick walls. \r\n 2. Structural bond multi-wythe \r\n non-reinforced brick walls with__________. \r\n a. Extend headers not less than \r\n 3 in. (76 mm) into backing. \r\n b. Maximum distance between \r\n adjacent headers: 24 in. (610 mm) either vertically or horizontally. \r\n c. When a single header does \r\n not extend through wall, overlap headers from opposite sides \r\n of wall at least 3 in. (76 mm). \r\n d. Minimum headers: 4%. \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. Provide minimum of one cavity \r\n wall tie for each 4 1/2 sq. ft. (0.42 m 2 ) of wall surface. \r\n b. Stagger ties in alternate \r\n courses. \r\n c. Maximum distance between \r\n adjacent ties: \r\n (1) Vertically: 24 in. (610 \r\n mm). \r\n (2) Horizontally: 36 in. (920 \r\n mm). \r\n \r\n d. Embed ties in horizontal joints \r\n of facing and backing. \r\n e. Provide additional ties at \r\n openings: \r\n (1) Maximum spacing around \r\n perimeter: 36 in. (920 mm). \r\n (2) Install within 12 in. \r\n (305 mm) of opening. \r\n \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. Use continuous prefabricated \r\n joint reinforcement to bond multi-wythe walls; spaced not more \r\n than 16 in. (406 mm) vertically. \r\n \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n \r\n 3. Stack bond: \r\n a. Embed continuous No. 2 steel \r\n reinforcement or No. 9 gage wire in horizontal joints at vertical \r\n intervals not to exceed 16 in. (406 mm). \r\n b. Provide not less than one \r\n longitudinal bar or wire for each 6 in. (152 mm) of wall thickness \r\n or fraction thereof. \r\n \r\n \r\n \r\n NOTE: \r\n 3.03.D Note special bonding requirements \r\n for high-lift grout, section 3.05.B. \r\n 3.03.D.2 Masonry headers, metal ties \r\n or continuous joint reinforcement. \r\n E. Anchoring: \r\n \r\n 1. Anchor exterior brick walls \r\n facing or abutting concrete members with dovetail, flat-bar or wire \r\n anchors inserted in slots built into concrete. \r\n a. Maximum anchor spacing: \r\n (1) Vertically: 24 in. (610 \r\n mm). \r\n (2) Horizontally: 36 in. (920 \r\n mm). \r\n \r\n b. Maintain a space not less than \r\n 1/2 in. (12.7 mm) wide between masonry wall and concrete members. \r\n c. Keep space free of mortar \r\n or other rigid material to permit differential movement between \r\n concrete and masonry . \r\n \r\n 2. For intersecting bearing or shear \r\n walls carried up separately: \r\n a. Regularly block vertical \r\n joint with 8-in. (203 mm) maximum offsets. \r\n b. Provide joints with rigid \r\n steel anchors. \r\n c. Space anchors not more than \r\n 4 ft. (1.2 m) apart vertically. \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. When acceptable to the Architect/Engineer, \r\n eliminate blocking and provide rigid steel anchors spaced not \r\n more than 24 in. (610 mm) apart vertically. \r\n \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n \r\n 3. Anchor non-bearing partitions \r\n abutting or intersecting other walls or partitions with: \r\n a. Cavity wall ties at vertical \r\n intervals of not more than 24 in. ( 610 mm). \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n a. Masonry bonders in alternate \r\n courses \r\n \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n \r\n 4. Attach brick veneer to backing \r\n with metal veneer ties: \r\n a. Use one tie for each 4 sq. \r\n ft. (0.37 m 2 \r\n ) of wall area. \r\n b. Maximum space between adjacent \r\n ties: \r\n (1) Vertically and horizontally: \r\n 24 in. (610 mm). \r\n c. Embed ties at least 2 in. (51 \r\n mm) in horizontal joint of facing. \r\n d. Provide additional ties at \r\n openings: \r\n (1) Maximum spacing around \r\n perimeter: 36 in. (914 mm). \r\n (2) Install within 12 in. \r\n (305 mm) of opening. \r\n \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 3.03.E 4 Tie spacing is based \r\n on a design wind pressure of 20 psf (958 N/m 2 ). Maximum \r\n spacing should be decreased for higher wind pressures. Recommended \r\n spacing for: \r\n 30 psf (1436 N/m2): \r\n Vertically: 24 in. (610 mm) \r\n Horizontally: 16 in. (406 mm) \r\n \r\n 40 psf (1913 N/m2): \r\n Vertically: 18 in. (457 mm) \r\n Horizontally: 16 in. (406 mm) \r\n \r\n \r\n \r\n \r\n 3.04 REINFORCED BRICK MASONRY: \r\n A. Brick Installation: \r\n \r\n 1. Lay brick plumb and true to \r\n lines. \r\n 2. Lay with completely filled \r\n mortar joints. \r\n 3. Do not furrow bed joints. \r\n 4. Butter ends of brick with sufficient \r\n mortar to fill head joints. \r\n 5. Slightly bevel mortar bed to \r\n incline towards cavity. \r\n 6. Rock closures into place with \r\n head joints thrown against two adjacent brick in place. \r\n 7. Do not pound corners and jambs \r\n to fit stretcher units after they are set in position. Where an \r\n adjustment must be made after mortar has started to harden, remove \r\n mortar and replace with fresh mortar. \r\n \r\n \r\n NOTE: 3.04.A If hollow \r\n units are specified, alter to conform to requirements of the units. \r\n B. Forms and Shores: \r\n \r\n 1. Provide substantial and tight \r\n forms. \r\n 2. Leakage of mortar or grout \r\n is not permitted. \r\n 3. Brace or tie forms to maintain \r\n position and shape. \r\n 4. Do not remove forms and shores \r\n until masonry has hardened sufficiently to carry its own weight \r\n and other temporary loads that may be placed on it during construction: \r\n a. For girders and beams: Minimum \r\n 10 days. \r\n b. Under brick slabs: Minimum \r\n 7 days. \r\n \r\n \r\n \r\n C. Placing Reinforcement: \r\n \r\n 1. Position metal reinforcement \r\n accurately. \r\n 2. Secure against displacement: \r\n a. Hold vertical reinforcement \r\n firmly in place by means of frames or other suitable devices. \r\n b. Horizontal reinforcement \r\n may be placed as brickwork progresses. \r\n \r\n \r\n 3. Spacing: \r\n \r\n a. Minimum clear distance between \r\n longitudinal bars, except in columns: Nominal diameter of bar \r\n or 1 in. (25 mm). \r\n b. Minimum clear distance between \r\n bars in columns: Not less than 1/2 times bar diameter or 1/2 \r\n in. (38 mm). 4 \r\n \r\n 4. Minimum thickness of mortar or \r\n grout between brick and reinforcement: 1/4 in. (6.4 mm), except: \r\n a. 1/4 - in. (6.4 mm) bars may \r\n be laid in 1/2-in.(12.7 mm) horizontal mortar joints. \r\n b. No. 6 gage or smaller wires \r\n may be laid in 3/8-in. (9.5 mm) mortar joints. \r\n \r\n 5. Minimum width of collar Joints containing both horizontal and vertical \r\n reinforcement: 1/2 in. (12.7 mm) larger than sum of diameters of \r\n horizontal and vertical reinforcement. \r\n 6. Splice reinforcement or attach \r\n reinforcement to dowels by placing in contact and wiring. \r\n 7. Do not splice reinforcement \r\n at points other than shown on drawings, unless approved by the \r\n structural engineer. \r\n 8. Shape and dimension reinforcement \r\n as shown on drawings: \r\n a. Cold bend all bars. \r\n b. Do not straighten or repair \r\n in a manner that will injure material. \r\n c. Do not use bars with kinks \r\n or bends not shown on drawings. \r\n d. Reinforcement can be heated \r\n when entire operation is approved by structural engineer. \r\n \r\n \r\n \r\n \r\n 3.05 GROUTING: \r\n A. Low-Lift Grouting: \r\n 1. Keep grout core clean from mortar \r\n and drippings. \r\n 2. Grout spaces less than 2 in. \r\n (51 mm) in width at intervals of not more than 24 in. (610 mm) in \r\n lifts of 6 to 8 in. (152 to 203 mm) as the wall is built. \r\n 3. In grout spaces more than 2 \r\n brick in thickness: \r\n a. Place or float brick in grout. \r\n b. Minimum grout between brick: \r\n 3/8 in. (9.5 mm). \r\n \r\n 4. Agitate or puddle grout during \r\n and after placement to insure complete filling. \r\n 5. Stop grout 1/2 in. (38 mm) \r\n below top of masonry: \r\n a. If grouting is stopped for \r\n 1 hr. or more. \r\n b. Except when completing grouting \r\n of finished wall. \r\n \r\n 6. If brick headers are used for \r\n ties in low-lift grouting space: \r\n a. Maximum: 8% of wall area. \r\n NOTE: 3.05.A.6 \r\n Using headers for tying wythes is not recommended; however, if \r\n selected, construction should conform to the requirements of this \r\n section. \r\n \r\n \r\n B. High-Lift Grouting: \r\n \r\n 1. For running bond, provide one \r\n metal tie for each 3 sq. ft. (0.28 m 2 ) of wall with maximum \r\n spacing: \r\n a. Vertically: 16 in. (406 mm). \r\n b. Horizontally: 24 in. (610 \r\n mm). \r\n \r\n 2. For stack bond, provide one metal \r\n tie for each 2 sq. ft. (0.19 m 2 ) of wall with maximum \r\n spacing: \r\n a. Vertically: 12 in. (305 mm). \r\n b. Horizontally: 24 in. (610 \r\n mm). \r\n \r\n 3. Keep grout core clean from mortar \r\n and droppings. \r\n 4. Provide cleanout holes by omitting \r\n every other brick in bottom course on one side of wall. \r\n 5. Prior to closing cleanout holes \r\n and pouring grout, use high-pressure jet stream of water or high-pressure \r\n air to remove excess mortar from grout space and to clean reinforcement. \r\n 6. Do not plug cleanout holes \r\n until condition of area to be grouted has been approved. \r\n 7. Before pouring grout, plug \r\n cleanout holes with masonry units and brace against grout pressure. \r\n 8. Grout spaces 2 in. (51 mm) \r\n or more in width in lifts not exceeding 4 ft. (1.2 m) at intervals: \r\n a. Coarse grout: Not more than \r\n 48 times the least clear dimension of grout space. \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n a. Fine grout: Not more than 64 \r\n times the least clear dimension of grout space. \r\n \r\n \r\n \r\n ******** \r\n \r\n \r\n \r\n \r\n b. Not to exceed height of 12 \r\n ft. (3.7 m). \r\n 9. Do not place grout until the entire \r\n wall has been in place 3 days. \r\n 10. Vibrate or agitate grout during, \r\n and after placement to insure complete filling of grout space. \r\n 11. Stop grout 1 1/2 in. (38 mm) \r\n below top of masonry: \r\n a. If grouting is stopped for \r\n 1 hr. or more. \r\n b. Except when completing grouting \r\n of finished wall. \r\n \r\n 12. Provide grout blocks at convenient \r\n intervals to meet project requirements. \r\n \r\n \r\n 3.06 CLEANING: \r\n A. Cut out any defective joints and \r\n holes in exposed masonry and repoint with mortar. \r\n B. Clean all exposed unglazed masonry: \r\n \r\n 1. Apply cleaning agent to sample \r\n wall area of 20 sq. ft. (2 m 2 \r\n ) in location acceptable to the Architect/Engineer. \r\n 2. Do not proceed with cleaning \r\n until sample area is approved by Architect/Engineer. \r\n 3. Clean initially with stiff \r\n brushes and water. \r\n 4. When cleaning agent is required: \r\n a. Follow brick manufacturers \r\n recommendations. \r\n b. Thoroughly wet surface of \r\n masonry on which no green efflorescence appears. \r\n c. Scrub with acceptable cleaning \r\n agent. \r\n d. Immediately rinse with clear \r\n water. \r\n e. Do small sections at a time. \r\n f. Work from top to bottom. \r\n g. Protect all sash, metal lintels \r\n and other corrodible parts when masonry is cleaned with acid \r\n solution. \r\n h. Remove green efflorescence \r\n in accordance with brick manufacturers recommendations. \r\n \r\n \r\n \r\n NOTE: 3.06 If care is \r\n taken during laying and the wall is acceptable, the requirements of \r\n this section can be deleted. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60058,"ResultID":176290,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11C - Guide Specifications for Brick Masonry, \r\n Part 4 \r\n July 1972 (Reissued May 1998) \r\n \r\n \r\n INTRODUCTION \r\n \r\n \r\n This issue of Technical Notes and the following issue, Technical \r\n Notes 11D , contain the required additional \r\n sections and statements to be incorporated into the \"Guide Specifications \r\n for Brick Masonry\", Technical Notes 11A \r\n Revised and 11B Revised. This will make \r\n the guide specifications in those Technical Notes suitable for \r\n Engineered Brick Masonry. \r\n The sections contained in these Technical Notes deal primarily \r\n with the quality assurance, selection of units, strength and construction \r\n tolerances to provide masonry that meets the minimum design requirements \r\n for Engineered Brick Masonry. \r\n In the construction of Engineered Brick Masonry, quality control may \r\n be maintained in either of two ways: (1) by testing the brick and controlling \r\n the mortar which can be done by laboratory tests or by mixing proportions, \r\n or (2) by periodic testing of masonry prisms. This Technical Notes \r\n covers quality control by method (1), testing brick and control \r\n of mortar. Technical Notes 11D \r\n covers quality control by method (2), testing masonry prisms. \r\n \r\n When quality control by materials testing (brick \r\n and mortar) is to be used, the design compressive strength (f m ) can be assumed, using Table \r\n 2 of the BIA Standard, \"Building Code Requirements for Engineered Brick \r\n Masonry\", and the quality control requirements of this Technical \r\n Notes should be incorporated into the guide specifications in Technical \r\n Notes 11A Revised and 11B \r\n Revised. \r\n \r\n All other sections of the Guide Specifications for Brick Masonry (Technical \r\n Notes 11A Revised and 11B \r\n Revised) are appropriate for Engineered Brick Masonry. \r\n \r\n QUALITY ASSURANCE BASED ON BRICK AND MORTAR TESTS \r\n Guide Specifications and Notes \r\n \r\n PART I - GENERAL \r\n \r\n 1.02 QUALITY ASSURANCE \r\n \r\n \r\n Delete section and notes for 1.02.A in Technical Notes 11A \r\n Revised , and substitute the following quality control requirements \r\n based on brick tests. \r\n A. Brick Tests: \r\n \r\n \r\n \r\n 1. Preconstruction Tests: \r\n \r\n a. Test five brick for compressive strength to determine acceptability \r\n of units for compliance with specifications. \r\n b. Use brick similar to those selected for use, matching color, \r\n texture, raw material, moisture content and coring. \r\n c. Cost of tests shall be borne by the General Contractor. \r\n \r\n 2. Site Control Tests: \r\n \r\n a. Test units selected at random from units delivered to the \r\n project. \r\n b. Cost of tests of units after delivery shall be borne by \r\n the General Contractor, unless tests indicate that units do \r\n not conform to the requirements of the specifications, in which \r\n case cost shall be borne by the seller. \r\n \r\n 3. Test in accordance with ASTM C 67-__________, with the following \r\n additional requirements: \r\n \r\n \r\n a. If the coefficient of variation of the compression samples \r\n tested exceeds 12%, obtain compressive strength by multiplying \r\n average compressive strength of specimens by \r\n 1 - 1.5 ( V - 0.12 ) \r\n 100 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where v is the coefficient of variation of sample tested. \r\n \r\n \r\n \r\n \r\n Add the following to Section 1.02 in Technical Notes 11A Revised. \r\n C. Preconstruction Requirements: \r\n \r\n \r\n 1. Prebid conference: \r\n \r\n \r\n \r\n a. A prebid conference, directed by the Architect/Engineer, \r\n will be held one week prior to the bid opening to discuss: \r\n \r\n (1) Structural concept. \r\n (2) Method and sequence of masonry construction. \r\n (3) Special masonry details. \r\n (4) Quality control requirements. \r\n (5) Material requirements. \r\n (6) Job organization. \r\n (7) Workmanship. \r\n \r\n b. Attendance is mandatory for all prospective: \r\n \r\n (1) General contractors. \r\n (2) Masonry subcontractors. \r\n (3) Brick suppliers. \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C This requirement may be deleted if not necessary for the \r\n project due to bidders being knowledgeable with engineered brick \r\n masonry. \r\n 1.02.C.1.b Invitation to attend should be extended to others, \r\n such as the inspectors (local building department and other government \r\n agencies) and Owner. \r\n \r\n \r\n 2. Preconstruction Testing and Certification: \r\n \r\n \r\n \r\n a. After award of the contract, the General Contractor shall: \r\n \r\n (1) Within 14 days, submit to the Architect/Engineer for \r\n approval the name of the independent laboratory which will \r\n perform the site control tests and provide the certificates \r\n and test reports required in Section 1.03. \r\n (2) Upon approval of the laboratory, certificates and test \r\n reports, and prior to any masonry construction, make arrangements \r\n for the following tests: \r\n \r\n (a) Brick tests in accordance with preconstruction requirements, \r\n Section 1.02.A \r\n (b) Mortar tests in accordance with mortar section. \r\n \r\n \r\n b. Masonry work can begin only after approval of testing. \r\n c. Testing is acceptable if test results indicate that materials \r\n meet the minimum requirements of Part II - Products. \r\n d. Cost of preconstruction testing shall be borne by the General \r\n Contractor, unless tests indicate that units do not conform \r\n to the requirements of the specifications, in which case cost \r\n shall be borne by the seller. \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C.2 Inspection, laboratory and testing for quality control \r\n can be a responsibility of the Structural Engineer. If so, revise \r\n section. \r\n \r\n \r\n 3. Preconstruction Conference: \r\n \r\n \r\n \r\n a. A preconstruction conference, directed by the Architect/Engineer, \r\n will be held after the award of the General Contract, but prior \r\n to beginning of masonry work to discuss: \r\n \r\n (1) Structural concept. \r\n (2) Method and sequence of masonry construction. \r\n (3) Special masonry details. \r\n (4) Standard of workmanship. \r\n (5) Quality control requirements. \r\n (6) Job organization. \r\n \r\n b. Attendance is mandatory for: \r\n \r\n (1) General contractor job superintendent. \r\n (2) Masonry subcontractor job superintendent. \r\n (3) Masonry subcontractor foreman. \r\n (4) At least two masons. \r\n (5) Authorized representative of the brick supplier. \r\n (6) Mortar material suppliers. \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C.3.b Invitations to attend should be extended to others, \r\n such as inspectors (local building department and other government \r\n agencies) and Owner. \r\n \r\n \r\n \r\n D. Job Site Quality Control: \r\n \r\n \r\n \r\n 1. Site control brick and mortar tests: \r\n \r\n a. Use compressive strength of brick units and compressive \r\n strength of mortar cubes to control quality. \r\n b. Test brick in accordance with site control requirements, \r\n Section 1.02.A. \r\n c. Test mortar cubes in accordance with mortar section. \r\n d. Test five brick and three mortar cubes for each 100,000 \r\n brick or fraction thereof. \r\n e. Brick and mortar to be selected at random by the Architect/ \r\n Engineer. \r\n f. Site control data shall be acceptable if material exceeds \r\n specified strength. \r\n g. Cost of tests shall be borne by the General Contractor. \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.D.1.c Type M, S or N as specified in the mortar section. \r\n More than one mortar type may be specified. If so, provide sections \r\n to cover all requirements. Mortar design compressive strengths \r\n should be based on laboratory tests of mortar made from materials \r\n mixed to the proportion specification as required by the mortar \r\n section. \r\n 1.02.D.1.e As calculated by the Structural Engineer. May vary \r\n for different parts of the building. If so, provide sections to \r\n cover all design strengths. \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n 1. Site control brick and mortar batching: \r\n \r\n \r\n a. Use compressive strength of brick units and control on material \r\n proportions used in batching mortar to control quality. \r\n b. Test brick in accordance with site control requirements, \r\n Section 1.02.A. \r\n c. Control mortar batches to conform to proportion specification \r\n specified in mortar section. \r\n d. Test five brick for each 100,000 brick or fraction thereof. \r\n e. Site control data shall be acceptable if brick compressive \r\n strengths meet the requirements of Part II and mortar is batched \r\n to proportion specification. \r\n f. Cost of tests shall be borne by the General Contractor. \r\n \r\n \r\n \r\n \r\n \r\n PART II - PRODUCTS \r\n \r\n 2.01 BRICK \r\n \r\n \r\n A. Facing Brick: \r\n \r\n \r\n 1. Delete Note and replace with: \r\n \r\n \r\n NOTE: \r\n \r\n 2.01.A.1 Grades and Types. Brick subject to the action of weather \r\n or soil, but not subject to frost action when permeated with water, \r\n shall be of grade MW or grade SW, and where subject to temperature \r\n below freezing while in contact with soil shall be grade SW. Brick \r\n used in loadbearing or shear wall construction shall comply with \r\n the dimensional and distortion tolerances specified for type FBS \r\n of ASTM C 216-__________. Where such brick do not comply with \r\n these tolerance requirements, the compressive strength of brick \r\n masonry shall be determined by prism tests. \r\n \r\n \r\n \r\n \r\n PART Ill - EXECUTION \r\n \r\n 3.02 GENERAL ERECTION REQUIREMENTS \r\n \r\n \r\n Delete Section 3.02.I in Technical Notes 11B Revised, and \r\n replace with the following Section 3. 02.I and add Section 3. 02.J. \r\n I. Mortar Joint Thickness \r\n \r\n \r\n 1. Lay brick with __________-in. mortar joints, not to exceed \r\n 1/2 in. (12.7 mm). \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 3.02.I Coordinate joint thickness with brick specified in 2.01.A.2. \r\n \r\n J. Construction Tolerances: \r\n \r\n \r\n \r\n 1. Maximum variation from plumb in vertical lines and surfaces \r\n of columns, walls and arrises: \r\n \r\n a. 1/4 in. (6.4 mm) in 10 ft. (3 m). \r\n b. 3/8 in. (9.6 mm) in a story height not to exceed 20 ft. \r\n (6 m). \r\n c. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 2. Maximum variation from plumb for external corners, expansion \r\n joints and other conspicuous lines: \r\n \r\n a. 1/4 in. (6.4 mm) in any story or 20 ft. (6 m) maximum. \r\n b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 3. Maximum variation from level of grades for exposed lintels, \r\n sills, parapets, horizontal grooves and other conspicuous lines: \r\n \r\n a. 1/4 in. (6.4 mm) in any bay or 20 ft. (6 m). \r\n b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 4. Maximum variation from plan location of related portions of \r\n columns, walls and partitions: \r\n \r\n a. 1/2 in. (12.7 mm) in any bay or 20 ft. (6 m). \r\n b. 3/4 in. (19 mm) in 40 ft. (12 m) or more. \r\n \r\n 5. Maximum variation in cross-sectional dimensions of columns \r\n and thicknesses of walls from dimensions shown on drawings: \r\n \r\n a. Minus 1/4 in. (6.4 mm). \r\n b. Plus 1/2 in. (12.7 mm). \r\n \r\n \r\n NOTE: \r\n \r\n 3.02.J These construction tolerances are for engineered brick \r\n masonry only, and are based on actual dimensions. They are intended \r\n for the sole purpose of protecting the structural integrity of \r\n engineered brick masonry elements and may not be adequate for \r\n establishing construction tolerances associated with esthetics \r\n or visual requirements. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60059,"ResultID":176291,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11D - Guide Specifications for Brick \r\n Masonry, \r\n Part 4 Continued \r\n Aug. 1972 (Reissued Sept. 1988) \r\n \r\n \r\n INTRODUCTION \r\n \r\n \r\n \r\n This issue of Technical Notes is a continuation of Technical \r\n Notes 11C Revised and contains \r\n additional sections and statements to be incorporated into the \"Guide \r\n Specifications for Brick Masonry\", Technical Notes 11A \r\n Revised and 11B Revised. This will \r\n make the guide specifications in those Technical Notes suitable \r\n for Engineered Brick Masonry. \r\n The sections contained in these Technical Notes deal primarily \r\n with the quality assurance, selection of units, strength and construction \r\n tolerances to provide masonry that meets the minimum design requirements \r\n for Engineered Brick Masonry. \r\n \r\n In the construction of Engineered Brick Masonry, quality control \r\n may be maintained in either of two ways: (1) by testing the brick \r\n and controlling the mortar which can be done by laboratory tests or \r\n by mixing proportions, or (2) by periodic testing of masonry prisms. \r\n This Technical Notes covers quality control by method (2), \r\n prism testing. Technical Notes 11C \r\n covers quality control by method (1), testing brick and control of \r\n mortar. \r\n \r\n When quality control is maintained by prism tests, the brick masonry \r\n strength is determined in accordance with paragraph 4.2.2.1 of the \r\n BIA Standard, \"Building Code Requirements for Engineered Brick Masonry\". \r\n Test prisms are built as the walls are constructed and tested in compression \r\n at 7 days or 28 days. If prism tests are used, the quality control \r\n requirements of this Technical Notes should be incorporated \r\n into the guide specifications in Technical Notes 11A \r\n Revised and 11B Revised. \r\n \r\n All other sections of the Guide Specifications for Brick Masonry \r\n (Technical Notes 11A Revised \r\n and 11B Revised) are appropriate for \r\n Engineered Brick Masonry. \r\n \r\n QUALITY ASSURANCE BASED ON PRISM TESTS \r\n Guide Specification and Notes \r\n \r\n PART I - GENERAL \r\n \r\n 1.02 QUALITY ASSURANCE \r\n \r\n \r\n Delete sections and notes for 1.02 in Technical Notes \r\n 11A Revised, and substitute the following quality control requirements \r\n based on prism tests. \r\n A. Prism Tests: \r\n \r\n \r\n 1. Preconstruction Prisms: \r\n \r\n a. Build ten prisms: \r\n \r\n (1) Of site materials insofar as possible. \r\n (2) Use brick units similar as to color, texture, raw \r\n materials, moisture content and coring. \r\n (3) Under same conditions, insofar as possible, as the \r\n structure. \r\n (4) With same bonding, insofar as possible, as for structure. \r\n (5) With same mortar as for the structure. \r\n (6) With same joint thickness. \r\n (7) With same workmanship. \r\n \r\n \r\n 2. Site Control Prisms: \r\n \r\n a. Build prisms as required by Section 1.02.D.1 at the \r\n direction of the Architect/Engineer. \r\n \r\n (1) Of site materials. \r\n (2) Of brick units selected at random from units delivered \r\n to the project. \r\n (3) At the project site. \r\n (4) With same bonding, insofar as possible, as the structure. \r\n (5) With site mortar. \r\n (6) With same joint thickness as for the structure. \r\n (7) With same workmanship. \r\n \r\n \r\n \r\n 3. Dimensions \r\n \r\n \r\n a. Minimum height: 12 in. (305 mm). \r\n b. Height-to-thickness ratio (h/t) range: \r\n \r\n (1) Minimum: 2 \r\n (2) Maximum: 5 \r\n \r\n \r\n 4. Mark each specimen for identification. \r\n 5. Store prisms: \r\n \r\n a. Preconstruction prisms: \r\n \r\n (1) In air at temperatures not less than 65 o ; \r\n F. (18.3 o C.). \r\n \r\n b. Site control prisms: \r\n \r\n (1) At site for not less than 24 hr. \r\n (2) Thereafter, in air at temperatures not less than \r\n 65 o F.(18. o C.). \r\n \r\n \r\n 6. Test prisms: \r\n \r\n a. Preconstruction prisms: \r\n \r\n (1) Five after aging 7 days. \r\n (2) Five after aging 28 days. \r\n \r\n b. Site control prisms: \r\n \r\n (1) After aging 7 days. \r\n \r\n c. Cap each prism with suitable material to provide bearing \r\n surfaces on each end: \r\n \r\n (1) Plane within 0.003 in. (0.076 mm). \r\n (2) Approximately perpendicular to the axis of the prism. \r\n \r\n \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.A.6.c It is suggested that calcined gypsum be used for the \r\n capping material. \r\n \r\n \r\n \r\n 7. Test in accordance with relevant provisions of ASTM E \r\n 447-__________, with the following provisions: \r\n \r\n \r\n a. For h/t less than 5, reduce specimen compressive strength \r\n by correction factors as follows: \r\n \r\n \r\n \r\n alnterpolate to obtain intermediate values. \r\n \r\n b. If the coefficient of variation of the sample tested \r\n exceeds 10%, obtain the compressive strength by multiplying \r\n the average compressive strength of the specimens by \r\n \r\n 1 - 1.5 ( V - 0.10 ) \r\n 100 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where v is the coefficient of variation of the sample tested. \r\n \r\n \r\n \r\n \r\n B. Brick Tests: \r\n \r\n \r\n \r\n 1. Preconstruction Tests: \r\n \r\n a. Test five brick for compressive strength to determine \r\n acceptability of units for compliance with specifications. \r\n b. Use brick similar to those selected for use, matching \r\n color, texture, raw material, moisture content and coring. \r\n c. Cost of tests shall be borne by the General Contractor. \r\n \r\n 2. Test in accordance with ASTM C 67-__________, with the \r\n following additional requirements: \r\n \r\n \r\n a. If the coefficient of variation of the compression samples \r\n tested exceeds 12%, obtain compressive strength by multiplying \r\n average compressive strength of specimens by \r\n \r\n 1 - 1.5 ( V - 0.12 ) \r\n 100 \r\n \r\n \r\n \r\n \r\n where v is the coefficient of variation of sample tested. \r\n \r\n \r\n \r\n \r\n C. Preconstruction Requirements: \r\n \r\n \r\n \r\n 1. Prebid conference: \r\n \r\n a. A prebid conference, directed by the Architect/ Engineer, \r\n will be held one week prior to the bid opening to discuss: \r\n \r\n (1) Structural concept. \r\n (2) Method and sequence of masonry construction. \r\n (3) Special masonry details. \r\n (4) Quality control requirements. \r\n (5) Material requirements. \r\n (6) Job organization. \r\n (7) Workmanship. \r\n \r\n b. Attendance is mandatory for all prospective: \r\n (1) General contractors. \r\n (2) Masonry subcontractors. \r\n (3) Brick suppliers. \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C This requirement may be deleted if not necessary for \r\n the project due to bidders being knowledgeable with engineered \r\n brick masonry. \r\n 1.02.C.1.b Invitation to attend should be extended to others, \r\n such as the inspectors (local building department and other \r\n government agencies) and Owner. \r\n \r\n 2. Preconstruction Testing and Certification: \r\n \r\n a. After award of the contract, the General Contractor \r\n shall: \r\n \r\n (1) Within 14 days, submit to the Architect/Engineer \r\n for approval the name of the independent laboratory which \r\n will perform the site control tests and provide the certificates \r\n and test reports required in Section 1.03. \r\n (2) Upon approval of the laboratory, certificates and \r\n test reports, and prior to any masonry construction, make \r\n arrangements for the following tests for each combination \r\n of brick and mortar: \r\n \r\n (a) Tests of ten prisms in accordance with preconstruction \r\n requirements, Section 1.02.A. \r\n (b) Test five brick in accordance with Section 1.02.B. \r\n \r\n \r\n \r\n b. Masonry work can begin only after approval of testing. \r\n c. Testing is acceptable if test results indicate that \r\n materials meet the minimum requirements of Part II - Products, \r\n or Section 3.02.K. \r\n d. Cost of preconstruction testing shall be borne by the \r\n General Contractor. \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C.2 Inspection, laboratory and testing for quality control \r\n can be a responsibility of the Structural Engineer. If so, \r\n revise section. \r\n \r\n 3. Preconstruction Conference: \r\n \r\n a. A preconstruction conference, directed by the Architect/Engineer, \r\n will be held after the award of the General Contract, but \r\n prior to beginning of masonry work to discuss: \r\n \r\n (1) Structural concept. \r\n (2) Method and sequence of masonry construction. \r\n (3) Special masonry details. \r\n (4) Standard of workmanship. \r\n (5) Quality control requirements. \r\n (6) Job organization. \r\n \r\n b. Attendance is mandatory for: \r\n \r\n (1) General contractor job superintendent. \r\n (2) Masonry subcontractor job superintendent. \r\n (3) Masonry subcontractor foreman. \r\n (4) At least two masons. \r\n (5) Authorized representative of the brick supplier. \r\n \r\n (6) Mortar material suppliers. \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.C.3.b Invitations to attend should be extended to others, \r\n such as inspectors (local building department and other government \r\n agencies) and Owner. \r\n \r\n \r\n \r\n D. Job Site Quality Control: \r\n \r\n \r\n \r\n 1. Site control prism tests: \r\n \r\n \r\n a. Use 7-day compressive strength of brick prisms to control \r\n quality. \r\n b. Build, store and test prisms in accordance with site \r\n control requirements, Section 1.02.A. \r\n \r\n c. Build three prisms for each \r\n 5000 sq. ft. (465 m 2 ) \r\n of wall area as directed by the Architect/Engineer. \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n \r\n \r\n c. Provide three prisms for each story height. \r\n d. Site control test data shall be acceptable if the 7-day \r\n prism strength indicates that the 28-day strength will be \r\n equal to or greater than the required minimum ultimate compressive \r\n strength. See Section 3.02.K. \r\n e. Cost of control prisms to be borne by the General Contractor \r\n \r\n \r\n \r\n \r\n NOTE: \r\n \r\n 1.02.D.1.c Select, depending upon whichever is more frequent. \r\n \r\n E. Furnish Sample Panel: \r\n \r\n \r\n 1. 4 ft. (1.2 m) long by 3 ft. (1 m) high, of the proposed \r\n color range, texture, bond, mortar and workmanship. \r\n 2. Erect panel in the presence of the Architect/Engineer \r\n before installation of materials. \r\n 3. Provide separate panels for each type of brick or mortar. \r\n 4. Do not start work until Architect/Engineer has accepted \r\n sample panel. \r\n 5. Use panel as standard of comparison for all masonry work \r\n built of same material. \r\n 6. Do not destroy or move panel until work is completed and \r\n accepted by Owner. \r\n \r\n \r\n \r\n \r\n 1.03 SUBMITTALS \r\n \r\n \r\n Add the following section to 1.03 in Technical Notes 11A \r\n Revised: \r\n D. Prism Test Reports: \r\n \r\n \r\n \r\n 1. Test reports are to be submitted to Architect/Engineer \r\n for approval. \r\n 2. Testing and reports are to be completed by an independent \r\n laboratory. \r\n 3. Test reports shall show: \r\n a. Age at test. \r\n \r\n \r\n b. Storage conditions. \r\n c. Dimensions (h/t). \r\n d. Compressive strength of individual prisms. \r\n e. Coefficient of variation (v). \r\n \r\n f. Ultimate compressive strength \r\n of masonry (f m ) \r\n which has been corrected for the coefficient of variation \r\n and the hit of the prisms tested. \r\n \r\n \r\n \r\n \r\n \r\n PART II -PRODUCTS \r\n \r\n 2.01 BRICK \r\n \r\n \r\n A. Facing Brick: \r\n \r\n \r\n \r\n 1. Delete Note and replace with: \r\n \r\n NOTE: \r\n \r\n 2.01.A.1 Grades and Types. Brick subject to the action of \r\n weather or soil, but not subject to frost action when permeated \r\n with water, shall be of grade MW or grade SW and where subject \r\n to temperature below freezing while in contact with soil shall \r\n be grade SW. Brick used in loadbearing or shear wall construction \r\n shall comply with the dimensional and distortion tolerances \r\n specified for type FBS of ASTM C 216-__________. Where such \r\n brick do not comply with these tolerance requirements, the \r\n compressive strength of brick masonry shall be determined \r\n by prism tests. \r\n \r\n \r\n \r\n \r\n PART III -EXECUTION \r\n \r\n 3.02 GENERAL ERECTION REQUIREMENTS \r\n \r\n \r\n Delete Section 3.02.I in Technical Notes 11B Revised, \r\n and replace with the following Section 3.02.I and add Sections \r\n 3.02.J And 3.02.K \r\n \r\n \r\n I. Lay brick with __________-in. mortar joints, not to exceed \r\n 1/2 in. (12.7 mm). \r\n J. Construction Tolerances: \r\n \r\n 1. Maximum variation from plumb in vertical lines and surfaces \r\n of columns, walls and arrises: \r\n \r\n a. 1/4 in. (6.4 mm) in 10 ft. (3 m). \r\n b. 3/8 in. (9.6 mm) in a story height not to exceed 20 \r\n ft. (6 m) \r\n c. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 2. Maximum variation from plumb for external corners, expansion \r\n joints and other conspicuous lines: \r\n \r\n a. 1/4 in. (6.4 mm) in any story or 20 ft. (6 m) maximum. \r\n \r\n b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 3. Maximum variation from level of grades for exposed lintels, \r\n sills, parapets, horizontal grooves and other conspicuous \r\n lines: \r\n \r\n a. 1/4 in. (6.4 mm) in any bay or 20 ft. (6 m). \r\n b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. \r\n \r\n 4. Maximum variation from plan location of related portions \r\n of columns, walls and partitions: \r\n \r\n a. 1/2 in. (12.7 mm) in any bay or 20 ft. (6 m). \r\n b. 3/4 in. (19 mm) in 40 ft. (12 m) or more. \r\n \r\n 5. Maximum variation in cross-sectional dimensions of columns \r\n and thicknesses of walls from dimensions shown on drawings: \r\n \r\n a. Minus 1/4 in. (6.4 mm). \r\n b. Plus 1/2 in. (12.7 mm). \r\n \r\n \r\n \r\n K. Minimum Ultimate Compressive Strength \r\n of Masonry (f m )__________psi \r\n ( __________kgf/cm 2 ). \r\n \r\n NOTE: \r\n \r\n 3.02.K Ultimate compressive strength as determined by the \r\n Structural Engineer may vary for different parts and walls \r\n of the building. If so, provide sections to cover all design \r\n requirements. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60060,"ResultID":176292,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 11E - Guide Specifications for Brick Masonry, \r\n Part 5, Mortar and Grout \r\n September 1991 \r\n \r\n Abstract : This Technical Notes is a guide specification \r\n for mortar and grout used in brick masonry. Using this Technical \r\n Notes, a specifier can prepare a job specification for Section \r\n 04100. Notes are provided to help the specifier understand certain \r\n decisions that affect the project specifications. The guide specification \r\n is in accordance with the Construction Specifications Institutes \r\n (CSI) Masterformat. \r\n Key Words : brick masonry, grout, \r\n guide specification, mortar. \r\n INTRODUCTION \r\n This Technical Notes is a \r\n continuation of Technical Notes 11 Series on \"Guide Specifications \r\n for Brick Masonry\" and contains the requirements for mortar and \r\n grout for brick masonry. This Technical Notes is appropriate \r\n for both empirically designed and rationally designed brick masonry. \r\n \r\n The guide specification in this Technical \r\n Notes is in accordance with the Construction Specifications \r\n Institutes Masterformat and is based on the requirements of BIA M1 \r\n Standard Specification for Portland Cement-Lime Mortar for Brick Masonry \r\n contained in Technical Notes 8A \r\n and ASTM C 270 Mortar for Unit Masonry. Mortar conforming to the requirements \r\n of BIA M1 will meet all of the requirements of portland cement-lime \r\n mortars of ASTM C 270. A complete discussion of mortar properties \r\n is contained in Technical Notes 8 . \r\n \r\n GENERAL \r\n Mortar requirements differ from concrete \r\n requirements because the primary function of mortar is to bond masonry \r\n units into an integral element. The basic mortar ingredients include \r\n portland cement, hydrated lime, sand and water. Masonry cements, \r\n proprietary mortar mixes, are sometimes used to replace portland \r\n cement and hydrated lime or combined with portland cement to make \r\n mortar. BIA M1, ASTM C 270 and ASTM C 1142 Ready-Mixed Mortar for \r\n Unit Masonry are the recommended standards for mortar to be used \r\n with brick masonry. \r\n Grout is different from both concrete \r\n and mortar. Grout is a high slump mixture used to fill cells of \r\n masonry units or between wythes of masonry to resist stresses and \r\n develop bond with reinforcement. Grout can consist of portland cement, \r\n hydrated lime, fine or coarse aggregate and water. Grout should \r\n be specified by ASTM C 476 Grout for Masonry. \r\n \r\n RECOMMENDED MORTAR USES \r\n \r\n Selection of a particular mortar type is \r\n usually a function of the needs of the finished structural element. \r\n For example, where high wind loads are expected, high lateral strength \r\n may be required and, hence, mortar with high flexural bond strength \r\n should be considered. For loadbearing walls and reinforced brick masonry, \r\n high compressive strength may be the governing factor. In some projects \r\n considerations of durability, color, flexibility, etc., may be of \r\n most concern. No single type of mortar is best for all purposes. Factors \r\n which improve one property of mortar may do so at the expense of others. \r\n For this reason, when selecting a mortar, evaluate properties of each \r\n mortar type and choose that type and materials which will best meet \r\n all requirements. Technical Notes 8B \r\n discusses the selection of mortar types in depth. The following sections \r\n briefly discuss selection of mortar. \r\n \r\n Type N Mortar \r\n Type N mortar is suitable for general \r\n use in exposed masonry above grade. It is recommended for use in \r\n parapet walls, chimneys and exterior walls when subject to severe \r\n exposure. \r\n \r\n Type S Mortar \r\n Type S mortar is recommended for use in \r\n reinforced and unreinforced masonry where higher flexural strengths \r\n than Type N are required. \r\n \r\n Type M Mortar \r\n Type M mortar is recommended for use in \r\n masonry in contact with earth such as foundations, retaining walls, \r\n paving, sewers and manholes, and in reinforced masonry. \r\n \r\n Type O Mortar \r\n Type O mortar is suitable for interior \r\n use in non-loadbearing applications. \r\n \r\n SPECIFYING MORTAR \r\n Mortars are specified in one of two ways: \r\n proportions or properties, but not both. Mortar prepared by the \r\n proportion requirements should not be compared to mortar prepared \r\n by the property requirements. \r\n The proportion specification requires \r\n that mortar materials be mixed according to given volumetric proportions \r\n or weight. If mortar is specified by this method, no laboratory \r\n testing of the mortar is required. \r\n If mortar is specified by the property \r\n specifications, compressive strength, water retention and air content \r\n tests must be performed on mortar mixed in the laboratory. Field \r\n mortar is then mixed to the proportions selected from these laboratory \r\n tests. \r\n When neither proportion nor property is \r\n specified, the proportion specifications govern. \r\n \r\n SPECIFYING GROUT \r\n Grout is specified by proportion using \r\n ASTM C 476. Either fine or fine and coarse aggregate can be used \r\n in grout. Experience has shown that grout mixed to the specified \r\n proportions performs well with brick masonry since the grout compressive \r\n strength closely matches the compressive strength of the brick masonry. \r\n Grout must have adequate compressive strength, bonding with reinforcement \r\n and for embedment of anchor bolts. There is usually no need to specify \r\n compressive strength of grout unless required by design. Grout strength \r\n can be verified by field testing using ASTM C 1019. Slump of the \r\n grout is usually specified to be between 8 and 11 in. (203.2 and \r\n 279.4 mm). \r\n \r\n CONCLUSION \r\n This Technical Notes is a \r\n guide specification for mortar and grout for brick masonry. Notes \r\n are provided to assist in editing the specification. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of \r\n America. The information contained herein must be used in conjunction \r\n with good technical judgment and a basic understanding of the properties \r\n of masonry. Final decisions on the use of information contained \r\n in this Technical Notes are not within the purview of the \r\n Brick Institute of America and must rest with the project architect, \r\n engineer, owner or all. \r\n \r\n \r\n 04100 MORTAR AND GROUT \r\n \r\n \r\n Guide Specification & Notes \r\n PART 1 GENERAL \r\n 1.01 SECTION INCLUDES \r\n A. Mortar for masonry. \r\n \r\n \r\n B. Grout for masonry. \r\n C. Repointing mortar. \r\n \r\n 1.02 RELATED SECTIONS \r\n A Concrete: Section 03__________. \r\n B. Masonry: Section 04__________. \r\n C. Masonry Cleaning: Section 04500. \r\n D. Structural Metal Framing: Section \r\n 05100. \r\n E. Rough Carpentry: Section 06100. \r\n F. Waterproofing: Section 07100. \r\n \r\n NOTE: \r\n 1.02 Some of these broadscope sections \r\n may not be included. Other narrow scope sections under these broadscope \r\n sections may be added. \r\n \r\n \r\n 1.03 PRODUCTS INSTALLED BUT NOT FURNISHED \r\n UNDER THIS SECTION \r\n A. Reinforcing Steel: Section 03210. \r\n B. Metal Accessories: Section 04150. \r\n C. Masonry Units: Section O4200. \r\n D. Flashing and Sheet Metal: Section \r\n 07600. \r\n \r\n 1.04 REFERENCES \r\n \r\n A. ACI 530.1/ASCE 6-__________ - Specifications \r\n for Masonry Structures. \r\n B. ASTM C 91 - __________, [UBC Standard \r\n No. 24-16] - Masonry Cement. \r\n C. ASTM C 144 - __________ - Aggregate \r\n for Masonry Mortar. \r\n D. ASTM C 150 - __________, [UBC Standard \r\n No. 26-1] - Portland Cement. \r\n E. ASTM C 207-__________, [UBC Standard \r\n No. 24-18] - Hydrated Lime for Masonry Purposes. \r\n F. ASTM C 270-__________, [UBC Standard \r\n No. 24-20] - Mortar for Unit Masonry. \r\n G. ASTM C 404-__________ - Aggregates \r\n for Masonry Grout. \r\n H. ASTM C 476-__________, [UBC Standard \r\n No. 24-29] - Grout for Masonry. \r\n I. ASTM C 780-__________ - Preconstruction \r\n and Construction Evaluation of Mortars for Plain and Reinforced \r\n Unit Masonry. \r\n J. ASTM C 979-__________ - Pigments \r\n for Integrally Colored Concrete. \r\n K. ASTM C 1019-__________, [UBC Standard \r\n No. 24-28] - Sampling and Testing Grout. \r\n L. ASTM C 1142-__________ - Ready-Mixed \r\n Mortar for Unit Masonry. \r\n M. BIA Technical Notes 8A - \r\n \"Specifications for Portland Cement-Lime Mortar for Brick Masonry\" \r\n BIA M1-88). \r\n \r\n NOTE: \r\n 1.04 The applicable date for each \r\n reference can be given here or in Section 01090-Reference Standards. \r\n Alternate standards are given for Uniform Building Code specifications. \r\n \r\n \r\n \r\n 1.05 SUBMITTALS \r\n \r\n A. Submit data indicating proportion \r\n or property specifications used for mortar. \r\n B. Submit test reports for mortar \r\n materials indicating conformance to ASTM C 270 [UBC Standard \r\n No. 24-20] property specifications. Report proportions resulting \r\n from laboratory testing used to select mortar mix. \r\n C. Submit test reports for field sampling \r\n and testing mortar in conformance to ASTM C 780. \r\n D. \r\n Submit test reports for grout materials indicating conformance \r\n to ASTM C 476 [UBC Standard No. 24-29]. \r\n E. Submit test reports for field sampling \r\n and testing grout in conformance to ASTM C 1019 [UBC Standard \r\n No. 24-28]. \r\n F. Samples: Submit two ribbons of \r\n mortar for conformance with color. \r\n \r\n NOTE: \r\n 1.05.A ASTM C 270 and UBC Standard \r\n No. 24-20 require that mortar be specified by proportion or \r\n property, not both. \r\n 1.05.B ASTM C 270 and UBC Standard \r\n No. 24-20 require comparison of laboratory prepared mortars \r\n to establish proportions for field-mixed mortar when the property \r\n specifications are used. \r\n 1.05.C ASTM C 780 allows preconstruction \r\n evaluation of mortar and comparison of field prepared mortars. \r\n Mortar prepared in the field should not be compared to values \r\n found in the property specifications of ASTM C 270 or UBC \r\n Standard No. 24-20. \r\n 1.05.E ASTM C 1019 or UBC Standard \r\n No. 24-28 is used to test uniformity of grout preparation \r\n during construction. \r\n \r\n \r\n \r\n \r\n 1.06 DELIVERY, STORAGE AND HANDLING \r\n \r\n A. Store materials in dry location \r\n and protected from dampness and freezing. \r\n B. Stockpile and handle aggregates \r\n to prevent contamination from foreign materials. \r\n \r\n \r\n 1.07 ENVIRONMENTAL REQUIREMENTS \r\n \r\n A. Follow requirements for cold and \r\n hot weather construction in ACI 530.1/ASCE 6 [Uniform Building \r\n Code]. \r\n \r\n PART 2 PRODUCTS \r\n 2.01 MORTAR MATERIALS \r\n \r\n A. Cementitious materials: \r\n 1. Portland Cement: ASTM C 150 [UBC \r\n Standard No. 26-1], Type__________. \r\n 2. Hydrated Lime: ASTM C 207 [UBC \r\n Standard No. 24-18], Type S__________. \r\n 3. Masonry Cements: ASTM C 91 [UBC \r\n Standard No. 24-16], Type__________. \r\n \r\n B. Sand: ASTM C 144. \r\n C. Admixtures: \r\n 1. No air-entraining admixtures \r\n or material containing air-entraining admixtures. \r\n 2. No antifreeze compounds shall \r\n be added to mortar. \r\n 3. No admixtures containing chlorides \r\n shall be added to mortar. \r\n \r\n D. Water: Clean and potable. \r\n E. Mortar pigment: \r\n 1. ASTM C 979: Pigment shall not \r\n exceed 10% of the weight of portland cement. \r\n 2. Carbon black shall not exceed \r\n 2% of the weight of portland cement. \r\n \r\n NOTE: \r\n 2.01.A Allowable flexural tensile \r\n stresses for masonry built with air-entrained portland cement-lime \r\n mortars, or with masonry cement mortars are lower than those \r\n built with portland cement-lime mortars. \r\n 2.01.A.1 Only Types I, II or III. \r\n 2.01.A.3 Types M, S, or N. \r\n 2.01.B Sand not conforming to ASTM \r\n C 144 must have mortar meet the property specification requirements. \r\n 2.01.E Limits on amount of pigments \r\n should be halved when using masonry cement mortars. \r\n \r\n \r\n \r\n \r\n 2.02 GROUT MATERIALS \r\n A. Cementitious materials: \r\n \r\n 1. Portland Cement: ASTM C 150 [UBC \r\n Standard No. 26-1], Type__________. \r\n 2. Hydrated Lime: ASTM C 207 [UBC \r\n Standard No. 24-18], Type S__________. \r\n \r\n B. Aggregates: \r\n 1. Fine aggregate: ASTM C404. \r\n 2. Coarse aggregate: ASTM C 404. \r\n \r\n C. Water: Clean and potable. \r\n D. Admixtures. \r\n \r\n NOTE: \r\n 2.02.A.1 Only Types 1, II or III. \r\n 2.02.D Grout admixtures are used \r\n to decrease grout shrinkage, aid in pumping grout, or for \r\n other reasons. The use of such admixtures should not adversely \r\n affect the performance of the grout. \r\n \r\n \r\n \r\n \r\n 2.03 MORTAR AND GROUT MIXES \r\n A. Mortar - ASTM C 270 [UBC Standard \r\n No. 24-20] or BIA M1: \r\n \r\n 1. Type based on proportion specifications. \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n \r\n \r\n 1. Type__________based on property \r\n specifications to achieve __________ psi strength, __________% \r\n air content, __________% water retention. \r\n \r\n NOTE: \r\n 2.03.A Mortar mixes can be specified \r\n separately by specifying ASTM C 270, UBC Standard No. 24-20 \r\n or BIA M1; or by specifying ASTM C 1142 alone. \r\n 2.03.A.1 Type M, S, N or O depending \r\n on design requirements. \r\n \r\n \r\n \r\n \r\n \r\n **OR** \r\n \r\n A. Mortar - ASTM C 1142: Type__________. \r\n \r\n \r\n NOTE: \r\n 2.03.A Ready mixed mortar can be \r\n mixed on-site or off-site. Types RM, RS, RN or RO. \r\n \r\n \r\n \r\n B. Grout: ASTM C 476 [UBC Standard No. \r\n 24-29] \r\n \r\n 1. Fine grout. \r\n 2. Coarse grout. \r\n 3. Slump: __________inches (__________mm). \r\n \r\n NOTE: \r\n 2.03.B The use of fine or coarse \r\n grout is based on the size of the grout space and the height \r\n of the grout pour. \r\n 2.03.B.3 Specify desired slump between \r\n 8 and 11 inches (203.2 and 279.4 mm). Higher slump is necessary \r\n for smaller dimensioned grout spaces and with higher unit/grout \r\n volume ratios. \r\n \r\n \r\n \r\n \r\n PART 3 EXECUTION \r\n 3.01 FIELD MORTAR MIXING \r\n \r\n A. All cementitious materials and \r\n aggregate shall be mixed between 3 and 5 min. in a mechanical \r\n batch mixer with the maximum amount of water to produce a workable \r\n consistency. \r\n B. Control batching procedure to ensure \r\n proper proportions by measuring materials by volume. Sand measurement \r\n by shovel count shall not be permitted. \r\n C. If water is lost by evaporation \r\n within 2 1/2 hours after initial mixing, retemper with water. \r\n D. Discard all mortar which is more \r\n than 2 1/2 hours old. \r\n \r\n NOTE: \r\n 3.01 ASTM C 270 or BIA M1 can be \r\n referenced for field mortar mixing. \r\n 3.01.B Materials can be specified \r\n by weight if volume proportions are converted to weight proportions \r\n \r\n \r\n \r\n 3.02 FIELD GROUT MIXING \r\n \r\n A. Control batching procedure to ensure \r\n proper proportions by measuring materials by volume. \r\n \r\n NOTE: \r\n 3.02 ASTM C 476 can be referenced \r\n for field grout mixing. \r\n 3.02.A Materials can be measured \r\n by weight if volume proportions are converted to weight proportions. \r\n \r\n \r\n \r\n \r\n 3.03 INSTALLATION \r\n \r\n A. Install mortar and grout in accordance \r\n with ACI 530.1/ASCE 6. \r\n \r\n 3.04 REPOINTING MORTAR \r\n \r\n A. Use mortar materials listed in \r\n 2.01, Type N. \r\n B. Prehydrate the mortar by the following \r\n method. Mix dry ingredients together. Then add only enough water \r\n to make a damp, stiff mix which will retain its form when pressed \r\n in a ball. After 1 to 2 hours, add sufficient water to bring \r\n it to the proper consistency. \r\n \r\n NOTE: \r\n 3.04.A If materials and proportions \r\n of existing mortar are known, use those instead of Type N \r\n mortar if the existing mortar provided sufficient durability. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60061,"ResultID":176293,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 13 - Ceramic Glazed Brick Facing for Exterior Walls \r\n May 1962 (Reissued March 1982) \r\n \r\n INTRODUCTION \r\n It is generally agreed that most disintegration \r\n of masonry units results from water in the masonry and is due to crystal \r\n pressure of (1) ice forming in the pores of the masonry, or (2) migration \r\n of salts and subsequent crystallization within the pores of the masonry. \r\n It is also a well established fact, confirmed by numerous laboratory \r\n tests, as well as extensive observations of masonry buildings, that \r\n the principal cause of rain penetration through brick and tile walls \r\n is openings between mortar and masonry units. Also, it is well established \r\n that much of the water that enters a masonry wall through such openings, \r\n by absorption of the masonry or as a result of condensation within \r\n the wall, escapes by capillary action and evaporation from the face \r\n of the wall. \r\n This process, by which moisture is eliminated \r\n from the masonry, has for years been known as \"breathing\" and is an \r\n important factor contributing to the durability and resistance to \r\n water penetration of masonry walls. Its importance is graphically \r\n presented in the publication, Walls Breathe ?, of the Western \r\n Waterproofing Company (Missouri Corporation), St. Louis, Missouri, \r\n which states: \r\n \"At first glance, the statement that lifeless \r\n brick, stone or concrete must breathe may seem strange-yet it is \r\n just as true of a masonry wall as of the human body. If your pores \r\n are sealed by a nonporous coating which prevents transpiration-evaporation \r\n of moisture-you cannot remain alive. Neither can masonry. \r\n \"This is true because excessive moisture \r\n continuously gets into the walls and must be eliminated before \r\n it causes trouble. It usually enters as rain water (1) through \r\n the pores in building materials, (2) into incompletely bonded mortar \r\n joints, (3) around copings, sills, and belt courses, (4) as condensation \r\n of vapor from the interior of the structure (this action is more insidious \r\n and far-reaching than most people realize), (5) through capillary \r\n contact with the ground. \r\n \"Without water in the wall there would be \r\n little or no problem of masonry disintegration and disruption. The \r\n only ways to get rid of the excess moisture are ( 1 ) through continuous \r\n cavities within walls (hollow wall construction) with adequate weep \r\n holes at various locations in the wall, (2) by evaporation through \r\n the exterior of the masonry.\" \r\n When exterior walls are faced with ceramic \r\n glazed brick or when an impervious coating is applied to the exterior \r\n face of walls, water cannot enter the walls through the pores of the \r\n brick nor can it escape by this means from the face of the wall. For \r\n this reason, it becomes especially important to reduce the water entering \r\n the wall to an absolute minimum and to provide positive means of escape \r\n for water that permeates the wall, either as rain or as condensed \r\n vapor. The amount of water that may be expected to enter a wall as \r\n a result of rain varies with the exposure which may be defined roughly \r\n in terms of the resultant wind pressure and precipitation maps, shown \r\n in Fig. 1, as: \r\n Severe: annual precipitation 30 in. \r\n or over; wind pressure 30 lb per sq ft or over. \r\n Moderate: annual precipitation 30 \r\n in. or over; wind pressure 20 to 25 lb per sq ft. \r\n Slight: annual precipitation less \r\n than 30 in.; wind pressure 20 to 25 lb per sq ft or annual precipitation \r\n less than 20 in. \r\n \r\n \r\n FIG. 1 \r\n \r\n The following recommendations covering wall \r\n design and construction are applicable to severe and moderate exposures \r\n as defined above. \r\n RECOMMENDATIONS \r\n Design. \r\n 1. Cavity wall construction is recommended. \r\n \r\n \r\n \r\n \r\n 2. For walls enclosing heated areas, provide \r\n vapor barrier on warm side of cavity. \r\n 3. For walls exposed on both sides; such \r\n as free-standing walls, wing walls and parapet walls; ventilate \r\n cavity. \r\n 4. Provide adequate flashing. \r\n 5. Provide adequate expansion joints (3/4 \r\n in. per 100 ft of wall) and an expansion joint on each side of each \r\n corner, located not more than 10 ft nor less than 4 ft from the \r\n corner. \r\n 6. Provide flexible anchorage to columns \r\n and beam. \r\n \r\n Specifications. \r\n 1. Specify highly plastic mortar; 1 cement: \r\n 1 type S lime:6 sand or 1 cement:1/2 type S lime: 4 1/2 sand are recommended. \r\n 2. Specify full head and bed joints and \r\n that cavity be kept clean and weep holes open. \r\n 3. The Specifications of the Facing Tile \r\n Institute for Select Quality Ceramic Glaze Structural Facing Tile, \r\n dated November 1959, provide: \"Where ceramic glaze units are required \r\n for exterior use, the manufacturers should be consulted for material \r\n suitable for this purpose.\" \r\n \r\n Specifiers of ceramic glazed brick for exterior \r\n use are urged to comply with this recommendation and, in so doing, \r\n to indicate to the manufacturers the geographic location of the project, \r\n the type of construction, that is, enclosure walls, parapets, etc., \r\n and the wall design, including flashing details and mortar specified. \r\n SUGGESTED DETAILS \r\n Window Sills . Place \r\n through flashing under and behind all sills. Extend ends of sill flashing \r\n beyond the jamb line on both sides and turn them up at least 1 in. \r\n into the wall. Slope all sills to drain water away from the building. \r\n Where the undersides of sills do not slope away from the building, \r\n provide a drip notch or extend flashing and bend down to form a drip. \r\n (See Fig. 2.) \r\n \r\n \r\n \r\n \r\n Window Sills \r\n \r\n \r\n FIG. 2 \r\n \r\n Opening Heads . Install \r\n through flashing over all openings except those completely protected \r\n by overhanging projections. At steel lintels, place flashing under \r\n and behind the facing material and over the top of the lintel and \r\n bend its outer edge down to form a drip. (See Fig. 3.) \r\n \r\n \r\n \r\n \r\n Opening Heads \r\n \r\n \r\n FIG. 3 \r\n \r\n Spandrels . In skeleton-frame \r\n structures, spandrels may be flashed continuously at beams, or with \r\n reglets. When the entire spandrel is flashed, two-piece flashings \r\n may be used, provided they are lapped at least 4 in. When cavity walls \r\n are supported by concrete spandrel beams, place the flashing on the \r\n shelf angle and extend it at least 8 in. up the beam and anchor it \r\n into a reglet. When galvanized or stainless steel covered angles are \r\n used, flashing may not be necessary except to cover joints between \r\n lengths. (See Fig. 4.) \r\n \r\n \r\n \r\n \r\n Spandrels \r\n \r\n FIG. 4 \r\n \r\n Parapet Walls . Unless \r\n coping is impervious with watertight joints, place through flashing \r\n in the mortar bed beneath it. Where the coping provides an adequate \r\n drip, the flashing may stop at the wall surface. However, where the \r\n copings are flush with the surface of the wall, extend the flashing \r\n at least 1/4 in. on both sides and turn it down to provide a drip. \r\n Follow the same procedure when topping out piers, pilasters, etc. \r\n Ventilate parapet as shown in Fig. 5. \r\n \r\n \r\n \r\n \r\n Parapet Walls \r\n \r\n \r\n FIG. 5 \r\n \r\n CONSTRUCTION \r\n Draining Cavity . Since \r\n its resistance to rain penetration is the most important single feature \r\n of the cavity wall, the minimum 2-in. cavity width should be maintained. \r\n An air space of less than 2 in. is difficult to keep free of mortar \r\n \"bridging\" or \"droppings\". \r\n The proper draining of the cavity will depend \r\n a great deal on the ease with which the moisture is permitted to escape \r\n at the bottom. Positive means of drainage are provided by weep holes \r\n placed in the exterior wythe at the bottom of the cavity. \r\n In curtain and panel wall construction, \r\n the weep holes over lintels or spandrel beam supports should be spaced \r\n 32 in. (4 brick lengths) apart. Spacing of weep holes at foundation \r\n support should be 2 ft on centers. \r\n Many cavity walls in which weep holes are \r\n left open have functioned satisfactorily for years. In such construction, \r\n the weep holes are formed by omitting a vertical joint in the exterior \r\n brickwork at intervals of 2 to 3 ft, or by inserting oiled rods or \r\n pins in head joints which are removed when the mortar is ready for \r\n tooling. However, open weep holes provide access for insects and, \r\n when they are placed over lintel or spandrel flashing, they may contribute \r\n to wall staining and, during high winds, the air movement through \r\n the weep holes into the cavity may reduce the resistance of the wall \r\n to heat flow. \r\n For this reason, it is recommended that, \r\n in general, \"wicks\" be placed in weep holes. They may be made of fiberglass \r\n or similar inorganic material, or sash cord which has been used successfully \r\n in many cases, although it will, of course, in time rot out. \r\n If the weep holes are formed by omitting \r\n whole vertical joints, a piece of 1/2 - in. fiberglass insulation \r\n can be placed in such joints. \r\n The weep holes will not be effective in \r\n draining the cavity if they are permitted to become plugged with mortar \r\n droppings as the wall is constructed. Keeping the cavity clean and \r\n free of mortar droppings is easily accomplished by a skilled mason. \r\n The simplest method consists of beveling the cavity edge of the mortar \r\n bed immediately after \"stringing\" the mortar. The mason does this \r\n with the flat of his trowel as indicated in Fig. 6. When the mortar \r\n is spread in this way, very little if any mortar will be squeezed \r\n out of the bed joints into the cavity when the units are laid. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Keeping the Cavity Clean \r\n FIG. 6 \r\n \r\n \r\n \r\n Immediately following the setting of the \r\n masonry unit, the mason should spread any mortar which protrudes into \r\n the cavity over the back of the unit, using the flat of his trowel. \r\n This prevents the mortar from falling to the bottom of the cavity \r\n and clogging the weep holes, and also provides a relatively smooth \r\n interior surface which aids in placing insulation if it is used. \r\n Another method commonly used to keep the \r\n cavity clean consists of wood strips to which two lengths of wire \r\n or heavy string are attached. These strips may be 4 to 6 ft long, \r\n and are placed on each tier of metal ties. The mason then builds up \r\n the two wythes to the level of the next row of ties and, before proceeding \r\n with the wall, lifts out the wood strip, bringing with it any accumulated \r\n droppings. \r\n \r\n Vapor Barrier . Where \r\n a vapor barrier is to be installed on the warm side of the wall, the \r\n wythe to which the vapor barrier is to be applied should be built \r\n up ahead of the other wythe at least 16 in., or the vertical distance \r\n between the wall ties. Before the second wythe is built up to the \r\n same level, the cavity of the first wythe should be given one brush \r\n coat of water emulsion asphalt paint. Since this coating is to serve \r\n as a vapor barrier, the paint used should be a vapor resistant type; \r\n also, it should be a water emulsion type so that it can be applied \r\n cold to a newly laid wall. \r\n \r\n Fig. 7 shows a vapor barrier applied to \r\n the inner wythe of a brick and tile cavity wall. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Brush coat of water emulsion asphalt paint \r\n provides vapor barrier on backup. \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60062,"ResultID":176294,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 14 - Brick Floors and Pavements, \r\n Part 1 - Design and Detailing \r\n Sept. 1992 \r\n \r\n \r\n \r\n \r\n \r\n Abstract: This Technical Notes \r\n describes the proper design and detailing of a variety of brick paving \r\n assemblies. Design considerations covered include traffic, site conditions, \r\n drainage, edge restraints, joints and appearance. Typical details of \r\n various mortarless and mortared brick paving assemblies are shown. \r\n \r\n Key Words: brick, design, flexible \r\n pavements, flooring, mortared paving, mortarless paving, paving, rigid \r\n pavements. \r\n INTRODUCTION \r\n Since brick is derived from the earth, it \r\n is only natural that it be used as a paving material. Brick is a small \r\n element paving material which provides an aesthetically pleasing, stable \r\n and durable surface. Brick paving assemblies are comprised of the brick \r\n surface along with a base to provide support. In any paving assembly, \r\n the base is of prime importance, for if it is improperly designed or \r\n constructed, the entire system is prone to failure. \r\n This Technical Notes series discusses \r\n a variety of brick paving assemblies for residential and commercial \r\n applications. Although the principles are the same for all brick paving \r\n assemblies, the recommendations may not be appropriate for industrial \r\n type floors or heavy vehicular applications. Further information on \r\n flexible brick pavements in road and street applications can be found \r\n in the Brick Institute of Americas Flexible Brick Pavements: Design \r\n and Installation Guide [1]. This Technical Notes classifies \r\n paving assemblies by type of paving surface and type of base. Design \r\n considerations are given for traffic loads, drainage, site conditions, \r\n edge restraints, expansion joints, membranes, slip/skid resistance and \r\n appearance. Other Technical Notes in this series address material \r\n selection, installation techniques and special brick paving assemblies. \r\n CLASSIFICATION OF PAVING ASSEMBLIES \r\n Paving assemblies are classified by the type \r\n of brick paving surface and the type of base supporting the surface. \r\n The paving surface receives the traffic wear, protects the base and \r\n transfers loads to the base. The base and subbase (if required) provide \r\n structural support to the paving system by distributing the load to \r\n the subgrade. A subbase consisting of graded aggregates may be required \r\n when subgrade conditions are poor. \r\n Types of Brick Paving Surfaces \r\n The two types of brick paving surfaces are \r\n mortarless and mortared. Mortarless brick paving contains sand between \r\n the units which are laid on a variety of materials. Conversely, mortared \r\n brick paving consists of units with mortar between the units and always \r\n laid in a mortar setting bed. \r\n Types of Bases \r\n Flexible Base. A flexible base consists \r\n of compacted crushed stone, gravel or coarse sand. Only mortarless brick \r\n paving is suitable for this type of base. \r\n Semi-Rigid Base. This type of base \r\n consists of asphalt concrete, commonly referred to as asphalt. Only \r\n mortarless brick paving is suitable over this type of base. \r\n Rigid Base. A rigid base is defined \r\n as a reinforced or unreinforced concrete slab on grade. Mortarless or \r\n mortared brick paving may be placed over this type of base. \r\n Suspended Diaphragm Base. Suspended \r\n diaphragm bases are structural roof or floor assemblies of concrete, \r\n steel or wood. Mortarless or mortared brick paving is suitable for this \r\n type of base depending on the stiffness of the diaphragm. \r\n \r\n EXAMPLES OF BRICK PAVING ASSEMBLIES \r\n Many combinations of bases, setting beds and \r\n brick paving surfaces can be used. The paving assemblies included are \r\n suggested methods based on experience for the various types of traffic \r\n uses. Although not all potential paving assemblies are shown due to \r\n space limitation, the following are the most popular configurations. \r\n Flexible Base Pavements \r\n Only mortarless brick paving should be laid \r\n over a flexible base. Flexible bases include crushed stone, gravel or \r\n coarse sand. Applications for flexible bases range from residential \r\n patios to city streets. Flexible paving systems are typically the most \r\n economical to install since less labor and fewer materials are involved. \r\n The thickness of each layer in a flexible pavement depends upon the \r\n imposed loads and the properties of each layer. A pavement subjected \r\n to heavy vehicular traffic requires a thicker base than a pavement subjected \r\n to pedestrian traffic. \r\n Figure 1 is a typical section through a flexible \r\n brick pavement. Brick pavers are set in a 1 in. to 1 1/2 in. (25 to \r\n 38 mm) sand setting bed over a compacted base, subbase (if necessary) \r\n and compacted subgrade. Many commercial pedestrian and vehicular applications \r\n can use this type of assembly. Pavements subjected to vehicular traffic \r\n must be designed to accommodate the wheel loads. The Flexible Brick \r\n Pavements design guide covers design and installation requirements \r\n for heavy vehicular loading. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Mortarless Brick Paving \r\n Aggregate Base \r\n FIG. 1 \r\n \r\n \r\n In residential pedestrian applications, the \r\n detail in Fig. 2 can be used. The brick pavers are laid directly on \r\n the compacted sand and subgrade. This application works best when the \r\n subgrade is compacted or on undisturbed earth, and where frost heave \r\n is not a consideration. A geotextile can be used beneath the sand base \r\n where the soil conditions are poor. \r\n \r\n \r\n \r\n \r\n Mortarless Brick Paving \r\n \r\n \r\n Sand Base \r\n FIG. 2 \r\n \r\n \r\n Semi-Rigid Base Pavements \r\n Asphalt bases are classified as semi-rigid \r\n bases. Only mortarless brick paving is suitable over this type of base. \r\n Figure 3 is an example of an asphalt base and an asphalt setting bed \r\n supporting the mortarless brick paving. The mortarless brick paving \r\n and asphalt setting bed can also be laid on a concrete base. These assemblies \r\n are suitable for medium to heavy vehicular traffic, pedestrian malls \r\n or other pedestrian areas. \r\n \r\n \r\n \r\n \r\n Mortarless Brick Paving \r\n \r\n \r\n Asphalt Base \r\n FIG. 3 \r\n \r\n \r\n The detail shown in Fig. 4 is another paving \r\n assembly on a semi-rigid base. Two layers of No. 15 building felt or \r\n one layer of No. 30 felt act as a cushion between the brick pavers and \r\n the base and help accommodate size variations. This detail is only suitable \r\n for residential pedestrian applications. \r\n \r\n \r\n \r\n \r\n Mortarless Brick Paving \r\n \r\n \r\n Concrete or Asphalt Base \r\n FIG. 4 \r\n \r\n \r\n Rigid Base Pavements \r\n Mortarless or mortared brick paving may be \r\n laid over a rigid concrete base. The brick paving assembly shown in \r\n Fig. 4 is applicable for mortarless paving over a new or existing concrete \r\n slab. Only residential pedestrian applications are appropriate for this \r\n assembly. A similar assembly is shown in Fig. 5 where sand is used as \r\n a setting bed. These assemblies are not appropriate in vehicular applications, \r\n areas of large rainfall or in freezing climates where the pavement may \r\n heave when saturated. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Mortarless Brick Paving \r\n Concrete Base \r\n FIG. 5 \r\n \r\n \r\n Figure 6 shows a typical example of mortared \r\n brick paving over a reinforced concrete slab on grade. Mortared brick \r\n paving can be used for any type of pedestrian or vehicular traffic in \r\n both interior and exterior applications. This type of assembly is especially \r\n well-suited for heavy vehicular areas such as streets or parking lots \r\n and where surface drainage is necessary. \r\n \r\n \r\n \r\n \r\n Mortared Brick Paving \r\n \r\n \r\n Concrete Base \r\n FIG. 6 \r\n \r\n DESIGN CONSIDERATIONS \r\n Traffic \r\n The weight and amount of traffic often dictate \r\n which paving system to use. The brick paving assembly must be capable \r\n of supporting traffic loads plus its own weight. The appropriate thickness \r\n of the subbase, base and brick paving units must be considered to adequately \r\n distribute vertical traffic loads. Three general classifications of \r\n traffic are light, medium and heavy, and should be considered when determining \r\n the subbase, base and brick paver thicknesses. The classifications of \r\n traffic are defined as follows: \r\n Light Traffic. Residential pedestrian \r\n traffic only, such as on patios and walkways. \r\n Medium Traffic. Commercial pedestrian \r\n traffic, such as on city sidewalks, building entrances and shopping \r\n malls. Light vehicular traffic, such as on residential driveways, commercial \r\n entranceways and parking lots. \r\n Heavy Traffic. Heavy vehicular traffic, \r\n such as streets, crosswalks, loading docks and roads. The term heavy \r\n refers to both axle loads and frequency of loading. \r\n Heavy vehicular traffic on grade will generally \r\n require rigid, semi-rigid, or thick flexible bases. Medium and light \r\n traffic may be supported on any of these or on suspended diaphragms. \r\n Load Resistance \r\n Vertical Loads. Vehicular traffic, \r\n pedestrian traffic and the weight of the paving assembly impose vertical \r\n loads upon the paving system. These loads are distributed to each pavement \r\n layer in a radiating manner. Each layer resists a proportion of the \r\n load depending on its strength and thickness. The most important aspect \r\n of designing the pavement to resist vertical loads is determining the \r\n appropriate thickness of the base. Inadequate base thickness will result \r\n in premature failure of the paving system, while excessive thickness \r\n will result in increased costs. For light and medium traffic applications, \r\n the minimum required thickness of each base material will normally govern. \r\n Pavements subjected to vehicular traffic, other than residential driveways, \r\n generally require design by an engineer. \r\n Base Thickness ΓÇö The \r\n minimum thickness of an aggregate base depends primarily upon the strength \r\n of the subgrade. Typically, a flexible base of properly graded crushed \r\n stone or gravel should be a minimum thickness of 4 in. (100 mm). The \r\n minimum thickness of a reinforced concrete or an asphalt base in pedestrian \r\n and light vehicular traffic applications is 4 in. (100 mm), provided \r\n it bears on adequate subgrade. Concrete and asphalt bases usually require \r\n a subbase. Very heavy loading requires an increase in thickness for \r\n all types of bases. Additional information on base design is available \r\n from the appropriate reference [2,7]. \r\n Paving Surface Thickness \r\n ΓÇö A mortarless brick paving surface can be supported on a flexible \r\n base, a semi-rigid base, a rigid base or a suspended diaphragm. Typically \r\n the base is designed to resist vertical loads independent of the brick \r\n paving surface. However, the brick paving surface does, in fact, contribute \r\n to the load-carrying capabilities of the pavement and may be considered \r\n in design if it is of sufficient thickness and constructed properly. \r\n In order for the brick pavers to be considered when calculating thickness, \r\n they must be compacted into place as described in Technical Notes \r\n 14A and the Flexible Brick Pavements \r\n design guide. If brick pavers are not compacted into place, they \r\n should be neglected in the pavement thickness design but still must \r\n meet certain minimum thicknesses to act as a wearing surface. These \r\n suggested minimum thicknesses for mortarless brick paving are: light \r\n traffic, 1 1/2 in. (38 mm); medium traffic, 2 1/2 in. (57 mm); and heavy \r\n traffic, 2-5/8 in. (67 mm). In order for the brick pavers to be considered \r\n in resisting load they must have a 2-5/8 in. (67 mm) minimum thickness, \r\n excluding chamfers, to achieve interlock. Interlock is the effect of \r\n frictional forces, induced by sand beneath and between the brick pavers, \r\n which restricts movement of the paver and transfers loads between adjacent \r\n pavers. In the case of heavy traffic, the brick pavers and sand setting \r\n bed are compacted into place and contribute to the load-carrying capabilities \r\n of the system. \r\n A mortared brick paving surface should always \r\n be supported by a rigid base or suspended diaphragm. Without a rigid \r\n support, the paving system will deflect and cause cracking in the brick \r\n paving surface. The primary resistance to vertical loading is developed \r\n by the flexural strength of the concrete slab on grade or the roof or \r\n floor diaphragm. There is no minimum thickness for the paving unit to \r\n adequately transfer vertical loads. The required thickness to perform \r\n adequately as a result of horizontal loads and pavement deflection is \r\n in the range of 1/2 in. (13 mm) to 2 1/4 in. (57 mm) depending on traffic \r\n conditions and slab support. Thicker pavers are more likely to stay \r\n in place in the event of cracking. \r\n Horizontal Loads. In addition to vertical \r\n loads, vehicular traffic imparts horizontal forces to the paving assembly \r\n from braking, acceleration and turning actions of the wheels. Resistance \r\n to horizontal forces is provided by the bond pattern of the brick paving \r\n assembly, the pavement edging and the bond of the brick units to the \r\n base. \r\n Mortarless brick paving resists horizontal \r\n forces by transferring these forces through brick units and sand filled \r\n joints to rigid edging by means of an interlocking bond pattern. The \r\n greatest resistance to horizontal forces is obtained when the direction \r\n of vehicular traffic flow is perpendicular to the long joints in the \r\n bond pattern. Therefore, continuous joints in running bond and other \r\n bond patterns should be laid perpendicular to the traffic flow. The \r\n herringbone bond pattern resists loads in all directions and should \r\n be used in heavy vehicular areas. \r\n Mortared brick paving resists horizontal forces \r\n imparted by vehicles due to the bonding of the units to the base by \r\n the mortar setting bed and full head joints. Thus, bond pattern and \r\n unit orientation are not critical for load transfer in mortared paving. \r\n Drainage \r\n Adequate drainage of flexible and rigid paving \r\n systems is an extremely important design consideration for successful \r\n performance and durability. Ponding water can cause deterioration of \r\n the paving in areas of repeated freeze/thaw and cause slippery conditions. \r\n Continued saturation of the base, subbase and subgrade can reduce load \r\n capacity due to weakening of the soil and cause deformations or rutting \r\n of the pavement. \r\n The best way to obtain drainage of the pavement \r\n is to slope the paving surface to provide as much surface drainage as \r\n possible. A slope of 1/8 in. to 1/4 in. per ft (1 to 2 mm per 100 mm) \r\n is suggested. Large paved areas and vehicular traffic areas may require \r\n a slope greater than 1/4 in. per ft (2 mm per 100 mm). The paving system \r\n should be sloped away from buildings, retaining walls and other elements \r\n capable of collecting or restricting surface runoff. To improve surface \r\n drainage, the direction of continuous mortar joints should run parallel \r\n to the desired direction of surface runoff. \r\n Mortarless paving requires both surface and \r\n subsurface drainage. The majority of drainage should occur on the surface. \r\n However, some water will penetrate downward until it reaches an impervious \r\n layer. This layer may be a concrete or asphalt base, a flexible base \r\n compacted to high density, an impervious soil such as clay or an impervious \r\n membrane used to separate pavement layers. Water not drained off the \r\n pavement surface will percolate to the top of this impervious layer, \r\n possibly causing pending of the water. Due to these conditions, subsurface \r\n drainage is required. \r\n Mortarless brick paving constructed over a \r\n porous base such as gravel may permit drainage through the entire system \r\n to the subgrade. The use of a geotextile between the sand setting bed \r\n and the base will permit drainage without allowing migration of the \r\n sand setting bed into the base. \r\n Drainage in mortared brick paving systems \r\n is restricted to the surface by full mortar joints and good bond between \r\n the brick paving units and the mortar. A drainage system should be designed \r\n so standing water is kept to a minimum. \r\n Surface runoff is removed by pavement edge \r\n drainage or by drains within the paving. Drains and drainage systems \r\n must be designed to remove the anticipated amount of water. The amount \r\n of drainage required varies with the size and location of the pavement \r\n and the amount of annual rainfall. Most commercial paving applications \r\n require gutters, scuppers or surface grates for surface drainage. In \r\n subsurface drainage applications, drains should have slotted openings \r\n on all sides below the paving surface. Setting bed material should be \r\n protected from washout into the drains by the use of screens or geotextiles. \r\n To prevent water from pending against curbs, \r\n weepholes should be installed through the curb at a maximum spacing \r\n of 24 in. (600 mm) o.c. along the entire edge. The weepholes should \r\n be formed by tubes or pipes with sufficient size to allow water drainage. \r\n Curb gutters can also be used when the gutter is sloped toward a drain. \r\n Figures 7 and 8 are examples of drainage in flexible and rigid base \r\n paving systems. \r\n \r\n \r\n \r\n \r\n Drainage of Flexible Paving \r\n \r\n \r\n Aggregate Base \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Drainage of Rigid Paving \r\n \r\n \r\n FIG. 8 \r\n \r\n \r\n Site \r\n The site may involve anything from a small \r\n residential patio to a major urban renewal project encompassing several \r\n city blocks. During the planning stages, consideration should be given \r\n to the location of existing or proposed underground utilities and storm \r\n drains convenient to the user. Flexible brick pavements are ideal in \r\n areas where frequent underground work will be required since removal \r\n and reinstallation is easy and existing materials can be reused. \r\n Successful installations also depend upon \r\n proper subgrade preparation. All vegetation and organic materials should \r\n be removed to the proper depth from the area to be paved. Soft spots \r\n such as utility trenches containing poor subbase material should be \r\n removed and refilled with suitable material which is properly compacted. \r\n Edge Restraints \r\n Many different types of edge restraint materials \r\n exist, Including brick, rigid plastic, wood, stone, steel, aluminum \r\n and concrete. Existing walls or structures may also be used as an edge \r\n restraint. The particular application and site conditions determine \r\n which material to use. Any of the materials previously listed can be \r\n used in light traffic applications. Only concrete, brick or stone embedded \r\n in concrete, some varieties of rigid plastic, or metal should be used \r\n in areas subjected to light or medium traffic. Heavy traffic applications \r\n require cast-in-place concrete, granite or curbs of equal strength. \r\n Asphalt or an asphalt pavement does not provide adequate edge restraint \r\n for paving subjected to vehicular traffic. \r\n Edge restraints are necessary in mortarless \r\n brick pavements as they hold the pavers together and prevent spreading \r\n and movement of pavers due to horizontal traffic loads. Intermediate \r\n restraints may be used within the pavement when there is an interruption \r\n in the paving surface or on sloped or curved areas. Intermediate restraints \r\n will provide additional thrust resistance to traffic loads and pavement \r\n creep. \r\n Edge restraints are not necessary in mortared \r\n brick paving but may be used for aesthetic reasons, to reduce chipping \r\n of perimeter brick or to control landscaping. Any of the edge restraint \r\n materials mentioned may be used. \r\n Expansion Joints \r\n Due to differential moisture and temperature \r\n changes, allowances for movement of various materials which comprise \r\n the paving assembly should be considered. Expansion joints are used \r\n in the brick paving to accommodate these movements. Expansion joint \r\n size and location vary for each paving assembly relative to climate, \r\n location, orientation, paving unit color and exposure to solar radiation. \r\n Although there are numerous formulae and guides for predicting the anticipated \r\n movement of materials, proper joint placement often depends on experience \r\n gained from similar past paving applications, along with good engineering \r\n judgment. \r\n Mortarless brick paving usually has the ability \r\n to move slightly and accommodate size changes. Consequently, expansion \r\n joints in mortarless brick paving are not generally required. \r\n Placement of expansion joints is critical \r\n in mortared brick paving assemblies. Expansion joints in brick paving \r\n which is bonded to the base must align with control joints in the concrete \r\n base below. If this is not possible, a bond break between the mortar \r\n setting bed and concrete slab must be used. However, this may not be \r\n sufficient to prevent cracking of the mortared brick paving near the \r\n control joint location. A typical expansion joint in mortared brick \r\n paving is shown in Fig. 9. \r\n In most cases, an expansion joint spacing \r\n of 16 ft (5 m) in exterior mortared brick paving is adequate. Expansion \r\n joints in interior mortared brick paving may be spaced a maximum of \r\n 24 ft (7 m) apart. However, these distances are dependent on many factors \r\n and local conditions including \r\n \r\n \r\n \r\n \r\n \r\n \r\n Expansion Joints \r\n FIG. 9 \r\n \r\n \r\n those described above. Dimensions should be \r\n measured at right angles to each other in order to keep the recommended \r\n distances from being exceeded in either direction. Expansion joint material \r\n should be placed along fixed objects such as drains or adjacent walls. \r\n Suggested placement of expansion joints for mortared brick paving are \r\n shown in Fig. 10. \r\n Expansion joint filler materials must be highly \r\n compressible and be durable when exposed to weather or abrasion. Generally, \r\n paving joint fillers made of materials such as polyethylene or premolded \r\n cellular elastomeric rod are acceptable. Materials which do not easily \r\n compress, such as cork or asphaltic control joint fillers, are not appropriate \r\n expansion joint fillers. The top of the joint is sealed with an elastomeric \r\n sealant. \r\n \r\n \r\n \r\n \r\n Typical Expansion Joint \r\n Placement In Mortared Brick Paving \r\n \r\n FIG. 10 \r\n \r\n \r\n Membranes \r\n Membranes are used in brick paving applications \r\n to separate layers in a paving system, accommodate differential movement \r\n or serve as a waterproofing element. Membrane materials include geotextiles, \r\n sheet membranes and liquid membranes. \r\n Flexible Base Pavements. In flexible \r\n base applications geotextiles may be used to separate layers. In some \r\n cases, poor soil conditions may warrant the use of a geotextile to prevent \r\n subgrade soil from migrating upward into the compacted subbase or base. \r\n In other cases an open-graded, stone base may require a geotextile above \r\n it to prevent the sand setting bed from filtering down through the base. \r\n The opening size of the geotextile should be small enough to prevent \r\n sand filtration. Geotextiles can also be used to prevent erosion or \r\n used to reinforce the subgrade. If used to reinforce the subgrade, the \r\n sections of geotextile must be lapped a minimum distance. Consult the \r\n geotextile manufacturer for specific recommendations. Building felt \r\n and other impervious membranes should not be used since they inhibit \r\n drainage. \r\n Rigid Base Pavements. Mortared brick \r\n paving and concrete bases have considerably different thermal and moisture \r\n movements. In applications where the spacing between expansion joints \r\n is larger than 16 ft (5 m), it is important to break the bond between \r\n the rigid base and the mortar setting bed by means of a membrane. Polyethylene \r\n plastic sheets or building felt can be used as the bond break. The bond \r\n break will allow the brick paving surface to move independently of the \r\n base, but still permit the paving system to provide the necessary transfer \r\n of loads. Bond breaks should be used when the brick expansion joint \r\n and concrete control joint are not aligned. \r\n Waterproofing is used in roof deck applications \r\n where it is important to prevent water penetration. The waterproofing \r\n is often applied in liquid form but can also be sheet membranes. Care \r\n should be taken to prevent damage or penetrations to waterproofing membranes \r\n during pavement construction. Technical Notes 14B \r\n provides details for brick paving over roof decks. \r\n Slip and Skid Resistance \r\n The slip resistance characteristics of a paving \r\n surface relate to pedestrian traffic, while skid resistance characteristics \r\n relate to vehicular traffic. Slip and skid resistance are measures of \r\n the slipperiness of a surface. A surface with high slip or skid resistance \r\n is relatively safe, while a low resistance may indicate a hazardous \r\n surface. Both slip resistance and skid resistance are adversely affected \r\n by water on the surface of the pavement. \r\n It is the surprise of walking from a slip \r\n resistant surface onto a wet or nonslip resistant surface that causes \r\n many falls. Since the slip resistance relies on the microtexture of \r\n the paving brick, a brick with a rougher or wire cut surface will have \r\n a higher slip resistance. \r\n Skid resistance measures the potential of \r\n vehicles skidding on the roadway surface. The skid resistance depends \r\n upon the macrotexture of the paving surface. Brick texture, joints between \r\n pavers and pavers with chamfered edges have positive effects on the \r\n overall skid resistance of the brick pavement. Skid resistance values \r\n of brick pavers fall within the range of concrete and asphalt pavements \r\n [5]. \r\n Over time, the skid resistance of all paving \r\n surfaces decreases because of the polishing effect of traffic.. The \r\n skid resistance of most brick paving is initially very high and decreases \r\n while in use, approaching an equilibrium condition after one year [8]. \r\n The skid resistance values are also affected by seasonal factors. \r\n Aesthetics \r\n The visual impact of brick paving results \r\n from the interplay of many factors including size, shape, pattern, color \r\n and texture. An endless variety of bond patterns can be achieved with \r\n brick paving. The most popular paving patterns are shown in Fig. 11. \r\n These patterns may be laid with or without mortar joints. Patterns such \r\n as herringbone, basketweave variations and some running/stack bond combinations \r\n require brick pavers with lengths twice its width when laid in mortarless \r\n brick paving. Two examples of paver sizes appropriate for mortarless \r\n paving bond patterns are 4 in. (100 mm) by 8 in. (200 mm) and 3 3/4 \r\n in. (95 mm) by 7 1/2 in. (190 mm). For mortared brick paving, nominal \r\n dimensions are often used where the paving unit dimensions listed include \r\n the mortar joint thickness. Thus, when laying out patterns with mortar \r\n joints, it is best to use nominal dimensions. \r\n \r\n \r\n \r\n \r\n Brick Paving Patterns \r\n \r\n \r\n FIG. 11 \r\n \r\n Brick pavers are manufactured in a variety \r\n of colors such as reds, browns, buffs, grays and others, including ranges \r\n and blends of colors. The type of traffic on the paving units should \r\n be considered when choosing color. For example, a light colored brick \r\n will show dirt and stains more than a darker colored brick. Also, color \r\n patterns can serve a function. Two or more different colors can be used \r\n to create patterns which guide traffic, such as marking traffic lanes \r\n or parking spaces. \r\n SUMMARY \r\n This Technical Notes describes brick \r\n paving assemblies and covers their design and detailing. Critical design \r\n concerns in brick paving systems include base preparation, drainage \r\n and load resistance. Pertinent design criteria is provided to aid the \r\n development of a proper brick paving system. The details provided in \r\n this Technical Notes will provide an adequate pavement \r\n system for most applications. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used in conjunction with good \r\n technical judgment and a basic understanding of the properties of brick \r\n masonry. Final decisions on the use of the information contained in \r\n this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project architect, engineer \r\n and owner. \r\n REFERENCES \r\n 1. Flexible \r\n Brick Pavements: Design and Installation Guide, Brick Institute \r\n of America, Reston, VA, 1991, 26 pp. \r\n 2. Flexible \r\n Pavement Guide for Roads and Streets , National Stone Association, \r\n Washington, DC. January 1985, 27 pp. \r\n 3. Hammett, \r\n M., Smith, R.A., Rigid Paving with Clay Pavers , BDA Design \r\n Note 8, Brick Development Association, England, December 1988, 15 \r\n pp. \r\n 4. Knapton, \r\n J., Mavin, K.C., Clay Segmental Pavements , Design Manual 1, \r\n Clay Brick and Paver Institute, Australia, January 1989, 23 pp. \r\n 5. Kulakowski, \r\n B.T., Evaluation of the Frictional Characteristics of Brick Pavers , \r\n Final Report submitted to the Brick Institute of America, Pennsylvania \r\n Transportation Institute, University Park, PA, November 1991, 57 pp. \r\n 6. Smith, \r\n R.A., Flexible Paving with Clay Pavers , BDA Design Note 9, \r\n Brick Development Association, England, October 1988, 12 pp. \r\n 7. Thickness \r\n Design for Concrete Highway and Street Pavements , Portland Cement \r\n Association, Skokie, IL, 1984, 44 pp. \r\n 8. Walsh, \r\n I.D., The Use of Clay Pavers in the Highway , Proceedings No. \r\n 44, Clay Paving Bricks, The Institute of Ceramics, Stoke-on-Trent, \r\n United Kingdom, November 1989, 8 pp. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60063,"ResultID":176295,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes \r\n 14A - Brick Floors and Pavements, Part II - Materials and Installation \r\n January 1993 \r\n Abstract : This Technical Notes \r\n describes the materials and installation methods used to construct \r\n brick paving assemblies. Materials covered include brick, setting \r\n bed materials, base materials and membranes. Installation procedures \r\n for flexible, semi-rigid and rigid base paving assemblies are described. \r\n Maintenance issues are also discussed. \r\n Key Words : brick, flexible pavements, \r\n installation, maintenance, mortared paving, mortarless paving, paving, \r\n rigid pavements. \r\n INTRODUCTION \r\n The longevity of brick paving applications \r\n has been proven through many years of successful in-service performance. \r\n This performance is the result of proper design, proper selection \r\n of materials and good workmanship. Even though brick is the uppermost \r\n surface, it is the base which requires the closest scrutiny and adequate \r\n preparation for proper performance of the entire system. However, \r\n all paving materials and layers should be analyzed and constructed \r\n properly. \r\n This Technical Notes deals with the \r\n proper selection of materials and their installation. Guidance is \r\n also provided for the maintenance of brick paving assemblies. Other \r\n Technical Notes in this series address design, detailing and \r\n special brick paving assemblies including floors. \r\n \r\n SELECTION OF MATERIALS \r\n Brick \r\n Paving brick selection is usually based \r\n on its weather resistance, abrasion resistance, and appearance relating \r\n to bond patterns, size and tolerances. Brick used in paving applications \r\n should conform to ASTM C 902 Specification for Pedestrian and Light \r\n Traffic Paving Brick or the proposed ASTM Specification for Heavy \r\n Vehicular Paving Brick (As of the date of this publication, this standard \r\n had not completed the ASTM consensus process.) \r\n \r\n Durability . For exterior pavements, \r\n resistance to deterioration due to freezing in the presence of moisture \r\n is of the utmost importance. Repeated freezing and thawing of moisture \r\n within a paving assembly can increase the rate of deterioration and \r\n may result in cracking or spalling of the units. The overall durability \r\n of the pavement under these conditions is dependent upon the quality \r\n of materials and the drainage efficiency of the pavement. See Technical \r\n Notes 14 Revised for information \r\n on drainage. \r\n Three weathering classes found in ASTM C \r\n 902 are SX, MX and NX. Class SX pavers are intended for use where \r\n the brick may be frozen while saturated with water. Class MX pavers \r\n are intended for exterior use where freezing conditions are not present. \r\n Finally, Class NX pavers are acceptable for interior use where protected \r\n from freezing when wet. The durability of a paving brick is measured \r\n using combinations of its compressive strength, 24 hr cold water absorption \r\n and saturation coefficient. Table 1 shows the physical property requirements \r\n found in ASTM C 902 for durability in each class. \r\n Alternates to these requirements are also \r\n found in ASTM C 902. The alternates include a maximum water absorption, \r\n a 50 cycle freezing and thawing test, a sulfate soundness test, and \r\n a performance alternate. The maximum saturation coefficient in Table \r\n 1 is not required when the average 24 hr cold water absorption is \r\n less than 6 percent. The maximum saturation coefficient and maximum \r\n cold water absorption in Table 1 are not required when the brick passes \r\n the 50 cycle freezing and thawing test. The sulfate soundness test \r\n is used as an alternate test in place of the requirements of Table \r\n 1. The performance alternate allows the manufacturer to furnish data \r\n showing that the units perform well in a similar application of similar \r\n exposure and traffic. The performance alternate must be found acceptable \r\n by the specifier. Alternates are provided in ASTM C 902 because the \r\n performance of units is not easily determined by limiting physical \r\n properties alone. The use of alternates does not signify that the \r\n brick are of a lower quality, but allows the use of units which are \r\n known to have good performance. \r\n \r\n \r\n \r\n \r\n 1Requirements for molded brick. \r\n \r\n \r\n \r\n Abrasion Resistance . Paving brick \r\n are exposed to the continual abrasive effect of pedestrian and vehicular \r\n traffic. Of these two types of traffic, pedestrian traffic can cause \r\n the most wear of the pavement surface. The impact force of high-heeled \r\n shoes causes the highest degree of abrasion. Tires, without studs, \r\n do not have such a drastic effect, although brick streets will polish \r\n over time with repeated tire traffic. \r\n Abrasion resistance is a measure of the \r\n resistance of paving brick to the wearing action due to traffic. ASTM \r\n C 902 lists two ways in which the abrasion resistance of brick pavers \r\n can be determined: 1) an abrasion index calculated by dividing the \r\n 24 hr cold water absorption by the compressive strength (units of \r\n psi) and then multiplying by 100, or 2) by the volume abrasion loss \r\n in accordance with ASTM C 418 Test Method for Abrasion Resistance \r\n of Concrete by Sandblasting. The abrasion requirements for pavers \r\n by traffic type are shown in Table 2. \r\n \r\n \r\n \r\n \r\n \r\n Slip and Skid Resistance . The slip \r\n resistance of a paving surface is related to pedestrian traffic, while \r\n skid resistance is related to vehicular traffic. Slip resistance and \r\n skid resistance are measures of the slipperiness of a paving surface. \r\n Slip resistance and skid resistance are adversely affected by the \r\n accumulation of water on the pavement surface. Over time, the skid \r\n resistance of all paving surfaces decreases because of the polishing \r\n effect of traffic. The skid resistance of most brick is initially \r\n very high and decreases while in use, approaching an equilibrium condition \r\n within one year after placement. Since both slip and skid resistance \r\n rely on the microtexture of the paving brick, a brick with a rougher \r\n texture such as a wire cut paver will provide a higher slip and skid \r\n resistance. \r\n There are no requirements for testing slip \r\n and skid resistance in ASTM C 902, although there are methods for \r\n testing skid resistance in the proposed ASTM Specification for Heavy \r\n Vehicular Paving Brick. The latter specification references ASTM E \r\n 303 Method for Measuring Surface Frictional Properties using the British \r\n Pendulum Tester (BPT). Skid resistance values of new brick pavers \r\n vary between 51 and 87 which fall within the range of concrete and \r\n asphalt pavements. [4] \r\n \r\n Dimensions . Brick pavers are available \r\n in a wide range of sizes. The most commonly available sizes of pavers \r\n are listed in Table 3. Some pavers used in mortarless applications \r\n may have a small chamfer not exceeding 3/16 in. (5 mm) in depth or \r\n width, or rounded edges with a radius less than 3/16 in. (5 mm). Chamfers \r\n provide a better path for surface drainage along the pavement surface, \r\n better slip and skid resistance and reduce the amount of chippage \r\n along the top edges of the brick during installation and use. The \r\n chamfer dimension is subtracted from the specified height when determining \r\n the thickness of the pavement surface layer for design. Pavers used \r\n in mortarless applications, especially heavy vehicular pavements, \r\n may be made with lugs or spacers. These lugs, usually 1/8 in. (3 mm) \r\n in size, space the pavers apart and provide a controlled gap for jointing \r\n sand. Lugs also keep the paver edges from touching to reduce the amount \r\n of chippage during compaction and use. Lugs should be included when \r\n measuring the specified dimensions and when laying out a paving pattern. \r\n \r\n \r\n \r\n \r\n \r\n The dimensional tolerances for pavers from \r\n ASTM C 902 are listed in Table 4. Dimensional tolerances are more \r\n critical in mortarless brick paving applications than in mortared \r\n brick paving applications since thin sand joints cannot accommodate \r\n paver dimensional variation as easily as thicker mortar joints. Brick \r\n with larger dimensional variation will shift the alignment of the \r\n pattern, making installation difficult in mortarless herringbone and \r\n basketweave applications. \r\n \r\n \r\n \r\n \r\n \r\n Salvaged Brick . The use of salvaged \r\n brick is generally not recommended for paving applications. This is \r\n obviously true for used building or facing brick. The durability of \r\n brick depends upon the properties of the units. Generally speaking, \r\n salvaged brick will not be uniformly durable when used in a pavement \r\n which is exposed to weathering. Some older \"vitrified brick pavers\" \r\n are extremely durable, but are often difficult to distinguish from \r\n poor pavers. Only a pavers past performance can be used for comparison. \r\n \r\n Setting Bed Materials \r\n The setting bed, placed between the base \r\n and the paving surface, functions as a leveling course to help refine \r\n the finished grade due to slight irregularities in the base or the \r\n units. Setting bed materials may be sand, building felt, asphalt or \r\n mortar. \r\n \r\n Sand . Sand used as the setting bed \r\n should be a washed, well-graded angular sand with a maximum particle \r\n size of about 3/16 in. (4.8 mm). Sand should conform to either ASTM \r\n C 33 Specification for Concrete Aggregates or ASTM C 144 Specification \r\n for Aggregate for Masonry Mortar. In setting beds thinner than 1 in. \r\n (25 mm), smaller sand particles such as sands conforming to ASTM C \r\n 144 should be used. In setting beds thicker than 1 in. (25 mm) and \r\n all vehicular applications, sand conforming to ASTM C 33 should be \r\n used. Naturally occurring silica sand should be used in vehicular \r\n pavements. \r\n The sand should be free of salts and other \r\n deleterious materials to avoid efflorescence or staining. The use \r\n of dry sand-cement mixtures should be avoided. Although cement may \r\n tend to keep the sand in place initially, the mixture will likely \r\n break up in a short time due to flexing of the paving system and weathering. \r\n In addition, use of a sand-cement mixture makes removal and reuse \r\n of the paving units more difficult. \r\n Materials not suitable for use as the setting \r\n bed include sands with clay or dust in excess of that permitted in \r\n ASTM C 33 or C 144. Also, fine limestone screenings must not be used, \r\n since this material is normally too soft and may cause staining. \r\n \r\n Building Felt . In residential pedestrian \r\n applications, brick may be placed directly on an asphalt or concrete \r\n base. In these applications, building felt may serve as a cushion \r\n between the brick pavers and the base, and compensate for minor dimensional \r\n variations in the base or brick. Generally, two layers of No. 15 building \r\n felt or one layer of No. 30 building felt is appropriate. Building \r\n felt should conform to ASTM D 226 or D 227. \r\n \r\n Asphalt . Asphalt setting beds composed \r\n of aggregate and asphaltic cement may be used. Proportions of these \r\n materials are generally determined by specialty contractors or the \r\n asphalt plant and are beyond the scope of this Technical Notes ; \r\n however, an asphalt setting bed generally consists of 7% asphalt and \r\n 93% sand. This mix is typically prepared and heated at an asphalt \r\n plant before being delivered to the job. A tack coat of neoprene modified \r\n asphalt should be placed on top of the asphalt setting bed to help \r\n adhere the pavers to the setting bed. \r\n \r\n Mortar . Mortar setting beds are used \r\n in mortared brick paving applications. Mortar should conform to the \r\n proportion specifications of ASTM C 270 Specification for Mortar for \r\n Unit Masonry or ANSI A118.4 Specification for Latex-Portland Cement \r\n Mortar when a latex additive is used. \r\n For exterior mortared brick paving on grade, \r\n Type M mortar is preferred. Type M mortar consists of 1 part portland \r\n cement, 1/4 part hydrated lime and 3 3/4 parts sand; or 1 part Type \r\n M masonry cement and 3 parts sand. Type S mortar may be used for exterior \r\n applications when the pavement is not in contact with the earth, such \r\n as suspended diaphragms or in interior applications. Type S mortar \r\n consists of 1 part portland cement, 1/2 part hydrated lime and 4 1/2 \r\n parts sand; or 1 part Type S masonry cement and 3 parts sand. Portland \r\n cement should conform to ASTM C 150, Types I, II or III. Masonry cement \r\n should conform to ASTM C 91, Type M or S. Hydrated lime should conform \r\n to ASTM C 207, Type S, and sand should conform to ASTM C 144. The \r\n thickness of the mortar setting bed may vary from 3/8 in. to 1 in. \r\n (10 mm to 25 mm). \r\n Bond coats may be used between the concrete \r\n slab and mortar setting bed. Bond coats consist of portland cement \r\n mixed to a creamy consistency with water or a latex additive. The \r\n bond coat is used to create improved bond between the concrete slab \r\n and the mortar setting bed. It is installed as the setting bed and \r\n pavers are laid, and should not exceed 1/16 in. (2 mm). \r\n Latex-portland cement mortars improve bond \r\n strength, reduce water absorption and provide greater durability than \r\n conventional mortars. These mortars should be used in applications \r\n such as heavy vehicular traffic pavements or pavements where proper \r\n drainage is not possible. Latex-portland cement mortars are also useful \r\n in mortared brick paving over a suspended diaphragm and are typically \r\n used in thin-set mortar applications. Latex additives are water emulsions \r\n which are added to and may replace all or part of the mixing water. \r\n It is advisable to check latex-modified mortar and brick compatibility \r\n with respect to bond strength by preconstruction testing. \r\n \r\n Jointing Materials \r\n Materials used between brick pavers may \r\n be mortar or sand. Mortared brick paving uses mortar between the pavers. \r\n This mortar should be the same as the mortar used for the setting \r\n bed. In mortarless brick paving, the sand which is placed between \r\n the pavers should conform to ASTM C 144 (masons sand). However, the \r\n maximum particle size should not be larger than the joint size. Typically, \r\n 1/8 in. (3 mm) joints are used in mortarless brick paving. The sand \r\n should be clean and washed with no deleterious materials. When mortarless \r\n brick paving is used on slopes or in areas where jointing sand may \r\n be washed out, a portland cement-sand mixture can be used. This mixture \r\n should be used with caution as it often stains pavers during installation \r\n and makes their reuse difficult. If a sand-cement mixture is necessary, \r\n it should consist of 1 part portland cement and 6 parts sand. \r\n \r\n Base and Subbase Materials \r\n Base and subbase materials consist of crushed \r\n aggregate, gravel, sand, asphalt or concrete. Suspended diaphragms \r\n are usually made of concrete, steel or wood. Asphalt and concrete \r\n bases often require an aggregate subbase. Some flexible bases may \r\n require a subbase because of heavy traffic loads or poor subgrade \r\n conditions. \r\n \r\n Aggregate Bases and Subbases . Crushed, \r\n quarry-processed aggregate is often used as a base material because \r\n of its availability, ease of use in construction and good performance. \r\n Naturally-occurring gravel may also be used if it meets proper gradation \r\n requirements. The maximum size of aggregate used in construction depends \r\n upon the size of the project and the size of the compaction equipment \r\n being used. Proper gradation of materials is required to achieve adequate \r\n compaction. Gradation should conform to ASTM D 2940 for heavy traffic \r\n applications, while smaller projects can simply require aggregate \r\n graded down from 3/4 in. (19 mm) in size. Aggregates are produced \r\n from different raw materials and are called different names in different \r\n parts of the country. Therefore, aggregate should be specified by \r\n gradation rather than by name. \r\n Either dense graded or open graded aggregate \r\n may be used, although dense graded crushed aggregate develops a stronger, \r\n more impervious base. Open graded aggregate is often used in areas \r\n of poor drainage or in areas subjected to frost heave. If an open \r\n graded aggregate base is used beneath a sand setting bed, a geotextile \r\n must be used to prevent sand from filtering into the base. \r\n In residential pedestrian applications, \r\n sand bases can be used when the subgrade is compacted or bearing on \r\n undisturbed earth, and in areas where frost heave is not a consideration. \r\n Sand should conform to ASTM C 33 (concrete sand) and be clean and \r\n free of deleterious materials. Salts in the sand will often wick up \r\n through the brick, showing efflorescence on the surface. \r\n \r\n Asphalt Bases . New or existing asphalt \r\n bases may be used to support brick paving. Major defects such as cracks \r\n or holes in existing asphalt bases should be repaired prior to installation \r\n of brick. A membrane can be placed over an existing asphalt base to \r\n strengthen the pavement and prevent the sand setting bed from sifting \r\n through cracks in the asphalt. The specification of asphalt for bases \r\n is beyond the scope of this Technical Notes , but the asphalt \r\n should conform to ASTM D 3515 (hot-mixed asphalt), ASTM D 4215 (cold-mixed \r\n asphalt) or local codes. \r\n \r\n Concrete Bases . New and existing \r\n concrete bases may be used for brick paving. New concrete should be \r\n installed following recommended concrete practices. Where a mortar \r\n setting bed is bonded to a new concrete slab, a rough textured finish \r\n should be used such as that produced by a screed or wood float. Concrete \r\n bases should be properly cured before the brick pavers are installed. \r\n If brick paving is placed over existing concrete, the concrete should \r\n be sound, with major cracks properly repaired. A geotextile can be \r\n used to bridge cracks when using a sand setting bed to prevent sand \r\n from sifting into the cracks. The specification of concrete for bases \r\n is beyond the scope of this Technical Notes , but should conform \r\n to local codes. \r\n \r\n Membranes \r\n Membranes are used in brick paving applications \r\n to separate layers in a paving system, accommodate differential movement \r\n or serve as a waterproofing element. Membrane materials include geotextiles, \r\n sheet membranes and liquid membranes. \r\n Geotextiles or geosynthetics are used to \r\n separate pavement layers while still allowing drainage. They are composed \r\n of various types of fibers that are either woven or nonwoven. Thickness, \r\n permeability, elongation, grab strength, burst pressure and durability \r\n are properties of geotextiles which should be examined for their suitability \r\n in brick paving applications. The specification of geotextiles is \r\n beyond the scope of this Technical Notes . Geotextile manufacturers \r\n should be consulted on the suitability of their product in a particular \r\n brick paving application. \r\n Sheet membranes are often used as bond breaks \r\n or waterproofing membranes. Materials such as building felt, PVC, \r\n polyethylene or other proprietary membranes can be used in brick paving \r\n applications. Felt should conform to ASTM D 226 or D 227. Strength \r\n and thickness of these materials should be such that they will resist \r\n punctures. \r\n Liquid-applied membranes are often used \r\n to waterproof decks and may be used as bond breaks. When used to waterproof, \r\n liquid-applied membranes should be self-adhered to the base to minimize \r\n migration of water caused by leaks. Application and thickness of the \r\n liquid membranes should follow the manufacturers recommendations. \r\n \r\n INSTALLATION AND WORKMANSHIP \r\n One factor which has a great impact on the \r\n performance of brick pavements is workmanship. Proper preparation \r\n and compaction of the base is absolutely critical. There are numerous \r\n ways to install brick pavements which vary by region. The recommendations \r\n in this Technical Notes are based on experience and provide \r\n a minimum level of workmanship necessary for satisfactory performance. \r\n \r\n Subgrade Preparation \r\n One element common to all paving assemblies \r\n is the soil or subgrade. In preparation for the base or subbase, the \r\n subgrade should be excavated to the proper elevation, deleterious \r\n materials removed, and the subgrade compacted. If subsurface drainage \r\n is required, drain pipes should be installed and be properly backfilled. \r\n The entire subgrade should be compacted to 90-95% maximum density. \r\n \r\n Flexible Base Systems \r\n Only mortarless brick paving should be placed \r\n over flexible bases. Generally, flexible bases are the most economical \r\n type of base to install. Proper construction of the subbase, sand \r\n setting bed and brick pavers is necessary to ensure good performance. \r\n \r\n Subbase and Base Preparation . The \r\n subbase and base materials should be spread and compacted in layers. \r\n The thickness of these layers must be consistent with the capabilities \r\n of the compaction equipment. Heavy compaction equipment such as vibratory \r\n rollers may be necessary when constructing a street with crushed stone, \r\n whereas a plate vibrator may be used when constructing a sand base \r\n for a residential patio. Each material should be placed and compacted \r\n in layers no greater than 4 in. (100 mm). It is essential that the \r\n intended surface profile of the pavement is formed by the base so \r\n the pavers can be placed on a uniform thickness of bedding sand. \r\n If a geotextile is used, it should be placed \r\n after compaction of the subgrade or base. The geotextile should be \r\n placed smooth and be overlapped a minimum of 12 in. (300 mm) at its \r\n ends. The geotextile should be lapped further in conditions such as \r\n poor soils. The geotextile should be placed so that the material entirely \r\n covers the base and extends up the side of the excavated area to contain \r\n the setting bed material. Construction equipment should be kept off \r\n of the geotextile. Check the geotextile manufacturers literature \r\n for further installation recommendations. \r\n Edge restraints should be placed before \r\n base installation if the restraint is anchored below the base. The \r\n edge restraint should be installed after base compaction if it is \r\n intended to be anchored into the base. In the latter case, the base \r\n should extend at least 6 in. (150 mm) past the end of brick paving \r\n above. \r\n \r\n Setting Bed Preparation . The setting \r\n bed material should be spread over the base in a uniform thickness. \r\n A screed board is often used to spread the sand. The setting bed is \r\n not meant to and should not be used to fill in low spots nor its thickness \r\n adjusted to bring the pavement to the correct grade. Any changes in \r\n thickness or undulations in the sand will reflect on the pavement \r\n surface. To prevent disturbance of the sand it should not be spread \r\n too far in front of the laying face of the pavers. Prepared setting \r\n bed materials left overnight should be properly protected from disturbance \r\n and moisture. The moisture content of the sand during installation \r\n should be as uniform as possible, with the material moist but not \r\n saturated. Stockpiled sand should be kept covered to prevent contamination. \r\n \r\n Paver Installation . Pavers should \r\n be laid in the desired bond pattern with a 1/16 to 1/8 in. (2 to 3 \r\n mm) average joint width. The term \"handtight\" is a misnomer since \r\n sand between the pavers is desired. The joint width should not exceed \r\n 1/4 in. (6 mm). \r\n String lines or chalk lines may be used \r\n to keep the pattern aligned. Whole pavers should be laid first, followed \r\n by pavers cut to size. All pavers should be cut with a masonry saw \r\n to produce an accurate, clean, straight cut. A trial area may be laid \r\n out in advance of work to determine paver positions and minimize the \r\n amount of cutting required. \r\n In pedestrian paving applications, jointing \r\n sand may be swept into the joints. In some pedestrian and all vehicular \r\n paving applications, the brick should be vibrated into place using \r\n a mechanical plate vibrator/compactor. Compaction of the brick forms \r\n a more stable surface and promotes interlock between the sand and \r\n pavers. If a vibrator is used, the first pass of the vibrator should \r\n be prior to the spreading of jointing sand to force bedding sand into \r\n the joints from below. On subsequent vibrator passes, jointing sand \r\n is spread across the surface before compaction. Several passes of \r\n the vibrator may be necessary to fill the joints. Compaction should \r\n not occur within 3 ft (0.9 m) of any unrestrained edge. \r\n \r\n Semi-Rigid Base System \r\n Only mortarless brick paving should be placed \r\n over a semi-rigid asphalt base. Typically, an asphalt base is supported \r\n by an aggregate subbase. Each material layer is compacted as placed. \r\n An asphalt or bituminous setting bed is placed over the base. Usually \r\n delivered hot from the plant, the asphalt setting bed is rolled to \r\n a 3/4 in. (19 mm) depth. A tack coat of 2% neoprene-modified asphalt \r\n adhesive should be applied by a mop, squeegee or trowel on top of \r\n the asphalt setting bed. This tack coat should be very thin, not exceeding \r\n 1/16 in. (2 mm), to avoid pumping of the material between the pavers \r\n and onto the surface when hot. When the tack coat is dry to the touch, \r\n paving units may be laid in the desired bond pattern. After brick \r\n placement, sand should be swept into the joints. \r\n \r\n Rigid Base Systems \r\n Both mortarless and mortared brick paving \r\n systems may be laid over a rigid concrete base. Concrete bases may \r\n or may not be laid over an aggregate subbase depending upon the application \r\n and traffic. Typically, the concrete base should cure a minimum of \r\n seven days before installation of the setting bed and pavers. \r\n In mortarless applications, a sand or asphalt \r\n setting bed is laid directly on top of the concrete base. A 1/2 in. \r\n (13 mm) sand setting bed or 3/4 in. (19 mm) asphalt setting bed is \r\n used. A thin tack coat is applied to the asphalt setting bed. Membranes \r\n can be laid directly on the concrete base, but only after the base \r\n has cured properly. The pavers are laid and jointing sand is swept \r\n into the joints. \r\n When pavers are installed with mortar, standard \r\n bricklaying or tile setting procedures should be followed. The preferred \r\n method of mortar placement is with a trowel. The concrete base should \r\n be clean and slightly dampened, but be surface dry immediately prior \r\n to placing the mortar setting bed. The setting bed is laid in the \r\n desired thickness, no more than 2 ft (0.6 m) ahead of the laying of \r\n the paving units. Brick pavers should be buttered with mortar on the \r\n bottom and edges and shoved into the mortar setting bed. The joints \r\n between the units should be completely filled to minimize moisture \r\n penetration. Joints should be tooled with a concave jointer when the \r\n mortar becomes thumbprint hard. \r\n When installing thin pavers, a thin mortar \r\n bed is used. As with full pavers, the concrete base is cleaned and \r\n dampened. However, a bond coat is applied to the concrete base prior \r\n to installation of the setting bed. The mortar setting bed and thin \r\n pavers are immediately installed on top of the bond coat. \r\n If care is exercised during mortar installation, \r\n cleaning can be avoided or kept to a minimum. Burlap bags rubbed over \r\n the surface or wet sand swept over the surface may remove some mortar \r\n droppings which are still soft. If cleaning is necessary, use procedures \r\n and cleaning solutions recommended in Technical Notes 20 \r\n Revised. Avoid the use of acid solutions when possible. \r\n An alternate method of installation of full \r\n or thin pavers involves placing pavers on a mortar setting bed and \r\n leaving a space the size of a mortar joint between the units for a \r\n grout mixture. A grout mixture with proportions of cement, lime and \r\n sand the same as the appropriate mortar but with greater flow is used. \r\n The grout is poured, injected or squeegeed into the joints after the \r\n pavers have set in the mortar. The joints are tooled to a concave \r\n finish when the grout is thumbprint hard. When grout is placed in \r\n the joints in this manner, special care must be taken to protect the \r\n units from grout stains. Pavers may have their top surface coated \r\n with paraffin or wax before they are laid. Failure to coat the pavers \r\n will result in stains on pavers that are difficult to remove. Coated \r\n pavers may be special ordered from the brick manufacturer, or the \r\n coating may be applied at the jobsite. The paraffin or wax should \r\n have a melting point between 150 and 170┬░F (66 and 77┬░C). Experience \r\n has shown that materials with lower melting points are often affected \r\n by hot sunlight, while those with higher melting points are difficult \r\n to remove. While applying the coating, care must be taken to prevent \r\n the edges or joint surfaces of the pavers from becoming coated since \r\n the edges must be clean for proper bond. The pavement should be steam \r\n cleaned soon after the mortar in the joints has cured. \r\n \r\n Pavement Tolerances \r\n The maximum variation from plane of the \r\n pavement surface should be ┬▒ 3/8 in. in 10 ft (┬▒ 10 mm in 300 mm). \r\n The edges of any two adjacent pavers should not differ by more than \r\n 1/16 in. (2 mm) in height for mortarless brick paving or 1/8 in. (3 \r\n mm) for mortared brick paving. Pavers adjacent to drainage inlets \r\n and channels should not be lower than the top of the drain and not \r\n be more than 3/16 in. (5 mm) above it. \r\n \r\n MAINTENANCE \r\n Although brick paving surfaces are very \r\n durable, some routine maintenance may be necessary. \r\n \r\n Snow Removal \r\n Snow removal from brick pavements should \r\n not present any particular problem. It can be removed by plowing, \r\n blowing or brushing away the snow. When using plows or shovels there \r\n are precautionary measures that can be taken to preserve the surface \r\n character of the brick. Metal blades should be rubber tipped or mounted \r\n on small rollers. The blade edge should be adjusted to a clearance \r\n height suitable for the pavement surface. Avoid the use of any chemicals \r\n containing rock salt to aid in melting ice. Use of these materials \r\n may cause efflorescence. A product called urea is used to melt ice \r\n at many airports without causing efflorescence. Otherwise, remove \r\n snow before it can be compacted or turn to ice. To render icy surfaces \r\n passable, use clean sand on the icy areas. \r\n \r\n Efflorescence \r\n Many times efflorescence, a white powdery \r\n substance produced by soluble salts, is unavoidable on a paving surface. \r\n Deicers used on adjacent areas may be deposited onto the brick pavement, \r\n soluble salts may be present within paving system components or salts \r\n may migrate from adjacent soils. Therefore, proper drainage and maintenance \r\n are especially critical to reduce the amount of efflorescence. If \r\n efflorescence does appear on the paving surface, natural weathering \r\n or traffic will usually eliminate it. See Technical Notes 23 \r\n Series for more information of efflorescence. \r\n \r\n Coatings \r\n Coatings or sealers are often desirable \r\n on interior brick floors to facilitate cleaning. Coatings on exterior \r\n brick pavements are not recommended unless the coating has been proven \r\n to perform on exterior brick pavements. Coatings generally have two \r\n purposes, to lock loose sand in the joints for mortarless paving and \r\n to prevent staining and facilitate cleaning. Coatings used to prevent \r\n jointing sand erosion should be applied to the joints only. All coatings \r\n used in exterior applications must have a high vapor transmission \r\n rate and not adversely affect the slip resistance of the pavement. \r\n Before any coating is applied, the pavement surface should be fully \r\n dry and clean. The choice of any coating should be based on its intended \r\n result. \r\n \r\n Repairs \r\n Repointing of mortar joints may be necessary \r\n due to deterioration of the mortar. Procedures given in Technical \r\n Notes 7F should be followed. A stronger \r\n repointing mix is recommended for paving applications than for wall \r\n applications. Type S mortar is usually sufficient to provide good \r\n durability as a repointing mortar. \r\n At some time, a brick pavement or utilities \r\n under the pavement may have to be repaired. In mortared brick paving, \r\n units and base materials that are removed should be discarded and \r\n not used again. The returned fill and subbase should be well compacted \r\n and the new base poured in place. The mortar and pavers should be \r\n replaced using techniques similar to those described for new construction. \r\n In making repairs on flexible brick pavements, \r\n the paving brick may be reused. A single unit is removed initially, \r\n preferably with a purpose-made tool to prevent damage of the paver. \r\n Adjacent pavers may subsequently be removed and stacked nearby to \r\n be used again if not damaged. Temporary edge restraints should be \r\n placed at the perimeter of the exposed area to minimize creeping of \r\n the pavement. At all times, vehicular traffic should be kept at least \r\n 6 ft (2 m) away from the work edges. Proper compaction of the new \r\n or returned fill material is very important. Fill material should \r\n be brought up to the proper level and compacted. If the area is too \r\n small to permit proper compaction, self-stabilized materials such \r\n as concrete should be used. One to two ft (0.3 to 0.6 m) of pavers \r\n around the perimeter of the excavated area should be removed so that \r\n accurate levels can be established from undisturbed work. The sand \r\n setting bed should be screeded and compacted. A thin layer of sand \r\n should be screeded on top of the setting bed to bring the setting \r\n bed to the proper level. The pavers are then re-laid in the correct \r\n bond pattern. If creep of the pavement has occurred during repairs, \r\n some units may have to be saw cut to fit, although temporary edge \r\n restraints should avoid excessive creep. Jointing sand should be spread \r\n over the top of the pavers and the system vibrated to the finished \r\n level with a plate compactor if appropriate. \r\n \r\n SUMMARY \r\n This Technical Notes describes the \r\n proper selection of materials and installation methods for brick paving \r\n assemblies. The importance of proper installation cannot be stressed \r\n enough for pavement performance and longevity. Information on maintenance \r\n of brick paving assemblies is also provided. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of \r\n America. The information contained herein must be used in conjunction \r\n with good technical judgment and a basic understanding of the properties \r\n of brick masonry. Final decisions on the use of the information contained \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project architect, engineer \r\n and owner. \r\n \r\n REFERENCES \r\n \r\n 1. American \r\n National Standard Specifications for the Installation of Ceramic \r\n Tile , Tile Council of America, Princeton, NJ, 1985, 57 pp. \r\n 2. Flexible \r\n Brick Pavements: Design and Installation Guide , Brick Institute \r\n of America, Reston, VA, 1991, 26 pp. \r\n 3. Harris, \r\n C.W. and Dines, N.T., Time-Saver Standards for Landscape Architecture , \r\n McGraw-Hill Book Co., New York, NY, 1988. \r\n 4. Kulakowski, \r\n B.T., Evaluation of the Frictional Characteristics of Brick \r\n Pavers , Final Report submitted to the Brick Institute of America, \r\n Pennsylvania Transportation Institute, University Park, PA, November \r\n 1991, 57 pp. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60064,"ResultID":176296,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 14B - Brick Floors and Pavements, Part III \r\n Nov./Dec. 1975 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n Technical Notes 14 \r\n Revised and 14A Revised, Parts I and \r\n II of this three part series deal with general considerations, classifications, \r\n materials selection, design factors, types of installations and suggested \r\n paving design assemblies. This issue of Technical Notes will \r\n discuss assemblies and installation techniques pertaining to special \r\n paving applications. \r\n Brick paving may be adapted to suspended diaphragm \r\n bases, reinforced brick structural slabs with conventional mortars and \r\n installations using high-bond latex modified mortars. This issue of \r\n Technical Notes will discuss these applications and suggest ways \r\n of cleaning and maintaining brick floors. \r\n SUSPENDED DIAPHRAGM BASES \r\n To assure long term performance on a roof \r\n deck or suspended plaza, certain special design factors must be considered \r\n to minimize the risk of deterioration. A roof deck plaza application \r\n generally must be structurally sound, esthetically appealing, durable \r\n and economical to install. Consequently, there are special moisture, \r\n thermal and structural considerations inherent in this type of application. \r\n Moisture. To insure an effective waterproofing \r\n system, it becomes necessary to give proper attention to base and counter \r\n flashing details of parapet walls as well as to the selection of the \r\n proper type of horizontal membrane. \r\n For mortarless paving, adequate drainage is \r\n very important to prevent damage to or displacement of pavers due to \r\n water and/or frost action. Sloping membranes in conjunction with porous \r\n base layers will permit water to percolate or run freely to roof drains. \r\n Special all-level roof drains are available which will handle both pavement \r\n surface and subsurface water (see Fig. 1). \r\n \r\n \r\n \r\n \r\n Reinforced Structural Concrete Slab \r\n FIG. 1 \r\n \r\n Consideration should be given to horizontal \r\n differential movement between structural concrete slabs and the waterproofing \r\n membrane. Built-up bituminous membranes generally have non-elastic properties. \r\n Seamless liquid waterproofing and rubber sheet membranes are usually \r\n elastic in behavior and are capable of adjusting to horizontal differential \r\n movement that may occur in the supporting base. \r\n Thermal Considerations. The thermal \r\n aspects of roof terraces are similar to those of normal roofs. The position \r\n of roof insulation is important with respect to the temperature variation \r\n of each element in a paved roof assembly. Under many conditions it is \r\n advantageous to place insulation directly over membrane waterproofing \r\n when considering thermal and condensation effects. \r\n Generally speaking, roof deck insulation should \r\n be of a non-rotting, moisture resistant, closed-cell type of material \r\n capable of retaining its thermal resistance in the presence of water. \r\n Traffic loadings may be supported on insulation materials in a deck \r\n assembly provided the insulation material is structurally adequate. \r\n Brick pavers like all materials change dimensionally \r\n with changes in temperature. A slip plane between pavers and a waterproofing \r\n membrane is recommended to avoid disruption of the membrane. For example, \r\n it may consist of a porous gravel cushion, asphalt impregnated protection \r\n board or other materials capable of withstanding both horizontal abrasive \r\n movement and vertical traffic loadings. \r\n Structural Considerations. The structural \r\n design of a suspended base should follow normal accepted design procedures. \r\n The dead weight of brick pavers combined with other materials and design \r\n conditions, such as live loads, vibration and impact from traffic, should \r\n be considered. For structural design purposes, the dead weight of mortared \r\n or mortarless brick pavers may be taken at approximately 10 psf per \r\n inch of thickness. Since brick pavers are available in various thicknesses, \r\n their total weight will vary. The most popular pavers mentioned in Part \r\n I are 1 5/8 in. to 2 1/4 in. thick, weighing approximately 16 to 22 \r\n psf, respectively. \r\n In residential wood joist design, consideration \r\n must be given to the additional weight of brick pavers. It will be necessary \r\n to consult a structural design loading table for wood joists and select \r\n a suitable grade and joist size. A good reference manual is \"Wood Structural \r\n Design Data\" by the National Forest Products Association (NFPA). The \r\n subfloor thickness and grade should also be checked for structural adequacy \r\n for supporting brick pavers. \r\n For mortared paving, diaphragm action becomes \r\n important in order to maintain the integrity of mortar joints. Deflection \r\n should be limited to l /600 of the span for mortared paving and \r\n l /360 for flexible paving. \r\n REINFORCED CONSTRUCTION \r\n Reinforced brick paving can be used to span \r\n an open space or for use over a fill which may tend toward uneven settlement. \r\n Reinforcement of the masonry can eliminate the necessity for a separate \r\n reinforced concrete slab or other rigid base. \r\n Reinforced brick masonry slabs are practical, \r\n especially over relatively short spans. They are capable of satisfying \r\n design loadings for pedestrian and vehicular traffic. Model building \r\n codes stipulate live loads ranging from 50 to 250 psf. A 2 1/4-in. thick \r\n brick slab may be designed to support a 50 psf live load, spanning almost \r\n 6 ft [Fig. 2(a)]. Also, using the same strength brick and mortar, but \r\n by simply turning a unit on edge to increase the slabs thickness, the \r\n design load capacity can be doubled (100 psf) and the span increased \r\n to over 7 ft [Fig. 2(b)]. \r\n \r\n \r\n \r\n \r\n Reinforced Brick Masonry \r\n FIG. 2 \r\n \r\n The design of reinforced brick masonry slabs, \r\n as shown in Table 1, is based on a rational analysis and the Standard, \r\n Building Code Requirements for Engineered Brick Masonry, BIA(SCPI), \r\n August 1969. For additional information on the design of reinforced \r\n brick masonry slabs, the 17 Series of BIA Technical Notes on Brick \r\n Construction contain design examples and calculation procedures. \r\n \r\n \r\n \r\n \r\n \r\n aNote: Design parameters for the above \r\n Table 1 are as follows: The brick compressive strength average is \r\n 8000 psi. The mortar is type M (1:1/4:3), portland cement-lime and \r\n sand. Reinforcement steel is ASTM A 82-66, fs = 20,000 psi. A simple \r\n span loading condition was assumed \r\n All mortar joints are 1/2 in. thick for \r\n the slabs shown, except as noted. \r\n \r\n \r\n Brick on Sheet Steel Forms. A variation \r\n of reinforced brick construction utilizes corrugated sheet steel as \r\n a base. The steel serves as combined form and reinforcing and can provide \r\n an economical solution to the problem of constructing brick floors over \r\n open spans. For continuous spans, negative steel is placed in grouted \r\n mortar joints. Brick are placed on a bed of mortar and vertical joints \r\n are filled with mortar or grout (Fig. 3). \r\n \r\n \r\n \r\n \r\n Corrugated Sheet Steel - Reinforced Brick \r\n Masonry Slab Assembly \r\n FIG. 3 \r\n \r\n A number of years ago, the Research and Development \r\n Department, Granco Steel Products Co., tested this method of construction \r\n to \"determine the feasibility of using 24-gauge Cofar (Cofar is the \r\n trade name for combined form and reinforcing corrugated sheet steel \r\n produced by the Granite City Steel Corp., Granite City, Illinois) on \r\n 14-ft spans, using bricks, mortar and steel acting compositely to give \r\n a structurally sound floor slab.\" \r\n Brick were standard size, dry-press, red brick \r\n with an average compressive strength of 7800 psi. The mortar was ASTM \r\n C 270, type M, of portland cement and hydrated lime. The steel form \r\n was of 24 gauge corrugated sheet steel (4.25-in. pitch, 1.2-in. depth) \r\n with positive reinforcement. \r\n The test specimen was approximately 17 in. \r\n wide and 5 1/2 in. deep over two continuous 14-ft spans. Test loads \r\n consisted of various increments of uniform and concentrated loads on \r\n combinations of one and two spans at a time. Repeated concentrated loads \r\n were applied and relieved for as many as 500,000 cycles. \r\n Conclusions to the test report emphasized \r\n three pertinent points: \r\n 1. The brick \r\n slab had adequate stiffness and minimal deflections. \r\n 2. Fatigue \r\n failure did not occur. \r\n 3. Failure \r\n occurred only when the actual uniform load exceeded 7 times the design \r\n load. (Granco engineers designed for 50 psf superimposed loads. When \r\n this specimen was tested, allowable design stresses were lower than \r\n now permitted. This perhaps explains why such a large factor of safety \r\n was exhibited.) \r\n HIGH-BOND MORTARED PAVEMENT \r\n General. Rigid brick paving installed \r\n with high-bond mortar may be generally more resistant to water penetration \r\n than paving with conventional mortars. This advantage is primarily the \r\n result of higher bonding characteristics between the mortar and brick \r\n unit. \r\n SUGGESTED BRICK PAVING DESIGN ASSEMBLIES \r\n The following assemblies illustrate how brick \r\n paving can be adapted to suspended diaphragm bases of various types. \r\n These support bases may consist of reinforced brick masonry slabs, reinforced \r\n concrete slabs, steel decking, and wood framing. \r\n Figure 1-Reinforced Structural Concrete \r\n Slab. This assembly is suitable for exterior pedestrian traffic. \r\n The pea gravel percolation layer will permit rapid drainage to occur, \r\n thus preventing possible damage from freeze-thaw cycles of trapped water. \r\n The protection board should be at least 1/8 in. in thickness and of \r\n asphalt impregnated material. \r\n Figure 2-Reinforced Brick Masonry Slab. \r\n The various types of reinforced brick masonry slabs, as illustrated, \r\n can support a wide range of live load conditions as shown in Table 1. \r\n Reinforced brick masonry slabs eliminate the need for other types of \r\n support bases. \r\n Figure 3-Corrugated Sheet Steel-Reinforced \r\n Brick Masonry Slab Assembly. This assembly combines both reinforced \r\n brick masonry and steel decking, constructed with positive and negative \r\n reinforcing steel for continuous span applications. \r\n Figure 4-Reinforced Structural Concrete \r\n Slab. This assembly is suitable for exterior pedestrian traffic \r\n and utilizes a bituminous leveling bed. \r\n Figure 5-Reinforced Structural Concrete \r\n Slab. This assembly, utilizing conventional build-up roofing, can \r\n be easily adapted to flexible brick paving suitable for outdoor pedestrian \r\n traffic. \r\n Figure 6-Steel Deck Base. This type \r\n of construction may be designed as a non-rated or rated fire resistive \r\n assembly. Figure 6 illustrates only the general material composition. \r\n For specific types of fire resistive assemblies consult Factory Mutual \r\n and Underwriters Laboratories. \r\n Figure 7-Wood Framing Assembly. This \r\n assembly is suitable for mortarless paving used in residential frame \r\n construction. \r\n Figure 8-Wood Framing Assembly. This \r\n assembly is suitable for mortared paving used in residential frame construction. \r\n INSTALLATION AND WORKMANSHIP \r\n There are certain factors that the designer \r\n should be aware of before a final design is selected. These factors \r\n will be discussed in relation to Figs. 1 through 8. \r\n Drains and Waterproofing. For suspended \r\n decks where control of surface drainage is important, all level drains \r\n and waterproofing membranes (Fig. 1) should be installed in strict accordance \r\n with the manufacturers instructions and specifications. \r\n Insulation. In Fig. 4, the insulation \r\n is required to support a specific design live load and also must be \r\n capable of withstanding the temperatures transferred through the protection \r\n board from the application of hot bitumen. Consequently, one installer \r\n of this system suggests that the insulation be capable of withstanding \r\n a minimum temperature of 300 ┬║F (149 ┬║C). \r\n \r\n \r\n \r\n \r\n Reinforced Structural Concrete Slab \r\n FIG. 4 \r\n \r\n \r\n \r\n Reinforced Structural Concrete Slab \r\n FIG.5 \r\n \r\n In Fig. 6, the insulation is usually installed \r\n in steep asphalt. If the roofing assemblys wearing surface is temporary \r\n in nature, the insulation may be laid loose and removed later for reuse. \r\n If a temporary installation is desired, the possibility of uplift due \r\n to high winds should be considered. \r\n \r\n \r\n \r\n \r\n Steel Decking Base \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n Wood Framing Assembly \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Wood Framing Assembly \r\n FIG. 8 \r\n \r\n Mortar. High-bond and latex modified \r\n portland cement mortars vary among manufacturers. Therefore, instructions \r\n for their installation should be carefully followed. When mortar joints \r\n are thumb-print hard, they should be properly tooled. Various types \r\n of conventional portland cement-lime mortars are discussed in Part I. \r\n Reinforced Brick Masonry Slabs. Brick \r\n masonry slabs spanning open spaces are constructed on forms with brick \r\n units spaced accordingly, to allow for proper joint thickness. Mortar \r\n is used to seal the bottom of the joint and also to serve as a support \r\n for reinforcing steel. After the steel is placed, all the joints are \r\n grouted. To insure complete filling of the joints, the grout should \r\n be carefully puddled. More detailed suggestions for constructing RBM \r\n soffits are given in Technical Notes 36 , \r\n Revised, \"Brick Masonry Details, Sills and Soffits\". \r\n CLEANING \r\n To facilitate cleanup of high-bond mortar \r\n or grouted installations, brick pavers may be prewaxed on the exposed \r\n face with a good grade of paraffin. The paraffin should have a melting \r\n range between 150 ┬║F (66 ┬║C) and 170 ┬║F (77 ┬║C). Experience has shown \r\n that paraffins with lower melting points are often affected by hot sunlight, \r\n while those with higher melting points are difficult to remove. Prewaxed \r\n pavers utilized in conjunction with conventionally grouted joints will \r\n also be easier to clean. While waxing the pavers, care must be exerted \r\n to prevent the edges or joint surfaces from becoming smeared with paraffin. \r\n The edges must remain clean for proper bond. \r\n When cleaning high-bond mortared pavement, \r\n it is recommended that cleaning be executed as soon as possible after \r\n the mortar joints have been allowed to cure. Due to high bond characteristics \r\n of this mortar, the pavement surface should not be left uncleaned for \r\n longer than three weeks. \r\n Steam cleaning is effective in melting the \r\n paraffin coating and lifting excess mortar. Drains should be protected \r\n from clogging by floating wax. A visual inspection after cleaning may \r\n reveal problem areas requiring scraping or light brushing with a wire \r\n brush. \r\n Generally speaking, if care is exercised during \r\n mortar application, cleaning can be avoided or held to a minimum. Mortarless \r\n installations should require little or a minimum amount of attention. \r\n On conventionally mortared installations, wet sand swept over the surface \r\n will often remove mortar droppings. Burlap bags may also be used to \r\n remove excess mortar as the mason progresses. If dry cleaning or hosing \r\n with water fails to flush the surface clean, use a cleaning solution \r\n and the procedures in Technical Notes 20 , \r\n Revised, \"Cleaning Brick Masonry\". Avoid the use of strong acid solutions \r\n where possible. Strong acids can dissolve mortar from the joints and \r\n kill grass and shrubbery. They may also cause \"acid burn\" discolorations \r\n on the brick paving. When applied in confined spaces, provide sufficient \r\n ventilation to dilute the harmful effects of acid fumes. \r\n CURING AND PROTECTION OF BRICK MASONRY \r\n PAVING \r\n It is suggested that rigid or mortared paving \r\n be allowed to set in an undisturbed condition for a period of at least \r\n 3 days. Afterwards, light pedestrian traffic is permissible with protection \r\n afforded to the paving as required. Protect from staining and light \r\n impact loads through the use of large sheets of plywood or hardboard. \r\n Full service of the pavement should be avoided until the masonry has \r\n cured a minimum of 28 days. \r\n For guidelines on cold weather protection, \r\n refer to the Technical Notes 1 Series, \"All Weather Construction\" \r\n and Technical Notes 11A Revised, \r\n \"Guide Specifications for Brick Masonry\", Section 1.05.C. \r\n Flexible brick pavement requires no curing \r\n time. However, before sweeping sand into the joints, spread damp sand \r\n in thin layers and permit it to dry. Sand must be clean and free of \r\n clay to avoid surface \"scumming\" of the finished paving. \r\n MAINTENANCE \r\n Brick floors and pavements are usually abrasion \r\n resistant and hard wearing. Therefore, they normally do not require \r\n coatings to maintain surface appearance. However, coatings and waxes \r\n are often desirable on interior brick floors to enhance their appearance \r\n and make the surfaces easier to clean. Coatings on exterior brick pavement \r\n are not recommended. For interior brick there are a few aspects to be \r\n considered before applying any type of coating. \r\n In the past it has been recommended that a \r\n sealer be applied before waxing. In many cases this has proven satisfactory. \r\n However, sealer and wax compatibility should be checked prior to final \r\n application. \r\n Sealers generally have two purposes: (1) to \r\n lock loose sand in the cracks, and (2) provide an impervious finish. \r\n If a sealer is to be used, it should be tried on a small area and evaluated \r\n before full application. A compatible wax should be selected, preferably \r\n a water emulsion type recommended for brick floors. \r\n Before a coating is applied, the floor surface \r\n should be dry. Each maintenance situation, whether it be with a sealer \r\n and wax or a synthetic sealer-finish material (spray-buffing process), \r\n must be judged on its own merits to determine the most economical means \r\n for maintaining a brick floor. \r\n Snow removal on large or small areas of brick \r\n pavement should not present any particular problem. However, there are \r\n precautionary measures that can be taken to preserve the character of \r\n the brick. Avoid the use of chemicals and rock\" salt to aid in melting \r\n ice. Use of these materials will introduce soluble salts to the masonry \r\n and may, in turn, be a source of efflorescence. To render icy surfaces \r\n passable, use clean sand on the affected area. \r\n For snow plowing efficiency, it is suggested \r\n that, where a metal plow blade is used, the edge should be rubber tipped, \r\n or mounted on small rollers. The blade edge should be adjusted to a \r\n clearance height suitable to the pavement surface. Regardless of the \r\n method used, needless chipping of the edges of the brick should be avoided. \r\n CONCLUSION \r\n The Brick Institute of America has attempted \r\n to discuss the many factors involved in the design and installation \r\n of brick paving. The suggestions offered should be utilized under the \r\n close direction of a competent professional. Their use does not preclude \r\n nor supplant professional judgment, but merely provides general and \r\n detailed information on which this judgment can be based. The designer, \r\n anticipating the use of suggested paving details shown, should analyze \r\n his design conditions in conjunction with the factors discussed in this \r\n series of Technical Notes. \r\n The Brick Institute of America can not \r\n assume responsibility for results or designs obtained from suggestions \r\n and recommendations discussed. It is beyond the scope of the Institute \r\n to anticipate every design situation that may arise, and the designer \r\n is urged to consider all of the factors. \r\n REFERENCES: \r\n 1. Building \r\n Code Requirements for Engineered Brick Masonry, 1969, BIA Standard. \r\n 2. \" Brick \r\n Masonry Details, Sills and Soffits ,\" Technical Notes 36 , \r\n Revised, July/Aug. 1981, Brick Institute of America. \r\n 3. \"Good \r\n Practice for Construction of Mortarless Brick Paving and Flooring,\" \r\n Brick Association of North Carolina, Greensboro, North Carolina. \r\n 4. \"Brick \r\n Floors and Brick Paving,\" BDA Technical Note, May 1973 Brick Development \r\n Association, London, England. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60065,"ResultID":176297,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 15 - Salvaged Brick \r\n May 1988 \r\n \r\n Abstract : The use of salvaged brick in new building construction \r\n is discussed. Factors affecting the selection include altered physical \r\n properties (durability), esthetics, economics, building code requirements \r\n and experimental testing. \r\n Key Words : brick, masonry, mortar \r\n bond , salmon brick , salvaged brick . \r\n INTRODUCTION \r\n Selecting building material requires the \r\n consideration of four factors: esthetics, design properties, economics \r\n and required level of performance. Salvaged brick are occasionally \r\n selected for their \"rugged appearance\" and sometimes for their low \r\n initial cost. Rare is the case when salvaged brick are chosen for \r\n their design properties. In general, walls using salvaged brick are \r\n weaker and less durable than walls constructed of new brick masonry \r\n units. Most salvaged brick are obtained from demolished buildings \r\n which stood 40 to 50 yr, or more. In fact, it may be next to impossible \r\n to salvage brick from modern structures which use brick set in portland \r\n cement mortars. When brick are initially placed in contact with mortar, \r\n they absorb some particles of the cementitious materials. It is virtually \r\n impossible to completely clean these absorbed particles from the surfaces \r\n of the brick units. This may greatly affect the bond between brick \r\n and mortar when reused. \r\n MANUFACTURING METHODS \r\n In the early 1900s, manufacturing methods \r\n were markedly different from those of today. De-aired brick were unknown; \r\n coal- and wood-fired periodic and scove kilns were commonplace. The \r\n modern solid, liquid or gas-fired tunnel kilns with accurate temperature \r\n controls throughout were also unknown. Manufacturing conditions years \r\n ago were generally such that large volumes of brick were fired under \r\n greater kiln-temperature variations than could be tolerated today. \r\n These conditions resulted in a wide variance in finished products. \r\n Brick from the high-temperature zones were hard-burned, high-strength, \r\n durable products; those from low-temperature zones were under-burned, \r\n low-strength products of low durability. These temperature variations \r\n also resulted in a wide range in absorption properties and color. \r\n The under-burned brick were more porous, slightly larger, and lighter \r\n colored than the harder-burned brick. (It is the nature of ceramic \r\n products to shrink during firing. Generally, for a given raw clay, \r\n the greater the firing temperature, the greater the shrinkage and \r\n the darker the color.) Their usual pinkish-orange color resulted in \r\n the name salmon brick . \r\n During these bygone years, prevalent methods \r\n of construction made production of both hard-burned and salmon brick \r\n economically feasible. Most masonry buildings had loadbearing brick \r\n walls which were a minimum of 12 in. in thickness. The hardest, most \r\n durable units were used in exterior wythes; the salmons (and others) \r\n were used for the interior wythes and were not exposed to the exterior \r\n elements. Much sorting and grading of brick was performed at the construction \r\n site by the mason, although the brick manufacturers eventually assumed \r\n this responsibility. \r\n The advent of skeleton frames marked the \r\n beginning of high-rise construction and the gradual demise of thick \r\n loadbearing masonry wall construction. (Despite the reduction in its \r\n use, loadbearing remains a very economical method for constructing \r\n low- and mid-rise buildings). Architects and engineers began to design \r\n non-loadbearing walls, and gradually decreased wall thicknesses. This \r\n evolution in design and construction techniques necessitated a change \r\n in brick manufacturing procedures. Slowly but surely, the demand for \r\n salmon brick dwindled. After the use of hollow backup units became \r\n prevalent, the need for salmon brick became practically non-existent. \r\n At the same time, having invented the thinner, lighter weight panel \r\n wall, designers focused their attention on wall strength which they \r\n equated to compressive strength of the individual brick. \r\n Because the principal demand was for high \r\n compressive strength and durability, manufacturers had to produce \r\n a high proportion of well-burned brick. This demand necessitated a \r\n change in manufacturing methods. Thus, an evolution in design and \r\n construction techniques brought on a significant and beneficial evolution \r\n in the production of brick. (For a synopsis of present day manufacturing \r\n methods, see Technical Notes 9 \r\n Revised, \"Manufacturing, Classification and Selection of Brick; Manufacturing \r\n - Part 1\"). \r\n MATERIAL SELECTION \r\n Physical Properties . Several arguments \r\n are often advanced in favor of the use of salvaged brick. Among these \r\n are: \r\n 1. Because brick are extremely durable, \r\n they can be salvaged and used again. \r\n 2. If the brick were satisfactory at the \r\n time they were first used, they are satisfactory at present. \r\n Both arguments are fallacious. \r\n When brick are initially placed in contact \r\n with mortar, they absorb some water and some particles of cementitious \r\n materials. The initial rate of absorption (suction) is an important \r\n factor which greatly affects the bond between brick and mortar. Brick \r\n with extremely high or extremely low suctions do not develop good \r\n bond. (For discussion of bond strength between mortar and new clay \r\n masonry units, see Technical Notes 8 \r\n Revised, \"Mortars for Brick Masonry\"). \r\n With salvaged brick, more factors influence \r\n bond. Pores in brick are filled with particles of lime, dirt and other \r\n deleterious matter. Many bedding surfaces of salvaged brick will not \r\n be thoroughly clean, but will instead be covered with mortar. The \r\n bond between new mortar and old mortar is not very strong. If the \r\n original mortar bond was weak, the new bond will be adversely affected. \r\n The bond to salvaged brick is considerably less than to similar new \r\n brick and has been demonstrated many times by comparative tests (see \r\n Experimental Tests Section in this Technical Notes ). \r\n Most authorities agree that water penetration \r\n through masonry results from incompletely filled joints and incomplete \r\n bond between brick and mortar. That is, water penetrates through flaws \r\n at joints rather than directly through the brick and mortar. Thus, \r\n masonry walls of salvaged brick, with their inferior mortar bond, \r\n are likely to be more susceptible to water penetration and weaker \r\n under lateral loading than similar masonry of walls constructed of \r\n new units. The ultimate compressive strength of the walls will also \r\n be lower if salmon brick are present. \r\n The durability of masonry depends upon the \r\n quality of materials and mortar bond. Generally, salmon brick do not \r\n provide the same durability as new brick when exposed to weathering. \r\n With the thinner masonry walls of today, brick are used primarily \r\n as a facing material to provide a weather resistant barrier of protection. \r\n Thus, many salmon brick are eventually placed in exposed faces of \r\n walls constructed of salvaged brick. Even where solid brick walls \r\n are used, many salmons are likely to be exposed to weathering, because \r\n it is impossible to accurately sort and grade salvaged brick. With \r\n soft, highly absorptive salmon brick exposed to the weather, and with \r\n poor mortar bond permitting excessive water penetration, it is quite \r\n likely that masonry of salvaged brick will spall, flake, pit, and \r\n crack due to freezing and thawing in the presence of excessive moisture. \r\n One common characteristic of most manufactured \r\n building materials is a reasonable degree of uniformity within a particular \r\n grade or within a given manufactured lot. Salvaged brick lack this \r\n distinction. Hard-burned and soft-burned brick, hopelessly mixed during \r\n wrecking operations, effectively create a material stockpile of two \r\n widely differing grades of materials (see Figure 1). A sample of the \r\n material will contain specimens of each grade. If tested for absorption \r\n or compression strength properties, the sample will show widely diversified \r\n characteristics. The average absorption or strength will not approximate \r\n the true values for either grade, but will lie somewhere between. \r\n In effect, it is difficult to determine whether salvaged brick will \r\n meet present day material specifications or building code requirements. \r\n \r\n \r\n \r\n \r\n \r\n \r\n When existing walls are demolished, hard-burned \r\n brick and salmons are hopelessly mixed. It is virtually impossible \r\n to distinguish between durable and non-durable units. \r\n FIG. 1 \r\n \r\n \r\n Esthetics . Salvaged brick may satisfy \r\n the desire for a rugged, colorful masonry surface. Architects often \r\n desire the extreme range of colors from dark-red to the whites and \r\n grays of units still partially covered with mortar. But most frequently \r\n the light pink color of the salmon creates the desired effect. Unfortunately, \r\n the pink in salmons results from under-burning which produces units \r\n that must not be exposed to weathering. Excessive disintegration due \r\n to weathering can soon drastically alter the appearance originally \r\n desired (See Figs. 2 - 4). \r\n \r\n \r\n \r\n \r\n \r\n \r\n A chimney of salvaged brick which has \r\n spalled considerably \r\n within a relatively short time after \r\n construction (Knoxville, Tennessee). \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n A close-up of a wall indicating the excessive \r\n spalling that is likely to occur \r\n where salvaged brick are exposed to \r\n weathering. \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Because of the greater likelihood that \r\n moisture will be present, \r\n salvaged brick should not be used for \r\n exterior patios, walks, pavements, etc. \r\n FIG. 4 \r\n \r\n \r\n All pink brick are not necessarily under-burned. \r\n During recent years the architectural demand for a variety in colors \r\n has led to the extensive use of raw clays which burn other than dark \r\n red when fired to maturity. Today, among other colors, many hard-burned, \r\n pink brick are available. These units may conform to the requirements \r\n for highest quality under applicable ASTM specifications. (Many pink \r\n brick conform to Grades SW or MW (severe or moderate weathering) under \r\n ASTM C 216 or C 62. \r\n Many manufacturers blend different colored \r\n brick to provide a rustic appearance similar to salvaged brick. There \r\n are advantages to using new brick: the architect may specify any desired \r\n color blending and may specify the desired grade under ASTM specifications. \r\n Thus, he can obtain the desired esthetic effect without sacrificing \r\n durability or strength, a feat which is nearly impossible to accomplish \r\n when using salvaged brick. \r\n Economics . Although in many instances \r\n salvaged brick have sold for more money than new brick, a principal \r\n reason for their use is their low prevailing initial cost. But initial \r\n economy often proves to be false economy. For example, labor costs \r\n are usually higher for salvaged brick due to the required sorting \r\n and cleaning of the units. Maintenance costs for salvaged-brick masonry \r\n are very likely to exceed this initial cost considering: 1) cutting \r\n out and replacing disintegrated units; 2) tuck pointing mortar joints \r\n to reduce leaks and repair cracks; and 3) repeated attempts at waterproofing. \r\n (The dangers of coating masonry of under-burned units are discussed \r\n in Technical Notes 6A , \"Colorless \r\n Coatings For Brick Masonry\". Under-burned units may undergo accelerated \r\n disintegration if impermeable coatings are applied to the exterior \r\n wall face). In many cases, the initial economics of salvaged brick \r\n prove false and result in higher total expenditures. \r\n BUILDING CODE REQUIREMENTS (See references) \r\n American Standard Building Code Requirements \r\n for Masonry , ANSI A41.1, Section 2.1.1 (appendix commentary): \r\n \"Irrespective of the original grading of \r\n masonry units, compliance with code requirements of material which \r\n has been exposed to weather for a term of years cannot be assumed \r\n in the absence of test. Much salvaged brick comes from the demolition \r\n of old buildings constructed of solid brick masonry in which hard-burned \r\n bricks were used on the exterior and salmon brick as back-up, and, \r\n since the color differences which guided the original brick masons \r\n in their sorting and selecting of bricks become obscured with exposure \r\n and contact with mortar, there is a definite danger that these salmon \r\n bricks may be used for exterior exposure with consequent rapid and \r\n excessive disintegration. Before permitting their use, the building \r\n official should satisfy himself that second-hand materials are suitable \r\n for the proposed location and conditions of use. The use of masonry \r\n units salvaged from chimneys is not recommended, since such units \r\n may be impregnated with oils or tarry material.\" \r\n National Building Code , Section \r\n 1401.2: \r\n \"Second-hand units: Brick and other second-hand \r\n masonry units which are to be reused, shall be approved as to quality, \r\n condition and compliance with the requirements for new masonry units. \r\n The unit shall be of whole, sound material, free from cracks and other \r\n defects that would interfere with its proper laying or use, and shall \r\n be cleaned free from old mortar before reuse.\" \r\n Standard Building Code , Section \r\n 1401.2: \r\n \"1401.2.1 Masonry units may be reused when \r\n clean, whole and conforming to the other requirements of this chapter, \r\n except that the allowable working stresses shall be 50% of those permitted \r\n for new masonry units. \r\n 1401.2.2 Masonry units to be reused as structural \r\n units in areas subject to the action of the weather or soil shall \r\n not be permitted unless representative samples are tested for compliance \r\n with the applicable requirements of 1402.\" \r\n Uniform Building Code , Section \r\n 2406 (k): \r\n \"Reuse of Masonry Units. Masonry units may \r\n be reused when clean, whole and conforming to the other requirements \r\n of this section. All structural properties of masonry of reclaimed \r\n units, especially adhesion bond, shall be determined by approved test. \r\n The allowable working stresses shall not exceed 50 percent of that \r\n permitted for new masonry units of the same properties.\" \r\n EXPERIMENTAL TESTS \r\n At various times interested parties have \r\n conducted tests to compare salvaged-brick masonry to masonry of similar \r\n new brick. One of the more comprehensive series of tests was conducted \r\n many years ago by the Engineering Experiment Station, University of \r\n New Hampshire. The following statements are from this test report: \r\n (Project No. 98, \"Relative Adhesion of Mortars to New and Used Brick\", \r\n for Star Brick Yard, Epping, NY (1934-1935)). \r\n \"The object of this study was to determine \r\n by laboratory methods the relative adhesion of different standard \r\n mortars to new and used or reclaimed brick . . . (using only) those \r\n materials . . . that would generally be employed . . . \r\n \". . . as far as materials are concerned \r\n . . . a wall laid up with used or reclaimed bricks . . . differ(s) \r\n from one laid up with new bricks . . . (only) in the adhesion of the \r\n mortar to the brick surfaces. It is this quality with which this study \r\n is concerned.\" \r\n Four types of used brick were tested and \r\n compared to the same four types of new brick (a total of eight types). \r\n (The report describes the eight brick types tested as including hard \r\n and soft, water-struck and sand-struck, new and old brick). Seven \r\n different standard mortars were employed. In describing the testing \r\n procedures, the report states, in part: \r\n \"The brick to be tested were selected and \r\n were cleaned of all loose particles of mortar which could be removed \r\n by means of a hammer and wire brush. No attempt, however, was made \r\n to remove any particle of mortar, etc. which adhered so firmly to \r\n the brick surface that pounding and wire brushing would not release \r\n it.\" \r\n The bulk of the report is too large to reproduce \r\n in its entirety. However, the following excerpts from the conclusions \r\n to the tests are of interest: \r\n \" . . . The adhesion of mortar to new (hard) \r\n bricks was materially greater than to second hand bricks.\" \r\n \"With but few exceptions the adhesion of \r\n mortar to hard bricks was far greater than . . . to soft bricks of \r\n the same type.\" \r\n \"Without exception . . . failure of the \r\n mortar to adhere to the surface of used brick far exceeded the failures \r\n of the joint between mortars and new brick. In other words, it appears \r\n that the capillary pores of the second hand brick were so plugged \r\n . . . that the new mortar could not gain any appreciable hold on the \r\n surface of the brick.\" \r\n \" . . . (The tests indicate) that the adhesive \r\n strength of mortar to the hard brick exceeded its cohesive strength...\" \r\n \"With (all) used brick . . . cohesive strength \r\n of the mortars exceeded many times the adhesive strength of the same \r\n mortars to the surfaces of the brick.\" \r\n \" . . . within the limits of the test . \r\n . . relative adhesion of mortars to . . . reclaimed brick . . . (is) \r\n less than half what can be expected if the same mortars are used with \r\n new brick of the same type and degree of hardness.\" \r\n SUMMARY \r\n This Technical Notes has discussed \r\n the use of salvaged brick in new brick masonry wall construction. \r\n The considerations are based on existing knowledge and experience. \r\n No effort is made or implied that this is a total discussion of the \r\n subject matter, since conditions vary widely throughout the country. \r\n However, it is a basis from which the designer can decide on the use \r\n of salvaged brick in new masonry structures. \r\n Final decisions on the use of the information \r\n and suggestions discussed in this Technical Notes are not within \r\n the purview of the Brick Institute of America and must rest with the \r\n project designer, owner or both. \r\n REFERENCES (Building codes undergo \r\n continual revision. The editions listed are those current as the publication \r\n date of this Technical Notes ). \r\n 1. American \r\n Standard Building Code Requirements for Masonry; ANSI A41.1; National \r\n Bureau of Standards (Miscellaneous Publications 211); Washington, \r\n D.C.; July 15, 1954 (Reaffirmed 1970). \r\n 2. National \r\n Building Code, 1987 Edition; Building Officials and Code Administrators \r\n International; 4051 W. Flossmoor Road, Country Club Hills, Illinois. \r\n 3. Standard \r\n Building Code, 1985 Edition; Southern Building Code Congress International; \r\n 900 Montclair Road, Birmingham, Alabama. \r\n 4. Uniform \r\n Building Code, 1985 Edition; International Conference of Building \r\n Officials; 5360 South Workman Mill Road, Wittier, California. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60066,"ResultID":176298,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 16 - Fire Resistance \r\n Oct. 1974 (Reissued Oct. 1996) \r\n \r\n INTRODUCTION \r\n Provisions relating to fire safety represent \r\n the most important regulations of every building code, so far as the \r\n safety of the public is concerned. In contrast with the few structural \r\n failures that occur, fire collects a heavy toll of lives and a high \r\n loss of dollars every year. \r\n The performance of walls, columns, floors \r\n and other building members under fire conditions is of major importance \r\n to fire safety. However, these single elements are only part of the \r\n code requirement. It is also important for the code to provide for \r\n a balance between fire ratings of members and other provisions of \r\n equal importance, such as exit facilities, floor area limitations, \r\n separation minimums and height limitations. \r\n This Technical Notes discusses the \r\n fire test procedure used for brick masonry walls and lists the fire \r\n ratings of brick masonry walls and fire protection ratings for beams \r\n and columns. \r\n FIRE RESISTANCE RATINGS \r\n It has become standard practice to express \r\n the degree of fire resistance required for any member in terms of \r\n its ability to withstand exposure to fire as prescribed by the American \r\n Society for Testing and Materials Standard Methods of Fire Tests \r\n of Building Construction and Materials, E 119. \r\n This standard test, along with other ASTM \r\n fire test standards such as E 84, does not measure the fire \r\n hazard in terms of actual performance in a real fire situation. The \r\n standard does, however, give a comparison of the measure of performance \r\n between assemblies tested under similar conditions. \r\n Specifications in this test provide that \r\n the temperature on the exposed (fire) side of the test panel shall \r\n be controlled by the standard time-temperature curve, as shown in \r\n Fig. 1. The points on this curve that determine its character are: \r\n 1000 o F (538 ° C) \r\n at 5 min \r\n 1850 o F (1010 ° C) \r\n at 2 hr \r\n 1300 o F (704 ° C) \r\n at 10 min \r\n 2000 o F (1093 ° C) \r\n at 4 hr \r\n 1550 o F (843 ° C) \r\n at 30 min \r\n 2300 o F (1260 ° C) at 8 hr \r\n 1770 o F (966 ° C) at 1 hr \r\n \r\n \r\n \r\n \r\n \r\n \r\n Standard Time-Temperature Curve for ASTM \r\n E 119 Fire Test \r\n FIG. 1 \r\n \r\n Wall Specimens. The area exposed \r\n to fire shall be at least 100 sq ft (9 m 2 ) with no dimension less than \r\n 9 ft (2.7 m). Non-bearing walls and partitions are restrained at all \r\n four sides, but bearing walls and partitions are not restrained at \r\n the vertical edges. (See Fig. 2.) \r\n \r\n \r\n \r\n \r\n Fire Test Specimen Showing Placement of \r\n Thermocouples. \r\n FIG. 2 \r\n \r\n Columns. Two methods of test are \r\n permitted. If the fireproofing is structural, the column specimen \r\n must be at least 9 ft (2.7 m) long and acceptance is based on ability \r\n to carry an axial load. If the fireproofing is not structural, the \r\n minimum column length is 8 ft (2.4 m) and acceptance is based on temperature \r\n rise in the structural column. \r\n Hose Stream Test. For most ratings, \r\n (Strictly speaking, the ASTM procedure determines ultimate fire resistance \r\n periods, not fire ratings) ASTM E 119 requires that walls undergo \r\n a fire and hose stream test as well as the fire endurance test. (Two \r\n alternates are available. The hose stream test may be performed on \r\n a duplicate wall sample which has been subjected to a fire exposure \r\n test for one half of the determined fire resistance period (but not \r\n less than 1 hr); or the hose stream test may be performed on the original \r\n wall specimen. The latter is the usual case for brick walls.) The \r\n test subjects a specimen to impact, erosion and thermal shock over \r\n the entire area of the surface which has been exposed to the fire. \r\n The specifications carefully denote nozzle size, distance, duration \r\n of application and water pressure at the base of the nozzle. (Some \r\n of these requirements vary with the fire resistance period). (See \r\n Fig. 3.) \r\n \r\n \r\n \r\n \r\n After the fire test, a wall specimen is \r\n pivoted outward and \r\n a hose stream of water played over \r\n the hot face. \r\n FIG. 3 \r\n \r\n Loading. Throughout the fire endurance \r\n and hose stream tests, a constant superimposed load is applied to \r\n bearing walls to simulate a maximum load condition. The applied load \r\n shall be as nearly as practicable to the maximum load permitted by \r\n design in reference to nationally recognized structural design criteria. \r\n Columns are loaded to develop the design \r\n stresses and then subjected to the standard fire on all sides. Where \r\n the fire protection is not designed to carry loads, an alternate method \r\n of test may be used in which the column is not loaded. Temperature \r\n rise, the sole criterion here, is measured by at least three thermocouples \r\n located at each of four levels. \r\n CONDITIONS OF ACCEPTANCE (FIRE TESTS) \r\n Non-Bearing Walls and Partitions. \r\n (No combustible members framed in). The test is, successful and a \r\n fire resistance period may be assigned to the construction, if: \r\n 1. The wall \r\n or partition withstands the fire endurance test without passage of \r\n flame or gases hot enough to ignite cotton waste for a period equal \r\n to that for which classification is desired. \r\n 2. And, \r\n the wall or partition withstands the fire and hose stream test without \r\n passage of flame, of gases hot enough to ignite cotton waste, or of \r\n the hose stream. (Although ASTM E 119 does not specifically state \r\n what is meant by \"passage of the hose stream\", this is generally accepted \r\n to mean that no collapse of the wall occurs. For example, water passing \r\n through masonry joints is not a cause for rejecting the specimen). \r\n 3. And, \r\n the average temperature of nine thermocouples on the unexposed surface \r\n has not increased more than 250 ° F (121 ° C) \r\n above its initial temperature. \r\n Bearing Walls. The conditions of \r\n acceptance for bearing walls are essentially the same as for non-bearing \r\n walls and partitions (above), with the following addition: \r\n 1. The specimen must also sustain the applied \r\n load during the fire endurance test. \r\n Columns. Columns with integral structural \r\n fireproofing may be assigned a fire resistance period if they successfully \r\n sustain the superimposed load during the fire endurance test. \r\n For fireproofing of columns not designed \r\n to carry loads, a fire resistance period may be assigned if the average \r\n temperature rise does not exceed 1000 ° F (538 ° C) \r\n and the maximum temperature rise does not exceed 1200 ° F \r\n (649 ° C) at any one point. \r\n TERMINATION POINTS OF TEST METHOD \r\n When an assembly under test reaches any \r\n one of the acceptance criteria; (1) ignition of cotton waste, (2) \r\n average temperature rise on unexposed side above 250 ° F \r\n (121 ° C), or (3) fails to carry the design load if \r\n it is a load-bearing test; the test is terminated. The first two criteria \r\n relate to the function of providing a barrier against the spread of \r\n fire by penetration of the assembly, the third relating to structural \r\n integrity. \r\n The termination point for fire tests of \r\n brick masonry walls is almost invariably due to temperature rise (heat \r\n transmission) of the unexposed surface. Brick masonry walls successfully \r\n withstand the load during test and the hose stream test conducted \r\n immediately after the wall has been subjected to the fire exposure. \r\n This structural integrity of brick masonry walls is attested to in \r\n many fires where the masonry walls have remained standing when all \r\n other parts of the building have been destroyed or consumed during \r\n the fire. \r\n COMBUSTIBLE FRAMING OR FACING \r\n Conditions of Acceptance . The test \r\n procedure for walls supporting combustible framing or facing is essentially \r\n the same as for other walls. However, no hose stream test is required. \r\n The test is successful and a fire resistance period may be assigned \r\n if: \r\n 1. The protection \r\n withstands the test and no combustible members ignite. \r\n 2. And, \r\n the contact-surface temperature of combustible members does not increase \r\n more than 250 ° F (121 ° C). For members \r\n closely embedded on three sides in masonry, concrete, etc., the permissible \r\n temperature rise is 325 ° F (163 ° C). \r\n AMOUNT OF COMBUSTIBLES RELATED TO SEVERITY \r\n OF FIRE \r\n Burn-out tests conducted at the National \r\n Bureau of Standards, which were performed in fireproof structures \r\n with various concentrations of combustibles having calorific values \r\n in the range of wood and paper (7000 to 8000 Btu per lb) and assembled \r\n to represent building occupancies, indicate that the relation between \r\n the amount of combustibles and the fire severity is approximately \r\n as given in Table 1 which is reproduced from National Bureau of Standards \r\n Report, BMS92, Fire-Resistance Classifications of Building Constructions , \r\n October 1942. \r\n \r\n \r\n \r\n COMBUSTIBLE CONTENTS IN BUILDINGS \r\n In 1947, the Office of Technical Services \r\n of the Department of Commerce sponsored an investigation of the weights \r\n of combustible contents in various occupancies. This survey was made \r\n by the Public Buildings Administration under the supervision of the \r\n National Bureau of Standards and the results are reported in National \r\n Bureau of Standards Report, BMS149, Combustible Contents in Buildings , \r\n published July 1957. Regarding the weights of combustibles reported, \r\n the report states: \r\n \r\n \"Only the weights of combustible contents, \r\n finished flooring, interior finish, and trim are included in the \r\n weight totals. No combustible structural elements are included because \r\n they are a part of the building itself and not of the contents. \r\n In general, the amounts of combustibles \r\n were obtained by weighing combustible furniture, equipment, goods, \r\n and other combustible contents in sufficient quantity to enable \r\n the total weight of such material within each area to be computed. \r\n The weight of any combustible flooring material, showcases, partitions, \r\n door and window trim, and built-in fixtures which could not be weighed, \r\n was estimated from the thickness and area. All of the weights were \r\n converted to equivalent weights of combustibles having a calorific \r\n value in the range of wood and paper. \" \r\n \r\n Table 2 gives average combustible contents \r\n of various occupancies as included in the authors summary of BMS149. \r\n \r\n \r\n \r\n In order to determine the total fuel content \r\n or total conflagration hazard represented by a building and its contents, \r\n the fire hazard represented by the combustible materials incorporated \r\n in the structure itself must be added to the combustibles incident \r\n to the occupancy of the building. \r\n FIRE RESISTANCE \r\n The fire resistance ratings of walls and \r\n partitions are usually less than ultimate fire resistance periods \r\n as determined by test, since most building code requirements are in \r\n multiples of 1 hr with a 4-hr maximum. Table 3 gives ultimate fire \r\n resistance periods for solid brick loadbearing walls. These walls \r\n were tested under working loads of 160 psi of gross area, except the \r\n 4-in. walls which were loaded to 80 psi. Ratings for 8-in. or thicker \r\n solid brick walls apply when units are laid in any of the mortars \r\n included in ASTM Specification C 270. Ratings for 4-in. solid walls \r\n apply when the units are laid with type M, S or N mortar. \r\n \r\n \r\n \r\n \r\n a Adapted from BMS92, Reference \r\n 7. \r\n b To achieve these ratings, \r\n each plastered wall face must have at least 1/2-in., 1:3 gypsum-sand \r\n plaster. \r\n c Based on load failure. \r\n d Based on temperature rise \r\n (for non-loadbearing walls). \r\n \r\n Estimating Effects of Combustible Members. \r\n Where no fire tests are available for unplastered walls with combustible \r\n members framed in, the rating may be approximated from tests on similar \r\n walls without combustible framing by using the factors in Table 4. \r\n \r\n \r\n \r\n \r\n \r\n \r\n a Adapted from BMS92, Reference \r\n 7. \r\n b For walls plastered with \r\n 1/2-in., 1:3 gypsum-sand plaster on the side opposite combustible \r\n framing, add 1 hr to computed ratings over 3 hr and 1/2 hr to \r\n lesser ratings. No increase is permitted for plaster on the \r\n same side as combustible framing nor where combustible members \r\n enter from both sides. \r\n c Multiply ratings of unplastered \r\n walls with no combustible framing by the appropriate factor \r\n to compute ratings for similar unplastered walls which support \r\n combustible framing. \r\n d Walls of units which are \r\n not cored more than 25 percent. \r\n \r\n \r\n \r\n Fire Resistance Ratings. Figures \r\n 4 through 7 list fire resistance ratings for various brick walls. \r\n Ratings listed are for loadbearing walls tested with working loads \r\n of 160 psi of gross area, except the 4-in. wall in Fig. 5 was loaded \r\n to 92 psi and the 4-in. wall in Fig. 4 was loaded to 80 psi. \r\n \r\n \r\n \r\n \r\n One-Hour Fire Rating Construction Shown \r\n is Loadbearing. \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Two-Hour Fire Ratings Constructions Shown \r\n are Loadbearing. \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Three-Hour Fire Ratings Constructions \r\n Shown are Loadbearing. \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n Four-Hour Fire Ratings Constructions Shown \r\n are Loadbearing \r\n FIG. 7 \r\n \r\n Table 5 lists the fire resistance ratings \r\n for steel columns covered with brick. \r\n \r\n \r\n \r\n \r\n \r\n a Column fire resistance varies \r\n with the cross-sectional area of solid material; the larger the area, \r\n the greater the fire resistance for a given thickness of protection \r\n around the structural steel. Column dimensions are outside dimensions. \r\n Smaller columns may require more cover to achieve equal ratings. For \r\n columns that are not square, protection should equal that of a square \r\n column having equal or lesser cross-sectional area. \r\n b Thicknesses do not include plaster. \r\n \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Fire \r\n Resistance Ratings, December 1964; American Insurance Association, \r\n 85 John Street, New York, NY 10038. \r\n 2. Harry \r\n D. Foster; A Study of the Fire Resistance of Building \r\n Materials, Engineering Experiment Station Bulletin No. 104, \r\n January 1940; Ohio State University, Columbus, Ohio. \r\n 3. Standard \r\n Methods of Fire Tests of Building Construction and Materials, \r\n ASTM Designation E 119; American Society for Testing and Materials, \r\n 1916 Race St., Philadelphia, PA 19103. \r\n 4. Fire \r\n Resistance of Brick Walls, Technical News Bulletin No. 124, \r\n August 1927; National Bureau of Standards, Washington, D.C. \r\n 5. Ingberg, \r\n Griffin, Robinson, Wilson; Fire Tests of Building Columns, \r\n Technologic Paper No. 184, 1921; National Bureau of Standards, \r\n Washington, D.C. \r\n 6. Fire \r\n Endurance of Hollow Brick Walls, Technical News Bulletin, Vol. \r\n 35, No. 4, April 1951; National Bureau of Standards, Washington, \r\n D. C. \r\n The following three references are Building \r\n Materials and Structures Reports, published by the National \r\n Bureau of Standards, Washington, D.C.: \r\n 7. Fire-Resistance Classifications of Building Constructions, BMS92, \r\n October 7, 1942. \r\n 8. Fire \r\n Tests of Brick Walls, BMS143, November 30, 1954. \r\n 9. Combustible \r\n Contents in Buildings, BMS149, July 25, 1957. \r\n 10. Report \r\n of a Standard ASTM Fire Endurance and Hose Stream Test of an Unsymmetrical \r\n Limited Load Bearing Wall Assembly , Building Research Laboratory \r\n Report No. 5477, November 1973; Engineering Experiment Station, \r\n The Ohio State University, Columbus, OH 43210. \r\n 11. Report \r\n of a Standard ASTM Fire Endurance Test and Fire and Hose Stream \r\n Test on a Wall Assembly, Building Research Laboratory Report \r\n No. T-3660, October 1966; Engineering Experiment Station, The Ohio \r\n State University, Columbus, OH 43210. \r\n 12. Fire \r\n Resistance of a Brick Cavity Wall System, Report No. E.S. 6975, \r\n October 1968; Structural Research Laboratory, Richmond Field Station, \r\n University of California, Berkeley California. \r\n 13. \"SCR \r\n brick\" (Reg. U.S. Pat. Off., SCPI(BIA)) Wall Fire Resistance Test, \r\n by Ohio State University Engineering Experiment Station; Research \r\n Report No. 2, Structural Clay Products Research Foundation (BIA), \r\n September 22, 1952. \r\n 14. Report \r\n of a Standard ASTM Fire Endurance and Hose Stream Test , Building \r\n Research Laboratory Reports, Nos. T-1971, March 1962, and T-1972, \r\n March 1962; and Report of a Standard ASTM Fire Endurance and \r\n Hose Stream Test on a Wall Assembly, Report No. T-3016, August \r\n 1964; Engineering Experiment Station, The Ohio State University, \r\n Columbus, OH 43210. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60067,"ResultID":176299,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 16B - Calculated Fire Resistance \r\n June 1991 (Reissued Aug. 1991) \r\n \r\n Abstract : Fire-resistance periods for building components are normally \r\n determined by physical tests conducted according to ASTM E 119 Standard \r\n Methods of Fire Tests of Building Construction and Materials. This Technical \r\n Notes addresses analytical methods to determine fire ratings for building \r\n construction not specifically tested under ASTM E 119. Described are procedures \r\n for calculating the fire resistance of clay masonry walls including: 1) \r\n effects of plaster; 2) effects of air spaces; 3) multi-wythe construction; \r\n and 4) equivalent thickness for hollow masonry units. \r\n Key Words : brick, building codes, fire \r\n ratings, fire resistance period. \r\n INTRODUCTION \r\n Fire resistance is determined by standard test \r\n methods and used by model building codes to provide both life safety and \r\n property protection. Standards to establish fire resistance are developed \r\n and adopted by a consensus group. Model codes contain mandatory requirements \r\n which local jurisdictions adopt as law to govern building design and construction. \r\n Fire resistance is a property of all types of \r\n building construction and is related to whether the materials are combustible \r\n or non-combustible. Clay masonry is a non-combustible material and has \r\n excellent fire resistance in building construction. Accepted practice \r\n has been to determine the fire resistance of clay masonry walls by ASTM \r\n E 119 Method for Fire Tests of Building Construction and Materials. \r\n There are some instances when a particular type \r\n of building construction has not been physically tested by the ASTM E \r\n 119 test method. This Technical Notes provides an analytical method \r\n to determine the fire rating for building construction not specifically \r\n tested by ASTM E 119. This method is commonly known as the calculated \r\n fire resistance. This Technical Notes, the third in this series, \r\n concentrates on calculated fire resistance as it applies to model building \r\n code requirements. Other Technical Notes in this series address \r\n the ASTM E 119 test method and fire resistance ratings for bearing wall \r\n applications. \r\n DEFINITIONS \r\n To fully understand the calculated fire resistance \r\n procedure, two terms must be defined. These two definitions will be referenced \r\n throughout this Technical Notes . \r\n Fire Resistance Period : the property \r\n of a material or assembly to withstand fire or give protection from it \r\n for a specific period of time. As applied to elements of buildings, fire \r\n resistance is characterized by the ability to confine a fire, to continue \r\n to perform a given structural function, or both. \r\n Fire Rating : a time required, usually \r\n expressed in the lowest full hour, for an element in a building to maintain \r\n its particular fire resistance properties. Model building codes establish \r\n the required fire ratings for various building elements. \r\n THEORY \r\n The resistance of clay masonry walls to fire \r\n is a well established fact and has been found to be a function of wall \r\n mass or thickness. Fire resistance tests have been conducted on walls \r\n of solid and hollow clay units. During the ASTM E 119 fire test, the fire \r\n resistance of clay masonry walls is usually established by the temperature \r\n rise on the unexposed side of the wall specimen. Few masonry walls have \r\n failed due to loading or thermal shock of the hose stream. \r\n The method of calculating fire resistance periods \r\n is described in NBS BMS 92, \"Fire Resistive Classifications of Building \r\n Construction\", National Bureau of Standards, 1942. The construction must \r\n be similar to others for which the fire resistance periods are known, \r\n or of composite constructions for which the fire resistance periods of \r\n various components are known. Regarding the derivation of the general \r\n calculated fire resistance formulae, the authors state: \r\n \r\n \"In most cases the fire resistance period \r\n will be determined by the temperature rise on the unexposed side of \r\n the wall, and it is on this criterion that the following method of interpolation \r\n and extension is based. \r\n According to the general theory of heat \r\n transmission, if walls of the same material are exposed to a heat source \r\n that maintains a constant temperature of the surface of the exposed \r\n side, and the unexposed side is protected against heat loss, the time \r\n at which a given temperature will be attained on the unexposed side \r\n will vary as the square of the wall thickness. \r\n In the standard fire test, which involves \r\n specified conditions of temperature measurement and a fire that increases \r\n the temperature at the exposed surface of the wall as the test proceeds, \r\n the time required to attain a given temperature rise on the unexposed \r\n side will be different from where the temperature on the exposed side \r\n remains constant at the initial exposure temperature for any period. \r\n It has been found that comparisons fairly consistent with test results \r\n can be obtained by assuming the variation to be according to some lower \r\n power of n than the second. The fire resistance period of the wall can \r\n be then expressed by the formula: \r\n \r\n R = (cV) n Eq. \r\n 1 \r\n \r\n where: R \r\n = fire resistance period, hr \r\n \r\n \r\n c = coefficient depending on the \r\n material, design of the wall, and the units of measurement of R \r\n and V \r\n V = volume of solid material per \r\n unit area of wall surface, and \r\n n = exponent depending on the rate \r\n of increase of temperature at the exposed face of the wall \r\n \r\n \r\n \r\n For walls of a given material and design, \r\n it was found that an increase of 50 percent in volume of solid material \r\n per unit area of wall surface resulted in a 100 percent increase in \r\n the fire resistance period. This relationship gives a value of 1.7 for \r\n n. The lower value for n as compared with 2 for the theoretical condition \r\n of constant temperature of the exposed surface is to be expected as \r\n the rising temperature at the exposed surface would tend to shorten \r\n the fire resistance period of walls qualifying for relatively higher \r\n ratings.\" \r\n \r\n The fire resistance period of a wall may be \r\n expressed in terms of the fire resistance of the conjoined wythes of the \r\n wall as follows: \r\n \r\n \"If R 1 , R 2 , R 3 , etc. = fire resistance periods of walls (or component laminae of \r\n walls) having volumes of solid material per unit area of wall surface \r\n of V 1 , \r\n V 2 ,V 3 ,etc., respectively, also letting c and n be defined as \r\n above, then for walls in general, R 1 = (c 1 V 1 ) n , R 2 = (c 2 V 2 ) n , and R 3 = (c 3 V 3 ) n .\" \r\n \r\n The fire resistance period of the composite \r\n wall using the form of Eq. 1 will be: \r\n \r\n \r\n R = (c t V t ) n , Eq. 2 \r\n \r\n \r\n where: V t = V 1 + V 2 + V 3 \r\n and C t = (c 1 V 1 + c 2 V 2 + C 3 V 3 ) / V \r\n therefore, R \r\n = (c 1 V 1 + c 2 V 2 + c 3 V 3 ) n \r\n \r\n \r\n \r\n = (R 1 1/n + R 2 1/n + R 3 1/n ) 1.7 1 \r\n Eq. 3 \r\n \r\n \r\n \r\n Substituting 1.7 for n and 0.59 for 1/n, the \r\n general calculated fire resistance formula becomes: \r\n \r\n \r\n R = (R 1 0.59 + R 2 0.59 + R 3 0.59 ... + \r\n R n 0.59 ) 1.7 Eq. 4 \r\n \r\n \r\n where: R 1 , R 2 , and R 3 \r\n ... R 1 = known fire resistance periods of the component laminae, in hr \r\n The calculated fire resistance has been expressed \r\n in terms of the fire resistance periods of the component laminae of the \r\n wall, which need not be of the same material and design. \r\n For walls of similar materials but of different \r\n thicknesses, the formula can be adjusted to the following form: \r\n \r\n \r\n R 2 \r\n = R 1 (V 2 / V 1 ) 1.7 Eq.5 \r\n \r\n \r\n where V 1 \r\n and V 2 are the volumes of solid \r\n materials per unit area of wall surface, and R 2 and R 1 are the corresponding \r\n fire resistance periods. \r\n Using this theory, the fire resistance period \r\n of a wall assembly can be determined from the fire resistance periods \r\n of the component laminae. Either the fire resistance periods determined \r\n by fire tests or the fire rating established from the fire tests can be \r\n used. Use of actual fire resistance periods determined by tests will provide \r\n more accurate results than the use of fire ratings. This is because fire \r\n ratings are based on the lowest full hour achieved. As an explanation, \r\n a wall with a fire resistance period end point of 2 hours and 40 minutes \r\n will only attain a fire rating of 2 hours. Further, many fire tests of \r\n clay masonry walls are terminated once the wall attains the desired fire \r\n rating rather than continuing the fire test to its end point. The calculated \r\n fire resistance, using either the fire resistance period or fire rating, \r\n can thus be used to verify that the wall assembly equals or exceeds the \r\n fire rating required by the building code enforced in the area in question. \r\n CALCULATED FIRE RESISTANCE \r\n Multi-Wythe Construction \r\n The theory behind calculated fire resistance \r\n indicates that a multi-wythe wall, i.e., a wall consisting of two or more \r\n dissimilar materials, has a greater fire resistance than a simple summation \r\n of the fire resistance periods of the various layers. Equation 4 developed \r\n from NBS BMS 92 yields a calculated fire resistance if the fire resistance \r\n periods for each dissimilar material are known. The fire resistance periods \r\n can be used to determine the total fire resistance of a multi-wythe wall \r\n composed of a combination of concrete, concrete masonry or clay masonry. \r\n The fire rating of the multi-wythe wall will be the maximum number of \r\n full hours thus determined. \r\n Tables 1 through 5 are extracted from known \r\n fire resistance tests performed under ASTM E 119. Tables 1, 2, 4, 5 and \r\n 7 can be used to calculate fire resistance period for walls constructed \r\n of a combination of clay masonry, concrete masonry or concrete walls. \r\n \r\n \r\n \r\n 1 Units shall comply with the requirements \r\n of ASTM C 62, C 126, C 216 or C 652. \r\n 2 1 in. = 25.4 mm. \r\n 3 A 9 in. wall has a 120 min rating \r\n if the hollow spaces near combustible members are filled with fire resistance \r\n materials for the full thickness of the wall and for at least 4 in. above \r\n and below and between the combustible members. \r\n 4 Units shall comply with the requirements \r\n of ASTM C 34. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 units shall \r\n comply with the requirements of ASTM C 34, C 56, C 212 or C 530. \r\n 2 1 in. = 25.4 mm. \r\n 3 Ratings are for dense \r\n hard-burned clay or shale. \r\n 4 Cells filled with blue, \r\n stone, slag, cinders or sand mixed with mortar. \r\n 5 Ratings are for medium-burned \r\n clay tile \r\n \r\n . \r\n \r\n \r\n \r\n 1 1 in. = 25.4 mm. \r\n \r\n \r\n \r\n \r\n 1 Equivalent thickness is the average \r\n thickness of the solid material in the wall. It is found by taking the \r\n total volume of a wall unit, subtracting the volume of core spaces, \r\n and dividing this by the area of the exposed face of the unit. \r\n \r\n 2 Values between those shown \r\n in the table can be determined by direct interpolation. \r\n 3 Where combustible members are \r\n framed into the wall, the thickness of solid material between the end \r\n of each member and the opposite face of the wall, or between members \r\n set in from opposite sides, shall not be less than 93% of the thickness \r\n shown in the table. \r\n 4 Units shall comply with the requirements \r\n of ASTM C 55, C 73, C 90 or C 145. \r\n 5 Extracted from the 1991 Edition \r\n of the Standard Building Code, Southern Building Code Congress International, \r\n Table 3103.1. \r\n \r\n Effects of Plaster \r\n Sanded gypsum plaster applied to either face \r\n of a clay masonry wall will increase the fire resistance period of the \r\n wall. Tests of solid clay masonry unit walls show the effect of one coat \r\n of plaster on the fire exposed side of a specimen to be approximately \r\n the same as for one coat of plaster on the unexposed side. No test have \r\n been performed with plaster on only the unexposed side of hollow clay \r\n tile walls, but there is no reason to suspect performance different from \r\n that of solid clay masonry walls. \r\n The calculated fire resistance formula to include \r\n the effect of sanded gypsum plaster on either one or two sides becomes: \r\n \r\n \r\n R = (R n 0.59 + pl) 1.7 Eq. 6 \r\n \r\n \r\n \r\n where: R = calculated \r\n fire resistance of the assembly, hr \r\n \r\n \r\n R n = fire rating of individual \r\n wythe, hr \r\n pl = thickness coefficient of sanded gypsum \r\n plaster \r\n \r\n \r\n \r\n The thickness coefficients of plaster for use \r\n in the formula for determining the calculated fire resistance of plastered \r\n clay masonry walls are taken from NBS BMS 92. The constants were derived \r\n from available test results. The average thickness of plaster applied \r\n in the series of tests ranged from 1/2 inch (12.7mm) to 3/4 inch (19.1mm). \r\n These thicknesses are most likely to be used in new building construction \r\n or are found to be applied on existing walls in a building where the fire \r\n rating is not known. \r\n Values of pl for use in Equation 6 are given \r\n in Table 6. Thickness coefficients of sanded gypsum plaster should be \r\n selected based on the actual thickness of plaster applied to the wall \r\n and whether one or two sides of the wall is plastered. When using Equation \r\n 6, values for R 1 \r\n must be hourly ratings. Thickness coefficients for other types of plaster \r\n materials have not been determined to date. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Extracted from the 1991 \r\n Edition of the Standard Building Code, Southern Building Code \r\n Congress International, Table 3102.1B. \r\n 2 The fire resistance period \r\n for this thickness exceeds 240 minutes. \r\n 3 Dry unit weight of 35 \r\n pcf or less and consisting of cellular, perlite or vermiculite \r\n concrete. \r\n \r\n \r\n \r\n \r\n \r\n Effects of Air Spaces \r\n A continuous air space separating wythes of \r\n masonry will increase the calculated fire resistance of masonry walls. \r\n A continuous air space can occur between wythes of masonry or between \r\n masonry and concrete. The calculated fire resistance formula then becomes: \r\n \r\n R = (R 1 0.59 + R 2 0.59 + ...R n 0.59 + as) 1.7 Eq. \r\n 7 \r\n \r\n where: R = calculated \r\n fire resistance of the assembly, hr \r\n \r\n \r\n R 1 , R 2 and R 1 = fire rating of the individual wythes, hr \r\n as = coefficient for continuous air space \r\n \r\n \r\n \r\n NBS BMS 92 indicates that a continuous air space \r\n from 1/2 inch (12.7 mm) to 3 1/2 inch (89 mm) may be estimated by the \r\n use of a value 0.3 for each continuous air space. Thus a value of 0.6 \r\n would be used in multi-wythe wall with two continuous air spaces. Values \r\n for R 1 in Equation 7 \r\n must be in hours. \r\n Hollow Clay Masonry Walls \r\n Although many fire tests on hollow clay masonry \r\n walls have been conducted, it would be virtually impossible to test all \r\n combinations of unit size and shape used in construction. Fire resistance \r\n periods can be readily obtained or estimated from the units equivalent \r\n thickness. It is accepted practice to determine the fire resistance of \r\n concrete masonry units based on the type of aggregate used to manufacture \r\n the units and the equivalent thickness of solid material in the wall. \r\n Recent developments in the clay masonry industry have led to the use of \r\n the equivalent thickness method for determining the fire resistance of \r\n hollow clay masonry units which conform to ASTM C 652 Standard Specification \r\n for Hollow Brick Made From Clay or Shale. The equivalent thickness method \r\n permits the determination of fire resistance period of hollow clay units \r\n that may not have been physically tested under ASTM E 119. The fire resistance \r\n periods for hollow clay masonry units included in Table 7 are based on \r\n the equivalent thickness principle. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Values listed are for 1:3 \r\n sanded gypsum plaster. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Equivalent thickness is the \r\n average thickness of solid material in the wall. It is found by taking \r\n the total volume of a wall unit, subtracting the volume of core or \r\n cell spaces and dividing by the area of the exposed face of the unit. \r\n 2 Values between those shown \r\n in the table can be determined by direct interpolation. \r\n 3 Where combustible members \r\n are framed in the wall, the thickness of solid material between \r\n the end of each member and the opposite face of the wall. or between \r\n members set in from opposite sides, shall not be less than 93% of \r\n the thickness shown in the table. \r\n 4 Units shall comply with the \r\n requirements of ASTM C 652. \r\n 5 Extracted from the 1991 Edition \r\n of the Standard Building Code, Southern Building Code Congress International, \r\n Table 3104.4. \r\n \r\n \r\n \r\n Equivalent thickness is the average thickness \r\n of solid material in the wall. It is found by taking the total volume \r\n of a wall unit, subtracting the volume of core or cell spaces and dividing \r\n by the area of the exposed face of the unit. The equivalent thickness \r\n of hollow clay masonry units can be calculated from the actual thickness \r\n and the percentage of solid material in the unit. Both of these measurements \r\n can be obtained when the units are sampled and tested according to ASTM \r\n C 67 Methods of Sampling and Testing Brick and Structural Clay Tile. \r\n The equivalent thickness is based on the equation: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: E T = equivalent thickness, in. \r\n \r\n \r\n > V = net volume (gross volume less void \r\n area), in. 3 \r\n l = length of hollow brick, in. \r\n h = height of hollow brick, in. \r\n \r\n \r\n \r\n When the walls are plastered with sanded gypsum \r\n plaster, the effect of the plaster may be included by using Equation 6 \r\n once R n \r\n is calculated using the equivalent thickness method for the hollow clay \r\n masonry unit. However, Equation 6 can only be used when plaster consists \r\n of sanded gypsum materials. To determine the effects of other plaster \r\n materials for hollow clay masonry units, the only option is to include \r\n the thickness of the plaster when determining the net volume, V, in Equation \r\n 8. \r\n EXAMPLES OF CALCULATED FIRE RESISTANCE \r\n Multi-Wythe Construction \r\n A composite wall consists of 4 inch (100 mm) \r\n nominal face brick with a mortared collar joint and 4 inch (100 mm) siliceous \r\n aggregate concrete wall. The fire resistance rating is determined as follows: \r\n From Table 1 \r\n \r\n 4 inch nominal face brick, R 1 = 60 min (1 \r\n hr) \r\n \r\n From Table 5 \r\n \r\n 4 inch siliceous concrete wall, \r\n R 2 = 77.3 min \r\n (1.29 hr) \r\n \r\n Fire Resistance is calculated by Equation 4 \r\n \r\n \r\n R = (R 1 0.59 + R 2 0.59 ) 1.7 \r\n = [ (1.0) 0.59 + (1.29) 0.59 ] 1.7 \r\n = 3.70 hr \r\n \r\n \r\n \r\n Fire Rating is expressed in multiples of hours \r\n with 4 hr as a maximum required in all model building codes. A wall with \r\n a calculated fire resistance of 3.70 hr cannot attain a 4 hr fire rating. \r\n Thus, the fire rating is 3 hr. \r\n Effects of Plaster \r\n A 6 inch (150 mm) solid brick masonry wall has \r\n a 120 min (2 hr) fire rating from Table 1. Determine the fire rating with \r\n 3/4 inch (19.1 mm) thick sanded gypsum plaster on one and two sides. \r\n Using Equation 6 and Table 6 with 3/4 inch thick \r\n plaster on one side \r\n \r\n \r\n R = (R n0 \r\n 59 + pl) 1.7 \r\n = [(2) 0.59 + 0.45] 1.7 \r\n = 3.13 hr. Fire Rating = 3 hr \r\n \r\n \r\n \r\n Using Equation 6 and Table 6 with 3/4 inch thick \r\n plaster on two sides \r\n \r\n \r\n R = [(2) 0.59 + 0.90] 1.7 \r\n = 4.45 hr. Fire Rating = 4 hr \r\n \r\n \r\n \r\n Effects of Air Spaces \r\n A cavity wall consists of 4 in. (100 mm) nominal \r\n solid clay masonry units, a 2 in. (50 mm) air space and 8 in. (200 mm) \r\n limestone, cinder or unexpanded slag concrete masonry unit. The concrete \r\n masonry unit has actual dimensions of 8 x 8 x 16 inches and is 50% solid. \r\n The fire rating is determined by Eq. 7 as follows: \r\n From Table 1 \r\n \r\n \r\n 4 in. nominal solid clay unit, R 1 = 60 min or \r\n 1 hr \r\n A 2 in. air space, as = 0.30 \r\n \r\n \r\n \r\n An 8 x 8 x 16 CMU composed of limestone, cinder \r\n or unexpanded slag has an equivalent thickness of \r\n \r\n = \r\n 4 in., From Table 4, fire rating = 120 min (2 hr) Fire \r\n \r\n Resistance is calculated by Eq. 7: \r\n R = (R 1 0.59 + R 2 0.59 + as) 1.7 \r\n = [(2) 0.59 \r\n + (2) 0.59 \r\n + 0 3] 1.7 \r\n = 5.77 \r\n hr. Fire Rating = 4 hr \r\n \r\n \r\n \r\n Hollow Clay Masonry Walls \r\n Determine the equivalent thickness and fire \r\n rating for a nominal 8 x 4 x 12 in. (200 x 100 x 400 mm) hollow clay masonry \r\n unit with the coring pattern shown in Figure 1. \r\n \r\n \r\n \r\n \r\n Hollow Clay Masonry Unit Dimensions \r\n FIG. 1 \r\n \r\n First, determine the net volume of the unit. \r\n Gross volume = \r\n t x h x I \r\n \r\n \r\n \r\n \r\n = (7.625) (3.625) (11.625) \r\n = 321.3 in 3 \r\n \r\n \r\n \r\n \r\n \r\n Next, determine core area volume \r\n \r\n \r\n \r\n \r\n = 2 [(4.625) (3.625) (2.875)] + (4.625) \r\n (3.625) (0.625) \r\n = 106.9 in 3 \r\n \r\n \r\n \r\n \r\n \r\n Net volume = \r\n 321.3 - 106.9 \r\n \r\n \r\n \r\n = 214.4 in 3 \r\n \r\n \r\n \r\n % Solid =214.4/321.3 \r\n = 0.667, unit is 66.7% solid \r\n Determine equivalent thickness, E t by Eq. 8 \r\n From Table 7 a hollow clay masonry unit, unfilled, \r\n with an E t = 5.09 attains a 240 min or 4 hr fire rating. \r\n SUMMARY \r\n This Technical Notes has addressed analytical \r\n methods to determine fire ratings for building construction not tested \r\n under ASTM E 119, commonly known as calculated fire resistance. Procedures \r\n for calculating the fire rating of multi-wythe construction, plastered \r\n clay masonry walls, the effects of air spaces within wall construction \r\n and the equivalent thickness of hollow clay masonry units are presented. \r\n Fire ratings play an important part of building \r\n wall selection. The information presented in this Technical Notes will \r\n be useful for calculating the fire rating of untested wall assemblies \r\n composed of clay masonry and combinations of clay masonry with other construction \r\n materials such as concrete and concrete masonry. \r\n The information and suggestions contained in \r\n this Technical Notes are based on the available data and the experience \r\n of the engineering staff of the Brick Institute of America. The information \r\n contained herein must be used in conjunction with good technical judgment \r\n and a basic understanding of the fire resistance properties of brick masonry. \r\n Final decisions on the use of the information presented are not within \r\n the purview of the Brick Institute of America and must rest with the project \r\n architect, designer, owner or all. \r\n REFERENCES \r\n 1. Fire Protection \r\n Planning Report No. 13, \"Analytical Methods of Determining Fire Endurance \r\n of Concrete and Masonry Members - Model Code Approved Procedures\", Concrete \r\n & Masonry Industry Fire Safety Committee. \r\n 2. \"Fire Resistance \r\n of Various Masonry Walls\", G.E. Troxell, University of California at \r\n Berkeley, 1967. \r\n 3. Fire Test \r\n Report #83-13, \"Two Hour Fire Resistance Tests of Higgins Brick Company \r\n Solid Grouted 5-Inch Hollow Brick Units\" by Fisher and Williamson. \r\n 4. International \r\n Conference of Building Officials Research Reports #1957, #2730 and #4062. \r\n 5. NBS Research \r\n Paper No. 37, Fire Resistance of Hollow Load Bearing Wall Tile, National \r\n Bureau of Standards, 1928. \r\n 6. \"Standard \r\n Building Code, Chapter 31\" Southern Building Code Congress, International, \r\n 1991 Edition. \r\n 7. Structural \r\n Engineers Association of California, \"Annual Report for the Fire Ratings \r\n Committee\", 1962. \r\n 8. Technical \r\n Notes on Brick Construction 16 \r\n Revised, \"Fire Resistance\", Reissued May 1987. \r\n 9. Williamson, \r\n R.B., \"Standard Fire Tests of Unloaded Hollow 6-inch Brick/Block Panels \r\n (filled with lightweight Aggregate; Vermiculite)\". \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60068,"ResultID":176300,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 17 - Reinforced Brick Masonry \r\n - Introduction \r\n Reissued Oct. 1996 \r\n Abstract: The concept and use of reinforced \r\n brick masonry (RBM) has a long history. This Technical Notes documents \r\n the history of RBM. Recent and current code provisions are enumerated. \r\n Several applications of RBM show the variety of possible uses. \r\n Key Words: applications, brick, constructions, \r\n history, reinforced brick masonry, reinforcement, research. \r\n \r\n \r\n INTRODUCTION \r\n Reinforced brick masonry (RBM) consists of \r\n brick masonry which incorporates steel reinforcement embedded in mortar \r\n or grout. This masonry has greatly increased resistance to forces that \r\n produce tensile and shear stresses. The reinforcement provides additional \r\n tensile strength, allowing better use of brick masonrys inherent compressive \r\n strength. The two materials complement each other, resulting in an excellent \r\n structural material. The principles of reinforced brick masonry design \r\n are the same as those commonly accepted for reinforced concrete, and similar \r\n formula are used. \r\n Brick masonry is one of the oldest forms \r\n of building construction, and reinforcement has been used to strengthen \r\n masonry since 1813. In the modern sense reinforced brick masonry in the \r\n United States is a relatively new type of construction, with specific \r\n design procedures and construction methods. These have been developed \r\n from experimental investigations beginning in the 1920s and with the \r\n experience of the performance of thousands of reinforced masonry buildings. \r\n These structures demonstrate the practicality and economy of the construction, \r\n and their performance confirms the soundness of the design principles. \r\n Figure 1 shows the Los Angeles Police Department, Devonshire Station, \r\n a reinforced brick structure, located 3 miles (4.8 km) from the epicenter \r\n of the Northridge earthquake. There was no structural damage and the building \r\n reportedly functioned as an emergency services coordination center following \r\n the 6.7 magnitude earthquake. \r\n \r\n \r\n Los Angeles Police Department, Devonshire Station \r\n FIG. 1 \r\n \r\n \r\n This Technical Notes presents the history \r\n of reinforced brick masonry with a review of recent research and applications. \r\n Other Technical Notes in this series provide information on the design \r\n of reinforced brick masonry including applications such as beams, lintels, \r\n and retaining walls. \r\n HISTORY \r\n Marc Isambard Brunel is credited with the discovery of reinforcd masonry. \r\n He first proposed the use of reinforced brick masonry in 1813 as a means \r\n of strengthening a chimney then under construction. However, it was in \r\n connection with the building of the Thames Tunnel in 1825 that he made \r\n his first major application of reinforced brick masonry. As a part of \r\n the construction of this tunnel, two brick shafts were built, each 30 \r\n in.(760 mm) thick, 50 ft (15 m) in diameter and 70 ft (21m) deep. \r\n The shafts were reinforced vertically with \r\n wrought iron rods 1 in. (25 mm) in diameter, built into the brickwork. \r\n Iron hoops, 9 in. (230 mm) wide and 1/2 in.(13 mm) in thickness, were \r\n laid in the brickwork as building progressed. The first shaft was built \r\n to a height of 42 ft (13 m) and then sunk by excavating soil from the \r\n interior, using what is now commonly known as the open method of cassion \r\n construction. The remaining 28 ft (8.5 m) of its height was added to the \r\n top of the shaft as it settled and was stabilized by underpinning. \r\n \r\n \r\n In spite of unequal settlement of the shaft no cracks developed in the \r\n brick masonry. As a result, these cond shaft was built to its entire height \r\n of 70 ft (21 m) before it was lowered. Richard Beamish, in his Memoirs \r\n of the Life of Sir Marc Isambard Brunel [1], describes this construction \r\n and states that, after an unequal settlement of 7 in. (180 mm) on one \r\n side and 3 in. (76mm) on the other, "the surge was alarming, but \r\n so admirably was the structure bound together that no injury was sustained." \r\n Brunel continued the use of reinforced masonry and in 1836 constructed \r\n test structures in an effort to determine the additional strength imparted \r\n to the masonry by the reinforcement. \r\n Other engineers became interested in this \r\n type of construction and in 1837 Colonel Pasley of the Corps of Royal \r\n Engineers conducted a series of tests on reinforced brick masonry beams \r\n and reported results comparable to those obtained by Brunel. Pasleys \r\n tests were designed to settle the prevailing argument as to whether the \r\n flat hoop iron used as reinforcement really strenthened brick beams. \r\n Three beams were built, each 18 in. (460 \r\n mm) wide and 12 in (305 mm) (4 brick courses) deep, with a 10 ft (3 m) \r\n span. One beam was built without reinforcement, with the brick laid in \r\n neat cement. The second beam was also laid in neat cement, but this beam \r\n was reinforced with 5 pieces of hoop iron; two placed in the top mortar \r\n joint, one in the middle joint and two in the bottom mortar joint. The \r\n latter of these obviously carried most of the tensile stress. The third \r\n beam was reinforced in the same manner as the second beam, but the brick \r\n were laid in a mortar composed of 1 part lime and 3 parts sand. The first \r\n beam failed at a load of 498 lb (2.2 kN); the second beam carried 4723 \r\n lb (21.0 kN); and the third beam failed at between 400 and 500 lb (1.8 \r\n and 2.2 kN); thus settling the dispute. The results point out that bond \r\n between the brick, mortar and reinforcement develops when cement-based \r\n mortars are used. \r\n As indicated by the placement of the reinforcementin \r\n Pasleys beams, the manner in which steel and masonry act together to \r\n resist forces was not completely understood at the time. The empirical \r\n formulae dereved from such tests could not be used to determine dimensions \r\n and reinforcement of structural members varying in cross section or span \r\n from those tested. However, the interest in reinforced masonry construction \r\n continued and, with the increased use of cement in mortar, additional \r\n tests were conducted. \r\n One such test that received widespread publicity \r\n was a reinforced brick beam tested at the Great Exposition in London in \r\n 1851. The "new cement," comercially known as Portland Cement \r\n was used in the construction. This test was highly successful, and the \r\n publicity which it received resulted in the more widespread use of portland \r\n cement in several European countries and, to a lesser degree, in the United \r\n States. \r\n N. B. Corson published an article in the \r\n July 19, 1872 issue of Engineering [5] in which he reviewed the data obtained \r\n from the Expositions test beam, Brunels test structures, tests of unreinforced \r\n masonry beams and arches, and the performance of a large number of masonry \r\n structures. From these data, Corson computed tensile stresses of unreinforced \r\n masonry and recommended an allowable tensile stress for use in the design \r\n of masonry lintels. This appears to be the first recorded technical discussion \r\n of the relation of tensile strength of masonry to mortar strength. However, \r\n it did not recognize the full effect of the metal reinforcement in increasing \r\n the tensile strength of a member. \r\n The use of reinforced brick masonry continued \r\n to spread. The benefits of combining the tensile strength of iron or steel \r\n with the compressive strength of masonry was evident to those familiar \r\n with the potential damage of earthquakes. The Palace Hotel opened in San \r\n Francisco in 1875, covering a full city block, rising seven stories in \r\n height. The 3 ft (0.9 m) thick solid brick walls were reinforced by iron \r\n bands every few feet. These formed a "basket" that completely \r\n encircled the building. This is one of the few large structures that endured \r\n the 1906 San Francisco earthquake [2]. \r\n During the period 1880 to 1920, there was \r\n little recorded use of reinforced brick masonry and experimental investigations \r\n of this type of construction appear to have been practically discontinued. \r\n \r\n In 1923, the Public Works Department of the \r\n Government of India published Technical Paper No. 38 [3], a comprehensive \r\n report by Undersecretary A. Brebner of extensive tests of reinforced brick \r\n masonry structures extending over a period of about two years. A total \r\n of 282 specimens were tested, including reinforced brick masonry slabs \r\n of varying thickness, reinforced brick beams, both reinforced and unreinforced \r\n columns, and reinforced brick arches. The tests reported by Brebner appear \r\n to be the first organized research program on inforced brick masonry and \r\n the data obtained provided answers to questions raised regarding this \r\n type of construction. This research marks the initial stage of the modern \r\n development of reinforced masonry. \r\n Following Brebners report and his statement \r\n of a rational design theory for reinforced brick masonry, its use increased, \r\n particularly in India and Japan. Both countries are subject to severe \r\n earthquakes, and buildings expected to withstand such shocks must be designed \r\n with relatively high resistance to lateral forces. Since structural steel \r\n and suitable lumber for concrete formwork were relatively expensive in \r\n these countries, engineers turned to reinforced brick masonry. It be- \r\n came standard construction for public and important private buildings, \r\n as well as for many types of engineering structures, such as retaining \r\n walls, bridges, storage bins and chimneys. \r\n Brebner wrote in 1923 of reinforced brick \r\n masonry, "In all, nearly 3,000,000 ft2 (279,000 m2) have been laid \r\n in the last three years." Skigeyuki Kanamori, Civil Engineer, Department \r\n of Home Affairs, Imperial Japanese Government, is reported in the July \r\n 15, 1930 issue of Brick and Clay Record [7] as stating, "There is \r\n no question that reinforced brickwork should be used instead of (unreinforced) \r\n brickwork when any tensile stress would be incurred in the structure. \r\n We can make them more safe and stronger, saving much cost. Further, I \r\n have found that reinforced brickwork is more convenient and economical \r\n in building than reinforced concrete and, what is still more important, \r\n there is always a very appreciable saving in time." Structures described \r\n by Kanamori include sea walls, culverts and railway retaining walls, as \r\n well as buildings. \r\n Research in the United States, sponsored \r\n by the Brick Manufacturers Association of America and continued by the \r\n Structural Clay Products Institute and the Structural Clay Products Research \r\n Foundation contributed much valuable material to the literature on reinforced \r\n brick ma- \r\n sonry. Since 1924, numerous field and laboratory tests have been made \r\n on reinforced brick beams, slabs and columns, and on full size structures. \r\n Fig. 2 is an example of a 1936 test to demonstrate the structural capabilities \r\n of reinforced brick masonry elements. \r\n \r\n \r\n Early Test of RBM Element \r\n FIG. 2 \r\n \r\n \r\n During this period, research was conducted \r\n on both reinforced and unreinforced brick masonry at the National Bureau \r\n of Standards, now the National Institute of Standards and Technology, \r\n and at practically all of the principal engineering colleges of the United \r\n States. As new data was developed through research, the er ratic performance \r\n of some of the earlier reinforced brick test specimens could be explained \r\n and, one by one, the principal variables affecting the strength of reinforced \r\n brick masonry have been identified and, to large degree, evaluated. \r\n \r\n In 1933 the Brick Manufacturers Association of America published Brick \r\n Engineering, Vol. 111, Reinforced Brick Masonry, by Hugo Filippi [6]. \r\n Regarding the uses of reinforced brick masonry, the author states, "Reinforced \r\n brick masonry is well adapted for use in the following types of structures, \r\n either wholly or in part: Buildings, Culverts and Bridges; Retaining Walls \r\n and Dams; Reservoirs; Sewers and Conduits; Tanks and Storage Bins; Chimneys \r\n and Circular Constructions; Abutments, Piers, Trestle Bents, etc. \r\n "In the United States alone, during \r\n the past year and one-half, more than 40 individual jobs of reinforced \r\n brick masonry have been built, consisting of such distinctive types of \r\n construction as highway bridges, storage bins, industry track trestle \r\n piers, floor and roof slabs, beams, girders and long lintels. At the present \r\n time approximately 50 additional jobs are either under construction or \r\n under consideration in various parts of the country." \r\n During the period referred to by Filippi, \r\n the development and use of reinforced brick masonry in the United States \r\n were in their early stages. A significant change in the use of RBM came \r\n after the 1933 Long Beach earthquake. It was realized that unreinforced \r\n structures were susceptible to major damage from earthquakes and that \r\n RBM could be used to save lives. Codes were developed that promoted the \r\n use of reinforced structures. Since that time thousands of such structures \r\n have been built and reinforced brick masonry construction has been adopted \r\n as standard practice for various types of structures in many areas. \r\n RECENT RESEARCH \r\n Research on reinforced brick masonry has \r\n continued. In 1984, the Technical Coordinating Committee for Masonry Research \r\n (TCCMAR) was formed for the purpose of defining and performing both experimental \r\n and analytical research and development necesary to improve structural \r\n masonry technology [9]. A unique aspect of this research was a phased \r\n step-by-step program of sepate, but coordinated research tasks. Initial \r\n research on materials was used in later tests on assemblies. These led \r\n to tests of building elements and then the combination of wall and floor \r\n elements. The research culminated in a full-scale, five story structure \r\n subjected to dynamic loading in 1993. Much of the research led to the \r\n development of a limit states design procedure for masonry. \r\n Interest in better utilization of brick masonrys \r\n high compressive strength has led to research in prestressed brick masonry. \r\n Knowledge about this form of reinforced brick masonry was increased by \r\n research in Great Britain. Research is currently underway in the United \r\n States, as is the development of design procedures. \r\n BUILDING CODE PROVISIONS \r\n Building codes first covered reinforced brick \r\n masonry in 1953 in the American National Standards Institutes A41.2 document \r\n [4]. Since that first code on RBM, other codes such as the Uniform Building \r\n Code and the Masonry Standards Joint Committee Code (ACI 530/ASCE5/TMS \r\n 402) have adopted provisions. \r\n Most code provisions on reinforced masonry \r\n arebased on allowable stress design (ASD). In ASD, the reinforcement in \r\n masonry is designed to resist all tensile forces. The reinforcement increases \r\n the masonrys shear resistance and may contribute to the compressive strength. \r\n The stress-strain relationship is linear at working loads and the strain \r\n is proportional to the distance from the neutral axis. Code requirements \r\n cover axial compression, flexure, and shear. \r\n The Uniform Building Code has provisions \r\n for slender wall design, which is loosely based on strength design. A \r\n more comprehensive design method, known as limit states design is in development. \r\n Limit states design considers the actual performance of the materials \r\n as they undergo load and deformation. Significant changes in the state \r\n of stress, such as cracking of the masonry and yielding of the steel, \r\n are identified. The capacity, or strength, of the element at these limit \r\n states is compared to that required to resist the applied load. These \r\n code provisions are expected to provide a complement to ASD. \r\n \r\n BASIC CONSTRUCTION PROCEDURES \r\n The earliest method of placing reinforcement \r\n into brick masonry was simply to place iron or steel bars in mortar joints \r\n as the bricks were laid. Later the reinforcement was placed in collar \r\n joints between two masonry wythes and surrounded by mortar or fine grout. \r\n \r\n Eventually the space between wythes was increased \r\n in width and filled with grout. Horizontal reinforcement and grout were \r\n placed as the outer wythes were completed. The next development was the \r\n "High Lift Grouting System" in which the brick masonry wythes \r\n are built up around the reinforcement and allowed to set for a minimum \r\n period of three days. Then grout is pumped into the space containing the \r\n reinforcement. This method was developed in the San Francisco area during \r\n the late 1950s. This double wythe reinforced brick masonry is shown in \r\n Fig. 3. \r\n \r\n \r\n Double Wythe Reinforced Brick Masonry \r\n FIG. 3 \r\n \r\n \r\n The most recent means of constructing reinforced masonry incorporates \r\n hollow brick. These units are manufactured with large open cells which \r\n align vertically when the units are laid. Vertical reinforcement is placed \r\n in the cells by laying the brick over or around the bars, or by threading \r\n the bar in after the brick are laid. Horizontal reinforcement is placed \r\n in bed joints or in continuous bond beams made by removing portions of \r\n the webs that connect the face shells. Spaces containing reinforcement \r\n are grouted in lefts of up to 5 ft (1.5m) to make grout pours of up to \r\n 24 ft (7.3m). Construction of reinforced hollow brick masonry is shown \r\n in Fig. 4 \r\n \r\n \r\n Reinforced Hollow Brick Masonry \r\n FIG. 4 \r\n \r\n \r\n \r\n APPLICATIONS AND EXAMPLES \r\n During the past 60 years, reinforced brick \r\n masonry has been used for the construction of a variety of structures. \r\n In those countries where labor costs are low, one of its principal uses \r\n has been for the construction of floor and roof slabs. However, in the \r\n United States, its most extensive use has been in the construction of \r\n vertical members, such as walls and columns. Since no forms are required \r\n for these members, reinforced brick masonry is competitive with reinforced \r\n concrete, and walls of minimum thickness and light structural members \r\n can be constructed at substantially less cost in reinforced brick masonry \r\n than in reinforced concrete. \r\n Reinforced brick beams and lintels allow the designer to achieve exposed \r\n brick on the underside of these elements as in \r\n Fig. 5. \r\n \r\n \r\n Reinforced Brick Beams \r\n FIG. 5 \r\n \r\n \r\n This provides a hoizontal finished surface that matches the vertical surface. \r\n The idea of brick hanging upside down must be disconcerting. Some designers \r\n seem reluctant to use RBM construction for brick lintels or soffits. As \r\n demonstrated by tests since 1837, the bond of the mortar and grout to \r\n the brick holds the brick in place. \r\n Structures of all sizes, from single story residences to 23 story buildings \r\n have been constructed of reinforced brick masonry as shown in Figs. 6 \r\n and 7. \r\n \r\n \r\n Reinforced Brick Masonry Single Family Residence, Ashbrun VA \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n Reinforced Brick Masonry High Rise, Cleveland, OH \r\n FIG. 7 \r\n \r\n \r\n The applications range from retaining walls to exterior cladding. The \r\n added tensile strength of the reinforcing steel opens the possibility \r\n for prefabricated brick panels. This method of design and construction \r\n is utilized frequently to achieve unusual shapes and bond patterns in \r\n brick masonry. See Fig. 8. \r\n \r\n Reinforced Brick Masonry Panels \r\n FIG. 8 \r\n \r\n \r\n SUMMARY \r\n The use of reinforced brick masonry has been \r\n recorded for over 175 years. RBM construction has been adapted to a wide \r\n variety of applications throughout its history. Beams, column, pilasters, \r\n arches, and other RBM elements have been used in buildings, culverts, \r\n retaining walls, silos, chimneys, pavements and bridges. Continuing research \r\n on RBM results in more economical structures able to withstand all types \r\n of loading. \r\n The information and suggestions contained in this Techical Notes are based \r\n on the available data and the experience of the engineering staff of the \r\n Brick Institute of America. The information contained herein must be used \r\n in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonry. Final decisions on the use of the \r\n information contained in this Technical Notes are not within the purview \r\n of the Brick Institute of America and must rest with the project architect, \r\n engineer and owner. \r\n \r\n \r\n REFERENCES \r\n 1. Beamish, R., Memoirs of the Life of Sire \r\n Marc Isambard Brunel, Longmans, London, England, 1862. \r\n 2. Berger, Molly W., "The Old High-Tech Hotel," Invention and \r\n Technology, Fall 1995, pp. 46-52. \r\n 3. Brebner, A., Notes on Reinforced Brickwork, Technical Paper No. 38, \r\n Government of India, Public Works Deparment, India, 1923. \r\n 4. "Building Code Requirements for Reinforced Masonry," American \r\n Standards A 41.2-1960, American Standards Association, New York, NY, 1960. \r\n 5. Corson, N. B., "Article on Brick Masonry," Engineering, London, \r\n July 19, 1872. \r\n 6. Filippi, Hugo, Brick Engineering, Volume III, Reinforced Brick Masonry, \r\n Brick Manufacturers Association of America, Cleveland, OH, 1933. \r\n 7. Kanamori, S., "Reinforced Brickwork Opens Greater Possibilities," \r\n Brick and Clay Record, Chicago, IL, Vol. 77, #2, July 1930, pp.96-100. \r\n 8. Plummer, H. C. and Blume, J. A., "Reinforced Brick Masonry and \r\n Lateral Force Design," Structural Clay Products Institute, Washington, \r\n D.C., 1953. \r\n 9. "Status Report, U.S. Coordinated Program for Masonry Building \r\n Research," Technical Coordinating Committee for Masonry Research, \r\n Nov. 1988. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60069,"ResultID":176301,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 17A - Reinforced Brick \r\n Masonry - Materials and Construction \r\n Reissued Aug. 1997 \r\n Abstract: This Technical Notes provides \r\n a discussion of the proper methods of constructing reinforced brick masonry. \r\n Materials used in reinforced brick masonry are included Construction of \r\n brick masonry, placement of steel reinforcement and grouting are addressed. \r\n Recommendations are provided to ensure that the completed masonry will \r\n provide adequate performance. Particular empahasis is placed on those \r\n aspects of construction that are unique to reinforced brick masonry. Various \r\n quality assurance procedures and tests are also explained. \r\n Key Words: bracing, brick ,construction, \r\n grouting, inspection, reinforced brick masonry reinforcement, shoring. \r\n \r\n \r\n INTRODUCTION \r\n Reinforced brick masonry (RBM) is different \r\n from more conventional brick veneer in many ways. Key to those differences \r\n is the concept of grouting the brick masonry. Ground brick masonry is \r\n defined as construction made with clay or shale units in which cavities \r\n or pockets in elements of solid units, or cells of hollow units are filled \r\n with grout. Common examples of RBM elements are beams, columns, pilasters, \r\n multi-wythe brick walls with grouted collar joints and hollow brick walls. \r\n This Technical Notes reviews the materials and construction practices \r\n used to build RBM elements. The different techniques are discussed with \r\n particular emphasis on the concepts of grouting and the placement of reinforcement. \r\n Quality assurance and minimum standards of workmanship to ensure a high \r\n level of consistency and adequate masonry performance are addressed. \r\n The information in this Technical Notes should \r\n be carefully reviewed by the mason contractor prior to constructing reinforced \r\n brick masonry. It should also be studied by the masonry inspector. Other \r\n Technical Notes in this series provide design theories and design aids \r\n for RBM elements such as beams, walls, columns and pilasters. \r\n RBM MATERIALS \r\n The materials used to construct RBM elements \r\n should comply with applicable ASTM standards. Brick should meet the requirements \r\n of ASTM C 62 Specification for Building Brick, C 216 Specification for \r\n Facing Brick, or C 652 Specification for Hollow Brick. Mortar should comply \r\n with the requirements of ASTM C 270 Specification for Mortar for Unit \r\n Masonry. Grout should comply with ASTM C 476 Specification for Grout for \r\n Masonry. Metal wall ties, bar positioners, and reinforcing bars and wires \r\n should comply with the applicable ASTM standards as required by the Specification \r\n for Masonry Structures (ACI 530.1/ASCE 6/TMS 602)[2], also known as the \r\n MSJC Specification. All metal wall ties, positioners and joint reinforcement \r\n should be corrision resistant or protected from corrosion by appropriate \r\n coatings. Refer to Technical Notes 3A for a discussion of the material \r\n properties of brick, mortar, grout and reinforcement. \r\n The materials in both fine and coarse grout \r\n should comply with the requirements of ASTM C 476 Specification for Grout \r\n for Masonry. Both fine grout and coarse grout should comply with the volume \r\n proportions given in ASTM C 476. Specifying grout by proportions is preferred \r\n over specifying a minimum grout strength. Typically, the maximum aggregate \r\n size should be 3/8 in. (9.5 mm) for coarse grout. While larger size aggregate \r\n can be used when filling large grout spaces, it must be noted that such \r\n grout likely cannot be pumped and will require placement by pouring from \r\n a hopper. \r\n It must be remembered that grout is different \r\n from concrete. Concrete is placed with a minimum of water into nonporous \r\n forms. Grout is poured with considerably more water, as the brick masonry \r\n creates absorptive forms. Grout should be sufficiently fluid to flow into \r\n the space to be filled, and surround the steel reinforcement, leaving \r\n no voids. It should be wet enough to flow without separation of the constituents. \r\n Whereas good mortar should stick to a trowel, it should be impossible \r\n for grout to do so. The water cement ratio as mixed, highly important \r\n in concrete work, is less important for grout in brick masonry. Although \r\n excessive water is detrimental to the strength and durability of the grout, \r\n when introduced into the brick masonry the water cement ratio rapidly \r\n changes from a high to a low value. Grout is often mixed too dry and stiff \r\n for proper placement. \r\n One concern with the use of a very fluid \r\n grout mixture is excessive shrinkage. Shrinkage can create voids in the \r\n grout space, which are to be avoided. For this reason, plasticizers and \r\n shrinkage-compensating admixtures are recommended for grout in brick masonry. \r\n Such admixtures will provide the necessary fluidity while also providing \r\n a hardened grout mixture with minimal voids. \r\n There is a temptation to fill the grout space \r\n with the mortar that is used to lay up the brickwork, especially when \r\n simultaneously laying brick and grouting. This is not recommended, but \r\n may be permitted by local building codes. It is common to find excessive \r\n voids in the grout space with this practice. Proper placement and consolidaton \r\n of grout or grout mixture with a shrinkage-compensating admixture and \r\n poured in a continuous process is much more likely to form a solid grout \r\n fill. \r\n RBM CONSTRUCTION \r\n The construction of RBM elements can be separated \r\n into three parts: brick masonry construction, placement of the steel reinforcement \r\n and grouting. Each of these steps is critical to the end result. Following \r\n is a review of the three construction procedures in the order of their \r\n execution. \r\n There are two key points to remember when \r\n laying the brick. First, the brick masonry is the permanent formwork for \r\n the grout. This masonry formwork must be built in a manner that facilitates \r\n placement and positioning of the steel reinforcement and installation \r\n of grout. Second, the quality of workmanship will have a significant impact \r\n on the strength of the RBM. Unfilled mortar joints and elements that are \r\n out-of-plumb will not provide the performance assumed by the designer. \r\n All RBM elements constructed of solid brick \r\n should be laid with full head and bed joints. The ends of brick should \r\n be buttered with sufficient mortar to fill the head joints. Furrowing \r\n of bed joints should not be deep enough to result in voids. Years ago, \r\n it was believed by some that the head joints in solid brick masonry could \r\n be made only half full and that the grout would flow into the remainder \r\n of the head joint and fill the voids. It was felt that the grout would \r\n form a shear key and make the brick masonry bond more strongly to the \r\n grout core. This is not the case. In fact, creation of voids is more likely \r\n with this practice, which reduces the masonrys strength and can promote \r\n efflorescence due to entrapped water. \r\n Hollow brick are normally laid with face \r\n shell bedding. That is, the units face shells are filled solidly with \r\n mortar and head joints are filled with mortar to a depth equal to the \r\n face shell thickness. In some instances, bed joints of cross webs are \r\n covered with mortar to confine grout or to increase net area. Head joints \r\n may be filled solid for similar reasons. \r\n Cleanouts and Maintaining a Clear Grout \r\n Space \r\n Cleanouts are used to remove all mortar droppings \r\n and debris from the bottom of a grout space and also to ensure proper \r\n placement of reinforcement prior to grouting. Cleanouts should be provided \r\n in the bottom course of all spaces to be grouted when the grout pour exceeds \r\n 5 ft (1.5 m) in height. In partially grouted masonry, a cleanout is recommended \r\n at each vertical bar. In fully grouted masonry, the spacing of cleanouts \r\n should not exceed 32 in. (813 mm) on center according to the MSJC Specification. \r\n For reinforced brick masonry elements constructed with solid brick, cleanouts \r\n should be formed by omitting brick in the bottom course periodically along \r\n the base of the element. For hollow brick masonry, cleanouts should be \r\n provided in the bottom course of masonry by removing the face shell of \r\n the cells to be grouted. Examples of cleanouts in brick masonry walls \r\n are shown in Figure 1. \r\n \r\n \r\n \r\n Example of Grout Space Cleanouts \r\n FIG. 1 \r\n \r\n \r\n The minimum cleanout opening dimension should be 3 in. (76 mm). However, \r\n smaller spaces can be used if it is shown with a demonstration panel that \r\n the spaces can be cleaned. \r\n The grout spaces should be cleaned prior \r\n to grouting. It is good practice to clean out grout spaces at the end \r\n of each work day so that mortar droppings can be easily removed. A high \r\n pressure water spray, compressed air or industrial vacuum cleaner should \r\n be used for this purpose. Many contractors have found that cleaning of \r\n the grout space is facilitated by placing a layer of sand or sheets of \r\n plastic film at the bottom of the cleanout to catch mortar droppings. \r\n After cleaning and prior to grouting, cleanouts should be closed with \r\n masonry units or sealed with a blocker to resist grout pressure. A minimum \r\n curing time of two days is recommended for the cleanout plugs or they \r\n should be adequately braced against the grout pressure. Bracing is discussed \r\n further in the section on Shoring and Bracing. \r\n For solid brick masonry, the top of the mortar \r\n bed joint should be beveled outward from the center of the grout space \r\n to minimize the amount of mortar extruded into the grout space when the \r\n brick are laid, as illustrated in Fig. 2. \r\n \r\n \r\n \r\n Beveling Mortar Bed Joints \r\n FIG. 2 \r\n \r\n \r\n Mortar protruding from bed or head joints into the grout space should \r\n be struck flush with the surface or removed prior to grouting. The maximum \r\n protrusion of a mortar fin should be 1/2 in. (13 mm). The spaces to be \r\n grouted should also be kept free of mortar droppings. One method of keeping \r\n collar joints clear consists of laying wood strips on the metal ties as \r\n the two wythes of brick masonry are built. The strips catch mortar droppings \r\n during construction and are removed by means of attached heavy strings \r\n or wires as the wall is built. To keep the cells of hollow brick clear \r\n for grouting, sponges are typically used, as shown in Fig. 3. \r\n \r\n \r\n \r\n Sponges to Keep Cell Clear of Mortar Droppings \r\n FIG. 3 \r\n \r\n \r\n Erection Tolerances \r\n All RBM elements should be laid within the \r\n permitted dimensional tolerances found in the MSJC Specifications. Masonry \r\n elements that are not constructed within these limits are not as strong \r\n in compression as those that are. The thickness of mortar joints will \r\n also influence the masonrys strength. Excessively thin or thick mortar \r\n joints will reduce brick masonrys tensile and compressive strength. The \r\n erection tolerances stated in the MSJC Specification are given in Table \r\n 1. \r\n \r\n \r\n \r\n This specification and its accompanying Building Code Requirements for \r\n Masonry Structures (ACI 530/ASCE 5/TMS 402) [1] [also known as the MSJC \r\n Code] stipulate minimum size of grout spaces that are dependent on the \r\n height of grout pour and the grout type. The limits given in Table 2 are \r\n to ensure adequate access of grout to the space. \r\n \r\n \r\n \r\n Shoring and Bracing \r\n RBM elements typically require temporary \r\n support during construction provided by shoring and bracing. These supporting \r\n members are typically of wood or steel construction. Temporary support \r\n is required for two reasons. First, grout is very fluid when placed and \r\n exerts considerable pressure on the surrounding brick masonry. Second, \r\n RBM elements gain strength over time as the mortar and grout cure and \r\n harden. RBM walls, columns and pilasters are often braced along their \r\n height. RBM beams and arches may require both shoring for vertical support \r\n and bracing for lateral load resistance and grout pressure resistance. \r\n Shoring and bracing should be left in place \r\n until it is certain that the masonry has gained sufficient strength to \r\n carry its own weight and all other imposed loads including temporary loads \r\n that occur during construction. The most common problem related to temporary \r\n supports for masonry elements is inadequate lateral bracing to resist \r\n wind pressures during construction until the masonry has gained sufficient \r\n strength to resist these loads. This is especially true when the roof \r\n and floor diaphragms have not been installed and anchored to the top of \r\n the masonry wall. Without proper bracing, the wall is a free-standing \r\n cantilever element and is more vulnerable to collapse. \r\n Appropriate time for removal of shoring and \r\n bracing depends on many factors. For example, proper curing of the mortar \r\n and grout may take considerably longer under cold weather conditions. \r\n The results of suitable compression tests of prisms or grout may be necessary \r\n as evidence that the masonry has attained sufficient strength to permit \r\n removal of shoring or bracing. Rules-of-thumb for the minimum time which \r\n should elapse before removal of shoring or bracing that have been recommended \r\n for many years include the following: \r\n 1. For RBM beams, 10 days after completion \r\n of the element \r\n 2. For RBM arches, 7 days after completion \r\n 3. Lateral bracing for walls, columns and pilasters, 7 days after placement \r\n of the grout. \r\n \r\n Longer time periods will be necessary with inadequate curing conditions. \r\n It is always a good idea to consult the project engineer for a recommended \r\n bracing scheme and the length of time required for bracing to remain in \r\n place. \r\n Curing Time Prior to Grouting. If \r\n grouting is performed too rapidly after construction the hydrostatic pressure \r\n of the grout can cause "blowout" of mortar joints or even entire \r\n sections of brickwork. This is especially true when the grout pour is \r\n high. Blowout of the grout can be avoided by a combination of proper curing \r\n time, adequate wall ties or joint reinforcement across the grout space \r\n and bracing. \r\n Recommended duration of curing prior to grouting \r\n depends upon the method of grouting and the extent of bracing to resist \r\n the grout pressure. If no bracing against grout pressure is provided, \r\n the masonry should be permitted to cure for at least 3 days to gain strength \r\n before placement of grout in lifts greater than 5 ft (1.5 m) in height. \r\n For shorter grout lift heights, grout may be poured relatively soon after \r\n the brick are laid. Since grout lift heights are very short, the mason \r\n contractor should adjust the speed of construction as needed to avoid \r\n blowout of the wall. \r\n Wall Ties Across Grout Spaces. Freshly \r\n placed grout exerts a hydrostatic pressure on the surrounding masonry \r\n formwork. This pressure increases with increasing pour height. To resist \r\n the grout pressure, wall ties are used across the grout space to tie the \r\n brick wythes together. For multi-wythe masonry walls, a minimum number \r\n of wall ties will already be provided to tie the wythes together in accordance \r\n with the building code. The wall ties resist the grout pressure by their \r\n tensile capacity. The ties provide the additional benefit of a positive \r\n mechanical anchorage between the grout core and the surrounding masonry. \r\n Ties may not be required across small grout spaces such as in columns \r\n or pilasters. \r\n Wall ties across grout spaces should be at \r\n least W 1.7 (9 gage) wire. For masonry elements laid in running bond, \r\n ties should be spaced not more than 24 in (610 mm) o.c. horizontally and \r\n not more than 16 in. (406 mm) o.c. vertically. If stack bond is used, \r\n the vertical spacing should be reduced to 12 in. (305 mm) o.c. All ties \r\n should be placed in the same line vertically to facilitate the grout consolidation \r\n process. Ties should be embedded at least one-half the thickness of the \r\n masonry wythe. \r\n Bracing Against Grout Pressure. For \r\n grout pour heights less than approximately 5 ft (1.5 m), bracing of the \r\n brick masonry may not be necessary. If the grout pour height is greater, \r\n consideration should be given to bracing the masonry. This is especially \r\n true when a longer curing time for the brick masonry prior to grouting \r\n is not feasible. Bracing members are typically externally applied wood \r\n construction. The bracing members should be designed by an engineer, based \r\n on the grout pour height. \r\n \r\n PLACEMENT OF STEEL REINFORCEMENT \r\n Steel reinforcement should be placed in accordance \r\n with the size, type and location indicated on the project drawings, and \r\n as specified. Dissimilar metals should not be placed in contact with each \r\n other because this can promote corrosion of the reinforcement. Nonmetallic \r\n flashing should be used when the flashing will come in contact with the \r\n reinforcement. If it is possible, all vertical steel reinforcement should \r\n be placed after completion of the masonry surrounding the grout space. \r\n This keeps the reinforcement out of the masons way during construction \r\n and makes cleaning of the grout space easier. It also prevents contamination \r\n of the reinforcement by mortar droppings or protrusions that can adversely \r\n affect grout bond to the reinforcement. \r\n Applicable building codes should be consulted \r\n regarding placement requirements for reinforcement in masonry elements. \r\n A summary of the placement requirements for reinforcement in masonry stated \r\n in the MSJC Code is given in Table 3. \r\n \r\n \r\n \r\n \r\n \r\n 1 In Flexual members, the "d" \r\n dimension is the distance from the extreme compression face to the \r\n centroid of the tensile reinforcement. \r\n \r\n \r\n \r\n These requirements are to ensure proper bond \r\n to the grout, corrosion protection and fire resistance of the reinforcement. \r\n Table 3 also identifies the tolerance limits on positioning reinforcement \r\n in masonry elements. Reinforcement should only be spliced where indicated \r\n on the project drawings. Reinforcement should not be bent or disturbed \r\n after placement of the grout. Vertical reinforcement should be accurately \r\n placed and secured prior to the grouting process. Reinforcement can be \r\n secured by wire ties or other spacing devices. Some examples of common \r\n bar spacing devices are shown in Fig. 4. \r\n \r\n \r\n \r\n Bar Spacing Devices \r\n FIG. 4 \r\n \r\n \r\n Vertical reinforcement should be braced at the top and bottom of the element. \r\n Additional positioners may be necessary to facilitate proper placement \r\n of the bars. When reinforcement is spliced in a grout space between wythes \r\n or within an individual cell of hollow brick masonry, the two bars should \r\n be placed in contact and wired together. Vertical reinforcement in hollow \r\n brick masonry may be spliced by placing the bars in adjacent cells, provided \r\n the distance between the bars does not exceed 8 in. (204 mm). \r\n Horizontal reinforcement is usually placed \r\n in the mortar joints as the work progresses or in bond beams at the completion \r\n of the bond beam course. In partially grouted walls, the bond beam should \r\n be grouted prior to further construction of brick masonry on top of the \r\n bond beam. For two-wythe, solid brick masonry walls, the horizontal reinforcement \r\n may be placed in the grouted collar joint. All horizontal bars should \r\n be on the same side of the vertical reinforcement to facilitate consolidation \r\n of the grout. \r\n \r\n GROUTING \r\n The most crucial aspect of constructing RBM \r\n elements is the grouting process. While grouting may seem a simple matter \r\n of filling cavities or cells of masonry, it is the one aspect of RBM construction \r\n that can cause the most problems. The most common problem is the creation \r\n of voids in the grout space due to stiff grout, excessive pour height, \r\n grout shrinkage, or blocked grout spaces. To ensure proper grouting, four \r\n sequential steps should be properly executed: preparation of the grout \r\n space, grout batching, grout placement and consolidation, and curing and \r\n protection. \r\n Preparation of the Grout Space \r\n The configuration and condition of the grout space can vary considerably. \r\n Common grout spaces for RBM elements are the cells of hollow brick, the \r\n collar joint between multi-wythe brick walls, the core of columns or pilasters \r\n and the depth of a beam. \r\n For a multi-wythe brick wall with a grouted \r\n collar joint, vertical grout barriers, or dams, should be built across \r\n the grout space for the entire height of the wall at intervals of not \r\n more than 25 ft (7.6 m). Grout barriers control the horizontal flow of \r\n grout and reduce segregation. With hollow brick, mortar is placed on the \r\n cross webs to confine grout to certain vertical cells. Wire mesh is installed \r\n beneath a bond beam to prevent the flow of grout into the masonry below \r\n the bond beam. Examples of common grout barrier techniques are shown in \r\n Fig. 5. \r\n \r\n \r\n \r\n Vertical Grout Barriers \r\n FIG. 5 \r\n \r\n \r\n Grout spaces should be checked to see that all foreign materials and debris \r\n have been removed prior to grouting. The reinforcement should be clean \r\n and properly positioned in the grout space. If cleanouts are used, they \r\n should be sealed and braced if needed. All grout barriers should be secured \r\n and braced, if necessary. \r\n The absorption rate of brick masonry will \r\n vary considerably with different units and weather conditions. To make \r\n the absorption more consistent, the grout space may be wetted prior to \r\n grouting. No free water should be on the units when the grout is placed. \r\n Grout Batching \r\n The quantities of solid materials in the \r\n grout mix should be determined by accurate volume measurement at the time \r\n of placing in the mixer. All materials for grout should be mixed in a \r\n mechanical mixer. Grout is most often supplied in bulk by ready-mix trucks \r\n and pumped into place because of the volume and speed of placement required. \r\n Batching on site is more common for smaller projects. When prepared on \r\n site, the grout mix should be batched in multiples of a bag of portland \r\n cement as a quality control measure. If less than a single bag of portland \r\n cement is used, extreme care should be used to accurately measure all \r\n parts. \r\n \r\n Water, sand, aggregate and portland cement should be mixed for a minimum \r\n of 2 minutes, then the hydrated lime (if any) and additional water should \r\n be added and mixed for an additional 5 to 10 minutes. Make and maintain \r\n as high a flow as possible, consistent with good workability. This means \r\n that the grout should be wet enough to pour without segregation of the \r\n constituent materials or excessive bleeding. Grout should be a plastic \r\n mix that is suitable for pumping. The grout slump should be tested in \r\n accordance with ASTM C 143 Test Method for Slump of Hydraulic Cement Concrete \r\n and should be between 8 and 11 in. (203 and 279 mm). \r\n \r\n Grout Placement and Consolidation \r\n Grout should be placed within 1 1/2 hours \r\n after the water is first added to the mix and prior to the initial set. \r\n Grout slump should be maintained during placement. The grout pour should \r\n be done in one or more lifts and the total height of each pour should \r\n be from the center of one course to the center of another course of brick \r\n masonry. When grouting is stopped for 1 hour or longer, the grout pour \r\n should be stopped approximately 1 1/2 in. (38 mm) below the top of the \r\n masonry to create a shear key. \r\n Whenever possible, grouting should be done \r\n from the unexposed face of the masonry element. Extreme care should be \r\n expanded to avoid grout staining on the exposed face or faces of the masonry. \r\n If grout does contact the face, it should be cleaned off immediately with \r\n water and a bristle brush. Waiting until after curing has occurred will \r\n make removal difficult. \r\n Grout in contact with brick solidifies more \r\n rapidly than that in the center of the grout space. It is, therefore, \r\n important to consolidate the grout immediately after pouring to completely \r\n fill all voids. The best procedure is to have two people performing the \r\n operation jointly; one to pour the grout and the other to consolidate \r\n it. A mechanical vibrator or pudding stick is used for this purpose, depending \r\n on the construction method used. \r\n There are two methods of RBM construction: \r\n simultaneous brick construction and grouting, and grouting after brick \r\n construction. These are sometimes referred to as "low lift" \r\n and "high lift" grouted masonry. In the first method, grout \r\n is placed in the masonry as the courses are laid. The grout is consolidated \r\n with a pudding stick or a mechanical vibrator. This method is typically \r\n used with narrow grout spaces. In the second method, the masonry is built \r\n to the story height or its full height, after which grout is poured from \r\n a hopper or pumped by mechanical means. The grout is consolidated with \r\n a low velocity vibrator with a 3/4 in. (19 mm) head. When grouting between \r\n wythes, the vibrator should be placed in the grout at points spaced 12 \r\n to 16 in. (305 to 406 mm) apart. The grout pour height restrictions given \r\n in Table 2 will limit the method of grout placement permitted in some \r\n instances. The mason contractor should give consideration to the advantages \r\n and disadvantages of each method. \r\n Simultaneous Brick Construction and Grouting. \r\n The main benefits of simultaneous construction and grouting are elimination \r\n of cleanouts, reduction of grout pressures, and simplicity of construction. \r\n With this method of grouting, the entire grout space can be kept entirely \r\n clear of blockage and can be easily inspected prior to grouting. Consolidation \r\n of the entire grout pour is also easier and bracing may be lessened or \r\n eliminated. \r\n For a multi-wythe brick wall with grouted \r\n collar joint, one wythe should be built up not more than 16 in. (406 mm) \r\n ahead of the other wythe. Typically, the grout pour height will not exceed \r\n 12 in. (305 mm) for such walls and a pudding stick may be used for consolidation \r\n purposes. If the grout is carried up too rapidly, there is a chance blowout \r\n will occur. If a wythe does move, even as little as 1/8 in. (3 mm) out-of-plumb, \r\n the work should be torn down rebuilt. This is because the bed joint bond \r\n has been broken and cannot be repaired merely by shoving the wall back \r\n into plumb. \r\n The grout should be placed to a uniform height \r\n between grout barriers and should be consolidated with a mechanical vibrator \r\n or pudding stick immediately after placement. Extreme care should be exercised \r\n during grout placement and consolidation to avoid displacement of the \r\n brick masonry. \r\n Grouting After Brick Construction. \r\n Grouting after construction of the masonry has become the industry standard \r\n due to its speed and the fact that grout is often supplied by ready-mix \r\n trucks. These trucks deliver large quantities of grout, but cannot remain \r\n on site indefinitely during construction. Grout delivery must be coordinated \r\n with brick construction and preparation of grout spaces. The grout spaces \r\n in RBM elements can be very small and become crowded with reinforcing \r\n bars and wall ties. In addition, some contractors have commented that \r\n the highly absorptive nature of some brick masonry causes the grout to \r\n dry out and not flow properly to the bottom of grout spaces if the lift \r\n height is too great. \r\n The first lift of grout should be placed \r\n to a uniform height between the grout barriers or the surrounding brick \r\n masonry, and should be mechanically vibrated to fill all voids. This first \r\n vibration should be done within 10 minutes after pouring the grout, while \r\n the grout is still plastic and before it has set. Grout pours in excess \r\n of 12 in. (305 mm) should be reconsolidated by mechanical vibration after \r\n initial water loss and settlement has occurred. The succeeding lift should \r\n be poured, vibrated and reconsolidated in a similar manner. In the first \r\n vibraton, the vibrator should extend 6 to 12 in. (152 to 305 mm) into \r\n the preceding lift. This further reconsolidates the first lift and closes \r\n any shrinkage cracks or separations that may have formed. The work should \r\n be planned for a single, continuous grout pour to the top of the wall \r\n in 5 ft (1.5 m) lifts. Under normal weather conditions, in the range of \r\n 40 to 90 degrees F of (4 to 32 degrees C), the waiting period between \r\n lifts should be between 30 and 60 minutes. \r\n \r\n Curing and Protection \r\n The masonry work, particularly the top of \r\n the grout pour, should be kept covered and damp to prevent excessive drying. \r\n The newly grouted masonry should be fog sprayed three times each day for \r\n a period of three days following construction when the ambient temperature \r\n exceeds 100 degrees F (38 degrees C) or 90 degrees F (32 degrees C) with \r\n a wind speed in excess of 8 mph (13 km/hr). The exposed faces of brickwork \r\n should be cleaned prior to the fog spraying. Cleaning will be much more \r\n difficult if it is postponed until after this curing. The water from cleaning \r\n will also aid in the curing process. Refer to the information in Technical \r\n Notes 1 Revised for proper construction and protection methods during \r\n excessive cold or hot weather conditions. \r\n For walls, columns and pilasters, at least \r\n 12 hours should elapse after construction before application of floor \r\n or roof members, except that 72 hours should elapse prior to application \r\n of heavy, concentrated loads such as truss, girder or beam members. \r\n QUALITY ASSURANCE MEASURES \r\n Not all masonry projects wil involve testing \r\n or inspection. However, the MSJC Code states that, "A quality assurance \r\n program shall be used to ensure that the constructed masonry is in conformance \r\n with the Contract Documents." A quality assurance program typically \r\n includes inspection of the work by an owners representative and periodic \r\n sampling and testing of masonry materials. \r\n Inspection \r\n The masonry inspectors job is to obtain \r\n good quality masonry construction and workmanship according to plans and \r\n specifications. The inspector should be able to explain the reasons for \r\n the specified procedures and know the important aspects of quality workmanship \r\n that will produce RBM elements with the properties assumed in the structural \r\n design. The inspector should verify clean grout spaces prior to grouting. \r\n Type and positioning of wall ties, bar positioners, joint reinforcement, \r\n and reinforcement should be verified against the project drawings and \r\n specifications. During the grouting process, the inspector should verify \r\n that: the grout is proportioned properly, the proper grouting technique \r\n is used, and all grout spaces are completely filled with grout. The inspector \r\n should look for darkening of the masonry due to water absorption from \r\n the grout as evidence of proper grout placement. Bracing and shoring should \r\n be inspected for proper installation. Protection measures such as covering \r\n the tops of uncompleted work, heated enclosures, and insulation blankets \r\n should be verified \r\n . \r\n Testing \r\n On some RBM projects, it may be necessary \r\n to conduct various quality control tests to ensure that the masonry has \r\n been constructed properly. The frequency of testing should be stated in \r\n the project specifications. Testing may be conducted prior to or during \r\n construction on the individual materials, e.g. brick, mortar, and grout. \r\n This is the most common form of quality control testing. Brick are typically \r\n tested for compressive strength prior to construction. Mortar may be tested \r\n in compression prior to construction in order to establish proportions \r\n of ingredients to be measured at the jobsite. The same is true for grout, \r\n which should also be tested to verify the slump. Prism compression tests \r\n are one example of such testing. The MSJC Specification stipulates the \r\n type, method and frequency of material and assemblage quality control \r\n tests required for masonry elements. This document states that prisms \r\n and grout will be tested for each 5000 sq.ft. (465 m2) of wall area or \r\n portion thereof when testing is required. Finally, tests of samples extracted \r\n from the constructed masonry may be necessary to verify the strength of \r\n elements when this is in question. A prism cut out of a masonry element \r\n to be used for compression testing is an example of such a test. For a \r\n review of the common quality control tests for brick masonry, refer to \r\n the Technical Notes 39 Series. \r\n Quality control tests can seem an onerous and unwanted expense, but they \r\n are provided for two very important reasons. First and foremost, tests \r\n can indicate consistency during construction. Dramatic changes in strength \r\n properties of elements as the work progresses can indicate a problem and \r\n should be explained. The second reason for testing is to monitor the strength \r\n gain of the masonry elements upon curing. The strength gain is monitored \r\n to indicate when shores or bracing can be removed, when loads can be applied \r\n to an element, and to verify that the strength assumed in the design has \r\n been achieved by the constructed masonry. \r\n SUMMARY \r\n Reinforced brick masonry is constructed in \r\n a manner that is different in many ways from conventional brick veneer \r\n construction. Proper materials and construction practices as dicussed \r\n in this Technical Notes should be followed to ensure that RBM elements \r\n achieve adequate strength and meet the applicable building code requirements. \r\n \r\n \r\n The information and suggestions contained in this Technical Notes are \r\n based on the available data and the experience of the engineering staff \r\n of the Brick Institute of America. The information contained herein must \r\n be used in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonry. Final decisions on the use of the \r\n information contained in this Technical Notes are not within the purview \r\n of the Brick Institute of America and must rest with the project architect, \r\n engineer and owner. \r\n REFERENCES \r\n 1. Building Code Requirements for Masonry \r\n Structures (ACI 530/ASCE 5/TMS 402-95), American Society of Civil Engineers, \r\n New York, NY, 1996 \r\n 2. Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602-95), \r\n American Society of Civil Engineers, New York, NY, 1996 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60070,"ResultID":176302,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 17B -REINFORCED BRICK MASONRY - BEAMS \r\n March 1999 \r\n \r\n Abstract: Reinforced brick masonry (RBM) beams are an efficient \r\n and attractive means of spanning building openings. The addition of steel \r\n reinforcement and grout permits brick masonry to span considerable distances \r\n while maintaining continuity of the building facade. Attractive \r\n brick soffits and elimination of steel support members are two of the \r\n advantages of reinforced brick masonry beams. This Technical Notes \r\n addresses the design of reinforced brick masonry beams. Building code \r\n requirements are reviewed and design aids are provided to simplify the \r\n design process. Illustrations indicate the proper detailing and typical \r\n construction of reinforced brick masonry beams. \r\n \r\n Key Words: beam, deflection, girder, lintel, reinforced brick \r\n masonry, reinforcement. \r\n \r\n INTRODUCTION \r\n \r\n Reinforced brick masonry (RBM) beams are widely used as flexural members. \r\n Common applications of RBM beams include girders supporting floor and \r\n roof systems, and arches and lintels spanning openings for windows and \r\n doors. Girder is the term applied to a large beam with a long span that \r\n usually supports smaller framing members. A lintel is a beam over a wall \r\n opening, typically simply supported with no framing members. The \r\n main advantage of RBM beams is that the structural element and the architectural \r\n finish are one and the same. In some cases, however, they provide economical \r\n solutions without considering the savings due to a built-in finish. They \r\n are often built as an integral part of a masonry wall as illustrated in \r\n Figure 1. RBM beams are designed to carry all superimposed loads, including \r\n that portion of the wall weight above supported by the beam. While steel \r\n lintels are more common, RBM beams provide distinct advantages over steel \r\n lintels. Among the advantages are: \r\n 1. More efficient use of materials. The masonry serves as a structural \r\n element with a relatively small amount of steel reinforcement added. \r\n 2.Elimination of differential movement. This movement is often the cause \r\n of cracks in masonry. \r\n 3. Inherent fire resistance. \r\n 4. Reduced maintenance. Periodic painting of exposed steel is eliminated. \r\n 5. Lower cost. \r\n This Technical Notes provides a review of the design of RBM beams. \r\n Factors influencing design and performance are reviewed. Design recommendations \r\n and aids are provided and their use illustrated with an example. \r\n For additional information about RBM beams and design calculations, refer \r\n to the Masonry Designers Guide (MDG) [2]. The MDG also provides an extensive \r\n review of the requirements of the Building Code Requirements for Masonry \r\n Structures (ACI 530/ASCE 5/TMS 402-95)[1], hereafter termed the MSJC Code. \r\n Other Technical Notes in this series provide the history of RBM, \r\n material and construction requirements, and design of other RBM elements. \r\n This Technical Notes does not address the design of deep beams \r\n (wall beams) or bond beams. A deep beam is one with a depth-to-span ratio \r\n exceeding 0.8. Assumptions made in this Technical Notes regarding \r\n the distribution of stress in beams under flexure and the loading conditions \r\n do not apply to deep beams. Bond beams are formed by placing horizontal \r\n reinforcement in a wall without an opening underneath. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n NOTATION \r\n \r\n Following are notations used in the text, figures, and table in this Technical \r\n Notes . \r\n A v = Area of shear reinforcement, in. 2 \r\n (mm 2 ) \r\n b = Length of bearing plate, ft (m) \r\n d = Effective depth of beam, in. (mm) \r\n d b = Nominal diameter of reinforcement, in. (mm) \r\n F s = Allowable steel stress, psi (MPa) \r\n f ΓÇÖ m = Specified compressive strength of masonry, psi (MPa) \r\n H = Height of beam, in. (mm) \r\n l d = Embedment length of reinforcement, in. (mm) \r\n M G = Design moment due to gravity loads, in.-lb (N-m) \r\n M s = Design moment due to in-plane shear, in.-lb (N-m) \r\n M w = Design moment due to out-of-plane wind or seismic load, in.-lb (N-m) \r\n P = Design concentrated load, lb (kg) \r\n s = Spacing of shear reinforcement, in. (mm) \r\n V = Design shear force, lb (kg) \r\n W = Width of beam, in. (mm) \r\n w p = Design uniform distributed load, lb/ft (kg/m) \r\n y = Distance from top of beam to bearing plate, ft (m) \r\n \r\n DETERMINATION OF LOADING \r\n \r\n \r\n The basic concept of a beam is as a pure flexural member. A flexural \r\n member spans an opening and transfers vertical gravity loads to its supports, \r\n as illustrated in Fig. 2(a). RBM beams act in this manner to support \r\n their own weight and other applied gravity loads. However, it is also \r\n common for RBM beams to be part of a masonry wall. As such, RBM beams \r\n are often subjected to out-of-plane wind and seismic forces, as depicted \r\n in Fig. 2(b). This causes bending of the RBM beam in the out-of-plane \r\n direction, which is often about the weak axis of the beam. In addition, \r\n reinforced masonry walls may be shear-resisting members, or \"shear walls\", \r\n which are part of the lateral load-resisting system of a building. \r\n In such a structural system, RBM beams may be used as connections between \r\n shear walls or piers, as illustrated in Fig. 2(c). Such beams \r\n are called coupling beams because they \"couple\" the shear walls or piers. \r\n If the relative sizes of the two piers being coupled are similar, the RBM \r\n beam is subject to considerable load when an in-plane shear force is applied \r\n to the wall. This is why damage to masonry shear walls is often concentrated \r\n at coupling beams following an earthquake or high-wind event. \r\n The designer should consider all aspects of loading for an RBM beam. \r\n It is difficult to predict the loading condition that will produce the critical \r\n design condition. For example, a RBM beam that is part of a wall will \r\n be subject to a combination of gravity loads and out-of-plane wind or seismic \r\n loads. Many factors influence the loading conditions for RBM beams. \r\n \r\n Arching Action \r\n \r\n Arching action is a property of all masonry walls which are laid in an overlapping \r\n bond pattern. Brick masonry will span, in a step-like manner similar \r\n to a corbel, over a wall opening when laid in running bond pattern. \r\n Vertical gravity loads above the openings are transferred to the wall elements \r\n on each side. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n This is the \r\n reason why sizable holes can be created in masonry walls without causing \r\n collapse. Arching action will occur provided that the following conditions \r\n are met: \r\n 1.An overlapping bond pattern is used in the masonry surrounding the opening. \r\n 2.The masonry above the apex of a 45 degree isosceles triangle above the \r\n beam exceeds 12 in. (300 mm). \r\n 3.There are no movement joints or adjacent wall openings that hinder the \r\n load path of arching action. \r\n 4.The abutments are sufficiently strong and rigid to resist the horizontal \r\n thrust due to arching action. \r\n These concepts are illustrated in Fig. 3. \r\n Provided arching action occurs, the self weight of masonry wall carried \r\n by the beam may be safely assumed as the weight within a triangular area \r\n above the beam formed by 45 degree angles, as shown in Fig. 3. The \r\n self weight of the wall must be added to the live and dead loads of floors \r\n and roofs which bear on the wall above the opening. If a stack bond \r\n pattern is used, the full area of brick masonry above the wall opening should \r\n be considered in the RBM beam design with no assumption of arching action. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Concentrated Loads \r\n \r\n Loads from beams, girders, trusses and other concentrated loads that frame \r\n into the wall must be applied to the RBM beam in the appropriate manner. \r\n Concentrated loads may be assumed to be distributed over a wall length equal \r\n to the base of a trapezoid whose top is at the point of load application \r\n and whose sides make an angle of 60 degrees with the horizontal. In \r\n Fig. 4, the portion of the concentrated load carried by the beam is distributed \r\n over the length indicated as a uniform load. The distributed load, \r\n wp, on the RBM beam is computed by the following equation: \r\n \r\n w p = P/(b + 2ytan 30) \r\n Eq. 1 \r\n where: \r\n w p = design uniform distributed load, 1b/ft (kg/m) \r\n P= design concentrated load, 1b (kg) \r\n b= length of bearing plate, ft (m) \r\n y= distance from top of beam to bearing plate, ft (m) \r\n This is approximately 0.866 times P divided by y. Because the apex \r\n of the 45 degree triangle is above the top of the wall in this example, \r\n the RBM beam should be designed assuming no arching action occurs. \r\n The designer should check the stress condition at bearing points for RBM \r\n beams. This applies to loads on the beam and to the beams reaction \r\n on the wall. The MSJC Code limits the bearing stress to 0.25 f┬óm, \r\n where f┬óm is the specified compressive strength of masonry. A rule-of-thumb \r\n recommended for many years is to provide a minimum of 4 in. (100 mm) of \r\n bearing length for masonry beams. The masonry directly beneath a bearing \r\n point should be constructed with solid brick or with solidly grouted hollow \r\n brick. Concentrated loads should not bear directly on ungrouted hollow \r\n brick masonry because of the potential for localized cracking or crushing \r\n of the face shells. \r\n \r\n Construction Loads \r\n \r\n When designing a RBM beam that is prefabricated or built on the ground and \r\n lifted into place, it is important to consider the loads during transport \r\n and handling. To address these loads, the beam may require reinforcement \r\n at both the top and bottom of the beam. Beams built in place are constructed \r\n on shores. These must be designed for the dead weight of the beam \r\n plus any superimposed load prior to adequate curing of the reinforced brickwork. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Movement Joints \r\n \r\n Movement joints are a necessity in masonry walls to accommodate differential \r\n movement and avoid cracking. It is common to place vertical expansion \r\n joints at or near the jamb of wall openings. In RBM buildings there \r\n is a reduced need for expansion joints and such joints may be spaced farther \r\n apart. Refer to Technical Notes 18 Series for a discussion \r\n of the placement of movement joints. The presence of a movement \r\n joint near a RBM beam will influence the loads and support conditions \r\n for the beam. For example, a simple support condition should be \r\n assumed since arching action will not occur if a movement joint is at \r\n or near the jamb of the opening. Furthermore, the beam will not act as \r\n a coupling beam between shear walls. This is, in fact, one means \r\n of simplifying the design and function of a RBM beam by eliminating loads \r\n due to in-plane shear. \r\n \r\n DESIGN OF RBM BEAMS \r\n \r\n RBM beam design should not be relegated to \"rule-of-thumb\" methods or \r\n arbitrary selection of beam configuration and steel reinforcement. \r\n In any beam design, a careful analysis of the loads to be carried and \r\n a calculation of the resultant stresses should be incorporated to provide \r\n adequate strength and to prevent excessive cracking and deflection. \r\n In addition to adequate strength, it is preferred that beams exhibit ductile \r\n behavior when overloaded. If the beam is overloaded, it should deform \r\n (deflect) a considerable amount prior to collapse. Deformation allows \r\n redistribution of loads to other members and provides visual indication \r\n that the beam is overloaded. Some building codes stipulate a maximum \r\n reinforcement ratio for RBM beams for this purpose. \r\n Another aspect is the relation between the RBM beams strength and its \r\n cracking moment. Failure of unreinforced masonry in flexure is brittle, \r\n exhibiting sudden cracking and often collapse. Consequently, a reinforced \r\n beam should provide a moment strength in excess of its cracking moment. \r\n The amount of this overstrength is somewhat arbitrary, but a factor of \r\n 1.3 is required by the Uniform Building Code[3]. This means that \r\n the moment strength of a cracked-section, RBM beam should exceed 1.3 times \r\n the cracking moment of the beam. This is not a requirement of the \r\n MSJC Code, but is considered good engineering practice. \r\n \r\n Beam Sizing \r\n \r\n In the design of an RBM beam, the required cross-sectional area of masonry \r\n is based primarily on the maximum bending moment. However, there \r\n are other factors to consider when sizing an RBM beam. For example, \r\n it is often desirable to have the width of the RBM beam coincide with \r\n the specified wall thickness. RBM beams are sometimes formed with \r\n special U-shaped, hollow brick for this reason. These brick may \r\n be manufactured specially for this purpose or they may be cut from full-size \r\n units at the site. Manufactured special shapes may not be readily \r\n available in many localities, so it is best to contact the brick manufacturer \r\n as early as possible before proceeding with a design based on their use. \r\n The beams depth will be determined by the appropriate number of courses \r\n of masonry units present. The beams depth should be taken as only \r\n those courses of solid brick or that are solidly grouted. The beams \r\n depth may be limited by the height of the wall above an opening. \r\n In such cases, compression steel may be necessary when sufficient masonry \r\n area is not provided. \r\n Lateral Bracing \r\n \r\n With short spans and relatively deep beams, there is little likelihood \r\n of excessive cracking, deflection or rotation. This may not be the \r\n case, however, for beams that are relatively long span, shallow or highly \r\n loaded. Such beams may be vulnerable to lateral torsional buckling. \r\n The designer should consider the lateral bracing conditions to ensure \r\n that the beam is laterally braced. The MSJC Code requires that the compression \r\n face of beams be laterally supported at a maximum spacing of 32 times \r\n the beam thickness. A brick veneer wall is laterally braced by wall \r\n ties to the backup system. A RBM beam that is part of a load-bearing \r\n wall system may not be laterally braced along its span length. In \r\n addition, movement joints at the jambs of a wall opening may result in \r\n a lack of lateral bracing for the beam at its supports. In such \r\n cases, attachment of the wall to the floor or roof diaphragm is the common \r\n means of providing lateral bracing for the beam. \r\n \r\n RBM Arches \r\n \r\n Design of RBM arches should begin with an analysis assuming the arch is \r\n unreinforced, in accordance with Technical Notes 31A \r\n or the ARCH computer program available from the Brick Industry Association. \r\n Such an analysis will indicate the locations of highest moment and shear, \r\n and the horizontal thrust at the abutments. Should the analysis \r\n so indicate, the arch should be designed as a reinforced beam. Further, \r\n if the conditions shown in Fig. 3 are not met, or if movement joints are \r\n provided at the abutments so that the arch may spread under load, the \r\n arch should be designed as if it were a straight, simply supported beam \r\n as a conservative measure. Alternately, a finite element analysis of the \r\n arch may be conducted to determine design moment, shear, and thrust values. \r\n \r\n RBM arches cause both a vertical bearing stress and a horizontal thrust \r\n on their abutments. The designer has the option of resisting the \r\n horizontal thrust of the arch by the abutments or providing room for movement \r\n as the RBM arch deforms under load. Judicious placement of vertical \r\n expansion joints and flashing will permit horizontal movement and simplify \r\n the arch design. This is recommended for longer span arches because \r\n providing adequate thrust resistance is difficult and movement joint spacing \r\n is limited. In this case, it is very important to provide adequate \r\n bearing at the abutments. \r\n \r\n STEEL REINFORCEMENT AND TIES \r\n \r\n The quantity of reinforcement required for an RBM beam is typically determined \r\n by the applied loads. However, the applicable building code may \r\n prescribe a minimum amount of reinforcement and this may dictate the amount \r\n of reinforcement required in a RBM beam. For example, all building \r\n codes now stipulate a minimum amount of reinforcement for masonry members \r\n in areas prone to earthquakes. Some building codes require that \r\n reinforcement in masonry coupling beams be uniformly distributed throughout \r\n the beams height. This may require additional reinforcement and \r\n grouting of the masonry above wall openings in RBM beams. \r\n \r\n Bond and Hooks \r\n \r\n Typically, reinforcement is inserted in masonry beams to resist tension. \r\n The tension must be transferred from the masonry to the reinforcement. \r\n This is achieved through adequate bond between the steel reinforcement \r\n and the masonry. The bond stress along the length of the reinforcement \r\n should not exceed an allowable bond stress of 160 psi (1.1 MPa), according \r\n to the MSJC Code Commentary. A minimum embedment length must be \r\n provided in order to not exceed this bond stress. Consequently, \r\n the MSJC Code stipulates a required bond length for reinforcement in tension, \r\n called the minimum embedment length. The minimum embedment length \r\n is computed by the following equation: \r\n \r\n l d = 0.0015d b F s \r\n Eq. 2 \r\n where: \r\n l d = embedment length of reinforcement, in. (mm) \r\n d b = nominal diameter of reinforcement, in. (mm) \r\n F s = allowable steel stress, psi (MPa) \r\n Table 1 provides the minimum development lengths for various bar and wire \r\n sizes, based on Grade 60 ksi (414 MPa) reinforcing bars and 70 ksi (483 \r\n MPa) steel wire. \r\n The ends of reinforcing bars and wires may require a standard hook to \r\n properly secure the reinforcement and to achieve its strength. In \r\n simply-supported beams, the peak moment is often at midspan. For \r\n this case, the reinforcement in RBM beams can likely be developed by the \r\n bond between the bar or wire and the surrounding masonry with no need \r\n for hooks at the ends of the beam. However, a cantilever RBM beam \r\n may require a hook at the support end. In addition, shear reinforcement \r\n should always be terminated with a hook. Standard hooks for principal \r\n reinforcement may be either a 90 degree or 180 degree turn. Often, the \r\n designated space for grout and reinforcement in RBM beams is very small. \r\n It can be difficult for a contractor to execute a reinforcement detail \r\n properly. Consider that a 180 degree hook doubles the number of \r\n bars at a given cross section. The designer should always consider \r\n the reinforcement placement, tolerances, and cover restrictions stated \r\n in the building codes. Technical Notes 17A \r\n Revised provides further information on bar sizes, placement requirements \r\n and construction tolerances. \r\n \r\n Shear Reinforcement \r\n Where shear reinforcement is required, it should be spaced so that every \r\n potential crack is crossed by shear reinforcement. Shear cracks \r\n are assumed to be oriented at a 45 degree angle to the longitudinal axis \r\n of the RBM beam. This restricts the spacing of shear reinforcement to \r\n one-half the beams effective depth, d. The spacing of shear reinforcement \r\n may be computed by the following equation: \r\n \r\n s = A v F s d/V \r\n Eq. 3 \r\n where: \r\n s= spacing of shear reinforcement, in. (mm) \r\n A v = area of shear reinforcement, in. 2 (mm 2 ) \r\n F s = allowable stress for shear reinforcement, psi (MPa) \r\n d= effective depth of beam, in. (mm) \r\n V= design shear force, 1b (kg) \r\n When shear reinforcement is required, it should be designed to resist \r\n the entire shear force. Shear reinforcement should always be placed \r\n parallel to the shear force. For RBM beams the shear reinforcement \r\n should be placed vertically. It can be difficult to provide shear \r\n reinforcement in RBM beams due to the limited size of grout spaces. \r\n This is especially the case with hollow brick units 6 in. (150 mm) or \r\n less in thickness and grout spaces between wythes less than approximately \r\n 2 in. (50 mm) in width. Consequently, it may be advantageous to \r\n increase the beams depth so that shear reinforcement is not necessary. \r\n In fact, this is often the method used by designers to determine the minimum \r\n depth of a RBM beam required for a given loading. \r\n \r\n Ties \r\n \r\n There are two instances when it may be necessary to include ties in reinforced \r\n brick beams. These instances occur only when the beam is formed by grouting \r\n between wythes. If the beam has sufficient depth, ties may be required \r\n between the wythes. The grout exerts a hydrostatic pressure that must \r\n be resisted during construction. The MSJC requires wall ties between wythes \r\n as follows: \r\n Wire size W1.7 (3.8 mm), one tie per 2 2/3 ft 2 (0.25 m 2 ) \r\n Wire size W2.8 (4.8 mm), one tie per 4 1/2 ft 2 (0.42 m 2 \r\n ) \r\n Maximum spacing of 36 in. (914 mm) horizontally \r\n and 24 in. (610 mm) vertically \r\n Rectangular or Z ties may be used. \r\n In beams that form deep soffits (large beam widths) it may be advisable \r\n to tie the soffit brickwork to the grout. Although the grout does \r\n bond to the brick, the metal ties should provide additional capacity and \r\n safety. Such ties are placed in the mortar joint and extend into \r\n the grout. \r\n \r\n DEFLECTION \r\n \r\n Deflection of RBM beams is considered a serviceability issue. Excessive \r\n deflection might cause damage to interior finishes, functional problems \r\n with doors or windows, and cracking of masonry supported by the beam. \r\n The MSJC Code requires that the deflection of RBM beams that support unreinforced \r\n or empirically-designed masonry should not exceed the lesser of 0.3 in. \r\n (7.6 mm) or span length divided by 600. Deflection of RBM beams \r\n may be computed based on uncracked or cracked section properties. \r\n Use of uncracked sections results in underestimating the deflection. \r\n Deflection based on cracked sections only are over-estimated and are more \r\n difficult to calculate. Use of uncracked section is recommended. \r\n \r\n Creep is a time-dependent property of brick masonry that will cause the \r\n deflection of RBM beams to increase over time. An accurate formula \r\n for the estimation of long-term deflections of RBM beams due to creep, \r\n that is applicable for all cases and easy to use, does not currently exist. \r\n A rule-of-thumb is that the long-term deflection of RBM beams due to creep \r\n will be approximately 50 percent greater than their instantaneous deflection. \r\n This means that a beam that deflects 1.0 in. (25 mm) when it is fully \r\n loaded will creep over time such that its final deflection will be approximately \r\n 1.5 in. (38 mm). \r\n \r\n DESIGN CURVES \r\n \r\n Maximum efficiency and safety dictate the need for a rational design of \r\n all RBM beams according to the applicable building code. However, \r\n it is often helpful for the designer to have design aids that can be used \r\n to quickly develop a preliminary beam design. The design curves \r\n in Figs. 5-9 are provided for that purpose. The size and configuration \r\n of masonry and quantity of reinforcement can be quickly determined from \r\n these curves based on the span of the beam and the uniform gravity load \r\n supported by the beam, including the beams self-weight. The curves \r\n are based on the following assumptions: \r\n 1.Compressive strength of masonry is not less than 2000 psi (14 MPa). \r\n For most brick masonry, this value will be exceeded. This value was chosen \r\n so that beam capacity was not limited by the masonrys compressive strength. \r\n 2.Elastic modulus of masonry is not less than 1600 ksi (11030 MPa). \r\n 3.The beam is simply supported and subject to uniform gravity loads only. \r\n 4.No compression or shear reinforcement is provided. \r\n 5.Deflection is calculated on uncracked section properties. The \r\n deflection limit of span length divided by 600 does not govern for span \r\n lengths less than 14 ft. (4.3 m). \r\n The effective depth, d, reflected in the design curves is based on the \r\n beam height, H, minus a value for masonry cover. The cover value \r\n is based on a reasonable approximation of brick, mortar and grout cover \r\n on the underside of reinforcement for the beams shown. The actual \r\n effective depth should always be checked for each particular RBM beam \r\n configuration. \r\n \r\n \r\n DESIGN EXAMPLE \r\n \r\n To illustrate the use of the Design Curves, consider the following example. \r\n A RBM beam is to span over a garage door with a clear span of 9 ft (2.7 \r\n m). The beam supports its own weight and the weight of the brick \r\n masonry wall above the beam, so that the uniform load on the beam is 250 \r\n lbs/ft (372 kg/m) of span. The RBM beam and the wall above the beam \r\n are nominal 6 in. (150 mm) wide and constructed with hollow brick. \r\n Determine the beam depth and reinforcement required for these conditions. \r\n From Figs. 5(b) and 5(e), one concludes that a 4 in. (100 mm) or 8 in. \r\n (200 mm) high by 6 in. (150 mm) wide RBM beam is not adequate for the \r\n given span and loading. Therefore, the applicable Design Curve is \r\n Fig. 6(b), which is for a full unit depth, RBM beam. For the given \r\n conditions, a minimum depth of 12 in. (300 mm) and one No. 4 bar are required. \r\n At this point, any deflection criteria should be considered and may require \r\n a greater beam depth. \r\n \r\n SUMMARY \r\n \r\n RBM beams are an attractive and efficient means of spanning openings. \r\n Attention to detailing of reinforcement and proper design are the key \r\n aspects addressed in this Technical Notes . The most common \r\n RBM beam configurations are shown with consideration of the inter-connection \r\n of beam and wall elements. Design curves provided in this Technical \r\n Notes can be used to develop preliminary beam designs for many different \r\n applications and loading conditions. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering \r\n staff of the Brick Industry Association. The information contained \r\n herein must be used in conjunction with good technical judgment and a \r\n basic understanding of the properties of brick masonry. Final decisions \r\n on the use of the information contained in this Technical Notes \r\n are not within the purview of the Brick Industry Association and must \r\n rest with the project architect, engineer and owner. \r\n \r\n REFERENCES \r\n \r\n 1. Building Code Requirements for Masonry Structures (ACI 530/ASCE \r\n 5/TMS 402-95), American Society of Civil Engineers, Reston, VA, 1996. \r\n 2. Masonry Designers Guide , John Matthys, ed., The Masonry Society, \r\n Boulder, CO, 1993. \r\n 3. Uniform Building Code , 1997 Edition, International Conference \r\n of Building Officials, \r\n Whittier, CA, 1997. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Design Curves \r\n for Partial Soldier Course Beams \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Design Curves for Soldier Course Beams \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Design Curve for \r\n 12 in. (305mm) Wide Beams \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Design Curves \r\n for 16 in. (406mm) Wide Beams \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Design Curves \r\n for 24 in. (610mm) Wide Beams \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60071,"ResultID":176303,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 17L - Four Inch RBM Curtain and Panel Walls \r\n Feb./Mar. 1973 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n Building Code Requirements for Engineered \r\n Brick Masonry, SCPI (BIA), August, 1969 defines a curtain wall as \r\n \"an exterior non-loadbearing wall not wholly supported at each story. \r\n Such walls may be anchored to columns, spandrel beams, floors or bearing \r\n walls, but not necessarily built between structural elements.\" It further \r\n defines a panel wall as \"an exterior non-loadbearing wall wholly supported \r\n at each story\". Curtain walls must be capable of supporting their own \r\n weight for the height of the wall. Panel walls are required to be self-supporting \r\n between stories. Both walls resist lateral forces such as wind pressures \r\n and must transfer these forces to adjacent structural members. This Technical \r\n Notes presents the design and construction of 4-in. brick masonry \r\n curtain and panel walls which are considered to span horizontally in resisting \r\n lateral forces. \r\n Recent structural research and rational design \r\n methods have greatly aided the design of 4-in. brick walls. However, exterior \r\n brick walls, 4 1/2 in. thick, were used prior to 1900 in the Church of \r\n St. Jean de Montmarte, Paris, France. Designed by M. A. deBoudot, these \r\n walls were reinforced with vertical wires through holes in the brick and \r\n horizontal wires in the mortar joints. One wall has an unsupported length \r\n of 29 ft 6 in. for the full height of 115 ft. Another wall is approximately \r\n 38 ft high with an unsupported length of 65 ft. The walls discussed herein \r\n differ from those designed by deBoudot in that they have a nominal thickness \r\n of 4 in. and contain only horizontal reinforcement. \r\n In the United States, one of the first buildings \r\n to be constructed with 4-in. reinforced brick masonry walls was completed \r\n in June, 1932. This building, a compressor house, was constructed at Wood \r\n River, Illinois, in the refinery of the Standard Oil Company (Indiana). \r\n All the walls and columns of this building were of reinforced brick masonry. \r\n The walls, with the exception of two bays, were nominally 4 in. thick. \r\n The wall height was 18 ft 6 in. with a (column) spacing of 15 ft 4 in. \r\n The horizontal mortar joint above the first course of brick was reinforced \r\n with two 3/8-in. round bars, placed about 1/2 in. from each face of the \r\n wall. Above this, the reinforcement was placed in every third horizontal \r\n mortar joint, at a vertical spacing of about 9 5/8 in. \r\n Two more recent examples of the 4-in. curtain \r\n wall located in the Denver, Colorado area are the Lakewood Brick Company \r\n building (Fig. 1) and the Kistler Printing Plant (Fig. 2). The Lakewood \r\n walls are 22 ft high and span continuously across steel and masonry composite \r\n columns spaced 20 ft on centers. The horizontal reinforcement varied from \r\n two No. 2 bars every second course at points of maximum moment to two \r\n No. 2 bars every fourth course at points of minimum moment. The Kistler \r\n Plant has similar spans, heights, and construction. \r\n \r\n \r\n \r\n \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n FIG. 2 \r\n The application of the 4-in. wall in commercial \r\n and industrial buildings utilizes the many intrinsic properties normally \r\n found in brick masonry. Brick presents a pleasing appearance without the \r\n problem of maintenance. Four-inch walls built with face brick exhibit \r\n the following physical properties without insulation or plastering: \r\n 1. U value of 0.76 BTU per sq ft per hr per \r\n deg F. \r\n 2. Sound transmission class of 45. \r\n 3. Fire resistance rating of 1 hr. \r\n 4. Average weight of 40 psf. \r\n Structural properties of 4-in. brick walls without \r\n reinforcement may be found in Research Report No 9, \"Compressive, \r\n Transverse, and Racking Strength Tests of Four-Inch Brick Walls,\" SCPI, \r\n August 1965. \r\n \r\n DESIGN CONSIDERATIONS \r\n Major factors to be considered in the design \r\n of 4-in. curtain or panel walls are (1) Structural, (2) Moisture Control, \r\n (3) Differential Movement, and (4) Special Considerations. The walls presented \r\n herein are designed in accordance with the SCPI Standard, Building \r\n Code Requirements for Engineered Brick Masonry, August, 1969, and \r\n the materials used should conform to the requirements for reinforced brick \r\n masonry as contained in this Standard. \r\n Structural. Since the 4-in. walls do \r\n not meet the requirements specified in the SCPI Standard for reinforced \r\n walls, they are designed as \"partially reinforced\", see Section 4.7.1 \r\n 1. The horizontal reinforcement in the wall resists the tensile stresses \r\n resulting from lateral pressures as the wall spans horizontally between \r\n structural elements such as columns, pilasters or cross walls. \r\n Since the lateral load due to wind can be either \r\n pressure or suction, the wall must be designed to resist the assumed lateral \r\n load acting in either direction. The maximum moment in the wall is used \r\n to calculate the required area of reinforcement, and to provide for stress \r\n reversals. This area of reinforcement is required in each wall face. It \r\n is recommended that the maximum area of reinforcement be provided throughout \r\n the length of the wall. This arrangement will provide more reinforcement \r\n than needed in portions of the wall near supports where the moment is \r\n less than maximum. However, the savings in fabrication and placement time \r\n will, in most cases, offset the added expense of the excess steel. Steel \r\n reinforcement should be lapped a minimum of 16 in. to insure the development \r\n of the tensile stresses without exceeding the allowable bond stresses. \r\n Bond and shear stresses should also be checked at points of maximum shear \r\n which would normally occur at the supports. \r\n However, due to the large span-to-depth ratios \r\n employed, the bending stresses usually govern. \r\n Where openings such as windows or doors occur, \r\n the effective section of the wall is, of course, reduced. This reduced \r\n section will affect not only the required area of reinforcement and strength \r\n of masonry but by reducing the stiffness of the wall will also affect \r\n the distribution of lateral loads in continuous walls. Since the tables \r\n contained herein are based on solid walls, walls with openings must be \r\n investigated by the designer. \r\n Figure 3 shows a typical application of a 4-in. \r\n curtain wall under construction. Care must be taken to assure proper placement \r\n of the reinforcement during construction. The bars may be spread apart \r\n or pushed together as successive brick are laid and pressed into position. \r\n Ladder or truss-type joint reinforcement provides two longitudinal bars \r\n connected by cross wires, thus aiding proper positioning and reducing \r\n the time and effort involved in placement. \r\n Care should be taken by the mason to insure \r\n that the reinforcement has mortar coverage both top and bottom as well \r\n as proper horizontal placement within the wall. The reinforcement should \r\n not be laid directly on top of the brick. Proper vertical placement can \r\n be attained by supporting reinforcement wires on small pads of mortar \r\n placed prior to full bedjoint mortar placement. \r\n The proposed usage of the building will determine \r\n the permissible deflection for the 4-in. brick wall. For the loads and \r\n spans presented in Table 2, the maximum calculated horizontal deflection \r\n is on the order of L/200 for simply supported walls. The actual maximum \r\n deflection will generally be less due to the restraint which may exist \r\n at the top and bottom of the wall. \r\n The general formula for the maximum deflection \r\n due to a uniformly distributed load on a simply supported beam is: \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n The \"Progress Report of the ASCE on Reinforced \r\n Masonry Design and Practice\", Journal of the Structural Division, Proceedings \r\n of the ASCE, Vol. 87, No. ST8, December, 1961, contains the following \r\n recommendation: \"When checking for deflection, it is recommended that \r\n the moment of inertia of the masonry cross section be computed neglecting \r\n the effect of the reinforcement, and then use the standard deflection \r\n formulae for flexural members \" \r\n Moisture Control. The control of moisture \r\n through the 4-in. wall should be considered by the designer. Heavy rains \r\n driven by high winds may result in water penetrating the wall. If this \r\n is objectionable, one method of handling the problem is to provide drainage \r\n space on the inside of the wall to permit the water to flow to the flashing \r\n at the base and to be conducted back to the outside through weep holes. \r\n Drainage wall types (Fig. 4) employ this principle. A second method is \r\n to provide a water barrier (parging) to the inside of the wall. Barrier \r\n wall types (Fig. 5) employ this principle. It is recommended that, where \r\n a maximum resistance to rain penetration is desired in areas of severe \r\n exposure, drainage wall type designs be used. Barrier wall types may be \r\n sufficient in areas of moderate exposure. \r\n \r\n \r\n \r\n Drainage Type Wall \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Barrier Type Wall \r\n FIG. 5 \r\n \r\n \r\n Differential Movement. When \r\n masonry walls are used to enclose a structural frame building, consideration \r\n must be given to the method of anchoring the walls to the framing elements \r\n in a manner which will permit each to move relative to the other. The \r\n frame and the enclosing walls differ in their reactions to moisture \r\n in the magnitude of thermal movements. These and other causes for differential \r\n movement are discussed in greater detail in Technical Notes 18 . \r\n No single recommendation on the \r\n positioning and spacing of expansion joints can be applicable to all \r\n structures. Each building design should be analyzed to determine the \r\n potential movements and provisions should be made to relieve excessive \r\n stress which might be expected to result from such movement. Generally, \r\n expansion joints may be located at or near corners, offsets, junctures \r\n and openings. Since 4-in. walls are considered to span horizontally, \r\n expansion joints where required must be located at vertical supports. \r\n The maximum recommended spacing for expansion joints for these 4-in. \r\n walls is 100 ft for a straight wall without openings. However, conditions \r\n may require expansion joints as close together as 40 ft. Typical 4-in. \r\n wall details relating to expansion joints and methods of anchoring are \r\n shown in Fig. 6. Table 1 presents the maximum vertical spacing of No. \r\n 6 gage, galvanized wire anchors at the wall-to-support connections. \r\n The load distribution per anchor was assumed to be 600 lb. Maximum spacing \r\n was limited to 24 in. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Four Inch Wall Details \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n (a) No. 6 gage galvanized wire anchors. \r\n (b) Load distribution assumed to be 600 lb \r\n per anchor \r\n (c) Maximum vertical spacing limited to 24 \r\n in. \r\n (d) Spacing is for an interior support of \r\n a continuous wall. Spacing at an end support is 24 in. \r\n \r\n \r\n Special Considerations. There are special \r\n design possibilities which the designer of structures incorporating 4-in. \r\n reinforced walls may desire to consider. One such consideration is to \r\n design the wall as a plate supported on three or four sides. Another consideration \r\n is to utilize the loadbearing capabilities of the 4-in. wall. The SCPI \r\n Standard may be used to design the wall to carry vertical loads in addition \r\n to lateral loads. \r\n The reinforced wall itself may be considered \r\n to act as a lintel over openings in the wall such as provided for windows \r\n and doors. The wall reinforcement should be checked to determine if it \r\n is adequate for the particular opening. Where the normal wall reinforcement \r\n is insufficient, supplemental steel should be added. Assuming a lintel \r\n to carry only the dead load of the wall for a height equal to one-half \r\n the opening span, a 4-in. brick masonry lintel, with an ultimate strength \r\n (f m ) of 2200 psi, an effective depth of \r\n 36 in. and two No 2 bars, will span an opening of 12 ft 6 in. This is \r\n neglecting other reinforcement which is in the wall above the opening. \r\n Therefore, depending on the actual wall and opening layout, wider openings \r\n may be spanned. Technical Notes 17B provides additional information on reinforced brick masonry lintels. \r\n \r\n DESIGN TABLES \r\n Design Assumptions. As presented herein, \r\n the 4-in. curtain wall is analogous to a one-way reinforced slab. In preparing \r\n the tables, a width of cross section \"b\" of 12 in. was selected. The effective \r\n depth \"d\" was assumed as 2 3/4 in. (Fig. 7). This dimension is based on \r\n the minimum thickness for a 4-in. nominal wall (3 1/2 in.) and the requirement \r\n by the SCPI Standard for shut-in. mortar coverage for bars or wire to \r\n in. or less in diameter embedded in the horizontal mortar joints. In order \r\n for the effective depth assumptions to remain as stated, raked joints \r\n could not be used. If raked joints are desired on 4-in. reinforced curtain \r\n walls, the effective depth must be reduced by the amount of raking of \r\n the joint and steel must be placed to maintain a minimum 5/8-in. coverage. \r\n It is not recommended that raked joints be used on 4-in. curtain walls \r\n for the above reason. Additional assumptions are as follows: \r\n 1. For stresses \r\n due to wind, the allowable stresses in brick masonry and reinforcing steel \r\n are increased by 1/3. \r\n 2. A brick masonry \r\n compressive strength (f m ) of 2200 psi resulting in an allowable brick masonry stress (f m ) \r\n equal to 0.32 (f m ) \r\n (1.33) or 936 psi. \r\n 3. An allowable \r\n steel stress (f s ) equal to 20,000 (1.33) or 26,600 psi. \r\n 4. Only type \r\n M or type S portland cement-lime mortars are to be used. \r\n 5. Architectural \r\n or engineering inspection is provided during construction. A 1/3 reduction \r\n in the allowable stresses is required if this inspection is not provided. \r\n 6. In a simple \r\n span or two continuous spans, the maximum shear is equal to 0.625 wL and \r\n the maximum moment is equal to 0.125 wL 2 . \r\n 7. In three \r\n or more continuous spans, the maximum shear is equal to 0.60 wL and the \r\n maximum moment is equal to 0.10 wL 2 . \r\n 8. Coursing \r\n is assumed to be three brick masonry courses per 8 in. of wall height. \r\n 9. Four-inch walls \r\n are solid without openings. \r\n \r\n \r\n \r\n \r\n \r\n Section Through Four Inch Brick Wall \r\n FIG. 7 \r\n \r\n \r\n Use of Tables. Table 2 \r\n provides the reinforcement requirements for various support conditions, \r\n span lengths and wind pressures. The steel areas tabulated are for one \r\n face of the wall. An equal amount must be provided in the opposite face. \r\n It should be noted that an expansion joint interrupts the continuity \r\n of the wall. The condition at the joint will therefore be one of simple \r\n support. \r\n \r\n \r\n (a) See Design Assumptions \r\n Table 3 gives the area of reinforcement \r\n as provided by various steel sizes and vertical spacings for one wall \r\n face. After the required area is selected from Table 2, the bar size \r\n and spacing which provides an area of reinforcement equal to or greater \r\n than what is required may be selected from Table 3. \r\n \r\n \r\n (a) Based upon three brick courses per 8 in. \r\n of height. \r\n In conjunction with the use of \r\n Table 2, a minimum value of 2200 psi for the compressive strength of \r\n brick masonry (f m ) is required. Lesser values \r\n of f m \r\n may be employed if the designer calculates the actual strength of masonry \r\n required by his design. Table 4 can be used in selecting unit strength \r\n and mortar type as determined by the calculated stresses. \r\n \r\n \r\n \r\n \r\n \r\n \r\n (a) Taken from Table 2, Building \r\n Code Requirements for Engineered Brick Masonry, SCPI (BIA), August, \r\n 1969. \r\n (b) See Design Assumptions. \r\n \r\n Design Example \r\n Given: Three \r\n continuous 20-ft spans \r\n \r\n\r\n \r\n Wind = 25 psf \r\n f m = 2200 psi \r\n f m = 0.32(f m )(1.33) = 936 psi \r\n f s = 20,000(1.33) = 26,600 psi \r\n \r\n \r\n \r\n Required: A s \r\n 1. Design by calculation: \r\n \r\n \r\n V (max) 0.60 wL = 0.60(25)(20) = 300 \r\n lb \r\n M (max) 0.10 wL 2 = 0.10(25)(20) 2 = 12,000 in. -lb \r\n \r\n \r\n \r\n \r\n \r\n Select one No. 2 bar (each face, every course): \r\n \r\n \r\n A s (each face) = 0.225 sq in. (Table 3) \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Check masonry stress (f m ): \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Check steel stress (f s ): \r\n \r\n \r\n \r\n \r\n \r\n Check shear at interior support: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Check bond: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 2. Selection from Table 2: \r\n \r\n \r\n A s = \r\n 0.188 in. 2 per face \r\n \r\n \r\n Selection from Table 3: \r\n \r\n \r\n One No. 2 bar in each wall face every \r\n course. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60072,"ResultID":176304,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 17M - Reinforced Brick Masonry Girders - Examples \r\n July 1968 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n \r\n \"Girder\" is the name applied to a large size beam which usually has \r\n smaller beams framing into it. A Reinforced Brick Masonry (RBM) girder \r\n consists of brick masonry in which steel reinforcement is embedded \r\n so that the resulting horizontal member is capable of resisting loads \r\n which produce compressive, tensile and shearing stresses. The principles \r\n of design for RBM girders and beams are the same as those commonly \r\n accepted for the working stress design for reinforced concrete flexural \r\n members, and similar formulae may be used. These formulae may be found \r\n in Technical Notes 17A , \"Reinforced \r\n Brick Masonry Flexural Design\", Technical Notes 17J, \"Design \r\n Tables For Reinforced Brick Masonry Flexural Members\", may be consulted \r\n for design tables and illustrative examples. \r\n \r\n APPLICATIONS \r\n \r\n Where a design requires horizontal structural members, the RBM girder \r\n or beam is most advantageous on projects where (1) the structural \r\n medium is brick, (2) the surrounding areas are brick, or (3) the appearance \r\n of brick is desired. The main advantage of RBM girders is that the \r\n structural finish and the architectural finish are one and the same. \r\n In some cases, however, they provide economical solutions without \r\n considering the savings due to a built-in finish. \r\n Additional advantages are that no forms are required for the erection \r\n of a RBM girder except for a work scaffold set at the bottom elevation \r\n of the girder. Brick girders are inherently fire-resistant, weather-resistant \r\n and maintenance-free. These properties, in addition to the high compressive \r\n strength of brick masonry, constitute savings in construction time \r\n and costs. \r\n The examples of RBM girders presented in this Technical Notes \r\n are representative of some uses for such members. They are by \r\n no means exhaustive. \r\n St. Hedwigs Church . Architect: J.T. Golabowski; Structural \r\n Engineer: William A. Herrmann. The design of St. Hedwigs Church (Fig. \r\n 1 ) in St. Louis, Missouri, built in 1957, incorporated a modified \r\n clerestory that extends the length of the church from front to rear \r\n (Fig. 2). In order to keep the nave and sanctuary clear of interior \r\n columns, the sidewalls of the clerestory were supported only at the \r\n ends. Exposed brick were used extensively both outside and inside \r\n the church. Structural members, 65 ft long, were required that would \r\n have a brick finish on both sides, and carry the roof load from above \r\n and part of the loads from the side roofs. \r\n \r\n \r\n \r\n St. Hedwigs Church - St. Louis, Missouri \r\n FIG. 1 \r\n \r\n \r\n \r\n Plan of St. Hedwigs Church St. Louis Missouri \r\n FIG. 2 \r\n \r\n \r\n \r\n Three types of girders were considered: \r\n \r\n \r\n 1. Prestressed \r\n concrete girders. These were eliminated because, with masonry on \r\n both sides, they would be too thick for the desired appearance. \r\n \r\n 2. Brick-encased \r\n steel plate girders. These would have been end-supported on steel \r\n columns built into the masonry walls. \r\n 3. RBM girders. \r\n These would be supported on RBM columns built integrally with the \r\n front and rear masonry walls. \r\n \r\n \r\n At that time, contractors in the St. Louis area were not familiar \r\n with RBM construction. Due to this, alternate bids were taken on both \r\n the brick-encased plate girder and RBM girder systems. All ten bidders \r\n indicated savings would be made with the RBM system. \r\n The church contractor, C. Rallo Contracting Company, Inc., reported \r\n that the total cost of the two RBM girders and supporting columns \r\n was only $8000; columns alone cost $600. The bid figures show two \r\n steel plate girders and four steel columns would have cost $8200 without \r\n the brick encasing. \r\n Figure 3 gives the overall dimensions of the RBM girder. The depth \r\n was dictated by the clerestory proportions. During the construction \r\n of the two girders, the only form needed was a work scaffold set to \r\n the bottom elevation of the girder. Soffit brick were laid out first \r\n (Fig. 4) with the bottom steel being placed next. Stirrups were then \r\n added and tied near the tops for stability. After that, it was just \r\n a matter of laying brick and placing grout in increments of three \r\n or four courses (Fig. 5). \r\n A building permit was issued for the job with the provision that \r\n one of the girders be successfully load-tested after completion. The \r\n specification required a test load equal to the design dead load plus \r\n twice the live load, in accordance with Building Code Requirements \r\n For Reinforced Concrete of the American Concrete Institute. \r\n \r\n \r\n \r\n Section of RBM Girder - St. Hedwigs Church \r\n FIG. 3 \r\n \r\n \r\n \r\n Soffit Brick in Place on Scaffold \r\n St. Hedwigs Church \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Completed RBM Girder - St. Hedwigs Church \r\n FIG. 5 \r\n \r\n Test loads of 67,500 lb were applied at each third point of the girder. \r\n This was in addition to the dead load of both the girder and the concrete \r\n roofs it supports. Pittsburgh Testing Laboratory performed the tests \r\n with calibrated hydraulic jacks through a fulcrum system. \r\n All deflection measurements checked out within the allowable limits. \r\n After 24 hr under full load, the maximum girder deflection was only \r\n half the amount allowed by the test provisions. Recovery after load \r\n release was 94 percent. \r\n Maryland City Shopping Center. Architect: Anthony F. Musolino \r\n & Associate; Structural Engineer: Lugi Iacono. A project in Maryland \r\n City, Maryland which extensively uses RBM girders is the Maryland \r\n City Shopping Center now nearing completion. The architect is well \r\n pleased with the use of RBM girders as handsome structural facades \r\n (Fig. 6). Details of two girders are shown in Figs. 7 and 8. The RBM \r\n girder in Fig. 7 is supported on RBM columns spaced 23 ft 4 in. on \r\n center. It carries half of the arcade roof load transmitted to it \r\n by a beam located 6 ft 8 in. from one support. Other girders are loaded \r\n similarly by beams at varying distances from the girder support. \r\n \r\n \r\n \r\n RBM Girder as Structural Facade - Maryland City Shopping \r\n Center \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Section of RBM Girder Maryland City Shopping Center \r\n FIG. 7 \r\n \r\n Another girder is utilized above a store front which is glazed for \r\n display purposes (Fig. 8). This girder supports a roof area of 500 \r\n sq ft carried by bar joists 4 ft 2 in. on center in addition to a \r\n 4-ft masonry parapet 8 in. thick. The column spacing for the girder \r\n is 25 ft. \r\n \r\n \r\n \r\n \r\n \r\n Section of RBM Girder Maryland City Shopping Center \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n Mt. Vernon Shopping Center . Architect: Anthony F. Musolino & Associate; Structural \r\n Engineer: Peter Dragan. The architectural beauty of repeating arches \r\n with the structural capability of RBM girders is displayed at the \r\n Mt. Vernon Shopping Center, Alexandria, Virginia (Fig. 9). The reinforced \r\n arches which form the bottom of the RBM girders are not intended to \r\n be structural. The girders transmit half the covered promenade roof \r\n load to their supporting solid brick masonry columns which are spaced \r\n 19 ft 9 in. on center (Figs. 10 and I 1). The girders were constructed \r\n of 8000 psi brick units and type M mortar. \r\n \r\n \r\n \r\n \r\n Mt. Vernon Shopping Center - Alexandria, Virginia \r\n FIG. 9 \r\n \r\n \r\n \r\n Elevation of RBM Girder and Arches - Mt. Vernon Shopping \r\n Center \r\n FIG. 10 \r\n \r\n \r\n \r\n Sections of RBM Girder and Arch Mt. Vernon Shopping \r\n Center \r\n FIG. 11 \r\n \r\n \r\n \r\n Alexander Art Center . Architect: Griffey and Stroll Associates; Structural Engineer: William \r\n Blanton. The designers of the Alexander Art Center at Athens, West \r\n Virginia were confronted with the problem of spanning over the main \r\n auditorium proscenium opening. A structural member having a fire-resistant \r\n brick finish was desired to support steel trusses which, in turn, \r\n support the roof loads over a clear span of 39 ft and a monorail system \r\n spaced 1 ft on center connected to the bottom chord of the trusses. \r\n The monorails will provide a flexible system for lighting and scenery \r\n movement. The designers felt that deflections in a brick-encased steel \r\n girder may cause cracking of the enclosing masonry. The encasing operation \r\n for the steel girder would require scaffolding similar to that used \r\n in the construction of RBM girders. Also, RBM was being utilized on \r\n the project in retaining walls and in loadbearing walls. These factors \r\n resulted in the final selection of a RBM girder spanning 50 ft 8 in. \r\n to solid brick masonry columns on either side of the proscenium. The \r\n girder section detailed in Fig. 12 is to be constructed of 8000 psi \r\n brick units and type M mortar. The total design load is 5820 lb per \r\n 1in ft of girder. \r\n \r\n \r\n \r\n Section of RBM Girder Alexander Art Center \r\n FIG. 12 \r\n \r\n \r\n \r\n The Art Center will also include a studio theater in which the 24-ft \r\n stage will be spanned by a RBM girder of the dimensions shown in Fig. \r\n 13. The loading was the same as for the larger girder plus an additional \r\n load of a prestressed concrete roof which spans 46 ft 6 in. This results \r\n in a total design load of 7064 lb per 1in ft. Figure 14 shows this \r\n girder. \r\n \r\n \r\n \r\n Section of RBM Girder Alexander Art Center \r\n FIG.13 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Completed RBM Girder - Alexander Art Center \r\n FIG. 14 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60073,"ResultID":176305,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 18 - Volume Changes and \r\n Effects of Movement, Part 1 \r\n Jan. 1991 \r\n Abstract : This Technical Notes describes the various movements \r\n that occur within buildings. Movement induced by changes in temperature, \r\n moisture, elastic deformations, creep, and other factors develop stresses \r\n if the brickwork is restrained. Restraint of these movements may result \r\n in cracking of the masonry. Typical crack patterns are shown and their \r\n causes identified. \r\n Key Words : brick, corrosion, cracks, \r\n differential movement, expansion \r\n INTRODUCTION \r\n The various materials and elements that \r\n are used to construct a building are in a constant state of motion. \r\n All building materials change in volume due to internal or external \r\n stimuli. These stimuli may be changes in temperature, moisture, elastic \r\n deformations due to loads, creep, or other factors. Restraint of these \r\n movements may cause stresses within the building elements which in \r\n turn may result in cracks. \r\n To avoid cracks, the design should minimize \r\n volume change, prevent movement or accommodate differential movement \r\n between materials and assemblies. A system of movement joints can \r\n eliminate cracks and the problems they cause. Movement joints can \r\n be designed by estimating the magnitude of the several types of movements \r\n which may occur in masonry and other building materials. \r\n This Technical Notes describes the \r\n various volume changes in brick masonry and other building materials. \r\n It also describes the effects of volume change when the materials \r\n are restrained. Other Technical Notes in this series address \r\n the design and detailing of movement joints and the types of anchorage \r\n which permit movement. \r\n MOVEMENTS OF CONSTRUCTION MATERIALS \r\n The design and construction of most buildings \r\n does not allow precise prediction of movements of building elements. \r\n Volume changes are dependent on material properties and are highly \r\n variable. Age of material and temperature at installation also influence \r\n expected movement. When mean values of material properties are used \r\n in design, the actual movement may be underestimated or overestimated. \r\n The designer should use discretion when selecting the applicable values. \r\n The types of movement experienced by various building materials are \r\n indicated in Table 1. \r\n Temperature Movements \r\n All building materials expand and contract \r\n with variations in temperature. For unrestrained conditions, these \r\n movements are theoretically reversible. Table 2 indicates the coefficients \r\n of thermal expansion for various building materials. \r\n \r\n \r\n \r\n \r\n Unrestrained thermal movement is the product \r\n of temperature change, the coefficient of thermal expansion, and the \r\n length of the element. The stresses developed by restrained thermal \r\n movements are equal to the change in temperature multiplied by the \r\n coefficient of thermal expansion and the modulus of elasticity of \r\n the material. The temperature change used for estimating thermal movements \r\n should be based on mean wall temperatures. For solid walls, temperatures \r\n at the center of the wall should be used. In cavity walls and veneers, \r\n the temperature at the center of each wythe or component should be \r\n used. In discontinuous construction, the wythes will have different \r\n temperatures due to the separation of the wythes by an air space. \r\n Surface temperatures of brick walls may \r\n be much higher than the ambient air temperature. Wall orientation, \r\n wall type and color are governing factors. It is possible for a dark, \r\n south facing wall to reach surface temperatures as high as 140 ° F \r\n (60 ° C), while the ambient air temperature is well below \r\n 100 ° F (37.7 ° C). The mean wall temperature \r\n of a 4 in. (100 mm) thick insulated brick veneer wall is very close \r\n to the surface temperature of the brick. A thicker or non-insulated \r\n wall may experience a smaller temperature difference between the outside \r\n and inside surfaces. \r\n Other materials such as metals or wood will \r\n expand and contract at rates different from that of brick masonry. \r\n These differences are important in applications such as window frames, \r\n railings, or copings which are attached to brick masonry. Distress \r\n may occur in either material. \r\n Moisture Movements \r\n With the notable exception of metals, many \r\n building materials tend to expand with an increase in moisture content \r\n and contract with a loss of water. For some building materials these \r\n movements are reversible; while for others they are irreversible or \r\n only partially reversible. \r\n Clay Products . Brick units expand \r\n slowly over time upon exposure to water or humid air. This expansion \r\n is not reversible by drying at atmospheric temperatures. A brick unit \r\n is smallest in size when it cools after coming from the kiln. The \r\n unit will increase in size due to moisture expansion from that time. \r\n Most of the expansion takes place quickly over the first few weeks, \r\n but expansion will continue at a much lower rate for several years \r\n (see Figure 1). The moisture expansion behavior of brick depends primarily \r\n on the raw materials and secondarily on the firing temperatures. Brick \r\n made from the same raw materials that are fired at lower temperatures \r\n will expand more than those fired at higher temperatures. \r\n \r\n \r\n \r\n \r\n Projected Moisture Expansion of Fired \r\n Brick vs. Time \r\n Fig. 1 \r\n \r\n Moisture expansion of individual brick or \r\n brick masonry can be measured for a given length of time. Predicting \r\n the total moisture expansion of brick is much more difficult. At present \r\n there are no standard tests to predict moisture expansion or measure \r\n moisture expansion which occurs in service. Based on past research, \r\n long term moisture expansion of brick can be estimated at between \r\n 0.0002 and 0.0009. A design value of 0.0003 should be used when designing \r\n composite masonry walls. A design value of 0.0005 should be used in \r\n veneer walls where an upper bound of movement is estimated. \r\n Concrete Masonry . Concrete masonry \r\n units experience shrinkage as a result of moisture loss and carbonation. \r\n Shrinkage of concrete masonry is affected by method of curing, aggregate \r\n type, change in moisture content, cement content, and wetting and \r\n drying cycles. Total shrinkage is determined by ASTM C 425 Test Method \r\n for Drying Shrinkage of Concrete Block which measures shrinkage from \r\n a saturated condition to a 17% moisture condition. Typical total linear \r\n shrinkage values range between 0.0002 to 0.0007. Type I concrete masonry \r\n units must conform to moisture content requirements found in the material \r\n specifications which limits wall shrinkage. \r\n Concrete . Concrete shrinks as it \r\n cures and swells as it becomes wet. Shrinkage of concrete is influenced \r\n by the water cement ratio, composition of the cement, type of aggregate, \r\n size of concrete member, curing conditions, and amount and distribution \r\n of reinforcing steel. Values of final shrinkage for ordinary concretes \r\n are generally of the order of 0.0002 to 0.0007 depending on the factors \r\n listed. \r\n Wood . Wood will shrink during the \r\n natural seasoning process as the moisture content drops from the fiber \r\n saturation point (28 to 30%) until it reaches equilibrium moisture \r\n content with local atmospheric conditions. Shrinkage occurs differently \r\n in the tangential, radial and longitudinal dimensions of the member. \r\n Table 3 indicates the range of shrinkage values for commonly used \r\n woods. Moisture expansion and contraction continues with changes in \r\n moisture content. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1Adapted from Reference 10 \r\n 2Dried from 30% moisture content \r\n to 0% \r\n \r\n \r\n \r\n \r\n Elastic Deformation \r\n In the structural design of a building, \r\n the designer must consider all forces imposed on the structure. These \r\n include dead loads, live loads, snow loads, and such external lateral \r\n forces as wind, soil, earthquake and blast. All of these forces create \r\n stresses in the building materials resulting in deflections of the \r\n building elements. \r\n All materials, when subjected to a force, \r\n respond to stress with an associated strain. The stress-strain relationship \r\n for masonry materials is approximately linear and is defined by the \r\n modulus of elasticity. Axial deformation is determined by dividing \r\n the stress by the modulus of elasticity and multiplying the quotient \r\n by the length under load. The deflections of horizontal elements, \r\n lateral deflections of walls and columns, and reductions in lengths \r\n of axially loaded structural elements due to design loads must be \r\n considered. \r\n Creep \r\n Creep, or plastic flow, is the continuing \r\n deformation of materials under load or stress. The magnitude of movement \r\n due to creep in masonry and concrete depends on the stress level, \r\n material age, duration of stress, material quality, and environmental \r\n factors. \r\n Brick . Creep in brick masonry primarily \r\n occurs in the mortar joints and is negligible. The ACI 530/ASCE 5 \r\n \"Building Code Requirements for Masonry Structures\" suggests 0.7 x \r\n 10 -7 in./in. per psi \r\n of load. \r\n Concrete Masonry . Concrete masonry \r\n exhibits more creep than brick masonry because of the cement content \r\n in the units. The ACI 530/ASCE 5 code suggests a value of 2.5 x 10 -7 in./in. per psi \r\n of load. \r\n \r\n Concrete . Creep is most significant \r\n in concrete frame structures. Creep in concrete begins after load \r\n is applied and proceeds at a decreasing rate. High-strength concretes \r\n show less creep than low-strength concretes. Creep is slightly greater \r\n in lightweight aggregate concretes than normal-weight concretes. In \r\n high-rise buildings, the total elastic and inelastic shortening of \r\n columns and walls due to gravity loads and shrinkage may be as high \r\n as 1 in. (25.4 mm) for every 80 ft (24.4 m) of height. \r\n Corrosion of Steel \r\n Corrosion of steel embedded in masonry can \r\n cause cracking or spalling of masonry. The volume of rust is greater \r\n than that of the steel from which it is formed. This volume increase \r\n causes pressure on the surrounding masonry. Metals embedded in grout, \r\n such as reinforcing bars, are less susceptible to corrosion than ties \r\n and joint reinforcement embedded in mortar joints since they are protected \r\n by the grout and not exposed. Other items in masonry susceptible to \r\n corrosion are steel lintels, steel shelf angles, joint reinforcement, \r\n anchor bolts and other metal fasteners in masonry. To minimize corrosion, \r\n do not use additives in mortar, such as calcium chloride, which would \r\n accelerate corrosion. See Technical Notes 44B \r\n for more on corrosion resistance of metal wall ties. \r\n Other Causes of Movement \r\n There are other causes of movement in building \r\n elements which may occur under given conditions. These include freezing \r\n expansion, carbonation of concrete and mortars, drift of the building \r\n frame, deflection of building elements, and the action of unstable \r\n soils. It is beyond the scope of this Technical Notes to discuss \r\n these items in detail. However, the designer should recognize and \r\n consider these factors. \r\n Masonry materials exhibit expansion due \r\n to freezing when saturated. Freezing expansion has a small effect \r\n on total expansion of masonry. Based on limited data, the freezing \r\n expansion for brick ranges from 0 to 10.3 x 10 -4 \r\n in./in. A design value for brick masonry of 2 x 10 -4 \r\n in./in. is recommended. The expansion occurs when saturated brick are \r\n subjected to temperatures at or below 14 ° F (-10 ° C). \r\n Carbonation is the chemical combination \r\n of hydrated portland cement with carbon dioxide present in air. Although \r\n it is known that materials containing portland cement shrink upon \r\n carbonation, little is known about the extent of the carbonation or \r\n the resulting shrinkage. \r\n The drift or side-sway of a structural frame \r\n may cause distress to brick masonry used as in-fill walls or exterior \r\n cladding. Wind or earthquake loads will be transferred to the more \r\n rigid brickwork if attached rigidly to the frame. The same is true \r\n for deflection of floor slabs or spandrel beams. Masonry built up \r\n in contact with these elements will be loaded due to the deflection \r\n of the member. Masonry intended to be non-loadbearing may become loadbearing. \r\n Foundation movements and differential settlement \r\n often cause cracking in masonry walls supported on foundations. Unstable \r\n soils or expansive soils are of special concern. Proper foundation \r\n design should be performed to ensure a stable support or allow uniform \r\n settlement. \r\n EFFECTS OF MOVEMENT \r\n Changes in building design have affected \r\n the design and behavior of many building components, including masonry \r\n walls. The most significant change for brick masonry is the shift \r\n from loadbearing masonry walls to skeleton frame construction. Other \r\n factors include the use of thinner walls, composite walls and insulated \r\n walls. The increased use of portland cement mortars and the tendency \r\n to specify high compressive strength mortars have become common. Although \r\n stronger units and mortars increase the compressive strength of the \r\n masonry, they do so at the expense of other important properties. \r\n Thus, masonry walls are thinner and more brittle than their massive \r\n ancestors. These thinner walls are more susceptible to cracking and \r\n spalling if provisions for differential movement are not accounted \r\n for properly. \r\n Cracking and Spalling \r\n Cracking is probably the distress which \r\n occurs most often in masonry walls. Cracks result from many different \r\n sources, but there are typical shapes and patterns of cracks. Often \r\n the type and magnitude of cracking will indicate the cause. \r\n It is more beneficial to show what can happen \r\n if movement is not considered in design than to show a properly designed \r\n and detailed project. Following are some typical locations where cracks \r\n occur in masonry walls and the major cause of each. Technical Notes \r\n 18A will describe ways to avoid these \r\n problems. \r\n Long Walls . Long walls or walls with \r\n large distances between expansion joints may cause distress within \r\n the wall. The expansion of the brickwork may force sealant material \r\n out of the expansion joint or crack the brickwork between expansion \r\n joints (see Fig. 2). Diagonal cracks often occur in piers between \r\n window or door openings. Such cracks usually extend from the head \r\n or sill at the jamb of the opening, depending upon the direction of \r\n movement and the path of least resistance. \r\n \r\n \r\n \r\n \r\n Expansion of Long Wall \r\n FIG. 2 \r\n \r\n Corners . An insufficient amount or \r\n improper location of expansion joints in walls can lead to cracking \r\n at the corners. Perpendicular walls will expand in the direction of \r\n the corner causing rotation and cracking near the corner. This typically \r\n occurs at the first head joint from either side of the corner (see \r\n Fig. 3). \r\n \r\n \r\n \r\n \r\n Crack at Corner \r\n FIG. 3 \r\n \r\n Offsets and Setbacks . Vertical cracks \r\n are quite common at wall setbacks or offsets if movement is not accommodated. \r\n When parallel walls expand towards the offset, the movement produces \r\n rotation of the offset causing vertical cracks (see Figs. 4 and 5). \r\n \r\n \r\n \r\n \r\n \r\n Crack at Offset \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Rotation at Offset \r\n FIG. 5 \r\n \r\n Shortening of Structural Frames . \r\n In frame structures, predominately concrete frame buildings, vertical \r\n shortening due to creep or shrinkage of the structural frame may impose \r\n high stresses on the masonry. These stresses may develop at window \r\n heads, shelf angles, and other points where stresses are concentrated. \r\n Fig. 6 shows brick veneer supported by a steel shelf angle on a concrete \r\n frame. Over time the concrete frame has shrunk and caused the steel \r\n shelf angle to bear on the masonry below. Because a horizontal expansion \r\n joint was not provided, stresses became concentrated on the mortar \r\n joint directly below the angle causing crushing of the masonry below. \r\n This phenomena can also cause bowing of brickwork between floors, \r\n if the brickwork is not adequately attached to the backing, or the \r\n backing is not sufficiently rigid. \r\n \r\n \r\n \r\n \r\n Spalling Due to Shortening of Structural \r\n Frame \r\n FIG. 6 \r\n \r\n Parapet Walls . Parapets exposed on \r\n three sides are subjected to extremes of moisture and temperature \r\n which may be substantially different from those in the wall below. \r\n Also, parapets lack the dead load of masonry above to help resist \r\n movement. Expansion can cause parapets to bow if restrained at both \r\n corners or move away from corners if restrained only at one end (see \r\n Fig. 7). \r\n \r\n \r\n \r\n \r\n Bowing of Parapet Due to Expansion \r\n FIG. 7 \r\n \r\n Foundations . Masonry walls above \r\n grade built on concrete foundations will expand while the concrete \r\n foundation will shrink. This differential movement will cause shear \r\n at the foundation interface if bonded together. Movement of the brick \r\n away from the corner or cracking of the concrete often results (see \r\n Fig. 8). \r\n \r\n \r\n \r\n \r\n Crack at Foundation Corner \r\n FIG. 8 \r\n \r\n Deflection and Settlement . Deflection \r\n and settlement cracks are identified by a tapering shape. Fig. 9 shows \r\n a deflection crack due to insufficient support of the brickwork on \r\n a lintel. The crack is wider at the steel angle and tapers to nothing. \r\n Technical Notes 31B Revised, \r\n Structural Steel Lintels, details the proper design of steel lintels \r\n supporting masonry. Deflection cracks may also occur at steel shelf \r\n angles attached to spandrel beams that deflect. \r\n \r\n \r\n \r\n \r\n Crack Due to Deflection \r\n FIG. 9 \r\n \r\n Fig. 10 shows a crack due to differential \r\n settlement of the foundation. If all settlement is equal, then little \r\n harm is done. Cracking occurs when one portion of a structure settles \r\n more than an adjacent part. \r\n \r\n \r\n \r\n \r\n Crack Due to Differential Settlement \r\n FIG. 10 \r\n \r\n Encased Columns . Where structural \r\n elements are rigidly encased in masonry, any movement of the column \r\n is transferred to the masonry, causing cracks. These movements may \r\n be due to drift of the building frame or lateral expansion from creep. \r\n These cracks occur on the exterior as well as the interior of the \r\n building (see Fig. 11). \r\n \r\n \r\n \r\n \r\n Encased Column \r\n FIG. 11 \r\n \r\n Curling of Concrete . If a concrete \r\n slab is cool and dry on top and warm and moist on the bottom, the \r\n top may become shorter than the bottom causing the slab to curl upward. \r\n Cast-in-place concrete slabs also curl up at the corners due to deflection \r\n when the forms are removed and loads applied. This curling can lift \r\n masonry attached to or laid on the concrete slab (see Fig. 12). \r\n \r\n \r\n \r\n \r\n Crack Due to Curling of Concrete Slab \r\n FIG. 12 \r\n \r\n Embedded Items . Items embedded in \r\n or attached to masonry may cause spalling or cracking when they move \r\n or expand. Joint reinforcement that is continuous across an expansion \r\n joint may buckle, pushing out adjacent mortar (see Fig. 13). Corrosion \r\n of metal elements within masonry causes volume increases of such a \r\n magnitude as to crack or spall the masonry. \r\n \r\n \r\n \r\n \r\n Spalling Due to Buckling of Joint Reinforcement \r\n FIG. 13 \r\n \r\n SUMMARY \r\n This Technical Notes describes the \r\n various movements that occur within all building materials and constructions. \r\n It also explains the effects of these movements. Cracking in brickwork \r\n can be eliminated if all factors are taken into consideration and \r\n the anticipated movement is accommodated. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of \r\n America. The information contained herein must be used in conjunction \r\n with good technical judgment and a basic understanding of the properties \r\n of brick masonry. Final decisions on the use of the information contained \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project architect, engineer, \r\n owner or all. \r\n REFERENCES \r\n More detailed information on subjects discussed \r\n here can be found in the following publications: \r\n 1. \"Building \r\n Code Requirements for Masonry Structures (ACI 530/ASCE 5)\", American \r\n Concrete Institute, Detroit, MI, 1988. \r\n 2. \"Building \r\n Movements and Joints\", Portland Cement Association, 1982. \r\n 3. Fintel, \r\n M., Ghosh, S.K., Iyengar, H., \"Column Shortening in Tall Structures-Prediction \r\n and Compensation\", Portland Cement Association, 1987. \r\n 4. Grimm, \r\n C.T., \"Masonry Cracks: A Review of the Literature,\" Masonry: Materials, \r\n Design, Construction, and Maintenance, ASTM STP 992, H.A. Harris, \r\n Ed., ASTM, Philadelphia, PA, 1988, pp. 257-280. \r\n 5. Grimm, \r\n C.T., \"Probablistic Design of Expansion Joints in Brick Cladding\", \r\n Proceedings of the 4th Canadian Masonry Symposium, University of \r\n New Brunswick, Canada, 1986, pp. 553-568. \r\n 6. Robinson, \r\n G.C., \"The Reversibility of Moisture Expansion\", American Ceramic \r\n Society Bulletin, Vol. 64, 1985, pp.712 -7 15. \r\n 7. Scheffler, \r\n M.J., Chin, I.R., Slaton, D., \"Moisture Expansion of Fired Bricks\", \r\n Fifth North American Masonry Conference, June 1990, pp. 549-562. \r\n 8. \"Shrinkage \r\n Characteristics of Concrete Masonry Walls\", Housing Research Paper \r\n No. 34, Housing and Home Finance Agency, April 1954. \r\n 9. Winter, \r\n G. and Nilson, A.H., \"Design of Concrete Structures\", McGraw-Hill \r\n Book Company, 1979. \r\n 10. \"Wood \r\n Handbook: Wood as an Engineering Material\", Agricultural Handbook \r\n 72, U.S. Department of Agriculture, Washington, D.C., 1987. \r\n 11. Young, \r\n J.E., and Brownell, W.E., \"Moisture Expansion of Clay Products\", \r\n Journal of the American Ceramic Society, Vol. 42, No. 12, 1959, \r\n pp. 571-581. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60074,"ResultID":176306,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 18A - Design and Detailing \r\n of Movement Joints, Part 2 \r\n December 1991 \r\n \r\n Abstract: Expansion joints are used in brick masonry to allow for movement \r\n and avoid cracking. This Technical Notes defines the different \r\n types of movement joints used in building construction. Equations \r\n are given to determine the proper size and spacing of brick expansion \r\n joints. Examples show the proper placement of expansion joints to \r\n avoid cracking of brick masonry. Information is also included on bond \r\n breaks, bond beams and flexible anchorage. \r\n \r\n Key Words: brick, differential movement, expansion joint, \r\n flexible anchorage, sealants. \r\n \r\n INTRODUCTION \r\n \r\n Because all materials in a building experience changes in volume, \r\n a system of movement joints is necessary to allow these movements \r\n to occur. Failure to permit these movements may result in cracks in \r\n brickwork as discussed in Technical Notes 18 . \r\n The type, size and placement of movement joints is critical to the \r\n proper performance of the building. This Technical Notes defines \r\n the different types of movement joints and discusses the proper design \r\n of expansion joints within brick masonry buildings. Details of expansion \r\n joints are provided for loadbearing and non-loadbearing applications. \r\n \r\n MOVEMENT JOINTS \r\n \r\n There are various types of movement joints in buildings: expansion \r\n joints, control joints, building expansion joints, and construction \r\n joints. Each type of movement joint is designed to perform a specific \r\n task, and they should not be used interchangeably. \r\n An expansion joint is used to separate brick masonry into \r\n segments to prevent cracking due to changes in temperature, moisture \r\n expansion, elastic deformation due to loads, and creep. Expansion \r\n joints may be horizontal or vertical. The joints are formed of highly \r\n elastic materials placed in a continuous, unobstructed opening \r\n through the brick wythe. This allows the joints to close as a result \r\n of an increase in size of the brickwork. Expansion joints must be \r\n located so that the structural integrity of the brick masonry is not \r\n compromised. \r\n A control joint is used in concrete or concrete masonry to \r\n create a plane of weakness which, used in conjunction with reinforcement \r\n or joint reinforcement, controls the location of cracks due to volume \r\n changes resulting from shrinkage and creep. A control joint is usually \r\n a vertical opening through the concrete masonry wythe and may be formed \r\n of inelastic materials. A control joint will open rather than \r\n close. Control joints must be located so that the structural integrity \r\n of the concrete masonry is not affected. \r\n A building expansion (isolation) joint is used to separate \r\n a building into discrete sections so that stresses developed in one \r\n section will not affect the integrity of the entire structure. The \r\n isolation joint is a through-the-building joint. \r\n A construction joint (cold joint) is used primarily in concrete \r\n construction where construction work is interrupted. Construction \r\n joints are located where they will least impair the strength of the \r\n structure. \r\n \r\n Expansion Joints \r\n \r\n Although the primary purpose of expansion joints is to accommodate \r\n movement, the joint must also resist water penetration and air infiltration. \r\n Figure 1 shows various ways of forming vertical expansion joints. \r\n A copper waterstop, a premolded foam pad or a neoprene pad may be \r\n included \r\n \r\n \r\n \r\n Vertical Expansion Joints \r\n FIG. 1 \r\n \r\n as a barrier to keep mortar or other debris from clogging the joint \r\n and aids in resisting water penetration. Fiberboard and other similar \r\n materials are not suitable for this purpose because they are not highly \r\n compressible and, after being compressed, they will not expand to \r\n their original size. \r\n When placing expansion joints in brick, materials such as mortar \r\n or joint reinforcement should not bridge the expansion joint. If this \r\n occurs, movement will be restricted and the expansion joint will not \r\n perform as intended. Expansion joints should be formed as the wall \r\n is built, as shown in Fig. 2. \r\n \r\n \r\n \r\n Expansion Joint Construction \r\n FIG. 2 \r\n \r\n Sealants are used on the exterior side of the expansion joint to \r\n act as a seal against water and air penetration. Many different types \r\n of sealants are available, although those which exhibit the highest \r\n movement capabilities are best. Elastomeric sealants must be highly \r\n elastic, resistant to weathering (ultraviolet light) and have high \r\n bond to adjacent materials. These elastomeric sealants are classified \r\n by three generic types: urethanes, silicones and polysulfides. Sealant \r\n manufacturers should be consulted for the applicability of their sealants \r\n as expansion joint materials. The sealant should conform to ASTM C \r\n 920 Specification for Elastomeric Joint Sealants. Many sealants require \r\n a primer to be applied to the masonry surface to ensure adequate bond. \r\n Compatibility of the sealant with adjacent materials such as flashings, \r\n metals, etc. must be taken into consideration. \r\n A backer rod, which is a circular foam rod, is used behind the sealant \r\n to keep the sealant at a constant depth and provide a surface to tool \r\n the sealant against. The sealant must not adhere to the backer rod. \r\n The depth of the sealant should be approximately one-half the width \r\n of the expansion joint, with a minimum sealant depth of 1/4 in. (6 \r\n mm). Increased resistance to water and air infiltration can be achieved \r\n by designing a two-stage joint as shown in Fig. 3. A two-stage joint \r\n is often used in a rain screen wall providing a vented or pressure-equalized \r\n joint. The space between the sealants must be vented to allow drainage. \r\n This is achieved by leaving a hole or gap in the sealant at the top \r\n and bottom of the joint. \r\n \r\n \r\n \r\n Two-Stage Expansion Joint \r\n FIG. 3 \r\n \r\n Vertical Expansion Joints \r\n \r\n Spacing of Vertical Expansion Joints. \r\n No single recommendation on the positioning and spacing of expansion \r\n joints can be applicable to all structures. Each building should be \r\n analyzed to determine the extent of movements expected within that \r\n particular structure. Provisions should be made to accommodate these \r\n movements and their associated stresses by a series of expansion joints. \r\n Generally, spacing of expansion joints is determined by considering \r\n the amount of expected wall movement and the size of compressibility \r\n of the expansion joint and expansion joint materials. \r\n \r\n Unrestrained expansion of the brickwork may be estimated by the following \r\n formula: \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n \r\n m u = total unrestrained movement of the brickwork, in. \r\n k e = coefficient of moisture expansion, in./in. \r\n k f = coefficient of freezing expansion, in./in. \r\n k t = coefficient of thermal expansion, in./in./ o F \r\n \r\n \r\n \r\n L = length of wall, in. \r\n \r\n \r\n \r\n \r\n The design value of the coefficient of moisture expansion for clay \r\n masonry is usually 0.0005 in./in. The coefficient for thermal expansion \r\n is 0.000004 in./in./ o F. The coefficient of freezing expansion \r\n is taken as 0.0002 in./in. Freezing expansion does not occur until \r\n wall temperatures go below 14 o F ( -10 o C). Further, \r\n the units must be saturated when frozen to cause expansion. Local \r\n conditions must be considered to determine if freezing expansion will \r\n occur, but is usually considered negligible. \r\n Equation 1 provides an estimate of the amount of movement occurring \r\n in a wan system. In addition to the amount of movement, there are \r\n other variables which may affect the size and spacing of expansion \r\n joints. These include wall restraint, elastic deformation due to loads, \r\n shrinkage and creep of mortar, construction tolerances and wall orientation. \r\n The following equation relates spacing between expansion joints to \r\n total unrestrained movement of the brick work and the expansion joint \r\n width. \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n \r\n S e = spacing between expansion joints, in. \r\n w j = width of expansion joint, in. \r\n e j = extensibility of expansion joint material, % \r\n \r\n \r\n \r\n \r\n The expansion joint is typically sized to resemble a mortar joint, \r\n usually 3/8 in. (10 mm) to 1/2 in. (13 mm). The maximum size of the \r\n expansion joint may depend on the sealant capabilities. Extensibility \r\n of highly elastic expansion joint materials are typically in the range \r\n of 25 % to 50%. Compressibility of backing materials can range up \r\n to 75%. \r\n The temperature change in brickwork used in Eqs. 1 and 2 is based \r\n on mean wall temperatures. The theoretical change in temperature is \r\n equal to the maximum or minimum mean wall temperature minus the mean \r\n wall temperature at the time of installation. Although this theoretical \r\n temperature difference is precise, it is difficult to accurately predict \r\n the temperature at the time of installation, and the minimum and maximum \r\n temperatures. Therefore, it is conservative to calculate the temperature \r\n variation based on the difference between the maximum and minimum \r\n mean wall temperature. \r\n Maximum mean wall temperatures vary from the maximum ambient air \r\n temperature to as high as 140 o F (60 o C) depending \r\n on wad orientation, location of insulation, color and density of the \r\n wan. Minimum mean wan temperatures will typically be close to the \r\n winter design temperature. Therefore, wan temperature differences, \r\n T, can vary from less than 50 o F (10 o C) to about \r\n 160 o F (71 o C). \r\n As an example of the use of Eq. 2, consider a brick veneer wall which \r\n is facing south. The color of the brick is a light red and the desired \r\n size of the expansion joint is 3/8 in. (10 mm). The extensibility \r\n of the sealant is 50%. Assuming appropriate values and no freezing \r\n expansion, Eq. 2 would give the following expansion joint spacing: \r\n \r\n \r\n \r\n Therefore, the maximum spacing for vertical expansion joints in a \r\n straight wall would be 17ft-4 in. (5.3 m). This spacing does not take \r\n into account window openings, corners or other material properties \r\n that may reduce the spacing of the expansion joints. The extent to \r\n which precautions should be taken to prevent masonry cracking will \r\n depend upon the intended use of the structure and its exposure. In \r\n most instances it is desirable to be conservative, but it may be economically \r\n desirable to exceed the maximum spacing as a calculated risk. An example \r\n would be when calculations show a need for expansion joints every \r\n 18 ft (5.5 m) but the expansion joint spacing is set at 20 ft (6.1 \r\n m) to match the spacing of the structural columns. Generally, vertical \r\n expansion joints should not exceed 30 ft (9.1 m) in walls without \r\n openings. \r\n \r\n Placement of Vertical Expansion Joints \r\n \r\n The actual location of vertical expansion joints in a structure is \r\n dependent upon the configuration of the structure as well as the expected \r\n amount of movement. In addition to adequately placing expansion joints \r\n within long walls, consideration should be given to placement of expansion \r\n joints at: corners, offsets, openings, wall intersections, changes \r\n in wall heights and parapets. \r\n Corners. Walls perpendicular to one another will expand towards \r\n their juncture, typically causing distress at the first head joint \r\n on either side of the corner (Fig. 4a). Expansion joints should be \r\n placed near corners to alleviate this stress. It is often not aesthetically \r\n pleasing to place expansion joints at the corner, although this is \r\n the best location. In such instances, an expansion joint should be \r\n placed within 10 ft (3.0 m) of the corner in either wall, but not \r\n necessarily both. The spacing of expansion joints around a corner \r\n should not exceed the spacing of expansion joints in a straight wall \r\n (Fig. 4b). For example, if the spacing between vertical expansion \r\n joints on a straight wall is 25 ft (7.6 m), then the spacing of expansion \r\n joints around a corner could be 10 ft (3.0 m) on one side of the corner \r\n and 15 ft (4.6 m) on the other side. Joint reinforcement may be added \r\n around wall corners to provide added tensile strength to the corner. \r\n Joint reinforcement should not bridge the expansion joint. \r\n \r\n \r\n \r\n Expansion Joints at Corners \r\n FIG. 4 \r\n \r\n Offsets and Setbacks . Parallel walls expand towards the offset rotating the short masonry leg, \r\n or causing cracks within the offset (Fig. 5a). Expansion joints should \r\n be placed at the offset to allow the parallel walls to expand (Fig. \r\n 5b). \r\n \r\n \r\n \r\n Expansion Joints at Offsets \r\n FIG. 5 \r\n \r\n Openings . \r\n Cracks often appear at window and door openings when the spacing between \r\n expansion joints is too large. In structures containing punched windows \r\n and door openings, more movement occurs above or below the openings. \r\n Less movement occurs along the line of windows since there is less \r\n masonry. This differential movement may cause cracks which emanate \r\n from the corners of the opening as in Fig. 6. This pattern of cracking \r\n does not exist in ribbon window structures. \r\n \r\n Window and door openings weaken the wall yet act as \"natural\" expansion \r\n joints. It is often desirable to locate vertical expansion joints \r\n along the edge or jamb of the opening. In cases where the masonry \r\n above an opening is supported by shelf angles attached to the structure, \r\n a vertical expansion joint can be placed alongside the opening, continuing \r\n through the horizontal support. \r\n \r\n \r\n \r\n Cracking In Structure With \"Punched\" Windows \r\n FIG. 6 \r\n \r\n In cases where the masonry above the opening is supported by loose \r\n lintels (unattached to the structure), special detailing and construction \r\n is required. If the expansion joint runs along side the opening as \r\n shown in Fig. 7a, the loose steel lintel must be allowed to expand \r\n independently of the masonry. To accomplish this a slip plane is formed \r\n with flashing placed above and below the angle. A backer rod and sealant \r\n is placed in front of the toe of the angle, and space left at the \r\n end of the angle. Thus, a pocket will be formed which will allow movement \r\n of the steel angle within the brickwork. If the joint cannot be built \r\n in this manner, then the vertical expansion joint should not be placed \r\n alongside the opening. An alternative may be to place it halfway between \r\n the windows. Location of the expansion joint alongside the window \r\n will influence the dead weight of the masonry bearing on the lintel. \r\n Instead of the usual triangular loading, the full weight of the masonry \r\n above the angle should be assumed to bear on the lintel. See Technical \r\n Notes 31B for more information \r\n on steel lintel design. \r\n \r\n \r\n \r\n Expansion Joint at Loose Lintel \r\n FIG. 7 \r\n \r\n Intersections and Junctions. Expansion joints should be located at intersections of masonry \r\n walls and walls which serve different functions. If the masonry is \r\n not required to be bonded at the intersection, an expansion joint \r\n should be incorporated. Walls which intersect at other than right \r\n angles are also vulnerable to cracking at the intersection. It may \r\n be necessary to separate adjacent walls of different heights to avoid \r\n differential movement. This is especially true if the difference is \r\n very large. Examples are shown in Fig. 8. \r\n \r\n \r\n \r\n Expansion Joints at Junctions \r\n FIG. 8 \r\n \r\n Parapets. \r\n Parapets are exposed on three sides to extremes of moisture and temperature \r\n which may cause substantially different movement from that of the \r\n wall below. Parapets also lack the dead load of masonry above to help \r\n resist movement. Therefore, all vertical expansion joints should be \r\n carried through the parapets. Additional expansion joints may be necessary \r\n halfway between those running full height, unless the parapet is reinforced. \r\n These additional expansion joints must continue down to a horizontal \r\n expansion joint, or continue to the base of the wall. \r\n \r\n Aesthetic Effects. Expansion joints are usually noticeable \r\n on flat walls of masonry buildings. There are ways to reduce the obvious \r\n demarcation. The use of a colored sealant which matches the brick \r\n helps to hide the joint. Also, masons sand can be rubbed into new \r\n sealant to remove the sheen, making the joint blend in more. Some \r\n projects have used toothed expansion joints where the expansion joint \r\n follows the bond pattern. This type of joint is not suggested because \r\n it is more difficult to keep debris out of the joint during construction \r\n which could interfere with movement. Further, most sealants do not \r\n perform well when subjected to both shear and tension. \r\n Conversely, it may be desirable to accentuate the expansion joint \r\n instead of trying to hide it. This is possible by recessing the brickwork \r\n at the expansion joint, or using special-shaped brick units as shown \r\n in Fig. 9. Architectural features such as quoins, recessed panels \r\n of brickwork or a change in bond pattern reduce the visual impact \r\n of vertical expansion joints. Also, expansion joints are less noticeable \r\n when located at reentrant corners. \r\n \r\n \r\n \r\n Accentuated Expansion Joint \r\n FIG. 9 \r\n \r\n Symmetrical placement of expansion joints on the elevation of buildings \r\n is usually most aesthetically pleasing. Further, placing the expansion \r\n joints such that wall areas and openings between expansion joints \r\n are symmetrical will reduce the likelihood of cracking. \r\n Other Considerations. Location of vertical expansion joints \r\n will be influenced by additional factors. Spandrel sections of brickwork \r\n supported by a beam or floor may crack due to deflection of the support. \r\n Reduced spacing of expansion joints will permit deflection to occur \r\n without cracking the brickwork. Wall segments which have different \r\n climatic exposure conditions will respond with different movement. \r\n An expansion joint should separate wall areas with different exposures. \r\n Thus, an exterior wall which continues past a glass curtainwall perpendicular \r\n to the wall should have an expansion joint at the curtainwall intersection. \r\n Movement joints must be provided in multi-wythe brick and concrete \r\n masonry walls. Expansion joints must be placed in the brick wythe \r\n and control joints must be placed in the concrete masonry, although \r\n they do not necessarily have to be aligned. \r\n \r\n Horizontal Expansion Joints \r\n \r\n Horizontal expansion joints may be required when brickwork is a non-loadbearing \r\n element. Horizontal expansion joints are needed if the brick wythe \r\n is supported on a shelf angle outside the frame or used as an infill \r\n wall within the frame. Horizontal expansion joints are located at \r\n steel shelf angles by providing space beneath the angle for movement \r\n to occur. In low-rise masonry buildings (below three stories) and \r\n buildings with shear walls it is not necessary to provide horizontal \r\n relief, but differential movement should be accounted for in the tie \r\n system, window details, and at the top of the wall. High-rise frame \r\n structures typically have horizontal expansion joints located at every \r\n floor level or every other floor level. Figure 10 is a typical detail \r\n of a horizontal expansion joint on a brick veneer building. Notice \r\n that a clear space or highly compressible material is placed beneath \r\n the angle, and that a backer rod and sealant are used at the toe of \r\n the angle to seal the joint. \r\n \r\n \r\n \r\n Expansion Joint at Shelf Angle \r\n FIG. 10 \r\n \r\n The size of the horizontal expansion joint should take into account \r\n movements of the brickwork and movements of the frame. These frame \r\n movements include both material and load induced movements, including \r\n deflection of the shelf angle. In some instances, the size of the \r\n expansion joint may get rather large and not aesthetically pleasing. \r\n An alternate detail shown in Fig. 11 allows more room for movement \r\n while providing a smaller-appearing joint. The special-shaped brick \r\n unit could also be placed below the steel angle and turned upside \r\n down. \r\n \r\n \r\n \r\n Alternate Expansion Joint Detail \r\n FIG. 11 \r\n \r\n Horizontal expansion joints are suggested when brick is used as an \r\n in still material within the frame of the structure. Expansion joints \r\n must be provided between the top course of masonry and the member \r\n above. Deflections of the frame should be considered when sizing the \r\n expansion joint. \r\n Shelf angles are required by model building codes in most locations \r\n especially those areas of high seismic risk. They are advisable in \r\n buildings with a flexible structural frame and are recommended when \r\n the backing is steel studs. \r\n \r\n BOND BREAKS \r\n \r\n Concrete and concrete masonry have moisture and thermal movements \r\n which are considerably different than those of brick masonry. Also, \r\n floor slabs and foundations are usually under different states of \r\n stress due to loading than are walls. Therefore, it may be important \r\n to separate these elements by bond breaks such as building paper or \r\n flashing. With bond breaks between foundations and walls; between \r\n slabs and walls; and between concrete and clay masonry, each element \r\n will be able to move somewhat independently while still providing \r\n the necessary support. Typical methods of breaking bond between walls \r\n and slabs, and walls and foundations are shown in Fig. 12. \r\n \r\n \r\n \r\n Bond Breaks in loadbearing Cavity Wall \r\n FIG. 12 \r\n \r\n When bands of clay brick are used in concrete masonry walls, or when \r\n bands of concrete masonry are used in clay brick walls, joint cracking \r\n may result due to the difference in material properties. It may be \r\n prudent to have the bond broken between the two materials with building \r\n paper or flashing, or to provide additional movement joints to eliminate \r\n this cracking. \r\n Breaking bond does not affect the compressive strength of the wall \r\n and generally does not affect the stability of veneer wythes. The \r\n weight of the masonry, anchorage and the frictional properties at \r\n the interface provide for stability. \r\n When it is necessary to anchor a masonry wall to the foundation and \r\n to the roof, it is still possible to detail the walls in a manner \r\n which allows some differential movement. Such anchorage will be required \r\n for loadbearing walls subjected to high winds or seismic forces (Fig. \r\n 13). \r\n \r\n \r\n \r\n Bond Break at Foundation \r\n FIG. 13 \r\n \r\n LOADBEARING MASONRY \r\n \r\n The potential for cracking in loadbearing masonry members is less \r\n than in non-loadbearing masonry members since compressive stresses \r\n resulting from dead and live loads help offset the effects of expansive \r\n movement. Adding reinforcement at critical sections such as parapets, \r\n points of load application and around openings to accommodate or distribute \r\n high stresses will also help control the effects of movement. Reinforcement \r\n may be placed in bed joints or in reinforced bond beams (Fig. 14). \r\n It should be noted that historically, old loadbearing structures did \r\n not have expansion joints, and did not crack. However, the walls were \r\n thicker and made of homogeneous materials as compared to structures \r\n built today. \r\n \r\n \r\n \r\n Bond Beams \r\n FIG. 14 \r\n \r\n NON-LOADBEARING MASONRY \r\n \r\n Non-loadbearing walls are usually thinner than loadbearing walls. \r\n The exterior wythe is often thermally isolated from the building by \r\n insulation and therefore is subjected to more differential movement. \r\n For these reasons, a series of vertical and horizontal expansion joints \r\n should be designed to permit differential movement. \r\n Brick veneer can be self-supporting up to a maximum height of 100 \r\n ft (30.5 m) provided the building has shear walls or rigid structural \r\n frames with stiff backing materials. For such a system, the structural \r\n frame provides the walls with lateral support and carries all other \r\n vertical loads. The wall is tied to the frame by flexible anchors \r\n or adjustable ties which permit differential movement. Allowance for \r\n differential movement between the exterior brickwork and the structure \r\n is provided at any openings and at the tops of walls. Vertical expansion \r\n joints as discussed earlier must be incorporated. \r\n \r\n Flexible Anchorage \r\n \r\n Where anchors tie walls to the structural frame or the backing to \r\n provide lateral support, the anchors and ties should be flexible; \r\n i.e. resist movement perpendicular to the plane of the wall (tension \r\n and compression) but not parallel to the wall (shear). This flexibility \r\n permits differential movements between the structure and the wall. \r\n Figure 15 shows typical methods for anchoring masonry walls to columns \r\n and beams. Details of anchoring brick to the backing are shown in \r\n Technical Notes 44B . \r\n \r\n \r\n \r\n Flexible Anchorage to Beams and Columns \r\n FIG. 15 \r\n \r\n The size and spacing of anchors and ties are based on tensile and \r\n compressive loads induced by lateral loads on the walls. Technical \r\n Notes 44B lists recommended \r\n tie spacing based on application. Anchors and ties must be able to \r\n accommodate the expected movement without obstruction and without \r\n becoming disengaged. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes defines the types of movement joints \r\n used in building construction. Details of expansion joints used in \r\n brickwork are shown. The recommended size, spacing and location of \r\n expansion joints are given. By using the suggestions in this Technical \r\n Notes , the possibility of cracks in brickwork can be reduced. \r\n Expansion joints are used in brick masonry to allow for the movement \r\n generated by materials as they react to their own properties, environmental \r\n conditions and loads. In general, vertical expansion joints should \r\n be used to break the brickwork into rectangular elements which have \r\n the same support conditions, the same climatic exposure and the same \r\n through-wall construction. The maximum spacing for vertical expansion \r\n joints is 30 ft (9.1 m). Horizontal expansion joints must be placed \r\n at shelf angles supporting brick masonry. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering \r\n staff of the Brick Institute of America. The information contained \r\n herein must be used in conjunction with good technical judgment and \r\n a basic understanding of the properties of brick masonry. Final decisions \r\n on the use of the information contained in this Technical Notes \r\n are not within the purview of the Brick Institute of America, \r\n and must rest with the project architect, engineer, owner, or all. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. ASTM \r\n C 920-86, Standard Guide for Use of Elastomeric Joint Sealants, \r\n Annual Book of Standards, Vol. 04.07. \r\n 2. Beall, \r\n C., \"Sealant Joint Design\", Water on Exterior Building Walls: Problems \r\n and Solutions, ASTM STP 1107, T.A. Schwartz, Ed., ASTM, Phila., \r\n 1991. \r\n 3. \"Building \r\n Movements and Joints\", Portland Cement Association, 1982. \r\n 4. Rainger, \r\n P., \"Movement Control in the Fabric of Buildings\", Nichols Publishing \r\n Co., New York, 1983. \r\n 5. Szoke, \r\n S.S., Carrier, G.J., \"Accommodating Movement in Brickwork\", Applications \r\n and Performance of Structural Materials and Exterior Facades, ASCE \r\n Convention, Boston, MA, October 27, 1986. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60075,"ResultID":176307,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19 - Residential Fireplace \r\n Design \r\n January 1993 \r\n \r\n Abstract: This Technical Notes covers the components, design \r\n and dimensions of residential wood-burning fireplaces. The recommendations \r\n are limited to single-face fireplaces. Concepts for increased energy \r\n efficiency as a supplemental heating unit are also addressed. Recommendations \r\n for the selection of materials as they relate to the construction \r\n of fireplaces are included. \r\n Key Words: brick, building codes, \r\n damper, design, energy efficiency, fireplace, heating, masonry, mortar. \r\n INTRODUCTION \r\n In past years, fireplaces were mostly decorative \r\n and seldom used for heating residences. Recently, there has been a \r\n revival of the use of fireplaces as a supplemental heating source. \r\n This use requires that fireplaces be built as a more functional unit. \r\n The combustion process, the variety of firebox \r\n configurations and the varying rates at which fuel is consumed are \r\n complex. Development of test methods to take into consideration the \r\n many variables affecting fireplace performance has been conducted \r\n for several years. However, the comparative performance of different \r\n fireplace configurations is not yet well documented. Thus the design \r\n suggestions in this Technical Notes are based on past proven \r\n performance. Although governed by the laws of thermodynamics, fireplace \r\n design is not an exact science, instead it is an empirical art to \r\n be applied with knowledge of basic principles and good judgment. \r\n Successful concepts that were discarded \r\n when fireplaces became mostly decorative are now finding new relevance. \r\n In addition, several new concepts have been developed which can increase \r\n the energy efficiency of conventional fireplaces. \r\n The purpose of this Technical Notes \r\n is to provide basic information for the design of successful, single-face, \r\n wood-burning fireplaces and to introduce concepts that can increase \r\n their energy efficiency. Other Technical Notes in this series \r\n discuss design, detailing and construction of other styles of residential \r\n fireplaces and the design of residential chimneys and masonry heaters. \r\n TYPES OF FIREPLACES \r\n There are several distinct types of fireplaces \r\n currently in use for residential applications. There are many individual \r\n variations within each general type, but most of the functional principles \r\n are similar. \r\n Single-Face \r\n Single-face fireplaces have been in use \r\n since early recorded history with developments in design through most \r\n of the major architectural periods. Most of the available information \r\n on the proper opening sizes, dampers, and flue sizing is based on \r\n empirical developments. \r\n Single-face fireplaces can provide relatively \r\n efficient room heating. The amount of radiated and reflected heat \r\n produced increases with the amount of brick masonry surrounding the \r\n fire. The amount of brick masonry surface area exposed to the fire, \r\n its distance from the fire and the size of the fire determine the \r\n amount of reflected and radiated heat. Also, the mass of the fireplace \r\n assembly stores heat and radiates the heat into the room after the \r\n fire is extinguished. Key elements of a single-face fireplace are \r\n shown in Figures 1a through 1c. \r\n \r\n \r\n \r\n \r\n Typical Single-Face Fireplace (See Table \r\n 1 for Dimensions) \r\n \r\n \r\n FIG. 1a \r\n \r\n \r\n \r\n \r\n \r\n Typical Single-Face Fireplace (See Table \r\n 1 for Dimensions) \r\n \r\n FIG. 1b \r\n \r\n \r\n \r\n \r\n \r\n Typical Single-Face Fireplace (See Table \r\n 1 for Dimensions) \r\n \r\n FIG. 1c \r\n \r\n \r\n \r\n Rumford Fireplaces. The Rumford fireplace \r\n is a single-face fireplace with a firebox which features widely splayed \r\n sides, a shallow depth and a high opening. These features increase \r\n energy efficiency. Performance tests indicate that the radiated and \r\n reflected heat output from a Rumford fireplace is higher than that \r\n from a conventional fireplace. Information on the design and construction \r\n of Rumford fireplaces is provided in Technical Notes 19C \r\n Revised. \r\n Rosin Fireplaces. The Rosin fireplace \r\n is a single-face fireplace with a specially curved back to the firebox, \r\n designed to increase energy efficiency. The Rosin has a cast refractory \r\n firebox with widely splayed sides which increases radiation and heat \r\n storage. The Rosin firebox can be retrofitted into an existing masonry \r\n fireplace or built into a new fireplace. \r\n Air-Circulating Fireplaces. Air-circulating \r\n fireplaces are so named because they circulate room air behind the \r\n combustion chamber through a series of brick baffles or steel plates. \r\n As a result, additional heat output can be distributed to the room \r\n or other areas of the residence by convection. \r\n Examples of this type of single-face fireplace \r\n are the Heatilator and the Brick-O-Lator [7]. This type of fireplace \r\n can be used as a supplemental heat source. Brick has the advantage \r\n of radiating the heat stored in the mass of the fireplace after the \r\n fire is out. Additional heat can be distributed to the room by continuing \r\n to circulate air long after the fire is out. \r\n Multi-Face \r\n Multi-face fireplaces have adjacent, opposite \r\n or all faces open to the room. Although generally associated with \r\n contemporary design, the multi-face fireplace is also of ancient origin. \r\n For example, the so-called corner fireplace which provides two adjacent \r\n open sides has been in use for several hundred years in Europe. Some \r\n multi-face fireplaces have unique design requirements which have to \r\n be met before satisfactory performance can be reached. These fireplace \r\n configurations are less energy efficient than single-face fireplaces. \r\n This is due to the lack of radiating surfaces and increased use of \r\n room air. Multi-face fireplaces are usually selected for aesthetics \r\n rather than energy efficiency. Multi-face fireplaces are discussed \r\n in Technical Notes 19C Revised. \r\n FIREPLACE DESIGN \r\n The performance of a fireplace is primarily \r\n governed by three factors: fuel combustion, air pressure differential \r\n between the firebox and the top of the chimney and temperature differential \r\n between air in the room of the fire and that at the top of the chimney. \r\n All must be considered in order to achieve successful combustion and \r\n exhaust performance. All fireplaces include the same four basic components. \r\n These are the base, firebox, smoke chamber and the chimney. Of these, \r\n all but the base influence burning performance. \r\n Base \r\n The base consists of the foundation and \r\n hearth support, as shown in Figs. 1a and 2. It is not necessary that \r\n all of the components shown be present. For slab-on-grade construction, \r\n the slab can provide both the foundation and the hearth support, providing \r\n it is adequately designed to support the weight of the fireplace assembly. \r\n \r\n \r\n \r\n \r\n Typical Base Assembly \r\n FIG. 2 \r\n \r\n Foundation. Masonry fireplaces must \r\n be supported with an adequate foundation. The foundation consists \r\n of either footings which support foundation walls or a structural \r\n slab. Local building codes should be reviewed for design soil pressures \r\n for foundations. The minimum requirements contained in most building \r\n codes for the foundation components are included in the following \r\n discussion. The foundation must be designed to carry the weight of \r\n the fireplace without excessive or differential settlement. \r\n Footings- Footings should be \r\n made of masonry or concrete and at least 12 in. (300 mm) thick, and \r\n extend at least 6 in. (150 mm) beyond the fireplace walls on all sides. \r\n The footings should penetrate below frost line unless they are located \r\n within a space maintained above freezing. Footings should be placed \r\n on undisturbed or properly prepared soils. \r\n Foundation Walls- Foundation \r\n walls raise the fireplace to the desired level and should be constructed \r\n of masonry or concrete with a minimum thickness of 8 in. (200 mm). \r\n There should be no voids except for the ash pit and external combustion \r\n air ducts formed in the base assembly, as shown in Figs. 1a and 2. \r\n Typically the shape of foundation walls matches the perimeter of the \r\n fireplace structure above. \r\n Structural Slab- The structural \r\n slab must be properly designed to support the weight of the fireplace \r\n assembly. When the fireplace is constructed on a slab-on-grade it \r\n is usually necessary to thicken the slab under the fireplace to support \r\n the loads from the fireplace and chimney. \r\n Hearth Support. Support for the hearth \r\n can be provided in a number of ways. These include the use of corbeled \r\n brickwork, a structural concrete slab or cantilevered reinforced brick \r\n masonry. The maximum projection of each brick in a corbel should not \r\n exceed one-half the height of the unit nor one-third its thickness. \r\n When corbeling from walls, the overall horizontal projection should \r\n be limited to one-half of the wall thickness unless the corbel is \r\n reinforced. These maximum horizontal individual and overall projections \r\n are consistent with current model building code requirements. Hearth \r\n support featuring corbeled brickwork and a structural slab are shown \r\n in Figs. 1a and 2. \r\n A structural concrete slab or reinforced \r\n brick masonry is used to span the foundation walls and may cantilever \r\n to support the hearth extension. \r\n Firebox \r\n The firebox consists of the hearth, fireplace \r\n opening, combustion chamber, throat and often a smoke shelf as shown \r\n in Figs. 1 and 3. The thicknesses of the firebox walls are set by \r\n the model building codes. When refractory brick or firebrick are used \r\n to line the walls the total thickness may be reduced. \r\n Hearth. The hearth consists of two \r\n basic parts, the inner hearth and the extended hearth. The hearth \r\n can be raised or flush with the floor surface. A fireplace hearth \r\n flush with the floor is shown in Figs. 1a and 3. \r\n Inner Hearth- The inner hearth \r\n is within the firebox area and forms the floor of the combustion chamber. \r\n All model building codes require that the inner hearth and the hearth \r\n support be noncombustible and a minimum of 4 in. (100 mm) thick. \r\n Extended Hearth- The extended \r\n hearth is that portion of the hearth that projects out into the room \r\n beyond the face of the fireplace and must be noncombustible. Model \r\n building codes require the extended hearth to be supported by noncombustible \r\n materials with no combustible material against the underside. Wooden \r\n forms or centers used to construct the hearth extension must be removed \r\n when construction is completed. The extended hearth may be a reinforced \r\n brick masonry cantilever. \r\n \r\n \r\n \r\n \r\n Typical Firebox Assembly \r\n FIG. 3 \r\n \r\n Model building codes also require that the \r\n hearth extend a minimum of 8 in. (200 mm) on each side of the fireplace \r\n opening and 16 in. (400 mm) in front of the fireplace opening. If \r\n the fireplace opening is greater than 6 ft 2 (0.55 m 2 ), building codes require \r\n hearth extensions of 12 in. (300 mm) on either side of the opening \r\n and 20 in. (500 mm) in front of the fireplace opening. \r\n Fireplace Opening . The fireplace \r\n opening is a very important element in fireplace design. The configuration \r\n and dimensions of most other components of the fireplace and chimney \r\n are based primarily on the dimensions of the fireplace opening selected. \r\n Figure 1 shows details and Table 1 provides the widths and heights \r\n of fireplace openings found to be the most satisfactory for appearance \r\n and successful operation. These dimensions may be varied slightly \r\n to allow for brick coursing. \r\n Proper Sizing- Firebox dimensions \r\n should be selected so that the fire fills the combustion chamber during \r\n operation. This provides greater heating efficiency. Careful consideration \r\n should be given to size of the fireplace opening best suited for the \r\n room in which it is to be located. Location and size are important \r\n not only from the standpoint of appearance, but also of operation. \r\n If the fireplace opening is too small, it may function properly but \r\n will not produce enough heat to warm the room. If the opening is too \r\n large, a fire that would fill the combustion chamber may overwhelm \r\n the room. In such a case, the firebox opening would require a larger \r\n flue area and consume larger amounts of interior air even if exterior \r\n combustion air is provided. Table 2 provides suggested widths of conventional \r\n fireplace openings appropriate for various room sizes. For example, \r\n a room with 300 ft 2 (28 m 2 ) of floor area is best served by a fireplace with an opening \r\n 30 in. (750 mm) to 36 in. (900 mm) wide. \r\n The shape of the fireplace opening is important \r\n aesthetically and functionally. Higher openings increase the radiant \r\n heating, increase the demand for room air and require taller chimneys. \r\n \r\n \r\n \r\n \r\n a Adapted from Book of Successful \r\n Fireplaces, 20th Edition. \r\n b SI conversion: mm = in. x 25.4. \r\n c L and M are shown in Fig. 1 and are equal to outside \r\n dimensions of flue lining plus at least 1 in. (25 mm). Determine \r\n flue lining dimensions from Fig. 5. L is greater than or equal to \r\n M. \r\n d Angle sizes: A - 3 x 3 x 1/4 in., B-3 1/2 x 3 x 1/4 \r\n in., C-5 x 3 1/2 x 5/16 in. \r\n \r\n Support Above Fireplace Opening- The \r\n brickwork above the fireplace opening must be adequately supported. \r\n There are several alternatives for support. These include brick arches, \r\n reinforced brick masonry lintels, stone, precast concrete and loose \r\n angle lintels. \r\n Brick arches usually require no steel reinforcement \r\n and are an attractive option. When determining the height of a fireplace \r\n opening which incorporates an arch use the maximum height to the arch \r\n soffit. Information on arch design may be found in Technical Notes \r\n 31 Series. \r\n Reinforced brick masonry (RBM) lintels may \r\n be built in place or prefabricated. The advantages of using RBM lintels \r\n are numerous, but include more efficient use of materials and exposed \r\n brick rather than steel at the top of the opening. RBM lintel design \r\n procedures are given in Technical Notes 17H. Loose steel \r\n angle lintels are the most prevalent means of support. For this reason, \r\n Table 1 gives recommended steel angle dimensions. If opening sizes \r\n other than those listed in Table 1 are used, information found in \r\n Technical Notes 31B Revised \r\n can be used for design of the loose steel angle lintel. \r\n \r\n \r\n \r\n \r\n a Reprinted with permission \r\n of Structures Publishing Company from Book of Successful \r\n Fireplaces, 20th Edition. \r\n b SI conversions: mm = ft. x 0.305; mm = in. x 25.4. \r\n \r\n \r\n \r\n \r\n General recommendations are: the steel angles \r\n should be at least 1/4 in. (6A mm) thick; the horizontal leg should \r\n be at least 3-1/2 in. (89 mm) for use with nominal 4 in. (100 mm) \r\n thick brick and 3 in. (75 mm) for use with nominal 3 in. (75 mm) thick \r\n brick. The minimum required bearing length on each end of the fireplace \r\n opening is 4 in. (100 mm). Steel angle lintels should have a space \r\n at their ends to permit thermal expansion. \r\n Combustion Chamber . The shape and \r\n depth of the combustion chamber will greatly influence draft, combustion \r\n air requirements and the amount of heat reflected and radiated into \r\n the room. Figure 1 illustrates the shape and Table 1 provides recommended \r\n dimensions for the combustion chamber. These dimensions may be varied \r\n slightly, but the information given is based on successful designs. \r\n Significant changes should not be made without consulting a fireplace \r\n design consultant. \r\n The sides and lower portion of the back \r\n of the combustion chamber should be vertical. Above the vertical portion \r\n of the back, the brick should be sloped forward towards the fireplace \r\n opening to support the metal damper and the clay flue lining. For \r\n the maximum amount of reflected heat into the room, the sloped portion \r\n of the back should be plane rather than concave. If it is concave, \r\n more heat will be reflected back into the fire rather than into the \r\n room. Greater splay of the sides also increases the amount of heat \r\n reflected into the room. \r\n The combustion chamber should be constructed \r\n of nominal 4 in. (100 mm) thick brick. When refractory brick or firebrick \r\n are used, model building codes permit the total wall thickness to \r\n be reduced. Thin mortar joints, not more than 1/4 in.(6.4 mm), should \r\n be specified. A 1 in. (25 mm) air space should be provided between \r\n the combustion chamber wall and the backup wall, although not required \r\n by building codes. This air space provides for thermal expansion of \r\n the combustion chamber. A noncombustible, compressible, fibrous insulation \r\n or similar material should be wrapped around the combustion chamber \r\n to ensure that this air space is maintained. The backup wall should \r\n be no less than 4 in. (100 mm) in thickness around the back of the \r\n combustion chamber to support the loads from the smoke chamber and \r\n chimney above. \r\n Throat. The throat is a slot-like \r\n opening directly above the top of the firebox through which flames, \r\n smoke and combustion gases pass into the smoke chamber and upward \r\n through the chimney. Because of its effect on draft, the throat of \r\n the fireplace should be carefully designed. It should be a minimum \r\n of 8 in. (200 mm) above the highest point of the fireplace opening. \r\n The throat is illustrated in Fig. 1a and appropriate dimensions are \r\n found in Table 1. \r\n Cast refractory and formed clay throats \r\n are available, built to certain angles and dimensions to fit most \r\n conventional fireplace dimensions. These elements are positioned on \r\n top of the firebox walls and eliminate the need of constructing brick \r\n courses to form the throat. Once in place, brick masonry can be built \r\n around the throat to give the appearance of conventionally built throats \r\n in the breastwork of the fireplace. \r\n Damper- The damper closes \r\n the fireplace opening to exterior air infiltration and can be used \r\n to control the burning rate of the fireplace. A metal damper may be \r\n placed in the throat, extending the full width of the throat opening, \r\n or at the top of the chimney. \r\n A throat damper should have an open area \r\n of approximately twice the area of the flue. The damper should have \r\n a valve plate which opens toward the back of the fireplace. Such a \r\n plate when opened, forms a barrier to deflect any down draft which \r\n may occur. Many different damper shapes are available. A high formed \r\n damper is recommended because it extends the throat with its construction \r\n and forms a critical portion of the smoke chamber. This damper type \r\n reduces the possibility of masonry blocking the valve plate of the \r\n damper. The damper should be spot bedded in mortar for a good fit \r\n and support, but not mortared in solidly at the ends because expansion \r\n could cause cracking in masonry. A noncombustible, compressible, fibrous \r\n insulation or similar material should be placed between the damper \r\n ends and adjacent masonry to allow differential movement. \r\n A chimney top damper is an alternative to \r\n the damper installed at the top of the throat. The damper is operated \r\n by a control chain which extends down into the firebox. This type \r\n of damper permits the chimney and flue to be heated when the fireplace \r\n is not in use and may help reduce water penetration into the flue. \r\n Chimney top dampers must be weighted or spring loaded to be in the \r\n open position if the operating mechanism fails. This is necessary \r\n so the damper remains open during operation of the fireplace. \r\n Smoke Shelf. The origin of and need \r\n for a smoke shelf is not clear. Some say its purpose is to provide \r\n a location for chimney sweeps to work from when cleaning large chimneys. \r\n Others contend it deflects down drafts and prevents direct access \r\n of water entering the top of the flue to the firebox. It also serves \r\n as a depository for ash which does not clear the chimney. The smoke \r\n shelf, if used, should be designed so that a uniform air flow results. \r\n The smoke shelf should be directly under the flue, be level across \r\n the face and in plane with the base of the damper. The smoke shelf \r\n should also extend the full width of the throat. It can be flat, extending \r\n back to and perpendicular to the rear wall of the smoke chamber, or \r\n curved to blend with the rear wall of the smoke chamber. Refer to \r\n Figs. 1a and 3 for details and Table 1 for recommended dimensions. \r\n Some designs, such as Rumford fireplaces, \r\n do not include a smoke shelf. These types of fireplace designs are \r\n often referred to as having \"the streamline effect\". In this instance, \r\n the flue tile is vertically aligned with the top of the last course \r\n of brick at the back of the firebox wall. Such a design provides a \r\n clear vertical passageway from the firebox to the top of the last \r\n chimney flue liner. \r\n Smoke Chamber \r\n The smoke chamber forms the chimney flue \r\n support, as shown in Figs. 1a, 1b and 4, and conveys by-products of \r\n the combustion process up to the chimney. The back wall of the chamber \r\n is built vertically and the side walls are sloped uniformly toward \r\n the center. The front wall above the throat is also sloped to meet \r\n and provide support for the bottom of the clay flue liner. Flue liners \r\n should be supported on all sides. The front wall above the throat \r\n should be supported by reinforced brick masonry or a steel angle, \r\n not by the damper. \r\n \r\n \r\n \r\n \r\n Typical Smoke Chamber Assembly \r\n FIG. 4 \r\n \r\n The slope of the smoke chamber should be \r\n smooth, with each course of brick corbeled to achieve the required \r\n angle. The inside of the smoke chamber should be parged with refractory \r\n mortar to reduce friction and prevent smoke leakage. Figures 1a and \r\n 4 show the shape of the smoke chamber and Table 1 gives recommended \r\n dimensions. \r\n There are alternative means of building \r\n the inside surface of the smoke chamber. Cast refractory materials \r\n or cut pieces of clay flue liner may be used. Dimensional coordination \r\n is important so that all components are correctly fitted without cracks \r\n or leaks of combustion products. \r\n Chimney Flue \r\n Draft of the fireplace is affected by the \r\n dimensions of the firebox opening, the shape and cross-sectional area \r\n of the flue and the height of the chimney. Figure 5 provides a graphical \r\n determination of the appropriate flue size for fireplace opening area \r\n and overall height [3]. For purposes of Fig. 5, the height is defined \r\n as the distance from the combustion chamber floor to the top of the \r\n last chimney flue liner. When using Fig. 5 it is normally best to \r\n use the smaller flue size when the opening and height selected intersect \r\n between standard flue sizes. Taller chimneys have a better draw than \r\n shorter chimneys with the same flue size. \r\n For fireplace openings greater than those \r\n given in Table 1 and Fig. 5, the area of the flue and height of the \r\n chimney can be determined by methods in Technical Notes 19B \r\n Revised. Chimney design and construction are also covered in Technical \r\n Notes 19B Revised. \r\n \r\n \r\n \r\n \r\n Flue Size Nomograph \r\n FIG. 5 \r\n \r\n Structural Considerations \r\n Masonry fireplaces must withstand wind and \r\n seismic loads resulting from local conditions. In areas of high wind \r\n and seismic activity, vertical and horizontal reinforcement may be \r\n required. Vertical reinforcement is located at least at each corner \r\n of the fireplace. Such reinforcement must be anchored to the foundation \r\n and properly lapped to be continuous for the entire chimney height. \r\n The size and spacing of reinforcement depends on design loads, overall \r\n dimensions of the fireplace and chimney, location of the reinforcement \r\n and means of attachment to the structure. Fireplaces and chimneys \r\n are typically attached to the structure by steel straps located at \r\n each floor or ceiling line. Consult the local building code for design \r\n loads and prescriptive requirements. For more information on chimney \r\n design see Technical Notes 19B \r\n Revised. \r\n Aesthetic Considerations \r\n The appearance of the fireplace has evolved \r\n through the centuries from the elaborately carved mantels of the Georgian \r\n Period to the smaller, streamlined fireplaces found in contemporary \r\n style homes. The aesthetic design of a fireplace is often based on \r\n the style of the house or room. The fireplace may project from adjacent \r\n walls to add emphasis to the fireplace or may be flush with its surroundings. \r\n The effect of a fireplace can be simple, just a rectangular opening \r\n with a brick surround in an otherwise blank wall. Conversely, a focal \r\n point can be created with an ornate brick area filling an entire wall. \r\n Functional aspects such as wood storage areas or seating can be incorporated. \r\n Brickwork can be combined with materials in other locations. \r\n The most prominent features of the fireplace \r\n are the fireplace surround, the mantel, and the hearth. Although certain \r\n aspects of these features must conform to building code requirements, \r\n the resulting appearance is limitless. \r\n Mantel. The mantel is a shelf or \r\n facing ornament above the fireplace opening. Depending on the architectural \r\n style of the room, the mantel may be recessed into the wall or may \r\n project out from the wall. Mantels may be built integrally with the \r\n fireplace or may be anchored to it. Specially carved mantels are sometimes \r\n used to surround the fireplace. Projecting mantels are usually made \r\n of corbeled masonry, wood, stone or other materials. All combustible \r\n materials used for the mantel must be at least 6 in. (150 mm) away \r\n from the fireplace opening. Combustible materials projecting out more \r\n than 1-1/2 in. (38 mm) must be 12 in. (300 mm) away from the top of \r\n the fireplace opening. Corbeled masonry must conform to the corbeling \r\n limitations listed in the Hearth Support section. All mantels \r\n should be securely attached to the masonry. The wall above the mantel \r\n is an area which is often integrated with the fireplace design. This \r\n may include patterned brickwork, brick sculptures or art work. Figure \r\n 6 is an example of a mantel and the possibilities above the mantel. \r\n \r\n \r\n \r\n \r\n FIG. 6 \r\n \r\n Fireplace Surround. The fireplace \r\n surround is the area immediately surrounding the fireplace opening. \r\n The first 6 in. (150 mm) adjacent to the fireplace opening must be \r\n noncombustible material. The fireplace surround may be integral with \r\n the mantel in the case of decorative tile, marble or other noncombustible \r\n material placed on either side of the opening. Alternately, a wooden \r\n surround may be combined with the mantel. The lintel forms the top \r\n of the fireplace opening and may also be made of various noncombustible \r\n materials. The shape of the lintel can be modified to add a certain \r\n look to the fireplace. A semi-circular arch is one simple way of dressing \r\n up the fireplace. An example is shown in Fig. 7. Other options include \r\n using a contrasting material such as cast stone for the lintel. \r\n Hearth Extension. The hearth extension \r\n is necessary for the safe operation of a fireplace and may also be \r\n a focal point of the fireplace. The hearth extension may be flush \r\n with the floor or may be raised. The extended hearth may be made of \r\n brickwork, slate or any other noncombustible material. The hearth \r\n extension may be only as small as allowed by the building code or \r\n may extend along the entire front face of the wall. The raised hearth \r\n may serve as additional seating for the room. A raised hearth brings \r\n the level of the fireplace up to eye level when seated. Raised hearths \r\n are shown in Figs. 6 and 7. \r\n \r\n \r\n \r\n \r\n FIG. 7 \r\n \r\n ENERGY EFFICIENCY WITH FIREPLACES \r\n Energy efficient fireplaces may be used \r\n for supplemental heating and to decrease the consumption of non renewable \r\n resources. Several modifications to conventional fireplace design \r\n make them more energy efficient. The modifications discussed here \r\n are appropriate to most conventional fireplace designs. Other energy \r\n efficient modifications to the shape and size of the firebox are the \r\n Rosin and Rumford fireplace designs. \r\n Location \r\n For maximum thermal benefit, the fireplace should be located entirely \r\n within the structure. This enables the mass of the fireplace to store \r\n heat within the residence. Heat stored in the brickwork is then radiated \r\n into the room long after the fire is extinguished. \r\n By choosing a central location, a more even \r\n heating of the living area results. Fireplace walls can be exposed \r\n in several rooms. Cold spots in areas away from the fire are kept \r\n to a minimum and, if the fireplace is an air-circulating type, heat \r\n can be vented into adjacent rooms more efficiently. \r\n Outside Air \r\n One way to increase the efficiency of a fireplace is to use air from \r\n outside the structure for combustion and draft. Conventional fireplaces \r\n draw air from the room, air that has already been heated to some extent. \r\n The drop in room air pressure, caused by the air loss, may result \r\n in increased infiltration from other areas of the structure. In very \r\n tightly built houses less air is available for proper combustion, \r\n so outside air must be intentionally provided. Even when outside air \r\n is provided, some interior room air is always necessary for proper \r\n combustion. \r\n There are many ways in which outside air \r\n can be brought into the firebox area. Each method requires three basic \r\n parts: the intake, the air passageways and the inlet. One example \r\n is shown in Figs. 1 and 2. Thight-fitting inlet dampers are tight-closing \r\n intake louvers and recommended to keepthe fireplace from becoming \r\n a source of air infiltration when not in use. \r\n Intake. The intake should be located \r\n on an ouside wall or on the back of the firplace. A screen-backed, \r\n closeable louver is required. Preferably, this will be a type that \r\n can be operated from inside the structure. Many building codes will \r\n not permit the intake to be located within a garage because of the \r\n presence of fuel fumes. Other possible locations for the intake are \r\n in a crawl space, attic or other unheated spaces. It is advisable \r\n to check local building code regulations for the appropriateness of \r\n other intake locations. \r\n Passageway. A passageway or duct \r\n connects the intake to the inlet. It must be formed of noncombustible \r\n material. Ducts with cross-sectional area ragning from 6 in. 2 (3870 mm 2 ) have been used successfully. The passageway can be \r\n built integral withthe fireplace base assembly or channeled between \r\n floor joists. It can aslo enter throught inlets located in the sides \r\n ofthe firebox. In any case, the passageway is usually insulated to \r\n reduce heat loss. \r\n Inlet. The inlet brings the outside \r\n air into the firebox. A damper is required to control the volume and \r\n direction of the air flow. This is necessary because cold outside \r\n air channeled into the fireplace expands and could possibly result \r\n in more air than is needed for draft and combustion. this can create \r\n a spill over effect into the room proior to the air being warmed. \r\n The inlet can be located in the sides or the floor of the combusiton \r\n chamber, preferably infront of the grate for best performance. If \r\n the inlet is located toward the back of the combustion chamber, ashes \r\n may be blown into the room by drafts for the inlet. As an option, \r\n the inlet can be located on or near the floor within 24 in. (600 mm) \r\n of the firebox opening. Any inlet should be closeable and designed \r\n to prevent burning material from dropping into concealed comustible \r\n spaces. \r\n A potential problem due to oncreased velocity of the air coming throught \r\n the inle is that the temperature within the combustion chamber can \r\n increase significantly. This can result in grates and inlet dampers \r\n being destroyed or distorted by the higher temperatures. To help decrease \r\n the velocity of the air through the inlet, a space before the inlet \r\n should be constucted as a stilling chamber, as shown in Figs. 1a and \r\n 2. \r\n Glass Fireplace Screens \r\n \r\n Glass screens can be used on both conventional \r\n fireplaces and fireplaces with an outside air supply. these screens \r\n should be sealed around the edges and have tight-fittingdoors and \r\n vents so that the fireplace is not a source of air infiltration or \r\n heat loss when not in use. The screens are normally closed when the \r\n fireplace is not being used. \r\n During a fire, glass screens provide a barrier which reduces the amount \r\n of heated air being channeled up the chimney, but still permit smoke \r\n and comustion gases to escape. The screens should be kept closed until \r\n it is safe to close the damper. \r\n Caution is necessary whenb fireplaces are operated with the glass \r\n screens in closed position. Increased temperatures due to higher air \r\n velocities through intakes can warp grates or metal in conjunction \r\n with the glass doors, cause expansion of the glass doors and the steel \r\n lintel above the fireplace opening and lead to early disintegration \r\n ofthe firebox mortar joints. \r\n SELECTION OF MATERIALS \r\n \r\n The proper selection of quality materials \r\n is essential to the successful performance ofthe fireplace and chimney. \r\n No amount of design, detailing and construction can compensate for \r\n the imporoper selection of materials. \r\n Brick \r\n Building codes require that solid masonry units, i.e. cored up to \r\n 25 percent, be used for fireplace construction. Brick should conform \r\n to ASTM C 216 or C 62 for facing brick and building brick, respectively. \r\n In areas of hight seismic activity, the option exists to use hollow \r\n brick conforming to ASTM C 652 which can be vertically reinforcedand \r\n fully grouted. Grade SW should be specified for durability since the \r\n fireplace assembly is usually subject to severe exposure conditions. \r\n For the firebox, the use of refactory brick or firebrick which conform \r\n to ASTM C 27, low duty, permit a reduced wall thickness. Refractories \r\n are more resistant to high temperatures and thermal shock. Grade SW \r\n building brick or facing brick may be used as an alternative when \r\n exposure to wood-burning firesis anticipated. Currently, ASTM Committee \r\n C-15 is working ona standard specification for firebox brick which \r\n will replacethe discontinued ASTM C 64 previously used in most model \r\n building codes. \r\n Salvaged brick should not be used because they may not provide the \r\n strength and durablility necessary for satisfactory performance. The \r\n use of salvaged brick is discussed in Technical Notes 15 \r\n Revised. \r\n Mortar \r\n Combustion Chamber, Smoke Chamber and Flue. Mortars used in these \r\n locations are subject to high surface temperatures and possibly corrosive \r\n effects from combustion gases. The mortar joints at the top of the \r\n chimney flue may be subjected to periodic wetting and freeze-thaw \r\n cycling. The mortar must withstand these conditions while providing \r\n adequate support and a barrier to combustion gases. Mortars used for \r\n these three parts of the fireplace can be a refractory mortar or a \r\n conventional mortar. \r\n Refractory mortar should conform to ASTM C 199, medium duty, and may \r\n be one of several types. The properties of each should be evaluated \r\n for the intended use and exposure. Fireclay is the primary ingredient \r\n of refractory mortars, often mixed with calcium aluminate or sodium \r\n silicate as a binder. Refractory mortars must be used with thin joints. \r\n High-lime mortars, such as ASTM C 270 Type O portland cement-lime \r\n mortar, have been found to be more resistant to heat in the combustion \r\n chamber than high portland cement content mortars. The joint size \r\n also effects the performance of the mortar. In any case, mortar joints \r\n in the combustion chamber should be no greater than 1/4 in. (6.4 mm) \r\n thick to protect against the effects of cracking or deterioration \r\n through fireplace use. \r\n \r\n Conventional Brickwork. It is often \r\n more convenient and economical to use only one type of mortar for \r\n all components of the fireplace and chimney. Type N portland cement-lime \r\n mortar and Type S masonry cement mortar conforming to ASTM C 270 are \r\n good all-purpose mortars for most residential fireplaces and chimneys. \r\n Chimney wind loads in excess of 25 psf (1.2 kPa) may require Type \r\n S portland cement-lime mortar. Masonry in contact with earth should \r\n be laid with a Type M mortar. \r\n \r\n Clay Flue Liners \r\n \r\n Flue liners should conform to ASTM C 315. \r\n They should be free from cracks or other damage that might contribute \r\n to smoke or gas leakage. Clay flue liners come in rectangular, round \r\n and oval shapes. Rectangular flue liners are either modular or nonmodular \r\n in cross-sectional dimensions. Sizes stated in ASTM C 315 for rectangular \r\n and oval liners are outside dimensions. Modular sizes start at 3.5 \r\n in. (90 mm) and increase in 4 in. (100 mm) modules and may be specified \r\n by nominal dimensions. Round clay flue liners are specified as nominal \r\n inside diameter. See Technical Notes 19B \r\n Revised for a list of clay flue liner sizes. \r\n Steel Lintels \r\n \r\n Steel conforming to ASTM A 36 should be \r\n used for lintels supporting brick masonry in fireplace construction. \r\n Ties and Reinforcement \r\n Corrugated Metal Ties. Corrugated \r\n metal ties may be used to tie brick of the fireplace walls and the \r\n exterior brickwork to wood frame backups. Ties should be corrosion \r\n resistant, at least 22 gage, 7/8 in. (22 mm) wide, and long enough \r\n to be embedded at least half-way into each wythe thickness. \r\n Wire Ties. Wire ties are recommended \r\n for tying brick construction together. They should be at least wire \r\n size W1.7 (9 gage) and corrosion resistant. Ties should be fabricated \r\n from wire which conforms to ASTM A 82 or A 185. \r\n Prefabricated Joint Reinforcement. \r\n Prefabricated joint reinforcement should be corrosion resistant and \r\n fabricated from wire which conforms to ASTM A 82 or A 185. \r\n Bar Reinforcement. Reinforcement \r\n should conform to any of the following applicable standards: ASTM \r\n A 615, A 616 or A 617. \r\n Corrosion Resistance. Corrosion resistance \r\n is usually provided by zinc coatings or by using stainless steel. \r\n To ensure adequate resistance to corrosion, coatings or materials \r\n should conform to any of the following applicable standards: Zinc-Coating \r\n of Flat Metal-ASTM A 153, Class B-2 \r\n Zinc-Coating of Wire-ASTM A 641, Class 3 \r\n Copper-Coated Wire-ASTM B 227, Grade 30 HS \r\n Stainless Steel-ASTM A 167, Type 304 \r\n SUMMARY \r\n This Technical Notes describes the components \r\n of masonry fireplaces and covers design and material selection. Dimensions \r\n recommended for components of single-faced fireplaces are based on \r\n empirical data from field performance of fireplaces and the expertise \r\n of the technical staff of the Brick Institute of America. The recommendations \r\n contained herein will produce a functional and durable fireplace. \r\n The information and suggestions contained in this Technical Notes \r\n are based on available data and the experience of the engineering \r\n staff of the Brick Institute of America. The information contained \r\n herein must be used in conjunction with good technical judgment and \r\n a basic understanding of the properties of brick masonry. Final decisions \r\n on the use of the information contained in this Technical Notes are \r\n not within the purview of the Brick Institute of America and must \r\n rest with the project architect, engineer and owner. \r\n REFERENCES \r\n \r\n 1. Chimneys, Fireplaces, Vents and Solid \r\n Fuel Burning Appliances, NFiPA211, National Fire Protection Association, \r\n Quincy, MA, 1992. \r\n 2. Lytle, R.J. and Lytle, M.J., Book of Successful Fireplaces -How \r\n to Build, Decorate and Use Them, 20th Edition, Structures Publishing \r\n Co., Farmington, MI, 1977. \r\n 3. Morstead, H. and Knudsen, O., Fireplace Report, a Guide for the \r\n Design and Construction of Fireplaces and Chimneys, Alberta Masonry \r\n Institute, Calgary, Alberta, Canada. \r\n 4. Orten, V., The Forgotten Art of Building a Good Fireplace, Yankee, \r\n Dublin, NH, 1974. \r\n 5. Residential Masonry Fireplace and Chimney Handbook, Masonry Institute \r\n of America, Los Angeles, CA, 1989. \r\n 6. Shelton, J.W., The Measured Performance of Fireplaces and Fireplace \r\n Accessories, Williamstown, MA, 1978. \r\n 7. The Brick-O-Lator, Brick Association of North Carolina, Greensboro, \r\n NC, 1979. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60076,"ResultID":176308,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19A - Residential Fireplaces, \r\n Details and Construction \r\n May 1980 (Reissued Jan. 1988) \r\n \r\n Abstract: Brick masonry residential fireplaces can be made more energy \r\n efficient by providing a source of combustion and draft air drawn \r\n from the exterior of the structure. Proper detailing and construction \r\n can also contribute to the overall performance of the fireplace regarding \r\n both energy efficiency and structural integrity. Building code requirements \r\n often control the configuration of the fireplace as well as component \r\n sizes. \r\n \r\n Key Words: Bricks , combustion chamber, energy efficiency, \r\n firebrick, fireclay, fireplaces , hearths, masonry, mortar. \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes contains recommended details and construction \r\n techniques which, when used to execute a proper design, will yield \r\n a functional, energy-efficient fireplace. These same recommendations \r\n are applicable to conventional fireplace construction when the provisions \r\n for the exterior air supply system are omitted. \r\n This is the second in a series of Technical Notes dealing \r\n with the design and construction of fireplaces and chimneys. Technical \r\n Notes 19 Revised contains a comprehensive \r\n discussion of fireplace design and materials selection. Other Technical \r\n Notes in this series address design and construction of both residential \r\n and industrial chimneys. \r\n \r\n RECOMMENDATIONS \r\n General \r\n \r\n Energy-efficient fireplaces vary only slightly from conventional \r\n fireplaces. The recommendations to construct an energy-efficient fireplace \r\n include properly sizing and locating an exterior air supply for combustion \r\n and draft air, and tight-fitting dampers. Operation of the fireplace \r\n and other devices, such as glass screens, may also substantially affect \r\n the performance of the fireplace. They are not, however, addressed \r\n in this Technical Notes. Regardless of how much care is taken \r\n in the design and detailing process, workmanship remains a critical \r\n factor to the performance of fireplaces. The designer should, therefore, \r\n be familiar with the fireplace construction techniques of the locality \r\n in which the fireplace is to be built. \r\n No matter which fireplace configuration is selected by the designer, \r\n there are several common features that should be considered. Fireplaces, \r\n as discussed in this Technical Notes, are for burning wood \r\n and are not specifically designed or constructed for fuels that generate \r\n temperatures in excess of those generated by combusting wood. The \r\n primary function of the fireplace is to contain a fire safely and \r\n deliver heat to habitable spaces. \r\n The fireplace assembly must be isolated from combustible materials. \r\n General requirements incorporated into many building codes are: (1) \r\n All spaces between masonry fireplaces and wood or other combustible \r\n material should be firestopped by placing 1 in. (25 mm) of noncombustible \r\n material in such spaces. (2) In the plane parallel to the front wall \r\n of the fireplace, combustible material should not be placed within \r\n 6 in. (150 mm) of a fireplace opening. (3) Combustible material within \r\n 12 in. (300 mm) of the fireplace opening should not project more than \r\n 1/8 in. (3.2 mm) for each inch distance from the opening. A more specific \r\n discussion of these requirements or variations may be provided by \r\n local building codes. \r\n All void areas within the body of the fireplace from the foundation \r\n through the chimney should be solidly filled with masonry mortared \r\n in place. The only exceptions are the air passageway, the ashpit, \r\n the 1-in. (25 mm) airspace between the combustion chamber and the \r\n brickwork surrounding it, and the functional voids of the fireplace, \r\n such as the smoke chamber. \r\n Solidly filling the nonfunctional voids in the fireplace assembly \r\n increases its overall performance and durability as well as its structural \r\n integrity and resistance to rain penetration. All exposed mortar joints \r\n should be properly tooled. Concave jointing is preferred. \r\n For a graphic definition of fireplace components and a section through \r\n an energy-efficient fireplace, refer to Fig. 1. \r\n \r\n \r\n \r\n Single Face Fireplace Section \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n FIREPLACE BASE ASSEMBLY \r\n Foundation \r\n \r\n The foundation supports the fireplace base and thus the entire fireplace \r\n and chimney assembly. It must, therefore, be designed to carry these \r\n loads. However, most building codes disallow using the fireplace and \r\n chimney assemblage as a structural element to support other building \r\n components. When designing the foundation, care should be taken to \r\n account for soil condition and type. Undisturbed or well-compacted \r\n soil will generally be sufficient, however, some types of soil or \r\n the condition of the soil may require additional analysis. \r\n Building codes generally require that the foundation be at least \r\n 12 in. (300 mm) thick and, in plan view, extend a minimum of 6 in. \r\n (150 mm) beyond every face of the masonry bearing on it. It should \r\n also penetrate the frost line to reduce the possible \"heaving\" of \r\n the foundation, when the ground is frozen. \r\n \r\n Exterior Air Supply System and Ashpit \r\n \r\n There are many options to the construction methods and layout of \r\n the air passageway and ashpit discussed in this section. When varying \r\n from the suggested details, keep in mind the function which these \r\n components serve, as well as the manufacturers recommendations for \r\n a specific devices installation. \r\n The exterior air supply system is the component that is intended \r\n to increase the overall efficiency of the fireplace by diminishing \r\n the amount of heated air drawn from the structure for combustion and \r\n draft. As discussed earlier in this Technical Notes this provision \r\n may be deleted resulting in a conventional fireplace design. \r\n The exterior air for combustion and draft may be drawn directly from \r\n the exterior or from unheated areas of the building, such as crawl \r\n spaces. Local building codes may restrict the location of the air \r\n intake. For example, many do not allow air from a garage to be vented \r\n into habitable spaces. This decreases the possibility of introducing \r\n noxious gases from automobile exhausts into the house. When the fireplace \r\n configuration does not lend itself to practical incorporation of the \r\n air passageway in the base, the intake may be located on any exterior \r\n wall. No matter where the intake is located, it should be a screen-backed, \r\n closeable louver, preferably one that is operable from the interior \r\n of the building. \r\n \r\n The air passageway is generally incorporated \r\n into the base assembly. When this is not practical due to fireplace \r\n configuration or the level of the exterior grade at the fireplace, \r\n the fireplace may be changed by raising the hearth or the passageway \r\n may be formed of ductwork and attached to or incorporated into the \r\n floor system. In many locations, the perimeter of the air passageway \r\n should be insulated, especially when the ductwork is adjacent to or \r\n passing through heated areas. Many air passageway areas have been \r\n used successfully, usually varying from 6 to 60 sq in. (3870 to 38,700 \r\n mm 2 ). The smaller areas \r\n may, however, yield high velocity air flow and more rapid combustion, \r\n generally resulting in higher temperatures, which may produce negative \r\n results such as fireplace grate or combustion chamber deterioration. \r\n Larger areas may also present a potential difficulty by delivering \r\n air in excess of the combustion and draft requirements. The excess \r\n air, usually below room temperature, may be forced into the room containing \r\n the fireplace. The volumetric expansion of this air due to the exterior \r\n to interior temperature differential generally compounds the problem. \r\n \r\n The air inlet should be located in the base or sidewalls of the combustion \r\n chamber. Inlets have performed successfully, even when located in \r\n the rear wall of the combustion chamber. Care should be exercised \r\n when locating the inlet in the combustion chamber walls since an air \r\n surge may force smoke and gases into the room. The air inlet should \r\n be equipped with both directional and volume controls, so that the \r\n fire burns evenly and toward the rear of the combustion chamber. Thus, \r\n the best performance is generally achieved when the inlet is located \r\n near the front of the fireplace within the combustion chamber. \r\n \r\n The air inlet damper assembly area, as shown \r\n in Fig. 2, generally ranges from 6 to 60 sq in. (3870 to 38,700 mm 2 ) depending on the \r\n other components in the exterior air supply system. The critical factor \r\n affecting the performance of the fireplace is the proper operation \r\n of the air inlet damper. Opening the damper to a position that produces \r\n an area of from 2 to 16 sq in. (1300 to 10,300 mm 2 ) has proven to perform successfully \r\n in most areas. \r\n \r\n \r\n \r\n Combustion Chamber Plan \r\n FIG. 2 \r\n \r\n \r\n \r\n If corbeling is necessary to achieve proper size or location of the \r\n air inlet, it should be limited to a maximum horizontal projection \r\n of one-half (1/2) the distance from the ashpit face to the exterior \r\n of the fireplace assembly, see Fig. 3. \r\n \r\n \r\n \r\n Corbeling Limitations \r\n FIG. 3 \r\n \r\n \r\n \r\n The maximum projection for an individual unit should not exceed either \r\n one-half (1/2) the height of the unit, or one-third (1/3) the bed \r\n depth. \r\n The ash drop and ashpit are often not incorporated into the design \r\n due to either a configuration difficulty, such as slab-on-grade construction, \r\n or the absence of a desire by the designer or owner to have such a \r\n component included in the fireplace. \r\n Figure 4 shows a plan view of an air passageway and ashpit. The ashpit \r\n cleanout door may be oriented toward the interior of the building \r\n if sufficient space for cleanout exists. The ashpit cleanout door \r\n should be metal and fit tightly to reduce air infiltration. \r\n \r\n Hearth Support \r\n \r\n When construction reaches the stage shown in Fig. 4, sturdy, noncombustible \r\n forming, such as metal, is set in place to contain the slab pour. \r\n This is required since this forming is inaccessible for removal and \r\n is thus a permanent part of the fireplace. In slab-on-grade construction, \r\n this requirement is not necessary unless a raised hearth is used. \r\n The blackouts that form the opening in the slab for the ash drop and \r\n air inlet should be set so that they extend approximately 1 in. (25 \r\n mm) above the top of the finished slab. This will facilitate removal \r\n of the forms. The slab should be properly reinforced when it cantilevers \r\n from the fireplace wall to the floor system or spans across the air \r\n passageway and ashpit, as shown in Fig. 1. This reinforcement is also \r\n beneficial in resisting the stresses induced by the high temperatures \r\n the slab will be subjected to. Care should be taken to keep the top \r\n of the slab as nearly level as possible to reduce the difficulty of \r\n laying the combustion chamber base. \r\n \r\n \r\n \r\n Air Passageway and Ashpit Plan \r\n FIG. 4 \r\n \r\n \r\n \r\n Similar results may be obtained by eliminating the concrete slab \r\n and supporting the hearth on masonry. This is accomplished by solidly \r\n filling the base assembly with masonry mortared in place. The ash \r\n dump and air passageway are formed by the judicious use of corbeling. \r\n \r\n FIREBOX ASSEMBLY \r\n Combustion Chamber and Firebox \r\n \r\n Combustion chamber layout is critical since the chamber must be contained \r\n within the firebox assembly yet isolated from it. Figure 2 shows one \r\n method of properly locating the combustion chamber. Once desired dimensions \r\n have been selected from Table 1, in Technical Notes 19 \r\n Revised, the front wall (facing) of the fireplace is located and line \r\n A-A struck at the inside face position. Next, locate Point I on this \r\n line. Point I corresponds to the centerline of the combustion chamber \r\n in the direction perpendicular to the existing line. Squaring from \r\n Point I into the combustion chamber for the chambers depth, defines \r\n Point II. Striking a line connecting Points I and II results in Line \r\n B-B. From Point II, squaring perpendiculars to line B-B in each direction \r\n for a distance of one-half (1/2) the rear chamber wall dimension, \r\n thus locates Points c and d. On line A-A, measuring from Point I one-half \r\n (1/2) the fireplace opening dimension in each direction, thereby defines \r\n points a and b. Connecting these four points (a, b, c and d) gives \r\n the outline of the inside face of the combustion chamber. \r\n Preferable combustion chamber construction consists of firebrick, \r\n in accordance with ASTM C 64 and fireclay mortar, in accordance with \r\n ASTM C 105. Fireclay mortar joints should be 1/16 to 3/16 in. (1.6 \r\n to 4.8 mm) thick to reduce thermal movements and mortar joint deterioration. \r\n When using fireclay mortar, extremely thin mortar joints may be obtained \r\n by using the Pick and Dip method. This consists of dipping the \r\n unit into a soupy mix of fireclay mortar and immediately placing it \r\n in its final position. The mortar joints need be only thick enough \r\n to provide for dimensional irregularities in the unit being laid. \r\n Acceptable construction includes the use of Grade SW brick, in accordance \r\n with ASTM C 62 or ASTM C 216, and Type N or Type O. portland cement-lime \r\n mortar, in accordance with ASTM C 270 or BIA Designation M1-72. Type \r\n N or Type O, portland cement-lime mortar may also be used with the \r\n firebrick option. Mortar joints should be limited to 1/2 in. (12.7 \r\n mm) maximum and be properly tooled, resulting in a concave profile \r\n when using the portland cement-lime mortar. \r\n The brickwork surrounding the combustion chamber may be brought up, \r\n either at the same time as the combustion chamber, or after it has \r\n been completed. In any case, there should be a full course of masonry \r\n surrounding the combustion chamber, to allow for solidly filling the \r\n void created and maintaining a minimum 1-in. (25 mm) airspace between \r\n the firebrick and surrounding brickwork, see Fig. 2. This airspace \r\n may be filled with a compressible, noncombustible material, such as \r\n a fibrous insulation. The purpose of this material is to keep the \r\n space clear of obstructions. Either the airspace or the compressible, \r\n noncombustible material reduces the stress from thermal movements \r\n by isolating the combustion chamber. \r\n The wall behind the firebrick at the rear of the firebox should be \r\n at least 8 in. (200 mm) thick. A greater thickness may be required \r\n to support higher chimneys. \r\n With the exception of the combustion chamber walls, wall ties should \r\n be used at all intersections where the wall is not masonry bonded. \r\n These ties should be spaced a maximum of 16 in. (400 mm) vertically, \r\n and embedded at least 2 in. (50 mm) into bed joints of the brick masonry. \r\n Horizontal joint reinforcement may also be beneficial, most especially \r\n at the corners of adjacent wythes and in the wythe surrounding the \r\n combustion chamber walls. This precaution should help reduce cracking \r\n at these areas. \r\n The combustion chamber walls should be firebrick. Firebrick may be \r\n laid with any face exposed, but they are preferred as a stretcher \r\n course. However, if Grade SW brick are used, they should only be laid \r\n as a stretcher course since they may not be as durable as the firebrick. \r\n No fires should be built in the combustion chamber for thirty (30) \r\n days after construction. Fires before this time period drive off the \r\n moisture necessary for proper curing of the mortar. \r\n \r\n Lintels \r\n \r\n When placing the lintel above the fireplace opening and the lintel \r\n above the damper, a compressible, non-combustible material, such as \r\n insulation of a fibrous nature, should be placed at the end of the \r\n lintel where it is embedded in masonry. This precaution is a means \r\n of dealing with the dissimilar expansion characteristics of masonry \r\n and steel, which tend to induce stresses in the masonry, causing cracking. \r\n The use of a lintel above the damper is highly recommended. his lintel \r\n is provided so that the masonry does not bear directly on the metal \r\n damper which is subjected to extremely high temperatures, and high \r\n magnitude thermal movements. All lintels used in the fireplace should \r\n bear on the brick masonry at least 4 in. (100 mm) at each end. \r\n \r\n Damper \r\n \r\n The damper is then seated using the same mortar that was used in \r\n the combustion chamber. This is accomplished by spreading a mortar \r\n bed, just thick enough to ensure a level set of the damper and a seal \r\n that will prevent gas and smoke leakage. The damper should not be \r\n embedded in mortar, but merely seated on the thin setting bed. \r\n The damper assembly should only be in contact with masonry, on which \r\n it bears. To ensure this, once the damper assembly is seated, it should \r\n be wrapped with a compressible, noncombustible material, such as fibrous \r\n insulation, see Fig. 5. This material provides space for thermal expansion \r\n and movement of the damper during fireplace operation. \r\n \r\n \r\n \r\n Combustion Chamber and Smoke Chamber \r\n FIG. 5a \r\n \r\n \r\n \r\n \r\n \r\n Optional Smoke Shelf Configuration \r\n FIG. 5b \r\n \r\n SMOKE CHAMBER ASSEMBLY \r\n \r\n Beginning at the level of the smoke shelf, the front and sides of \r\n the smoke chamber are corbeled in and the rear wall is constructed \r\n vertically. This ensures total perimeter support for the flue liner. \r\n Corbeling limitations for this component are determined by the fireplace \r\n configuration itself. The maximum corbel for each unit is the horizontal \r\n distance to be corbeled divided by the number of courses from the \r\n bottom of the flue liner to the first corbeled course. The usual limitations \r\n for corbeling walls are not applicable in this area of the fireplace \r\n since the corbels are continuously laterally supported by adjacent \r\n masonry. The last two courses before the flue liner should be laid \r\n as headers. These headers should be cut to a length that provides \r\n total perimeter support of the flue liner, without obstructing the \r\n flue liner opening. \r\n The smoke shelf may be a flat surface or curved, to assist flow through \r\n the smoke chamber, see Fig. 5a. The entire smoke chamber should be \r\n parged. Care should be taken to ensure that the smoke shelf is kept \r\n free of mortar tailings and debris for the same flow considerations. \r\n This may be accomplished by placing a material such as an empty cement \r\n bag or plastic film on the smoke shelf during construction. When construction \r\n is completed, it can be removed through the damper throat, bringing \r\n any foreign material with it. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes has given suggested details and construction \r\n techniques for single-face residential fireplaces. Other Technical \r\n Notes in this series address fireplace design, as well as residential \r\n and industrial chimney design and construction. Emphasis has been \r\n placed on workmanship and proper construction methods. \r\n It should be noted that all fireplace designs, no matter how sophisticated, \r\n are empirical and based on past performance of specific configurations. \r\n Any variation from these configurations produces an \"experimental\" \r\n design. While small deviations from the dimensions and proportions \r\n given may have little or no effect on performance, larger magnitude \r\n changes should be carefully considered since they may have serious \r\n negative effects on the function of the fireplace. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the Brick \r\n Institute of Americas technical staff. \r\n This information should be recognized as recommendations and suggestions \r\n for consideration by the designers, specifiers, and owners of buildings \r\n when anticipating the design, detailing and construction of single-face \r\n residential fireplaces. The final decision to use or not to use these \r\n recommendations and types of products in brick masonry fireplaces \r\n is not within the purview of the Brick Institute of America and must \r\n rest with the project designer or owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. One \r\n and Two Family Dwelling Code, published \r\n by Interstate Printers and Publishers, Danville, Illinois, 1975 \r\n 2. Book \r\n of Successful Fireplaces, How to Build, Decorate and Use Them, 20th Edition, by R. J. Lytle and Marie-Jeanne Lytle, Structures \r\n Publishing Company, Farmington, Michigan, 1977. \r\n 3. How \r\n to Install A Fireplace, by Donald \r\n R. Brann, Direction Simplified, Inc., Briarcliff Manor, New York. \r\n 1976. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60077,"ResultID":176309,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19B - Residential Chimneys \r\n - Design and Construction \r\n June 1980 (Reissued Jan. 1988) \r\n \r\n Abstract : All residential chimneys. both for fireplaces and appliances, \r\n are designed and constructed to serve the same basic functions. They must \r\n provide fire protection and safely convey combustion by-products to the \r\n exterior of the structure at a rate that does not adversely affect the \r\n combustion process. Design, materials selection, construction, and building \r\n code requirements all have a significant impact on the chimneys potential \r\n to fulfill these functions. Chimney height and flue area are the two most \r\n critical factors in chimney desire. \r\n Key Words : bricks , building \r\n codes, chimneys , draft, flashing, flues , masonry, \r\n mortar. \r\n INTRODUCTION \r\n This Technical Notes addresses the design \r\n and construction of residential chimneys. Other Technical Notes in \r\n this Series deal with residential fireplaces and commercial chimneys. \r\n The design of residential chimneys is empirical and based on successful \r\n prototypes. The function of residential chimneys is to allow combustion \r\n by-products to be conducted away from the structure safely. \r\n GENERAL \r\n Residential chimneys generally fall into two \r\n categories: 1) chimneys serving fireplaces, and 2) chimneys serving appliances. \r\n While there are dissimilarities between the two types, they both serve \r\n the same basic functions. It is worthwhile, therefore, to consider their \r\n similarities. Both are constructed of similar materials and must meet \r\n the same building code requirements. Even though they may convey different \r\n combustion by-products at different velocities, they both must be designed \r\n and constructed to discharge these by-products at a rate that does not \r\n adversely affect the combustion process and to release the discharged \r\n material at a height and location that provides fire safety. \r\n Flues may slope to join with other flues so \r\n as to discharge through a common flue, or to achieve the desired location \r\n of the chimney. The maximum allowable slope is 30 deg from vertical. When \r\n combining flues the main discharge flue should be sized for the maximum \r\n combined flow from the smaller flues. Combining flues of dissimilar systems \r\n or fuels. i.e., appliances and fireplaces, is not allowed by many building \r\n codes. Separate flues may be incorporated into one chimney so long as \r\n minimum wall thickness requirements are met and a full wythe of brick \r\n is laid between them and bonded to the chimney walls. \r\n Building Code Requirements \r\n Building code requirements for chimneys may \r\n vary on a local basis. There are, however, several that are accepted nearly \r\n everywhere. They include: \r\n 1. Chimney wall thickness should be a nominal \r\n 4 in. (100 mm) unless no flue liner is used, in which case a nominal 8 \r\n in. (200 mm) is required. \r\n 2. Neither chimney nor flue liner may change \r\n size or shape within 6 in. (150 mm) of either floor components, ceiling \r\n components or rafters. \r\n 3. The minimum chimney height for fire safety \r\n is the greater of 3 ft (1.0 m) above the highest point where the chimney \r\n penetrates the roofline, or 2 ft (600 mm) higher than any portion of the \r\n structure or adjoining structures within 10 ft (3.0 m) of the chimney, \r\n see Fig. 1. \r\n 4. Chimney clearance from combustible material \r\n is a minimum of 2 in. (50 mm) except where the chimney is located entirely \r\n outside the structure, in which case 1 in. (25 mm) is acceptable. \r\n 5. The spaces between a chimney and combustible \r\n material should be firestopped using a minimum of 1-in. (25 mm) thick \r\n noncombustible material. \r\n 6. All exterior spaces between the chimney and \r\n adjacent components should be sealed. This is most commonly accomplished \r\n by flashing and caulking. \r\n 7. Masonry chimneys \r\n should not be corbeled more than 6 in. (150 mm) from a wall or foundation \r\n nor should a chimney be corbeled from a wall or foundation which is less \r\n than 12 in. (300 mm) in thickness unless it projects equally on each side \r\n of the wall, except that on the second story of two-story dwellings corbeling \r\n of chimneys or the exterior of the enclosing walls may equal the wall \r\n thickness. Corbeling may not exceed 1-in. (25 mm) projection for each \r\n course of brick protected. \r\n \r\n \r\n \r\n \r\n \r\n Building Code Dimension Requirements \r\n FIG. 1 \r\n \r\n Recommendations \r\n In many situations it may be desirable to use \r\n the chimney as a structural element. This may be accomplished within most \r\n building codes by maintaining the chimney wall thickness and adding a \r\n structural wall around the chimney. This structural wall may be built \r\n integrally with the chimney wall. Most building codes require a minimum \r\n of 4 in. (100 mm) of bearing. Considering all the building code dimensional \r\n requirements, the minimum wall thickness of a lined chimney to be used \r\n as a structural component is 10 in. (250 mm) consisting of: 1) 4-in. (100 \r\n mm) chimney wall (brick), 2) 2-in. (50 mm) of noncombustible material \r\n (brick), and 3) 4-in. (100 mm) bearing length (brick). An unlined chimneys \r\n minimum wall thickness is 14-in. (350 mm) consisting of the same elements \r\n as the lined chimney except that the chimney wall must be 8-in. (200 mm), \r\n see Fig. 2. \r\n \r\n \r\n \r\n \r\n Chimney Used as Structural Support \r\n FIG. 2 \r\n \r\n MATERIALS \r\n Brick \r\n The chimney, by the nature of its function, \r\n is at least partially exposed to weathering. The brick should conform \r\n to ASTM C 216, Grade SW, or ASTM C 62, Grade SW, to assure sufficient \r\n durability. Paving brick should conform to ASTM C 902, Class SX. \r\n Mortar \r\n To allow for both weathering and thermal considerations, \r\n Type N portland cement-lime mortar is recommended for the chimney. Type \r\n S portland cement-lime mortar is acceptable, and may be necessary when \r\n the chimney is subjected to high lateral forces such as wind loads in \r\n excess of 25 psf (1.2 kPa) or seismic loads. Where the chimney is in contact \r\n with earth, Type M portland cement-lime mortar is recommended. The mortar \r\n used to bed the flue liners should be able to perform well under high \r\n temperatures. Therefore, fireclay mortars are highly recommended. Type \r\n N portland cement-lime mortar is an acceptable substitute. For a comprehensive \r\n discussion of portland cement-lime mortar types and uses, see Technical \r\n Notes 8 Series. \r\n Flue Liners \r\n Flue liners should conform to ASTM C 315. They \r\n should be thoroughly inspected just prior to installation for cracks or \r\n other damage that might contribute to smoke and flue gas leakage. \r\n Flashing \r\n Corrosion-resistant sheet metal flashing is \r\n required by most building codes. Quality materials should be specified \r\n since replacement may be expensive and troublesome. See Technical Notes \r\n 7A Revised for selection of flashing materials. \r\n Chimney Caps \r\n A prefabricated chimney cap similar to the one \r\n shown in Fig. 3 should be used. This type cap provides better durability \r\n and is more easily made water-resistant than a cast-in-place cap. When \r\n a cast-in-place cap is used, it should incorporate the same shape as the \r\n prefabricated. The thickened sides and overhangs will reduce the potential \r\n for water penetration. \r\n \r\n \r\n \r\n \r\n Chimney Cap Detail \r\n FIG. 3 \r\n \r\n Rain Caps \r\n Rain caps vary from sophisticated turbine type \r\n metal caps to simple slabs set above the termination point of the flue \r\n liner. When specifying a manufactured rain cap, information regarding \r\n its effect on the gas flow through the chimney should be obtained from \r\n the manufacturer. If the cap is metal, it should be corrosion-resistant. \r\n Sealants \r\n Caulking is frequently considered a means of \r\n correcting or hiding poor workmanship, rather than as an integral part \r\n of construction. It should be detailed and installed with the same care \r\n as the other elements of the structure. In all cases, the use of a good \r\n grade, polysulfide, butyl, or silicone rubber sealant is recommended. \r\n Oil-based sealants should not be used. Regardless of the sealant used, \r\n proper priming and backing rope, are a must. \r\n Ties and Reinforcement \r\n Ties used in chimney construction should be \r\n corrosion-resistant metal ties. For a general discussion of ties and their \r\n placement, refer to Technical Notes 28 \r\n Revised. \r\n Reinforcing steel should conform to one of the \r\n following ASTM Standards: \r\n 1. Welded Wire-ASTM A 185 \r\n 2. Steel Bar-ASTM A 615, ASTM A 616 or ASTM \r\n A 617 \r\n 3. Wire-ASTM A 82 \r\n DESIGN \r\n Design of fireplace and appliance chimneys is \r\n limited to the determination of height requirements that when used in \r\n conjunction with proper flue sizes, detailing and construction will provide \r\n adequate draft. Building code requirements for minimum chimney height \r\n remain in effect and must be met or exceeded. \r\n Fireplace Chimneys \r\n The design of residential fireplace chimneys \r\n is directly related to: 1) the area of the fireplace opening, 2) the area \r\n of the flue liner, and 3) the height of the chimney. In most situations, \r\n the area of the fireplace opening is controlled by considerations other \r\n than the performance of the system, such as aesthetics. The other components \r\n of the system are usually designed based upon the desired fireplace opening. \r\n A frontal face velocity of 0.80 ft per second \r\n (0.245 m/sec) at the fireplace opening has been accepted by the American \r\n Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) \r\n to be sufficient to prevent smoke and gases from being discharged into \r\n habitable spaces. This is a minimum velocity and usually only encountered \r\n while starting a fire. Flue liner size as a function of fireplace opening \r\n size may be obtained from Technical Notes 19 \r\n Revised, Table 1. \r\n \r\n \r\n \r\n With the opening and flue sizes known, Equation \r\n 4 may be used to calculate the minimum chimney height to provide adequate \r\n draft in a properly designed, detailed and constructed assembly. The height \r\n calculated using Equation 4 is measured from the top of the fireplace \r\n opening, and is the minimum required to produce an adequate draft. Building \r\n code requirements previously discussed for minimum chimney heights are \r\n based solely on fire safety considerations and must always be met or exceeded. \r\n Procedure \r\n Step 1 . From Table 1 in Technical \r\n Notes 19 Revised select fireplace opening \r\n dimensions A and B and the corresponding flue liner size, L and M. Using \r\n Equation 1 calculate the Fireplace Opening Area, A o . From Table 1 determine the Minimum Flue Area, A F , using L and M. \r\n \r\n \r\n \r\n Step 2 . The Flue Friction Coefficient, \r\n K T must \r\n now be determined. The friction loss due to the acceleration of ambient \r\n air to Flue Gas Velocity, K 1 \r\n is always equal to 1.0 in residential applications. \r\n Based on the size of the flue selected, a preliminary \r\n damper size must be assumed. At this point in the design process, it is \r\n only necessary to decide if the damper throat area to be used will be \r\n equal to or twice the flue area. Once this decision has been made the \r\n Inlet Loss Coefficient, K 2 , \r\n may be determined. If the damper throat area is equal to the flue area, \r\n K 2 is \r\n equal to 2.5. If the damper throat is twice the flue area, K 2 is equal to 1.0. \r\n At this time decisions concerning general fireplace \r\n configuration must be made. The designer must determine whether or not \r\n to use a rain cap and if so, at what distance above the chimney termination \r\n point it will be placed. \r\n The Termination Coefficient, K 3 , may be selected using this \r\n information. If no rain cap is used K 3 equals 0.0. If a rain cap is set at \r\n a distance of D/2 (see Table 1 for equivalent diameter, D) above the termination \r\n point of the flue liner, K 3 may vary from 0.0 to 4.0. This information may be obtained \r\n from the manufacturer. \r\n Having determined K 1 K 2 , and K 3 , the Flue Friction Coefficient, K T , \r\n may be calculated using Equation 2. \r\n \r\n \r\n \r\n Step 3 . From Table 1 determine the Inside \r\n Perimeter, P I , \r\n of the flue liner previously selected and using Equation 3 calculate the \r\n Hydraulic Radius, R H . \r\n \r\n \r\n \r\n Step 4 . The general design equation for \r\n chimneys with rectangular flues (Equation 4) may now be used to calculate \r\n the Minimum Height, H. to produce adequate draft. \r\n This is the height of the chimney from the lintel \r\n above the fireplace opening. To obtain the height from the combustion \r\n chamber floor, add the opening height. Building code requirements for \r\n minimum chimney heights remain in effect. The greater of the values obtained \r\n from calculations and building code requirements should be used. \r\n \r\n \r\n \r\n Example \r\n Step 1 . From Table 1 in Technical \r\n Notes 19 Revised fireplace opening dimensions \r\n of 30 in. x 29 in. and a corresponding flue liner size of 12 in. x 12 \r\n in. were selected. Using Equation 1 calculate A o . \r\n \r\n \r\n \r\n From Table 1 \r\n \r\n \r\n \r\n Step 2 . Assuming that there is no rain \r\n cap and that the damper throat area is twice the flue area, Equation 2 \r\n may be utilized. \r\n \r\n \r\n \r\n Step 3 . From Table 1 determine P I and solve Equation 3 for \r\n the Hydraulic Radius. \r\n \r\n \r\n \r\n \r\n \r\n Step 4 . Substitute these values into \r\n Equation 4 and calculate the Minimum Height, H, to provide adequate draft. \r\n \r\n \r\n \r\n Appliance Chimneys \r\n Appliance chimneys are divided into two types \r\n those venting one appliance, see Fig. 4, and those venting two or more \r\n appliances, see Fig. 5. The two variables that are most commonly known \r\n to the designer are the input rating and configuration of the system. \r\n Typical design criteria are shown in Tables 2 and 3. Building code requirements \r\n for chimney heights should be considered as minimum heights for fire safety \r\n and should be strictly adhered to. \r\n \r\n \r\n \r\n \r\n Masonry Chimney Serving a Single Appliance \r\n (See Table 2) \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Masonry Chimney Serving Two or More Appliances \r\n (See Table 3) \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n a SI conversions: W = Btu/h x \r\n 0.293; m = ft x 0.3048; mm = in. x 25.4; mm 2 = in. 2 x 645 \r\n b not recommended. \r\n \r\n \r\n \r\n \r\n a SI conversions: W = Btu/h x \r\n 0.293; m = ft x 0.3048; mm = in. x 25.4. \r\n b Not \r\n recommended. \r\n \r\n CONSTRUCTION AND DETAILS \r\n General \r\n Since both fireplace and appliance chimneys \r\n have an identical function, their construction methods and materials \r\n are similar. Building code requirements insofar as construction is concerned \r\n are identical. \r\n Fireplace Chimneys \r\n General . The chimney of a fireplace \r\n is considered to be that portion of the fireplace from the base of the \r\n first flue liner to the top of the last flue liner, or any rain cap \r\n above it. \r\n Single-wythe chimneys should be attached to \r\n the structure. This is generally accomplished by using corrosion-resistant \r\n metal ties spaced at a maximum of 24 in. (600 mm) on center. Multi-wythe \r\n chimneys that are not masonry bonded should be bonded together using \r\n metal wire ties. \r\n Racking . Chimneys are generally not \r\n as wide as the body of the fireplace below. When racking back to achieve \r\n the desired dimensions or location of the chimney care must be exercised \r\n to insure that, since there is no limitation on the distance each unit \r\n may be racked, cores of the units are not exposed. Preferred construction \r\n consists of a setting bed over the racked face with uncored or paving \r\n brick set to provide a weather resistant surface. Mortar washes may \r\n also be used. They may not, however, be as durable. When using a mortar \r\n wash it should not bridge over the rack, but should fill each step individually. \r\n Both methods of racking are shown in Fig. 6. \r\n \r\n \r\n \r\n \r\n Racking \r\n FIG. 6 \r\n \r\n Flue Liners . The first flue liner should \r\n be supported along its entire perimeter by masonry. The liner should \r\n be bedded in mortar with the joints cut flush and smoothed on the interior \r\n and the exterior joint area parged. The flue liners should be set one \r\n section ahead of the chimney brickwork. \r\n Flashing . Base flashing and counter \r\n flashing are installed at the chimney/roof interface, see Fig. 7. The \r\n base flashing is installed first on the faces of the chimney perpendicular \r\n to the ridgeline with tabs at each corner. The flashing should extend \r\n a minimum of 4 in. (100 mm) up the face of the chimney and along the \r\n roof. Counter flashing is then installed over the base flashing. It \r\n is inserted into a mortar joint for 3/4 to 1 in. (19.1 mm to 25 mm) \r\n and mortared solidly into the joint. The counter flashing should lap \r\n the base flashing by at least 3 in. (75 mm). If the flashing is installed \r\n in sections, the flashing higher up the roofline should lap over the \r\n lower flashing a minimum of 2 in. (50 mm). All joints in the base flashing \r\n and counter flashing should be thoroughly sealed. The unexposed side \r\n of any bends in the flashing should also be sealed. \r\n \r\n \r\n \r\n \r\n Typical Section and Flashing Detail \r\n FIG. 7 \r\n \r\n Cricket . If a cricket is desired, usually \r\n for chimneys whose dimension parallel to the ridgeline is greater than \r\n 30 in. (750 mm) and do not intersect the ridgeline, it should be constructed \r\n similar to the one shown in Fig. 8. The dimensions of the cricket are \r\n based on the chimney measurements parallel to the ridgeline. The intersection \r\n of the cricket and the chimney should be flashed and counter flashed \r\n in the same manner as a normal chimney roof intersection. The flashing \r\n at the roofline should extend to at least 4 in. (100 mm) under the roofing \r\n material. For dimensions and construction details, see Table 4, and \r\n Fig. 9. \r\n \r\n \r\n \r\n \r\n Typical Flashing Detail \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Chimney Cricket Framing \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n Chimney Caps . There are, as discussed \r\n in the materials section, two options regarding chimney caps: 1) prefabricated, \r\n and 2) cast-in-place. Prefabricated caps generally provide superior \r\n performance as compared to the cast-in-place type. Regardless of which \r\n type cap is used, it should be thoroughly primed, backed, and sealed \r\n at the cap and flue liner interface to reduce the potential for water \r\n penetration. \r\n Prefabricated caps are set in place on a mortar \r\n bed. There should be a bond break between the brickwork and the setting \r\n bed to allow the cap to respond to the differential movement it will \r\n encounter without distressing the brickwork. Figure 3 depicts a typical \r\n prefabricated cap. From this figure, general configurations and waterproofing \r\n methods may be obtained. \r\n Cast-in-place caps should conform to the shape \r\n and minimum dimensions shown in Fig. 3. Feathering the cap to the edge \r\n should be avoided since this substantially reduces the thickness at \r\n the edge and therefore the potential for deterioration is increased. \r\n Waterproofing requirements are different since shrinkage of the concrete \r\n as it cures is a certainty. Flashing is highly recommended for cast-in-place \r\n caps. The flashing may also be considered as the bond break material. \r\n Adequate reinforcement should be placed in the cap to help control cracking \r\n due to shrinkage and thermal movements. Additional reinforcement may \r\n be necessary in the portion of the cap that overhangs the face of the \r\n chimney. Figure 3 shows one method of forming a cast-in-place chimney \r\n cap. \r\n When using a chimney cap that does not overhang \r\n the face of the chimney, the last two courses of the chimney brickwork \r\n should be corbeled out to form a drip to help reduce the amount of water \r\n allowed to run down the face of the chimney. The flue liner should extend \r\n a minimum of 2 in. (50 mm) above the top of the cap, see Fig. 3. \r\n Appliance Chimneys \r\n General . Fireplace and appliance chimneys \r\n have few dissimilarities. The general recommendations for the construction \r\n of fireplace chimneys and the proper consideration of three additional \r\n components should produce a functional appliance chimney. The three \r\n components, either not present in fireplace chimneys or incorporated \r\n into the body of the fireplace are: 1) the foundation, 2) the cleanout \r\n door, and 3) the thimble. \r\n Foundation . The foundation supports \r\n the chimney and must be sized to carry all superimposed loads. However, \r\n most building codes disallow using the chimney walls as structural elements \r\n to support other building components. When designing the foundation, \r\n care should be taken to account for soil conditions and type. Undisturbed \r\n or well-compacted soil will generally be sufficient, however, some types \r\n of soil conditions may require additional analysis. \r\n Building codes generally require that the \r\n foundation be at least 12 in. (300 mm) thick, and, in plan view, extend \r\n a minimum of 6 in. (150 mm) beyond each face of the masonry bearing \r\n on it. It should also penetrate the frost line to reduce the possibility \r\n of \"heaving\" of the foundation while the ground is freezing. \r\n Cleanout Door . A cleanout door may \r\n not be necessary when venting appliances that use clean burning fuels \r\n such as natural gas, however other fuels may produce combustion by-products \r\n that will accumulate at the bottom of the chimney and require periodic \r\n removal. The cleanout door should be of ferrous metal and set to provide \r\n as airtight a seal as possible. If desired, the cleanout door may be \r\n oriented toward the interior of the structure, however. the prime consideration \r\n in sizing and locating the door is the ease with which it can be used. \r\n Thimble . A thimble is the lined opening \r\n through the chimney wall that receives the smoke pipe connector, as \r\n shown in Fig. 10. A thimble should be set in the chimney at the location \r\n of the entrance of the pipe connector. It should be built integrally \r\n with the chimney and made as airtight as possible, by using either boiler \r\n putty or asbestos cement. The thimble should be set flush with the interior \r\n face of the flue liners, and at least 18 in. (460 mm) below the ceiling. \r\n The thimble should have a minimum of 8 in. (200 mm) of flue liner extending \r\n below its lowest point, see Fig. 10. \r\n \r\n \r\n \r\n \r\n Thimble Detail \r\n FIG. 10 \r\n \r\n SUMMARY \r\n This Technical Notes has given suggested \r\n design and construction methods for residential chimneys. Although there \r\n are differences. both appliance and fireplace chimneys use similar construction \r\n techniques and materials. Since the prime function of a chimney is fire \r\n safety both quality workmanship and materials should be used. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the Brick Institute of Americas technical staff. The \r\n recommendations and suggestions are offered as a guide for consideration \r\n by the designers, specifiers, and owners of buildings when anticipating \r\n the design, detailing and construction of residential chimneys. The \r\n final decision to use or not to use these recommendations and materials \r\n in brick masonry chimneys is not within the purview of the Brick Institute \r\n of America. and must rest with the project designer, or owner. \r\n REFERENCES \r\n 1. One \r\n and Two Family Dwelling Code, published by Building Officials and \r\n Code Administrators, Inc., Homewood, Illinois; International Conference \r\n of Building Officials, Whittier, California; and Southern Building Code \r\n Congress, International, Inc., Birmingham, Alabama. \r\n 2. Book \r\n of Successful Fireplaces, How to Build, Decorate and Use Them, 20th \r\n Edition, by R. J. Lytle and Marie-Jeanne Lytle, Structures Publishing \r\n Company, Farmington, Michigan, 1977. \r\n 3. How \r\n to Install a Fireplace, by Donald R. Brann, Direction Simplified, \r\n Inc., Briarcliff Manor, New York, 1976. \r\n 4. 1979 \r\n Equipment Volume, ASHRAE Handbook and Product Directory, by American \r\n Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., \r\n New York, New York, 1979. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60078,"ResultID":176310,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19C - Contemporary \r\n Brick Masonry Fireplaces \r\n April 1988 \r\n \r\n Abstract : Considerations and recommendations necessary for the \r\n successful design of fireplaces are addressed. Design and construction \r\n recommendations are included for Rumford fireplaces, air-circulating \r\n fireplaces and multi-face fireplaces. Concepts for increased energy \r\n efficiency are also provided. \r\n Key Words : brick , \r\n dampers, design , energy efficiency, fireplace , \r\n heating , masonry . \r\n INTRODUCTION \r\n \r\n There are many types of fireplaces available \r\n for residential applications. Conventional single-face fireplaces \r\n are discussed in Technical Notes 19 \r\n Revised and 19A Revised. These Technical \r\n Notes also provide information about the many energy-efficient \r\n features which may be applied to single-face fireplaces. This Technical \r\n Notes discusses fireplaces other than the conventional single-face \r\n fireplace. See Figures 1 and 2. Information is provided to design \r\n Rumford fireplaces, air-circulating fireplaces and multi-face fireplaces. \r\n Rumford air-circulating fireplaces are usually selected to provide \r\n a more energy-efficient fireplace. Multi-face fireplaces usually have \r\n lower energy efficiencies. They may be incorporated into a residential \r\n building for aesthetics and, as is true with all fireplaces, to add \r\n mass to the inside of the building for thermal storage. Other Technical \r\n Notes in this series provide information on masonry heaters, often \r\n referred to as Finnish or Russian Stoves, and residential chimneys. \r\n \r\n \r\n \r\n \r\n Contemporary Brick Masonry Fireplace \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Contemporary Brick Masonry Fireplace \r\n FIG. 2 \r\n \r\n INCREASED ENERGY EFFICIENCY \r\n General \r\n Increasing the energy efficiency of fireplaces \r\n has been a goal since fireplaces were first used for heating buildings. \r\n There are two types of energy efficiency which are of importance: \r\n 1) combustion of the wood, and 2) heating of the building or room. \r\n Any wood-burning appliance that does not \r\n have controlled intake of air for draft or combustion does not usually \r\n result in efficient combustion of the wood. Early fireplaces, although \r\n not designed or constructed much differently than fireplaces built \r\n today, had a higher efficiency in heating a building because they \r\n were the sole source of heat. The number of fireplaces per building \r\n and the comfort levels achieved greatly affect this efficiency. \r\n Todays fireplaces are typically used to provide supplemental heat \r\n to reduce the heating load on the mechanical heating system. Efficiency \r\n today is lower because fireplaces are used while interior temperatures \r\n are already comfortable. The major portion of heat obtained from \r\n a brick masonry fireplace is radiant heat from the fire and the \r\n re-radiated heat from the massive brick masonry. The masonry mass \r\n gradually warms from the fire and continues to provide heat to the \r\n building long after the fire is extinguished. Most of the recently \r\n constructed fireplaces are located on exterior walls. Unfortunately, \r\n this results in a substantial portion of the heat absorbed by the \r\n masonry mass being lost to the exterior. Thus, fireplaces, especially \r\n when being considered to provide supplemental heating, should not \r\n be located on exterior walls because this significantly reduces \r\n the heating efficiency. The fireplace should be centrally located \r\n on the interior of the building to maximize the performance of the \r\n fireplace as a source for supplemental heating. This central location \r\n also increases the safety of the fireplace because all chimney surfaces \r\n maintain higher temperatures which help to eliminate the problem \r\n of creosote build-up and possible chimney fires. \r\n \r\n The concepts for increasing energy efficiency \r\n in fireplaces, discussed here and in Technical Notes 19 \r\n Revised, are not new concepts. As early as the Fifth Century, metal \r\n doors were installed over fireplace openings to reduce air infiltration \r\n when the fireplace was not being used. Today, glass screens are used \r\n for this purpose. The metal doors provided both radiation to the room \r\n and a method to control the amount of combustion air to the fire. \r\n Openings in the firebox to introduce outside air for combustion and \r\n draft were commonly used in the 1700s. Air-circulating fireplaces \r\n were introduced in the 1600s, and in the 1700s the Rumford fireplace, \r\n a fireplace with obliquely flared sides which increase the amount \r\n of heat radiated to the room, was in common use. \r\n Adding energy-efficient features to a \r\n conventional fireplace should be carefully considered before attempting \r\n special fireplace designs. Conventional fireplaces with energy-efficient \r\n features are usually the most economical, easiest to construct and \r\n have the best track record for operational performance, i.e., proper \r\n draft and reduced smoking. In addition, operation has a significant \r\n effect on fireplace energy efficiency. Regardless of all the energy-efficient \r\n features incorporated into a fireplace, efficiency can only be achieved \r\n with proper operation. One operational feature, which is all too \r\n frequently overlooked, is the damper. The fireplace damper is usually \r\n designed so that its opening may be adjusted. The damper should \r\n be completely open when starting the fire, but during operation, \r\n the damper opening should be reduced to maximize the heat provided \r\n to the room while open sufficiently to discharge all of the smoke. \r\n The operation of the damper is usually easiest and safest when a \r\n rotary-controlled damper is used. Such dampers are controlled from \r\n the face of the fireplace and the operator does not have to reach \r\n into the firebox to adjust the damper as is necessary with most \r\n poker or chain-controlled dampers. Typical rotary and poker controls \r\n are shown in Fig. 3. The installation and proper operation of a \r\n rotary controlled damper could greatly increase the energy efficiency \r\n of any new or existing fireplaces. \r\n \r\n \r\n \r\n \r\n FIG. 3a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 3b \r\n \r\n \r\n \r\n \r\n \r\n Typical Fireplace Dampers and Controls \r\n FIG. 3c \r\n \r\n Rumford Fireplaces \r\n Most of the heat obtained from a brick \r\n masonry fireplace is radiant heat. Conventional fireplaces are typically \r\n deep, with only slightly flared sides. In this type of fireplace, \r\n most of the heat absorbed by the brick is radiated back to the fire \r\n or other portions of the firebox. This results in a hotter-burning \r\n fire, but does not allow much of the radiant heat to enter and warm \r\n the room. By decreasing the depth and flaring the sides of the firebox, \r\n a greater amount of radiant heat may be directed into the room. \r\n This configuration results in what is commonly referred to as a \r\n \"Rumford fireplace\". \r\n Typical dimensions for Rumford fireplaces \r\n are provided in Fig. 4 and Table 1. However, these dimensions are \r\n not precise dimensions, but are dimensions based upon successful \r\n performance of constructed Rumford fireplaces. Rumford fireplaces \r\n have a reputation for allowing a small amount of smoke to enter \r\n the room while the fireplace is cold because of the narrow depth \r\n of the firebox. In addition to the concern of smoking, several of \r\n the fireplace dimensions in Fig. 4 may be in violation of local \r\n building codes, i.e., the narrow, 16 in. (400 mm) firebox hearth. \r\n \r\n FIG. 4 \r\n Rumford Fireplace with Clay Flue \r\n Liner \r\n \r\n \r\n \r\n \r\n \r\n FIG. 4a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 4b \r\n \r\n \r\n \r\n \r\n \r\n FIG. 4c \r\n \r\n \r\n \r\n \r\n The Rumford fireplace usually requires \r\n either a flat plate throat damper or a chimney top damper, as shown \r\n in Fig. 3. The flat plate throat damper may not be commercially \r\n available, and a special damper may have to be manufactured to meet \r\n the dimensions of the fireplace design selected. The flat plate \r\n damper is simply two pieces of 1/4 in. (6 mm) plate steel, fastened \r\n together with hinges, and provided with a stop so that when in the \r\n open position the damper is opened slightly more than 90 deg. This \r\n type of damper requires a poker control, which should have at least \r\n one catch so that the damper cannot be blown shut by downdrafts. \r\n The flat plate damper is preferred for the Rumford-style fireplace, \r\n but fabrication costs may make its selection uneconomical. Chimney \r\n top dampers may be used in lieu of flat plate dampers. However, \r\n the chimney top damper should be spring-loaded so that it will be \r\n in the open position if the controlling mechanism ever fails. The \r\n Rumford fireplace design is such that cold air flows down the chimney \r\n through the rear half of the flue. As this air flows downward, it \r\n is warmed and reverses its flow upward from the throat through the \r\n front half of the flue. If chimney top dampers are used, they must \r\n be properly selected so that they do not impair this air flow in \r\n the chimney, because it provides suction to increase the drafting \r\n of smoke and gases from the firebox. In addition to the flat plate \r\n and chimney top dampers, conventional dampers have been successfully \r\n used in Rumford fireplaces with only slight modifications in the \r\n design of the firebox and smoke chamber. \r\n Another difference between a traditional \r\n Rumford fireplace and a conventional fireplace is the chimney. The \r\n original Rumford fireplaces had brick-lined chimneys. Thus, the \r\n dimensions for the Rumford fireplace provided in Table 1 have been \r\n slightly modified to accommodate modular clay flue liners. The result \r\n is a wider smoke shelf which may decrease the drafting capability \r\n of the assembly. \r\n The effect of the performance of the Rumford \r\n fireplace by using dampers other than the flat plate damper, or \r\n using clay flue liners and a wider smoke shelf is not well documented. \r\n These modifications should be carefully considered and further modifications \r\n may be recommended by an experienced fireplace contractor. \r\n Rumford fireplaces greatly increase the \r\n amount of radiant heat obtained from the fireplace. The energy efficiency \r\n of the Rumford fireplace may be increased through the use of other \r\n energy-efficient features, such as supplying outside air and using \r\n glass screens which should be closed when the fireplace is not in \r\n operation. \r\n Air-Circulating Fireplaces \r\n In addition to increasing the amount of \r\n radiant heat from a fireplace by altering its shape, increased energy \r\n efficiency can also be achieved by using an air-circulating fireplace. \r\n An illustration of an air-circulating fireplace is shown in Technical \r\n Notes 19 Revised. Air-circulating fireplaces may either provide \r\n natural air circulation or forced air circulation. The forced air \r\n circulation is typically accomplished by the use of low horsepower \r\n fans to reverse the natural air flow. With either system, interior \r\n air is drawn through baffles immediately behind the firebox where \r\n the air is heated and exhausted to warm the living areas of the \r\n building. \r\n With conventional fireplaces and Rumford \r\n fireplaces, the principal means of supplying heat is by radiation. \r\n In addition to radiation, there is a thermal convective loop which \r\n occurs between the fireplace and cooler interior surfaces of the \r\n building. This phenomena may cause some discomfort to the occupants \r\n of the building because it results in a flow of cool air close to \r\n the floor. Depending on natural air circulation, cool air entering \r\n the baffles from near the floor and warm air being exhausted at \r\n the ceiling may aggravate this situation. For this reason, it is \r\n preferable to reverse the natural air flow with low horsepower fans. \r\n The result is to intake air near the ceiling and force the heated \r\n air to be exhausted to the room near the floor. This provides a \r\n means for making the occupants of the room more comfortable. In \r\n addition to the comfort benefit, the forced air circulation provides \r\n safety. The baffles in which the air is warmed are usually located \r\n immediately behind the firebox. By the use of fans to provide forced \r\n air circulation, the air in the baffles is pressurized and if there \r\n are any leaks or cracks in the firebox, toxic gases remain in the \r\n firebox until they are discharged up the chimney. The combustion \r\n gases in the firebox would not be drawn through the circulating \r\n system and exhausted into the room as might occur with a natural \r\n air-circulating fireplace system. \r\n The energy efficiency of an air-circulating \r\n fireplace may be increased by installing and properly operating \r\n an external combustion and draft air system, by the use of glass \r\n screens, or by combining both. One such forced air-circulating fireplace \r\n is the Brick-O-Lator (The Brick-O-Lator ┬« , \r\n a registered trademark, by the Brick Association of North Carolina, \r\n P.O. Box 13290, Greensboro, NC 27415-3290, General Information Plans \r\n and Details; Brick-O-Lator, Brick Institute of America, Region 9, \r\n 5885 Glenridge Dr., Atlanta, GA 30328, General and Construction \r\n Information), as shown in Fig. 5. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Air Circulating Fireplace (Brick-O-Lator) \r\n FIG. 5a \r\n \r\n \r\n \r\n \r\n \r\n Air Circulating Fireplace (Brick-O-Lator) \r\n FIG. 5b \r\n \r\n \r\n \r\n \r\n \r\n Air Circulating Fireplace (Brick-O-Lator) \r\n FIG. 5c \r\n \r\n \r\n \r\n \r\n \r\n Air Circulating Fireplace (Brick-O-Lator) \r\n FIG. 5d \r\n \r\n Maximized radiant heating is provided \r\n by the Rumford fireplace, maximized convective heating is provided \r\n by the air-circulating fireplace. Masonry heaters, which are discussed \r\n elsewhere in this Technical Notes series, combine these two \r\n basic concepts. The masonry heater has baffles through which flue \r\n gases are circulated, warming a large portion of the fireplace, \r\n which in turn radiates heat to the surroundings and building occupants. \r\n MULTI-FACE FIREPLACES \r\n General \r\n Multi-face fireplaces are usually not \r\n as energy efficient as single-face fireplaces, simply because there \r\n is less mass surrounding the fire to hold and radiate heat to the \r\n room. However, such fireplaces are usually located on the interior \r\n of buildings, and a large portion of the stored heat is not lost \r\n to the exterior. As is true with all fireplaces, their efficiency \r\n can be increased with the proper installation and operation of glass \r\n screens and external combustion and draft air. Because of the diversity \r\n of the systems, the installation and operation of these energy-efficient \r\n features should be in accordance with the recommendations of the \r\n manufacturers of the glass screens and external air supply systems. \r\n Projected Corner Fireplaces \r\n The projected corner fireplace, shown \r\n in Fig. 6, is similar to a conventional, single-face fireplace with \r\n one side removed. Steel angles, supported on a noncombustible post, \r\n support the masonry above the opening. The only significant difference \r\n between this fireplace design and the conventional single-face fireplace \r\n is the shape of the damper. Instead of using a damper with tapered \r\n ends, a square-end damper, as shown in Fig. 3, should be used for \r\n the projected corner fireplace. The open side of this fireplace \r\n should have a short wall to help stop the escape of combustion gases \r\n when cross-drafts occur. This protection may be increased by corbeling \r\n the top of the short wall. The flanges of the damper should be fully \r\n supported on masonry as protection against intense heat. But, as \r\n is true with all metal dampers and lintels in any fireplaces, they \r\n should not be solidly embedded in the masonry. Otherwise, there \r\n will not be any freedom for thermal expansion. Dimensions for typical \r\n projected corner fireplaces are provided in Fig. 6. \r\n \r\n FIG. 6 \r\n Projected Corner Fireplace \r\n ________________________________________________________________________ \r\n \r\n \r\n \r\n \r\n \r\n FIG. 6a \r\n \r\n \r\n \r\n \r\n \r\n FIG.6b \r\n \r\n \r\n \r\n \r\n \r\n FIG.6c \r\n \r\n \r\n \r\n \r\n \r\n FIG.6d \r\n \r\n Three-Face Fireplaces \r\n Wide Face . The three-face fireplace \r\n with a wide front face is very similar to the projected corner fireplace, \r\n and also uses a square-end damper. The three-face fireplace is shown \r\n in Fig. 7, along with a table of typical dimensions. The width of \r\n the opening on the front face of this fireplace may range from 28 \r\n to 60 in. (700 to 1,500 mm). The sides of the fireplace are partially \r\n enclosed by short walls which help to eliminate smoking when there \r\n are cross-drafts. \r\n \r\n \r\n \r\n \r\n FIG. 7 \r\n Three-Face Fireplace, Wide Front \r\n Face \r\n ________________________________________________________________________ \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 7a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 7b \r\n \r\n \r\n \r\n \r\n \r\n FIG. 7c \r\n \r\n \r\n \r\n \r\n \r\n FIG. 7d \r\n \r\n Narrow Face . The three-face fireplace \r\n with a narrow front face is almost identical to the three-face fireplace \r\n with a wide front face. An illustration and table of dimensions \r\n for this type of fireplace are provided in Fig. 8. The width of \r\n the opening on the front face of this fireplace is maintained at \r\n 27 in. (675 mm). There is one major dissimilarity between the wide \r\n and narrow three-face fireplaces. The narrow, three-face fireplace \r\n requires two square-end dampers because of its narrowness and the \r\n distance it projects into the room. Welded angles or a steel tee \r\n are needed to support the dampers at the centerline of the fireplace. \r\n To allow for expansion, the dampers should not be solidly embedded \r\n in mortar nor mechanically fastened to the supporting centerline \r\n tee or welded angles. \r\n \r\n \r\n FIG. 8 \r\n Three-Face Fireplace, Narrow Face \r\n ________________________________________________________________________ \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 8a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 8b \r\n \r\n \r\n \r\n \r\n \r\n FIG. 8c \r\n \r\n \r\n \r\n \r\n \r\n FIG. 8d \r\n \r\n Double-Face Fireplaces \r\n The multi-face fireplaces discussed so \r\n far can be used at projecting corners of a room to bring the fireplace \r\n closer to the center of the room, or to provide a partial divider \r\n in a room. The double-face fireplace can be used as a room divider, \r\n or may even separate two rooms. The double-face fireplace is very \r\n similar to the narrow, three-face fireplace. It requires two square-end \r\n dampers and fireplace centerline steel tee, or welded steel angles, \r\n to support the dampers. The steel tee, or welded angles, should \r\n be supported on masonry at both ends, but must be free to move. \r\n The dampers are supported on the steel tee or welded angles and \r\n the masonry, and must be permitted to move independently of all \r\n their supporting members. The double-opening fireplace is shown \r\n with a table of dimensions in Fig. 9. \r\n \r\n FIG. 9 \r\n Two-Face Fireplace \r\n ________________________________________________________________________ \r\n \r\n \r\n \r\n \r\n \r\n FIG. 9a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 9b \r\n \r\n \r\n \r\n \r\n \r\n FIG. 9c \r\n \r\n \r\n \r\n \r\n \r\n FIG. 9d \r\n \r\n SUMMARY \r\n \r\n The basic concepts of detailing and construction \r\n provided in Technical Notes 19 \r\n Revised and 19A Revised are applicable \r\n to all of the fireplaces discussed in this Technical Notes . \r\n The information and suggestions contained in this Technical Notes \r\n are based on empirical data from actual performance of fireplaces \r\n and the experience of the technical staff of the Brick Institute of \r\n America. The information and recommendations contained herein should \r\n produce a functional and energy-efficient fireplace if followed with \r\n the use of good technical judgment. Final decisions on the design \r\n and use of the dimensions discussed are not within the purview of \r\n the Brick Institute of America, and must rest with the project designer, \r\n owner or both. \r\n REFERENCES \r\n \r\n 1. \"The \r\n Forgotten Art of Building A Good Fireplace\", Vrest Orton, published \r\n by YANKEE magazine, Dublin, New Hampshire, 1974. \r\n \r\n 2. Book \r\n of Successful Fireplaces - How to Build, Decorate and Use Them , \r\n 20th Edition, R. J. and Marie-Jeanne Lytle, published by Structures \r\n Publishing Company, Farmington, Michigan, 1977. \r\n \r\n 3. The \r\n Brick-O-Lator ┬« , \r\n Brick Association of North Carolina, Greensboro, North Carolina. \r\n \r\n 4. Book \r\n of Successful Fireplaces - How to Build Them , 18th Edition, \r\n The Donley Brothers Company, Cleveland, Ohio, 1965. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60079,"ResultID":176311,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19D - Brick Masonry \r\n Fireplaces, Part 1, Russian-Style Heaters \r\n Jan. 1983 (Reissued June 1987) \r\n \r\n Abstract: Brick masonry heaters \r\n may be used instead of conventional fireplaces to provide efficient \r\n supplemental heating for residential buildings. The design, detailing \r\n and construction of brick masonry fireplaces with baffle systems \r\n for combustion gases are discussed. Information regarding building \r\n code compliance, operation and the accessories required is presented \r\n with the basic principles by which these heaters provide supplemental \r\n heat for buildings. \r\n \r\n Key Words: brick , buildings (codes) , design , \r\n energy , fireplace, heating , masonry , \r\n mortar. \r\n \r\n INTRODUCTION \r\n \r\n \r\n There are many ways of improving the energy efficiency of fireplaces. \r\n Fireplace energy efficiency may be increased by providing glass screens \r\n or exterior air for draft and combustion; altering the shape of the \r\n firebox for increased radiant heating; incorporating baffles within \r\n the mass of the fireplace through which room air may be circulated \r\n for increased convective heating; or combinations of these features. \r\n These features, along with the proper design, construction and operation \r\n are discussed in Technical Notes 19 \r\n Revised, 19A Revised, and 19C , \r\n and are used to increase the efficiency of the wood-burning fireplace \r\n for heating the building or room. By altering the design of the fireplace \r\n to change the firebox shape and to replace the smoke chamber with \r\n a baffle system, greater heating and wood combustion efficiencies \r\n may be achieved. These alterations in the fireplace design result \r\n in a baffled brick masonry fireplace or brick masonry heater. \r\n The brick masonry heater is a concept that has been used for centuries \r\n in Northern and Eastern Europe. Various styles of brick masonry \r\n heaters are often referred to as \"Finnish\" or \"Russian\" stoves, \r\n although they are used in many other countries such as Belgium, \r\n Germany, Switzerland, Sweden, The Netherlands and Norway. The basic \r\n principles used to obtain the high heating and combustion efficiencies \r\n are: 1) controlled air intake to the combustion chamber or firebox; \r\n and 2) a baffle system through which hot combustion gases are circulated. \r\n The combustion gases circulated through the baffle system heat the \r\n walls of the heater, which in turn heat the room. The basic concepts \r\n of design, construction and operation are simple, but there are \r\n several concerns which must be addressed to insure safety and durability. \r\n Two basic designs of brick masonry heaters are discussed in this \r\n Technical Notes: the \"Russian Stove\" with a horizontal \r\n baffle system, and the \"Russian Stove\" with a vertical baffle \r\n system. Other Technical Notes in this Series address \r\n the \"Finnish\" or \"Fountain Style\" brick masonry heater and modifications \r\n which may be applied to result in contemporary designs of brick \r\n masonry heaters. \r\n These heaters are often referred to as stoves because as originally \r\n designed and built, they had provisions which permitted portions \r\n of the heater to be used for baking and cooking. This was done by \r\n circulating the hot combustion gases through baffles surrounding \r\n a brick oven and under exposed metal plates which were used for \r\n cooking. Such provisions are not practical for modern lifestyles \r\n because of the difficulty in controlling temperatures, thus the \r\n baking and cooking features are not addressed in this Technical \r\n Notes. However, the cooking features may be a consideration \r\n for designing and construction of an outside barbecue or cookstove. \r\n (See Reference 5). \r\n \r\n GENERAL \r\n Operation \r\n \r\n Operation of a brick masonry heater is \r\n simple. The firebox is loaded with about 20 lb (9.1 kg) of wood. \r\n The fire is ignited. Once good combustion of the wood begins, the \r\n firebox door is closed and the air intakes are adjusted to the proper \r\n setting so that good combustion is maintained. The combustion gases \r\n exhaust from the rear of the firebox, circulated through the baffle \r\n system, warm the entire mass of the brick masonry heater and then \r\n are exhausted to the exterior of the building through a conventional \r\n chimney constructed on top of the heater. The fire usually burns \r\n about 30 min when properly seasoned wood is used, and thus the firebox \r\n should be reloaded with 20 lb (9.1 kg) of wood four times in a 2-hr \r\n period for maximum heating. This procedure usually results in the \r\n brick masonry heater being sufficiently heated to keep a room, about \r\n 2400 ft 3 (68 m 3 ) warm for 8 to 12 hr. The operation \r\n will vary slightly, depending upon the size of the heater, the size \r\n of the room and the amount of heat needed to be comfortable. During \r\n the coldest months in severe climates such as those of Scandinavia, \r\n the heater usually needs to be operated twice a day, once in the \r\n morning and once in the evening. During the more moderate seasons, \r\n or in moderate climates, the heater may need to be operated only \r\n once, usually in the early evening, to supplement the heating requirements \r\n to maintain comfortable temperatures throughout the night. Other \r\n variations in operation, such as the number of loadings or the amount \r\n of wood used per loading during each firing, may also result in \r\n increased comfort. The operator should experiment with several variations \r\n of operation to determine the best performance for various seasons. \r\n \r\n Properly operated, these brick masonry heaters are very effective \r\n in supplying radiant heat to the area of the building surrounding \r\n the heater. These heaters are not only good sources of heat, but \r\n have wood-burning efficiencies of 80 to 90 percent. (See Reference \r\n 3). \r\n \r\n Building Code Requirements \r\n \r\n There are no major model building code requirements which specifically \r\n address brick masonry heaters. For the most part, the building code \r\n requirements for fireplaces and chimneys are applicable to brick \r\n masonry heaters except for those requirements which address the \r\n dimensioning of the firebox and smoke chamber. All building code \r\n chimney requirements and clearances for combustibles are applicable. \r\n There are, however, two concerns regarding safety which apply to \r\n the brick masonry heaters that are not presently listed in the major \r\n model building codes. The first concern is the integrity of the \r\n heaters enclosing walls. The walls forming the shell of the brick \r\n masonry heater should be at least two wythes of brick thick so that \r\n major cracks do not occur in the brick masonry heater. It is advisable \r\n to provide a nominal 1-in. (25 mm) air space between the two wythes. \r\n This will prevent cracks from penetrating through the interior to \r\n the exterior of the heater. Filling this 1-in. (25 mm) air space \r\n with compressible, non-combustible material, such as fiberglass \r\n insulation, will insure this separation. The two wythes should be \r\n tied together with corrosion-resistant metal ties. The insulation \r\n used to maintain a compressible space between the two wythes of \r\n brick should not affect the overall thermal performance of the brick \r\n masonry heater. To add to the integrity of the exterior wythe of \r\n the brick masonry heater, horizontal joint reinforcement should \r\n be placed in about every sixth course. Horizontal joint reinforcement \r\n should not be used on the interior wythe because the extreme differential \r\n thermal movements may deteriorate the mortar joints. \r\n The second concern is the temperature of the exterior surfaces \r\n of the brick masonry heater walls. The highest surface temperatures \r\n of the walls are normally between 100 o F (38 o C) \r\n and 130 o F (54 o C), but temperatures as high \r\n as 190 o F (88 o C) have been reported. Although \r\n these temperatures are much lower than those achieved with metal \r\n wood-burning stoves, sufficient clearances to combustibles should \r\n be maintained. A minimum 36-in. (900 mm) clearance is usually required \r\n between metal wood-burning stoves and combustibles. A minimum 12-in. \r\n (300 mm) clearance is recommended between the sides and back of \r\n the brick masonry heater and combustibles. At the floor line, this \r\n may be achieved by providing a 12-in. (300 mm) extended hearth. \r\n In front of the heater, a 20-in. (500 mm) extended hearth should \r\n be used. This is easily achieved when the heater is properly positioned \r\n in the room for maximum heating. This position is in the center \r\n of the room so that all four walls of the heater are providing radiant \r\n heat to the room. The brick masonry heater may also be installed \r\n against interior brick masonry walls. \r\n \r\n DESIGN AND CONSTRUCTION \r\n General \r\n \r\n The brick masonry heater should always be positioned entirely inside \r\n the building. It should never be located on an exterior wall. When \r\n incorporated into an exterior wall, much of the radiant heat being \r\n supplied will be lost to the exterior. In addition, the location \r\n on an exterior wall will usually result in at least one cold surface \r\n on which a considerable amount of creosote may form. A creosote \r\n fire can reach temperatures which could result in cracks within \r\n the heater that may become too large to allow safe operation because \r\n combustion gases may leak into the room. \r\n The actual dimensions of the masonry heater are limited by the \r\n available firebox door sizes, the number of baffles, and the height \r\n of the heater. For best performance, the heaters should not be more \r\n than one story in height, nor should they contain more than five \r\n baffle chambers. This is because the increased distances that the \r\n hot combustion gases must flow will result in a cooling of the gases. \r\n This causes a reduction in their heating capacity and could result \r\n in increased creosote deposits which may lead to potential fires. \r\n There are two types of Russian-style brick masonry heaters: the \r\n vertically baffled heater shown in Figures 1 and 2, and the horizontally \r\n baffled heater shown in Figures 3 and 4. Many of the features are \r\n similar for both. \r\n \r\n \r\n \r\n Brick Masonry Heater With Vertical Baffles \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Brick Masonry Heater With Vertical Baffles \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n Brick Masonry Heater With Horizontal Baffles \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n Brick Masonry Heater With Horizontal Baffles \r\n FIG. 4 \r\n \r\n \r\n The most critical factors for the proper \r\n performance of brick masonry heaters are the gas flow through the \r\n baffle system and the draft of the chimney. All openings between \r\n the baffles and the area enclosed by the baffles should be at least \r\n 64 sq in. (40,000 mm 2 ). The chimney should be constructed \r\n with clay flue liners with two wythes of brick surrounding the flue \r\n liners in such a way as to maintain a nominal 1-in. (25 mm) air \r\n space between the flue liners and the interior wythe of brick. \r\n \r\n Clearances between the brick masonry heater exterior walls and \r\n any combustible materials should be at least 12 in. (300 mm). This \r\n will require the masonry heater to be either centrally located within \r\n a room, or located adjacent to a brick masonry or other non-combustible \r\n interior wall with at least a 1-hr fire rating. To ensure clearances, \r\n it may be beneficial to provide an extended hearth around the entire \r\n masonry heater. Construction using the proper clearances also maximizes \r\n the use of the warmed brick masonry surface as radiant heat sources. \r\n \r\n Base Assembly \r\n \r\n The base assembly includes the foundation, extended hearth, and \r\n ash drop. These features are the same for both the vertically and \r\n horizontally baffled Russian-style heaters. \r\n Foundation. The foundation must be adequate to support the \r\n mass of the brick masonry heater and the masonry chimney. When designing \r\n the foundation, care should be taken to account for soil types and \r\n foundation conditions. Undisturbed or well-compacted soil will generally \r\n be sufficient, however, some types of soil or foundation conditions \r\n may require additional analysis, which may result in the need for \r\n special soil treatment or a unique foundation design. \r\n Building codes generally require that the foundation be at least \r\n 12 in. (300 mm) thick, and in plan view, extend a minimum of 6 in. \r\n (150 mm) beyond each face of the masonry heater. The foundation \r\n should be positioned so that the bottom of the footing is below \r\n the frost line to reduce the possibility of \"heaving.\" \r\n \r\n Unless the foundation is a thickened slab in a newly constructed \r\n slab-on-grade structure, masonry is usually used to construct the \r\n base assembly to the height of the hearth support. The hearth support \r\n may be solid masonry construction carried up from the foundation to \r\n support the entire hearth area. To conserve materials, the masonry \r\n is usually brought up only equal to the dimensions of the masonry \r\n heater itself and the brick masonry of the base assembly is corbeled \r\n out to form the support for the extended hearth. See Figures 1 through \r\n 4. An individual corbel should not exceed one-half the unit height \r\n nor one-third of the unit thickness. The total projections of the \r\n corbel should not exceed one-half the thickness of the base assembly, \r\n nor one-half of the thickness of the solid masonry wall forming the \r\n base assembly. A further discussion of corbeling is provided in Technical \r\n Notes 19A Revised. \r\n \r\n Extended Hearth. The extended hearth may be formed by placing \r\n a reinforced concrete slab on top of the corbeled base assembly. Non-combustible \r\n or removable forming should be placed so that it spans from the corbeled \r\n masonry assembly to the floor joists forming the opening for the brick \r\n masonry heater. Double joists should be used around the entire perimeter \r\n of the opening with a nailer to support the edge of the non-combustible \r\n extended hearth, as discussed in Technical Notes 19A \r\n Revised, except that the extended hearth for the brick masonry heater \r\n should be at least 20 in. (500 mm) in front of the firebox and 12 \r\n in. (300 mm) around the remaining perimeter of the heater. However, \r\n the extended hearth may be eliminated on one side, or the back of \r\n the heater if it is positioned against a non-combustible wall with \r\n a minimum fire rating of 1 hr. Once the reinforced concrete slab is \r\n installed, it may be finished with brick masonry pavers. If removable \r\n forming is used, the concrete slab used to support the extended hearth \r\n must be designed as a cantilever. \r\n Ashpit. Once the extended hearth is installed, the brick \r\n masonry heater is laid out. The dimensions of the brick masonry \r\n heater are determined by the size of the available firebox doors \r\n and the number of baffles used in the masonry heater. The masonry \r\n heater, because of its efficient combustion of wood, does not require \r\n a large ashpit. The ashpit is usually formed by providing an opening, \r\n usually three courses of brick in height, and as wide as the firebox. \r\n This results in an ashpit which may be accessed from the front face \r\n of the brick masonry heater. The ashpit may be modified so that \r\n it is accessed from either side, or even from the rear of the masonry \r\n heater. Directly above the ashpit will be the base for the brick \r\n masonry heater firebox. Thus, the ashpit should be formed with corbeled \r\n brick masonry which will support the firebox base or a reinforced \r\n concrete slab may be used to serve as the top of the ashpit and \r\n the support for the firebox base. Using the reinforced concrete \r\n slab requires a formed opening in the slab for the ash drop. \r\n \r\n Firebox Assembly \r\n \r\n The dimensions of the firebox will depend on the size of the firebox \r\n doors, and either the length of the baffle chambers in the horizontally \r\n baffled masonry heater or the number of baffle chambers in the vertically \r\n baffled masonry heater. Thus, the baffle chambers need to be sized \r\n prior to laying out the masonry heater dimensions of the firebox. \r\n There are several alternatives for constructing the firebox. The \r\n firebox base, sides and back should be lined with refractory units \r\n to obtain a thickness of at least 2 1/2 in. (63 mm). The refractory \r\n units on the rear wall of the firebox should extend to the top of \r\n the first baffle, as shown in Figures 1 and 2. \r\n The top of the firebox may be formed either by using a precast \r\n reinforced refractory concrete slab, or by using refractory units \r\n which will span the width of the firebox. Both options require slabs \r\n or units wide enough to bear at least 2 in. (50 mm) on the side \r\n walls of the firebox liner. Another alternative is to form the top \r\n of the firebox with a masonry arch constructed of refractory brick \r\n units. This method of forming the top of the firebox is compatible \r\n with using several types of Dutch oven doors for the front of the \r\n fireplace. \r\n \r\n Vertically Baffled . The baffle system for \r\n the vertically baffled Russian-style brick masonry heater is the \r\n easiest baffle system to build. There should be at least three vertical \r\n baffle chambers and usually no more than five, although successful \r\n systems have been built with up to nine. The greater the number \r\n of baffles, the longer the masonry heater needs to be fired to warm \r\n the entire mass of brickwork. This may decrease the efficiency of \r\n the system for both heating and combustion of the wood. It will \r\n also result in much hotter fires, which may augment the deterioration \r\n of the masonry heater. Another problem with using more baffles is \r\n that those portions of the heater which remain cooler invite creosote \r\n problems. \r\n \r\n The baffles should be formed by using a \r\n single wythe of brick masonry to separate the baffle chambers, which \r\n are usually 64 to 144 sq in. (40,000-90,000 mm 2 ) in cross-sectional area. These single wythe brick baffles \r\n should be masonry bonded to the interior wythe of the enclosing \r\n 8-in. (200 mm) brick masonry. Thus, thermal expansion of the baffles \r\n will impose a lateral load on the enclosing brick masonry which \r\n should be considered in the design. Major cracks in the heater should \r\n be avoided by keeping the wythes of the 8-in. (200 mm) thick enclosing \r\n brick masonry walls separated by a nominal 1-in. (25 mm) air space. \r\n To help insure that thermal expansion is provided for, this space \r\n may be filled with a compressible, noncombustible material. If a \r\n filler material is used, it may be easiest to construct the interior \r\n wythe with properly spaced ties, then wrap the heater with the compressible, \r\n non-combustible material, prior to constructing the exterior wythe. \r\n \r\n Another problem is that thermal movement may separate the baffles \r\n from the interior wythe and allow lateral movement of the baffles. \r\n Thus, in addition to the masonry bond to the interior wythe of the \r\n enclosing walls, metal ties should also be installed every 8 in. \r\n (200 mm) vertically. These metal ties should be the only metal inside \r\n the interior wythe of the enclosing walls of the brick masonry heater, \r\n except for reinforcement in concrete slabs. The top of the openings \r\n through the baffles may be formed by corbeling brick units, as shown \r\n in Figures 2 and 4. Other alternatives for forming the baffle openings \r\n are shown in Figure 5. There should be at least 12 in. (300 mm) \r\n of brick masonry covering the top of the baffle chambers. Baffles \r\n with openings at the bottom are again single-wythe brick masonry \r\n walls. The openings in the bottom of baffles may be formed by using \r\n corbeled brick masonry, brick masonry arches, or by masonry units, \r\n or reinforced, precast concrete long enough to span the width of \r\n the baffle chamber and bear a minimum of 2 in. (50 mm) on each side \r\n of the interior wythe of brick masonry. At the front face of the \r\n masonry heater, near the bottom of the baffle chamber, a clean-out \r\n door is recommended so that any ash buildup may be removed from \r\n the baffle chamber. \r\n \r\n \r\n \r\n \r\n Typical Vertical and Horizontal Baffle Constructions \r\n FIG. 5 a & b \r\n \r\n \r\n \r\n \r\n \r\n Typical Vertical and Horizontal Baffle Constructions \r\n FIG. 5 c & d \r\n \r\n \r\n \r\n \r\n \r\n Typical Vertical and Horizontal Baffle Constructions \r\n FIG. 5 e \r\n \r\n \r\n \r\n The last upward baffle chamber in the baffle system, i.e., the \r\n chamber at the front face of the heater, becomes the support for \r\n the conventional flue liner. By corbeling the top course of the \r\n last baffle chamber, the support for a conventional clay flue liner \r\n is obtained. \r\n \r\n Horizontally Baffled . The baffles for the \r\n horizontally baffled Russian-style brick masonry heater may be formed \r\n by using corbeled brick masonry, arches, a precast, reinforced concrete \r\n slab, or clay flue liners. When the slab is used, it should be sufficiently \r\n wide to span across the width of the baffle chamber and bear at \r\n least 2 in. (50 mm) on the interior wythe of each side wall of the \r\n baffle chamber. Arches or corbels used to form the air passageway \r\n may be started from the interior wythe of the baffle chamber wall. \r\n These are shown in Figures 3 and 5. The horizontal baffle system \r\n requires a clean-out at the bottom of each baffled area. The side \r\n and either the front or rear baffle chamber walls (depending on \r\n the number of horizontal baffles) and the top of the last baffle \r\n should be used to support the conventional flue liner for the chimney. \r\n There should be at least a 12-in. (300 mm) thickness of brick masonry \r\n forming the top of the last horizontal baffle. \r\n Clean-Outs. Clean-outs for the baffle chamber of either \r\n Russian-style brick masonry heater are optional. Usually, when properly \r\n seasoned wood is used under adequate air intake conditions, and \r\n at high temperature, creosote should not form in large quantities. \r\n In addition, because of the baffles, most soot and ash remain in \r\n the firebox. However, the installation of clean-outs is recommended \r\n to observe any buildup. If a buildup is occurring, the operation \r\n of the stove should be modified, so that the buildup no longer occurs. \r\n This may be accomplished by increasing the amount of combustion \r\n air being supplied through the firebox doors. \r\n Crown. The crown of the Russian-style brick masonry heater \r\n should terminate at least 12 in. (300 mm) below the ceiling of the \r\n room. Multi-story heaters are not recommended because the distance \r\n the combustion gases must flow, from the firebox through the baffles \r\n to the chimney, cools the gases and decreases performance. Typically, \r\n the distance from the firebox through the baffle chambers to the \r\n chimney should be limited to no more than 16 ft (4.9 m). The crown \r\n should be at least 12 in. (300 mm) thick, starting from the highest \r\n point of the baffle chamber. The crown may be flat, but is often \r\n constructed as an arch for esthetics. \r\n \r\n Chimney. The chimney for the Russian-style brick masonry heater \r\n is similar to those used for fireplaces. The chimney should be constructed \r\n with clay flue liners and 8 in. (200 mm) of brick masonry surrounding \r\n the flue liner in such a way that a nominal 1-in. (25 mm) air space \r\n is maintained between the flue liner and the surrounding brick masonry. \r\n The 8-in. (200 mm) chimney wall is recommended to help keep the chimney \r\n at a higher temperature to increase performance. Additional information \r\n on chimney design and construction is provided in Technical Notes \r\n 19B Revised. \r\n The chimney height required for draft is usually higher than that \r\n necessary for conventional fireplaces, but following the building \r\n code requirements for fire safety will usually result in a sufficiently \r\n high chimney. Most codes require that the chimney terminate at least \r\n 3 ft (1 m) above the roof at the highest point of exit and at least \r\n 2 ft (600 mm) above any portion of the building or any adjacent \r\n structure within 10 ft (3 m) of the chimney. If the draft is determined \r\n to be inadequate by a smoke test, the chimney height should be increased \r\n to provide adequate draft. \r\n The chimney for the Russian-style masonry heater must be free to \r\n move vertically to allow for the vertical thermal expansion of the \r\n masonry heater supporting it. This requires properly sealed flashing \r\n and counter-flashing where the chimney penetrates the roof line. \r\n \r\n Esthetics \r\n \r\n An additional consideration in the design of a brick masonry heater \r\n is the esthetics. Figures 1 through 4 show the basic heater design \r\n for function. This results in a rectangular mass of brick within \r\n the building, which may or may not be esthetically pleasing. Incorporating \r\n arches, corbels, racks and mantels into the design may greatly increase \r\n the esthetic value. \r\n \r\n SELECTION OF MATERIALS \r\n General \r\n \r\n The design and construction of a brick masonry heater using products \r\n available in the United States is slightly different than the construction \r\n of the heater in Europe. European heaters are usually constructed \r\n using a single wythe of 5-in. (125 mm) thick brick for the exterior \r\n shell. The exterior brick is then often covered with glazed ceramic \r\n tiles, set in high temperature-resistant epoxy grout. Using a single \r\n wythe around the firebox and baffles may result in cracking. The \r\n positive draft through the firebox and baffle chambers results in \r\n little danger of toxic gases escaping into the occupied areas of \r\n the building. By using multiple wythes for the exterior shell, the \r\n potential for a crack penetrating completely through the heater \r\n is substantially reduced. Single-wythe construction of masonry heaters \r\n is therefore not recommended. \r\n In addition to the construction differences of the exterior shell, \r\n the accessories used in Europe are not usually available in North \r\n America. There are methods to modify the design and construction \r\n so that products readily available in North America may be used \r\n in the brick masonry heater. The options also exist to either import \r\n the accessories or to fabricate accessories similar to those used \r\n in Europe. However, these options are usually uneconomical. Additional \r\n information regarding accessories may be obtained from the cited \r\n references. \r\n \r\n Brick \r\n \r\n Most building codes require that solid masonry units be used for \r\n fireplace construction. Solid brick should conform to ASTM C 216 \r\n or C 62 for facing brick or building brick, respectively. Hollow \r\n brick conforming to ASTM C 652 may be used if vertical reinforcement \r\n is required. \r\n If vertical reinforcement is to be used to provide resistance to \r\n cracking, the brick masonry heater may be constructed using a single \r\n wythe of reinforced, grouted hollow brick. Reinforced hollow brick \r\n masonry should be constructed using at least nominal 8-in. (200 \r\n mm) thick hollow brick units. The shell of the heater may also be \r\n constructed of a vertically and horizontally reinforced, fully grouted, \r\n multi-wythe brick masonry wall. The grout core should be at least \r\n 2 in. (50 mm) thick and the brick wythes must be properly tied. \r\n When face brick or building brick is used, the walls of the heater \r\n should be at least two wythes thick, using nominal 4-in. (100 mm) \r\n or 3-in. (75 mm) thick brick. Grade SW brick should be used because \r\n of its greater durability. \r\n Refractory brick, conforming to ASTM C 64, medium duty, should \r\n be used for the firebox. The lining for the back of the firebox \r\n should extend to the top of the first baffle chamber. These areas \r\n are exposed to the greatest amount of heat and the refractory units \r\n are more resistant to heat and thermal shock. \r\n \r\n Salvaged or used brick should not be used because they usually \r\n will not bond well with the mortar and lack the durability necessary \r\n for satisfactory performance. The use of salvaged brick is discussed \r\n in Technical Notes 15 . \r\n \r\n Mortar and Grout \r\n \r\n It is most convenient and economical to use only one type of mortar \r\n for the entire brick masonry heater and chimney construction. This \r\n becomes difficult when constructing a brick masonry heater because \r\n of the specific requirements of each component. The portions of \r\n the heater consisting of building, face or hollow brick should be \r\n constructed using a Type N, portland cement-lime mortar, conforming \r\n to the proportion specifications of ASTM C 270 or BIA M 1-72. The \r\n same mortar should be used for the chimney brickwork except when \r\n wind loads exceed 25 psf (1.2 kPa). Where high wind loads exist, \r\n a Type S, portland cement-lime mortar should be used. It may be \r\n desirable to use high temperature-resistant mortars, such as calcium \r\n aluminate mortars, for the interior wythes and baffles of the brick \r\n masonry heater. Such mortars will increase the durability of the \r\n heater. \r\n The firebox and all other components constructed of refractory \r\n units should be set using a fireclay mortar, conforming to ASTM \r\n C 105, medium duty. Other refractory mortars have also been successfully \r\n used, and thus any high temperature-resistant mortars that have \r\n performed well may be used. It is not within the purview of the \r\n Brick Institute of America to recommend proprietary products. The \r\n selection of the proper mortars should be determined by an experienced \r\n fireplace expert for the specific design being considered. \r\n For reinforced brick masonry, all cores of hollow brick masonry \r\n construction and the grout space of hollow wall construction must \r\n be fully grouted. The grout should conform to ASTM C 476. \r\n \r\n Flue Liners \r\n \r\n Clay flue liners used for the chimney or to form the baffle chambers \r\n should conform to ASTM C 315. They should be thoroughly inspected \r\n just prior to installation for cracks or other damage which might \r\n contribute to smoke or flue gas leakage. All flue liners should \r\n be set in fireclay mortar. \r\n \r\n Steel Lintels and Dampers \r\n \r\n Steel lintels should not be used inside the exterior 4-in. (100 \r\n mm) wythe of the brick masonry heaters because of the high temperatures \r\n involved. The difference in thermal expansion characteristics could \r\n cause cracking of the brick masonry heater. For the same reason, \r\n metal dampers are not used within the Russian-style fireplace. Lintels \r\n of corrosion-resistant steel, conforming to ASTM A 36, should be \r\n used over the firebox door and clean-out door openings. \r\n \r\n Ties and Reinforcement \r\n \r\n Corrugated Metal Ties. Corrugated metal ties may be used \r\n to attach the baffles to the interior wythe of the heater walls \r\n and to tie the two wythes of the exterior walls of the heater together. \r\n Ties should be corrosion-resistant, and at least 22 ga, 7/8 in. \r\n (22.2 mm) wide, and 6 in. (150 mm) long. \r\n Wire Ties. Wire ties are preferred for tying the brick masonry \r\n together. Wire ties should be at least 9 ga and corrosion-resistant. \r\n The ties should be fabricated from wire conforming to ASTM A 82 \r\n or ASTM A 185. \r\n Prefabricated Joint Reinforcement. Prefabricated joint reinforcement \r\n should be used for the exterior wythe of the heater walls. The joint \r\n reinforcement should be fabricated from wire which complies with \r\n ASTM A 82 or ASTM A 185, and should be corrosion-resistant. \r\n Reinforcement. Reinforcement should conform to any of the \r\n following applicable standards: \r\n \r\n Standard Specifications for Deformed and Plain Billet-Steel Bars \r\n for Concrete Reinforcement-ASTM A 615. \r\n Standard Specifications for Rail-Steel Deformed and Plain Bars \r\n for Concrete Reinforcement-ASTM A 616 \r\n Standard Specifications for Axle-Steel Deformed and Plain Bars \r\n for Concrete Reinforcement-ASTM A 617 \r\n \r\n Corrosion Resistance. Corrosion resistance is usually provided \r\n by a copper or zinc coating, or by using stainless steel. To ensure \r\n adequate resistance to corrosion, coatings or materials should conform \r\n to any of the following applicable standards: \r\n \r\n Zinc-Coating of Flat Metal-ASTM A 153, Class B-l, B-2, or B-3 \r\n Zinc-Coating of Wire-ASTM A 116, Class 3 \r\n Copper Coated Wire-ASTM B 227, Grade 30 HS \r\n Stainless Steel-ASTM A 167, Type 304 \r\n \r\n Firebox Doors. The doors for the firebox opening may be \r\n fabricated locally, ordered from Europe or may be conventional metal \r\n Dutch oven doors, which are the most economical. The brick masonry \r\n heater is not designed for airtight combustion and thus the doors \r\n need to be equipped with operable vents to control air intake into \r\n the firebox. \r\n The size of the firebox door is a major consideration in the design \r\n of the brick masonry heater. The height and width of the firebox \r\n and the width of the baffle chambers are usually the same as, or \r\n just slightly larger than, the firebox door. Other alternatives \r\n exist for the firebox design and firebox doors, and are discussed \r\n in other Technical Notes in this Series. The typical European-style \r\n door is shown in Figure 6. \r\n \r\n \r\n \r\n \r\n \r\n Typical Firebox Door \r\n FIG. 6a \r\n \r\n \r\n \r\n \r\n Typical Firebox Door With a Metal Screen \r\n (Fire Box and Clean-Out Doors) \r\n FIG. 6b \r\n \r\n \r\n \r\n \r\n \r\n Typical Dutch Oven Style Door \r\n FIG. 6c \r\n \r\n \r\n \r\n \r\n \r\n European Style Clean-Out Door Assembly \r\n (Fire Box and Clean-Out Doors) \r\n FIG. 6d \r\n \r\n \r\n \r\n Clean-out Doors. Clean-out doors used in Europe for the baffle system are tight-fitting \r\n doors which have tapered latches to ensure tightness of fit. These \r\n doors are shown in Figure 6. Conventional clean-out doors may be \r\n used, but to ensure tightness, refractory units should be placed \r\n within the door opening with a compressible, non-combustible material \r\n or set in a sand-lime mortar. This is shown in Figure 7. The refractory \r\n units increase the resistance to combustion gas leaks, provide protection \r\n to the metal door from high temperatures, and may easily be removed \r\n and replaced when cleaning, if necessary. Clean-out doors for the \r\n ash drop may be conventional clean-out doors, installed in the conventional \r\n manner. \r\n \r\n \r\n \r\n \r\n Clean-Out Door Backed with Firebrick \r\n FIG. 7 \r\n \r\n SUMMARY \r\n \r\n The information and suggestions contained in this Technical \r\n Notes are an accumulation of the available information within \r\n the Brick Institute of America on Russian-style fireplaces and brick \r\n masonry heaters. The information is based on empirical data from \r\n actual performance of such heaters here in North America and in \r\n Europe. The information and recommendations are provided for use \r\n with good technical judgment for the design and construction of \r\n a functional brick masonry heater. Final decisions on the design \r\n and use of materials as discussed in this Technical Notes are \r\n not within the purview of the Brick Institute of America, \r\n and must rest with the project designer, owner, or both. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. \"Complete \r\n Plans and Instructions for Construction and Operation of a Masonry \r\n Stove, Finnish, or Russian Fireplace,\" by Basilio Lepuschinko, \r\n Richmond, Maine, 1980. \r\n 2. \"How \r\n to Build a Russian Fireplace,\" by Jay Jarpe, Los Lunas, New Mexico, \r\n 1980. \r\n 3. \"A \r\n Russian-Type Fireplace Demonstration and Workshop, \" New Mexico \r\n Energy Institute, The University of New Mexico, Albuquerque, New \r\n Mexico, 1981. \r\n 4. \"On \r\n Building Masonry Firestoves,\" by J. Patrick Manley, Farmstead \r\n Magazine, Fall Issue 1980, No. 34. \r\n 5. \"Whats \r\n So Hot About A Russian Fireplace?\" by M. R. Allan, Yankee Magazine, \r\n Dublin, New Hampshire, February 1978. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60080,"ResultID":176312,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 19E - Brick Masonry Fireplaces, Part 2 - Fountain and \r\n Contemporary Style Heaters \r\n 1983 (Reissued Feb. 1988) \r\n \r\n Abstract : Brick masonry heaters \r\n may be used instead of conventional fireplaces to provide efficient \r\n supplemental heating for residential buildings. The design, detailing \r\n and construction of brick masonry fireplaces with baffle systems \r\n through which combustion gases are circulated are discussed. Information \r\n regarding building code compliance, operation and accessories is \r\n presented, along with the basic heating principles. \r\n \r\n Key Words : brick , buildings (codes) , \r\n design , energy , fireplaces, heating , \r\n masonry , mortar. \r\n \r\n INTRODUCTION \r\n \r\n \r\n The basic concepts of a fireplace designed with a baffle system replacing \r\n the conventional smoke chamber are discussed in Technical Notes \r\n 19D . Such fireplaces are often referred \r\n to as Russian-style fireplaces. These fireplaces, or brick \r\n masonry heaters, although capable of providing efficient heat, tend \r\n to eliminate the esthetic value of the fireplace because the firebox \r\n is typically deep within a small opening. An alternate approach to \r\n the fireplace designed to include a baffle system through which combustion \r\n gases are circulated is the Finnish or fountain-style heater. This \r\n Technical Notes provides the information necessary to properly \r\n design and construct a fountain-style brick masonry heater or to modify \r\n conventional fireplace designs to incorporate baffle systems to allow \r\n the circulation of combustion gases. \r\n The basic principles by which high efficiencies are obtained for \r\n heating the building interior and for the combustion of wood are \r\n the same as for the Russian-style brick masonry heater. Hot combustion \r\n gases circulating through the massive brick masonry heater, combined \r\n with properly controlled air intake for combustion, result in high \r\n efficiencies. The hot combustion gases are circulated through baffle \r\n chambers within the heater. The massive brick masonry is warmed \r\n and retains the heat. This warmed brick masonry radiates the heat \r\n long after the fire is extinguished. The basic concepts of design, \r\n construction and operation are simple, but there are several concerns \r\n which must be addressed to insure safety and durability. \r\n \r\n GENERAL \r\n Operation \r\n \r\n The operation of both the fountain-style brick masonry heater and \r\n the contemporary-style heaters is quite similar. Both systems have \r\n unique operational advantages which are directly related to their \r\n design and the way in which combustion gases are circulated through \r\n the massive brick masonry assembly. \r\n Typically, the combustion chamber or firebox is loaded with 10 \r\n lb (4.5 kg) to 20 lb (9.1 kg) of wood, after a fire with kindling \r\n is ignited. Once good combustion starts, the firebox doors or glass \r\n screens are closed and the air intakes adjusted to the proper setting \r\n so that good combustion continues. Unlike the Russian-style brick \r\n masonry heater, because of the design of the firebox, glass screens \r\n may be used on the fountain-style heater and the modified conventional \r\n fireplace. The glass screens or firebox doors used should be equipped \r\n with operable air inlets so that the air intake to the combustion \r\n chamber can be controlled. The metal firebox doors or glass screens \r\n selected for the firebox opening should be capable of withstanding \r\n the high temperatures in the combustion chamber. Temperatures of \r\n combusting wood will usually range from 1000 o F (540 o C) \r\n to 1500 o F (820 o C), and the temperature of \r\n the combustion gases near the fire usually ranges from about 800 o F \r\n (430 o C) to 1200 o F (650 o C). (See \r\n Reference 10). Thus, all components of the firebox should be capable \r\n of withstanding these temperatures. \r\n \r\n The 10 lb (4.5 kg) to 20 lb (9.1 kg) of \r\n wood loaded in the firebox will burn for about 30 min when properly \r\n seasoned wood is used with adequate draft and combustion air. For \r\n maximum heating, the firebox should be reloaded with about 10 lb \r\n (4.5 kg) to 20 lb (9.1 kg) of wood every 30 min for a 2-hr period. \r\n This procedure usually results in enough heat being supplied by \r\n the brick masonry heater to keep a 2400 ft 3 (68 m 3 ) room warm for a period of \r\n 8 to 12 hr during the coldest months in severe climates, such as \r\n in Scandinavia. Under these severe climate conditions, the heater \r\n is usually operated for a 2-hr period twice a day, once in the morning \r\n and once in the evening. During the more moderate seasons, or in \r\n the more moderate climates, operating the heater once in the evening \r\n may be adequate to supplement the mechanical heating system to maintain \r\n comfortable interior temperatures throughout the night. Other variations \r\n in operation, such as the number of loadings and the amount of wood \r\n used for each firing may also result in increased comfort. The operator \r\n should experiment with several operations to determine how to achieve \r\n the best performance for the various seasons. \r\n \r\n This method of operation may be used with any properly designed \r\n and constructed brick masonry heater. Because of the variations \r\n in the design of the fountain style heater and the modified conventional \r\n fireplace, the actual method of operation should be modified for \r\n the specific design. The contemporary-style brick masonry heater \r\n is usually operated the same as a conventional fireplace. \r\n Fountain-Style Heater . The fountain-style heater is shown \r\n in Figures 1 through 3. It consists of a relatively conventional \r\n fireplace firebox. The smoke chamber is rectangular and the baffle \r\n chambers for circulating the combustion are located on the sides \r\n of the smoke and combustion chambers. The baffle chambers meet under \r\n the combustion chamber where combustion gases are vented to the \r\n chimney. \r\n \r\n \r\n \r\n FIG. 1a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 1b \r\n \r\n \r\n \r\n \r\n \r\n Fountain-Style Brick Masonry Heater, Isometric \r\n FIG. 1c \r\n \r\n \r\n \r\n The heating output of the fountain-style heater may be increased \r\n by using a specially designed air supply system from the firebox \r\n doors to the smoke chamber. Providing the smoke chamber with this \r\n additional air ignites the combustion gases in the smoke chamber. \r\n The combustion gases burn at temperatures of about 1800 o F \r\n (1100 o C) to 2100 o F (1150 o C). This \r\n method of operation, because of the higher temperatures of the circulating \r\n combustion gases, greatly increases the heating capability of the \r\n heater. This second combustion within the heater also results in \r\n a very clean and complete combustion of the wood and its by-products. \r\n This nearly complete combustion maximizes the efficiency of the \r\n wood fuel and considerably reduces any creosote buildup within the \r\n brick masonry heater and chimney. \r\n \r\n \r\n \r\n Fountain-Style Brick Masonry Heater \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n Fountain Style Brick Masonry Heater \r\n FIG. 3 \r\n \r\n \r\n \r\n Contemporary-Style Heater . The contemporary-style heater, shown in Figs. 4 through 7, \r\n although much more efficient than a conventional fireplace, will \r\n not achieve the high efficiency normally obtained in the fountain-style \r\n heater. The fountain-style heater achieves efficiencies of about \r\n 80 to 95 percent and the contemporary-style heater provides a heating \r\n efficiency of about 70 to 80 percents. (See Reference 8). The contemporary-style \r\n heater is designed with a rectangular firebox with the throat located \r\n at the rear of the firebox. Combustion gases are circulated through \r\n baffle chambers within the smoke chamber and exhausted to a conventional \r\n fireplace chimney located on top of the smoke chamber. Although \r\n this type of heater does not provide as much heat, it is usually \r\n preferred because it provides the esthetic appearance similar to \r\n a conventional fireplace. \r\n \r\n \r\n \r\n \r\n Modified Conventional Fireplace \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Modified Conventional Fireplace \r\n FIG. 5 \r\n \r\n \r\n \r\n Building Code Compliance \r\n \r\n There are no major model building code requirements which specifically \r\n address brick masonry heaters or their baffle chambers. For the \r\n most part, the building code requirements for fireplaces and chimneys \r\n are applicable to the brick masonry heater except for those requirements \r\n which address the firebox and smoke chamber dimensions. All building \r\n code requirements for chimneys and clearances for combustibles are \r\n applicable. Because the temperatures normally achieved in the brick \r\n masonry heater are much higher than those obtained in conventional \r\n fireplaces, additional consideration should be given to safety and \r\n durability. \r\n The exterior walls of the brick masonry heater should consist of \r\n at least two wythes of brick masonry when constructed of solid units. \r\n The two wythes should be separated by a nominal 1-in. (25 mm) air \r\n space. This separation prevents any cracks from penetrating the \r\n interior wythe through the exterior wythe of the heater. Filling \r\n this 1-in. (25 mm) air space with a compressible, non-combustible \r\n material will insure that a separation is provided. The two wythes \r\n should be tied to each other with corrosion-resistant metal ties, \r\n placed 16 in. (400 mm) o.c. vertically and a maximum of 24 in. (600 \r\n mm) o.c., horizontally. The exterior wythe should contain horizontal \r\n joint reinforcement every 16 in. (400 mm) vertically to add to the \r\n integrity of the heater. The ties and joint reinforcement should \r\n not occur in the same course. These provisions should prevent \r\n problems due to thermal expansion and differential movement without \r\n affecting the overall thermal performance of the brick masonry heater. \r\n \r\n When reinforced brick masonry construction is required, the enclosing \r\n walls or shell of the heater may be constructed of fully grouted hollow \r\n wall construction or fully grouted hollow brick units. If the fully \r\n grouted hollow wall construction is to be used, the minimum 2 in. \r\n (50 mm) grout core must be fully grouted and contain sufficient horizontal \r\n and vertical reinforcement to resist structural and thermal stresses. \r\n The two wythes must also be adequately tied together with corrosion-resistant \r\n metal ties. If grouted hollow brick masonry is used, the cores must \r\n be fully grouted and sufficiently reinforced to resist structural \r\n and thermal stresses. Horizontal joint reinforcement should have proper \r\n mortar coverage in the bed joints and the units should not be less \r\n than 8 in. (200 mm) in thickness. For additional information on reinforced \r\n brick masonry construction and hollow brick, see Technical Notes \r\n 17 and 41 . \r\n In addition to the thermal movements, the exterior surface temperatures \r\n of the brick masonry heater also need to be considered. These surface \r\n temperatures normally range between 100 o F (38 o C) \r\n and 130 o F (54 o C). Temperatures as high as \r\n 190 o F (88 o C) have been reported on certain \r\n styles of brick masonry heaters and are typical when fountain-style \r\n heaters are operated with gas combustion occurring in the smoke \r\n chamber. \r\n A minimum 16-in. (400 mm) clearance is recommended between the \r\n sides and the back of the brick masonry heater and combustibles. \r\n At the floor line, this may be achieved by providing a 16-in. (400 \r\n mm) extended hearth. In the front of the heater, a minimum 20-in. \r\n (500 mm) extended hearth should be used. This is easily achieved \r\n when the heater is properly positioned in the room for maximum heating. \r\n This position is in the center of the room so that all four brick \r\n walls of the heater are providing radiant heat to the room. \r\n The brick masonry heater should always be positioned entirely inside \r\n the building. It should never be incorporated into an exterior wall, \r\n because much of the radiant heat would be lost to the exterior. \r\n In addition to this heat loss, the location on the exterior wall \r\n will usually result in at least one cold surface on which a considerable \r\n amount of creosote may form. A creosote fire may well result in \r\n sufficient damage to the heater so that it is no longer safe to \r\n operate. \r\n \r\n FOUNTAIN-STYLE HEATER \r\n General \r\n \r\n A typical design of a fountain-style heater \r\n is shown in Figs. 1 and 2. There are many variations to the design \r\n and construction of the fountain-style heater. The fountain-style \r\n heater, often referred to as a Finnish stove or vertical \r\n contra-flow masonry stove, is believed by most experts \r\n to be the most efficient brick masonry heater. For proper combustion, \r\n the air intake to the combustion chamber should be approximately \r\n 0.80 cfm/lb (0.00083 m 3 /sec/kg) of wood being burned \r\n in the combustion chamber. This requirement is for the typical size \r\n fountain-style heater, which is usually loaded with 10 lb (4.5 kg) \r\n to 20 lb (9.1 kg) every 30 min for a 2-hr period. \r\n \r\n Base Assembly \r\n \r\n In the fountain-style heater, the baffle system provides for the \r\n circulation of combustion gases under the hearth of the firebox \r\n where they are vented to the chimney. Thus, when designing and constructing \r\n this style heater, the baffle system and chimney support must be \r\n incorporated into the base assembly. \r\n Foundation . The foundation system must be adequate to support \r\n the mass of the brick masonry heater and the masonry chimney. When \r\n designing the foundation, care should be taken to account for soil \r\n types and foundation conditions. Undisturbed or well-compacted soil \r\n will generally be sufficient. However, some types of soils or foundation \r\n conditions may require special analysis. This could result in the \r\n need for special soil treatments or a unique foundation design. \r\n Building codes generally require that the footing be at least 12 \r\n in. (300 mm) thick, and in plan view extend a minimum of 6 in. (150 \r\n mm) beyond each face of the masonry heater and chimney assembly. \r\n The footing should be positioned so that its base is below the frost \r\n line to reduce the possibility of \"heaving.\" \r\n Hearth Support . The brick masonry used to form the hearth \r\n support is constructed directly on the foundation system. Even with \r\n a thickened slab in a newly constructed slab-on-grade structure, \r\n masonry is usually used to construct the base assembly to the height \r\n of the hearth support because to properly construct a fountain-style \r\n heater, a raised hearth is usually required. The hearth support \r\n may be solid masonry carried up from the footing to support the \r\n entire hearth area. To conserve materials, the base assembly is \r\n usually constructed of masonry which has the same dimensions in \r\n plan as the masonry heater and chimney assembly itself. The base \r\n assembly is corbeled to form the support for the extended hearth. \r\n A soot pocket should be formed at the base of the chimney assembly, \r\n approximately 20 in. (500 mm) to 24 in. (600 mm) below the firebox \r\n hearth. These dimensions will provide a soot pocket that is, approximately \r\n 8 in. (200 mm) in height, which will accommodate a standard size \r\n clean-out door. The baffle chamber is started at the top of the \r\n soot pocket. The baffle chamber should be at least 5 in. (125 mm) \r\n (about two courses of standard size brick) high. The last course \r\n of brick forming the soot pocket should be corbeled to provide the \r\n support for the chimney liner. The first chimney liner should be \r\n cut so that the entire front of the liner, for the height of the \r\n base baffle chamber, is removed. This opening is used to exhaust \r\n the combustion gases to the chimney. The baffle system needs to \r\n be designed so that the vertical baffle chamber, at least 3 in. \r\n (75 mm) wide and 16 in. (400 mm) long, may be continued up along \r\n the sides of the firebox. The remaining portion of the baffle chamber \r\n should be constructed so that the combustion gases will be directed \r\n to the rear of the base assembly and vented to the chimney. At the \r\n base of the baffle chamber, clean-out doors should be installed \r\n so that soot and ash deposits may be removed. The shell of the fountain-style \r\n heater is also started at the base of the baffle system. This shell \r\n should be constructed of two wythes of brick masonry separated by \r\n a nominal 1-in. (25 mm) air space and tied with metal ties. The \r\n exterior wythe should contain horizontal joint reinforcement. Because \r\n these vertical baffle chambers must extend up along the sides of \r\n the firebox, the size of the base is directly dependent upon the \r\n firebox dimensions. \r\n \r\n Extended Hearth . As the base assembly is constructed, the \r\n support for the extended hearth is usually formed so that the top \r\n of the extended hearth may be constructed at or slightly below the \r\n clean-outs. The extended hearth is usually formed by placing a reinforced \r\n concrete slab on top of the corbeled base assembly, as shown in Fig. \r\n 1. Non-combustible, or removable, forming should be placed so that \r\n it spans from the corbeled masonry to the floor joists forming the \r\n opening for the heater. Double joists should be used around the entire \r\n perimeter of the opening with a nailer attached to the joists to support \r\n the edge of the forming material. This type of construction is discussed \r\n in more detail in Technical Notes 19A \r\n Revised. To decrease the number of concrete slabs occurring within \r\n the heater assembly, the extended hearths may be formed by using trimmer \r\n arches, as shown in Fig. 3. \r\n The extended hearth should be at least 20 in. (500 mm) in front \r\n of the firebox opening and 16 in. (400 mm) around the remaining \r\n perimeter of the heater. The extended hearth may be eliminated on \r\n the back of the heater if it is positioned against a non-combustible \r\n wall with a minimum fire rating of 1 hr. Once the reinforced slab \r\n is installed, the extended hearth may be finished with brick pavers \r\n and at least one course of brick masonry should be placed to form \r\n the base of the fountain-style heater baffle chamber. If removable \r\n forming is used, the concrete slab used to support the extended \r\n hearth must be designed as a cantilever \r\n Ash Pit . The masonry heater, because of its efficient combustion \r\n of wood, does not require an ash pit. If an ash pit is desired, \r\n it should be positioned so that the ash drop occurs in the center \r\n of the firebox width, toward the front of the firebox. This location \r\n results in the ash pit being formed by brick masonry used to construct \r\n the portion of the baffle system in the base assembly. The ash drop \r\n should extend through the firebox hearth and hearth support. If \r\n an exterior combustion air system is desired, the optional ash pit \r\n should be eliminated and replaced with the vertical air passageway \r\n which forms the exterior combustion air inlet to the firebox. \r\n \r\n Firebox Assembly \r\n \r\n The firebox assembly is constructed on a reinforced concrete slab, \r\n which spans from the front to the rear of the heater. The reinforced \r\n concrete slab should be at least 2 1/2 in. (63 mm) thick and must \r\n be thick enough to satisfy the structural and reinforcement coverage \r\n requirements. The slab should bear at least 2 in. (50 mm) on the \r\n interior wythe of the shell of the brick masonry heater. The width \r\n of the slab must be limited to the outside dimensions of the firebox \r\n width so that the baffle chamber may be continuous to the base assembly. \r\n The typical dimensions of the firebox opening are: 12 in. (300 \r\n mm) to 18 in. (450 mm) wide, by 24 in. (600 mm) in height. The firebox \r\n is usually 18 in. (450 mm) to 24 in. (600 mm) deep, and about as \r\n wide as the firebox opening. The shape of the firebox is similar \r\n to that of a conventional fireplace without flared sides. The back \r\n wall of the firebox is sloped forward to form the throat. This slope \r\n usually begins at about 12 in. (300 mm) from the firebox hearth \r\n and should form a 4-in. (100 mm) throat that is as wide as the combustion \r\n chamber. \r\n The combustion chamber should be constructed of refractory brick \r\n units to obtain a thickness of at least 2 1/2 in. (63 mm). A sliding \r\n damper may be installed at the throat. The throat damper is usually \r\n installed so that it may be operated from the face of the fireplace. \r\n If a throat damper is used, sufficient provisions are necessary \r\n to allow for the thermal expansion so that the damper does not bind \r\n or crack the surrounding brick masonry. Whenever possible, a throat \r\n damper should not be used. \r\n If air is to be provided to the smoke chamber, provisions must \r\n be made in the face of the heater to form an air passageway. The \r\n air inlet is usually through specially fabricated firebox doors \r\n and placed so that the air enters the smoke chamber at the throat \r\n where the velocity of the combustion gases is the greatest. A specially \r\n designed firebox door is usually required to provide combustion \r\n air to the smoke chamber. \r\n \r\n Smoke Chamber Assembly \r\n \r\n The smoke chamber assembly should be constructed of refractory \r\n brick units. The base of the smoke chamber should be constructed \r\n of fire brick. The front and rear walls of the smoke chamber should \r\n be 12 in. (300 mm) to 16 in. (400 mm) high. The side walls should \r\n be 8 in. (200 mm) to 12 in. (300 mm) high to provide an opening \r\n for the combustion gases to enter the vertical baffle chambers. \r\n The top of the smoke chamber should be constructed of a 2 1/2 in. \r\n (63 mm) to 4 in. (100 mm) thick reinforced refractory-concrete slab. \r\n The slab thickness must be adequate for structural and reinforcement \r\n coverage requirements. The rear of the slab should bear at least \r\n 2 in. (50 mm) on the wythe of brick immediately behind the fire \r\n brick wall of the smoke chamber. The front and sides should bear \r\n at least 2 in. (50 mm) on the interior wythe of the shell of the \r\n heater. The distance from the bottom of this slab to the bottom \r\n of the baffle chamber should not exceed 5 ft (1.5 m), thus controlling \r\n the distance combustion gases are circulated and the height of the \r\n heater. \r\n The smoke chamber is often constructed with an opening directly \r\n into the chimney. This opening is installed to provide a by-pass \r\n for when little or no heating is required. It should be equipped \r\n with a rotating damper. This by-pass is shown in Figs. 1 through \r\n 3. \r\n \r\n Crown \r\n \r\n The crown of the fountain-style heater should be at least 12 in. \r\n (300 mm) thick, including the refractory slab forming the top of \r\n the smoke chamber. The crown should terminate at least 12 in. (300 \r\n mm) below the ceiling of the room. This may require that the baffle \r\n chambers be extended below the floor line of the room. \r\n \r\n Chimney \r\n \r\n \r\n The chimney for the fountain-style heater is similar to those used \r\n for residential appliances. The chimney should be constructed of fireclay \r\n flue liners and 8 in. (200 mm) of brick masonry surrounding the liner \r\n in such a way as to maintain a nominal 1 in. (25 mm) space between \r\n the flue liner and the brick chimney walls. Additional information \r\n on chimney design and construction is provided in Technical Notes \r\n 19B Revised. \r\n The chimney height required for draft is usually higher than that \r\n necessary for a conventional fireplace, but following building code \r\n requirements for fire safety will usually result in a sufficiently \r\n high chimney. The major model building codes require that chimneys \r\n must terminate at least 3 ft (1 m) above the roof at the highest \r\n point of exit and at least 2 ft (600 mm) above any portion of the \r\n building or adjacent structures within 10 ft (3 m) of the chimney. \r\n If draft is determined to be inadequate by a smoke test, the chimney \r\n height should be increased to provide adequate draft. \r\n \r\n CONTEMPORARY-STYLE HEATERS \r\n General \r\n \r\n The brick masonry heater formed by modifying a conventional fireplace, \r\n as shown in Figs. 4 through 7, is one of the easiest brick masonry \r\n heaters to construct and also retains most of the esthetic value \r\n of a conventional fireplace. This style of heater has the baffle \r\n system, through which combustion gases are circulated, incorporated \r\n solely in the smoke chamber assembly. Variations in the smoke chamber \r\n and the firebox are the only major differences from a conventional \r\n fireplace. The front and side sections of the contemporary-style \r\n heater are shown in Figs. 4 and 5, respectively. The heater under \r\n construction is shown in Fig. 6, and Fig. 7 shows a completed contemporary-style \r\n heater. \r\n \r\n Base Assembly \r\n \r\n The requirements for the base assembly are essentially the same \r\n as for the other brick masonry heaters and conventional fireplaces. \r\n The foundation system requirements discussed for fountain-style \r\n heaters are also applicable to the modified conventional fireplace. \r\n \r\n The hearth support is similar to that of a conventional fireplace, \r\n as discussed in Technical Notes 19 \r\n Revised and 19A Revised. The hearth \r\n support is usually constructed of a reinforced concrete slab, as previously \r\n discussed. For this style heater, it is necessary to have only a 20-in. \r\n (500 mm) extended hearth at the front face of the heater. The thickness \r\n of the side and rear walls at the floor line usually provides adequate \r\n fire protection. However, because the higher portions of this heater \r\n are much hotter, a minimum 12-in. (300 mm) clearance should be maintained \r\n between the back and sides of the heater and any combustible materials. \r\n \r\n If an ash pit is desired, it may be constructed the same as for a \r\n conventional fireplace. External combustion and draft air systems \r\n used with conventional fireplaces may also be incorporated into this \r\n style heater. Additional information is provided in Technical Notes \r\n 19 Revised and 19A \r\n Revised. \r\n \r\n Firebox Assembly \r\n \r\n The firebox is constructed as a rectangular box that is usually \r\n about 20 in. (500 mm) deep and 30 in. (750 mm) wide. The opening \r\n of the firebox is usually about 27 in. (675 mm) high. Immediately \r\n behind the top of the firebox opening, which is constructed of face \r\n or building brick on a steel lintel, is the top of the firebox. \r\n The top of the firebox is formed as a brick masonry arch, extending \r\n from the inside face of the heater and terminating about 6 in. (150 \r\n mm) to 8 in. (200 mm) from the rear wall of the firebox. At the \r\n crown of the arch, above the opening, the first horizontal baffle \r\n is constructed. This baffle extends about 8 in. (200 mm) to 12 in. \r\n (300 mm) on either side of the firebox, and is constructed of refractory \r\n units. \r\n \r\n Smoke Chamber Assembly \r\n \r\n The conventional smoke chamber is replaced by a baffle system as \r\n shown in Figs. 4 and 5. The baffle system begins at the top of the \r\n rear of the firebox. The baffle chambers should be about 7 1/2 in. \r\n (188 mm) by 7 1/2 in. (188 mm) square. Immediately above the first \r\n horizontal baffle are three horizontal baffle chambers, each separated \r\n by 5 in. (125 mm) of face or building brick. The baffle system is \r\n separated vertically into right and left chambers by 4 in. (100 \r\n mm) to 8 in. (200 mm) of brickwork. The second horizontal baffle \r\n above the firebox should be equipped with a clean-out so that any \r\n soot or ash deposits may be removed. \r\n \r\n \r\n \r\n Contemporary-Style Brick Masonry Heater Under Construction \r\n FIG. 6 \r\n \r\n Crown \r\n \r\n The crown of this modified conventional fireplace should be at \r\n least 12 in. (300 mm) thick, and terminate at least 12 in. (300 \r\n mm) from the ceiling of the room. A rotating damper should be installed \r\n at the center of the heater width. \r\n \r\n Chimney \r\n \r\n \r\n The chimney should be constructed as a lined chimney with 8 in. (200 \r\n mm) of brick masonry surrounding the flue liner in such a way that \r\n a nominal 1-in. (25 mm) air space is maintained between the flue liner \r\n and the brick. The flue liner support should be formed by the last \r\n course of brick masonry in the crown. The termination requirements \r\n as previously discussed apply and additional information regarding \r\n chimney design is provided in Technical Notes 19B \r\n Revised. \r\n \r\n \r\n \r\n Contemporary-Style Brick Masonry Heater \r\n FIG. 7 \r\n \r\n SELECTION OF MATERIALS \r\n General \r\n \r\n The accessories used in Europe are not usually available in the \r\n United States. The design and construction of the brick masonry \r\n heater using products available in North America are slightly different \r\n from the construction of the heater in Europe. There are methods \r\n to modify the design and construction so that products readily available \r\n in the United States may be used with the brick masonry heater. \r\n The option also exists to import the accessories or to fabricate \r\n accessories similar to those used in Europe. However, these options \r\n are usually uneconomical. Additional information regarding accessories \r\n may be obtained from the cited references. \r\n \r\n Brick \r\n \r\n Most building codes require that solid masonry units be used for \r\n fireplace construction. Solid brick should be nominal 3 in. (75 \r\n mm) or 4 in. (100 mm) thick, conforming to ASTM C 216 or C 62, for \r\n facing brick or building brick, respectively. If a single wythe \r\n of reinforced, grouted hollow brick is used, the hollow brick should \r\n be at least 8 in. (200 mm) wide and should conform to ASTM C 652. \r\n Grade SW brick should be used because of its greater durability. \r\n Refractory brick, conforming to ASTM C 64, medium duty, should \r\n be used for the firebox. The lining for the first baffle chamber \r\n of the contemporary-style heater and the smoke chamber of the fountain-style \r\n heater should also be constructed of refractory units because these \r\n areas are exposed to the greatest amounts of heat. The refractory \r\n units are more resistant to heat and thermal shock. \r\n \r\n Salvaged or used brick should not be used, because they usually \r\n will not bond well with the mortar and lack the durability necessary \r\n for satisfactory performance. The use of salvaged brick is discussed \r\n in Technical Notes 15 . \r\n \r\n Flue Liners \r\n \r\n Flue liners should conform to ASTM C 315. They should be thoroughly \r\n inspected just prior to installation for cracks or other damage \r\n that might contribute to smoke and flue gas leakage. \r\n \r\n Mortar and Grout \r\n \r\n It is most convenient and economical to use only one type of mortar \r\n for the entire brick masonry heater and chimney assembly. This becomes \r\n difficult when constructing a brick masonry heater because of the \r\n specific requirements of each component. The portions of the heater \r\n consisting of building, face or hollow brick should be constructed \r\n using a Type N, portland cement-lime mortar, conforming to the proportion \r\n specifications of ASTM C 270 or BIA M1-72. The same mortar should \r\n be used for the chimney brickwork except when wind loads exceed \r\n 25 psf (1.2 kPa). Where high wind loads exist, a Type S, portland \r\n cement-lime mortar, conforming to the proportion specifications \r\n of ASTM C 270 or BIA M1-72, should be used. It may be desirable \r\n to use high temperature-resistant mortars, such as calcium aluminate \r\n mortars, for the interior wythes and baffles of the brick masonry \r\n heater. Such mortars will increase the durability of the heater. \r\n The firebox and all other components constructed of refractory \r\n units should be placed using a fireclay mortar conforming to ASTM \r\n C 105, medium duty. Other refractory mortars have also been used \r\n successfully, and thus any high temperature-resistant mortars that \r\n have performed well may be used. It is not within the purview of \r\n the Brick Institute of America to recommend proprietary products. \r\n The selection of the proper mortars should be determined by an experienced \r\n fireplace expert for the specific design being considered. \r\n Grout is required for reinforced hollow walls and reinforced hollow \r\n brick construction. Such assemblies must be fully grouted. The grout \r\n should conform to ASTM C 476. \r\n \r\n Steel Lintels and Dampers \r\n \r\n Steel lintels should be used only above the firebox opening because \r\n of the high temperatures occurring within the heater. The thermal \r\n expansion characteristics of the different materials could cause \r\n cracking of the brick masonry heater. Lintels of corrosion-resistant \r\n steel, conforming to ASTM A 36, should be used to span over the \r\n firebox door openings. Non-combustible, compressible material should \r\n be placed at the ends of all lintels to provide for differential \r\n thermal movements. \r\n \r\n Ties and Reinforcement \r\n \r\n Corrugated Metal Ties . Corrugated metal ties may be used \r\n to anchor the baffles to the interior wythe of the heater walls \r\n and to tie the two wythes of the exterior walls of the heater. Ties \r\n should be corrosion-resistant, approximately 22 ga, 7/8 in. (22.2 \r\n mm) wide, and 6 in. (150 mm) long. Stiffer ties should not be used, \r\n as they may transfer stresses due to thermal expansion of the interior \r\n wythe to the exterior wythe of the brick masonry heater. \r\n Prefabricated Joint Reinforcement . Prefabricated joint reinforcement \r\n should be used only in the exterior wythe of the heater walls. T \r\n he joint reinforcement should be fabricated from wire which complies \r\n with ASTM A 82 or ASTM A 185, and must be corrosion-resistant. \r\n Reinforcement . Reinforcement should conform to any of the \r\n following applicable standards: \r\n \r\n Standard Specifications for Deformed Billet-Steel Bars for Concrete \r\n Reinforcement-ASTM A 615 \r\n Standard Specifications for Rail-Steel Deformed Bars for Concrete \r\n Reinforcement-ASTM A 616 \r\n Standard Specifications for Axle-Steel Deformed Bars for Concrete \r\n Reinforcement-ASTM A 617 \r\n \r\n Corrosion Resistance . Corrosion resistance is usually provided \r\n by a copper or zinc coating, or by using stainless steel. To ensure \r\n adequate resistance to corrosion, coatings or materials should conform \r\n to any of the following applicable standards: \r\n \r\n Zinc-Coating of Flat Metal-ASTM A 153, Class B-1, B-2, or B-3 \r\n Zinc-Coating of Wire-ASTM A 641, Class 3 \r\n Copper Coated Wire-ASTM B 227, Grade 30 HS \r\n Stainless Steel-ASTM A 167, Type 304 \r\n \r\n \r\n Firebox Doors \r\n \r\n The doors for the firebox opening may be fabricated locally, ordered \r\n from Europe, or may be conventional, metal Dutch oven doors, which \r\n are the most economical. The brick masonry heater is not designed \r\n for airtight combustion and thus the doors need to be equipped with \r\n operable vents to control air intake into the firebox. The size \r\n of the firebox opening is determined by the size of the firebox \r\n door used. Other alternatives which exist for the firebox design \r\n and firebox doors are discussed in other Technical Notes in \r\n this Series. Glass screens may be used, but they must be capable \r\n of withstanding the high temperatures and severe exposure occurring \r\n within the firebox. \r\n \r\n Clean-Out Doors \r\n \r\n \r\n Conventional clean-out doors may be used, but to ensure tightness, \r\n refractory units should be placed within the door opening with a compressible \r\n material or set in a sand-lime mortar. The refractory units increase \r\n the resistance to combustion gas leaks, provide protection to the \r\n metal door from high temperatures, and may easily be removed and replaced \r\n when cleaning. This is shown in Technical Notes 19D . \r\n Clean-out doors for the ash drop may be conventional clean-out doors, \r\n installed in the conventional manner. \r\n \r\n SUMMARY \r\n \r\n The information and suggestions contained in this Technical \r\n Notes are an accumulation of the available information within \r\n the Brick Institute of America on brick masonry heaters. The information \r\n is based on empirical data from actual performance of such heaters \r\n here in North America and in Europe. The information provided in \r\n this Technical Notes and Technical Notes 19D does \r\n not address all of the possible variations, or alterations, which \r\n may be incorporated into a brick masonry heater by design or construction \r\n requirements. The information and recommendations provided in this \r\n Technical Notes discuss the basic principles and guidelines \r\n by which fireplace experts using good technical judgment may design \r\n and construct a functional brick masonry heater. \r\n Final decisions on the design and use of materials, as discussed \r\n in this Technical Notes, are not within the purview \r\n of the Brick Institute of America and must rest with the project \r\n designer, owner, or both. \r\n \r\n ACKNOWLEDGMENTS \r\n \r\n The assistance provided by Mira Wisniewska, of Technical Translation \r\n International, Limited, 500 Fifth Avenue, Suite 200, New York, New \r\n York, 10036, who translated the articles listed in References 1 \r\n through 5, is greatly appreciated. The information provided by Heikki \r\n Hyytiainen to the members of the BIA Technical and Manpower Development \r\n Staff at the Masonry Stoves Workshop, held by Albie Barden in \r\n Camden, Maine, July 12-15, 1981, was most helpful, and is greatly \r\n appreciated. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. \"Tulisija-ja \r\n hormirakenteet. by Kari M├ñkel├ñ, Tekn. Iis. Tiilikeskus Oy, Iso \r\n Roobertinkatu 20,00120 Helsinki 12, Finland, 1980 Rakennustaito. \r\n (Fireplaces and Flue Structures) \r\n 2. Tiilessa\" \r\n on inhimillinen j├ñlki, Keskusuuni,Tiilikeskus Oy, Iso Roobertinkatu \r\n 20, 00120 Helsinki 12, Finland, 1980. (Brick Bears Traces of Human \r\n Touch). \r\n 3. Tiilessa\" \r\n on inhimillinen j├ñlki. L├ñmmitt├ñv├ñ Ja Lampoavaraava Takka, Tiilikeskus \r\n Oy, Iso Roobertinkatu 20,00120 Helsinki 12, Finland, (Fireplaces \r\n for Heating and Heat Storage, List of Materials and Supplies and \r\n Drawings). \r\n 4. Tarvitaanko \r\n uuneja jalleen by Professor Olavi Vuorelainen, Tiili, March \r\n 1978. (Are Stoves Again Required?) \r\n 5. Tilisijan \r\n suunnittelu\" by Heikki Hyytiainen, Architect, Tiili, March 1978. \r\n (Fireplace Design). \r\n 6. The \r\n Russian Fireplace, Colorado Masonry Institute, Suite 301, 3003 \r\n East Third Avenue at Milwaukee, Denver, Colorado, 80206, 1982. \r\n 7. Complete \r\n plans and Instruction for Construction and Operation of a Masonry \r\n Stove, Finnish or Russian Fireplace,\" by Basilio Lepuschinko, \r\n Richmond, Maine, 1980. \r\n 8. \"A \r\n Russian-Type Fireplace Demonstration and Workshop, New Mexico \r\n Energy Institute, The University of New Mexico, Albuquerque, New \r\n Mexico, May 1981. \r\n 9. Summit \r\n Pressed Brick and Tile Company, Thirteenth and Erie, Pueblo, Colorado, \r\n 81002. \r\n \r\n 10. The \r\n Woodburners Encyclopedia , Section One, by Jay Shelton, Vermont \r\n Crossroads Press, Waitsfield, Vermont, 05672, February 1978. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60081,"ResultID":176313,"Text1":" \r\n \r\n ABSORPTION: The weight of water a brick unit absorbs, when immersed in either cold or boiling water for a stated length of time \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 2 - Glossary of Terms Relating to Brick Masonry \r\n Jan/Feb 1975 (Reissued Sept. 1988) \r\n \r\n \r\n ABSORPTION : The weight \r\n of water a brick unit absorbs, when immersed in either cold or boiling water \r\n for a stated length of time. Expressed as a percentage of the weight of \r\n the dry unit. See ASTM Specification C 67. \r\n \r\n \r\n ADMIXTURES : Materials added to mortar to impart special properties \r\n to the mortar. \r\n ANCHOR : A piece or assemblage, usually metal, used to attach building \r\n parts (e.g., plates, joists, trusses, etc.) to masonry or masonry materials. \r\n ANSI : American National Standards Institute. \r\n ARCH : A curved compressive structural member, spanning openings \r\n or recesses; also built flat. \r\n \r\n Back Arch : A concealed arch carrying the backing \r\n of a wall where the exterior facing is carried by a lintel. \r\n \r\n Jack Arch : One having horizontal or nearly horizontal \r\n upper and lower surfaces. Also called flat or straight arch. \r\n \r\n Major Arch : Arch with spans greater than 6 ft and \r\n equivalent to uniform loads greater than 1000 lb. per ft. Typically known \r\n as Tudor arch, semicircular arch, Gothic arch or parabolic arch. Has rise \r\n to span ratio greater than 0.15. \r\n \r\n Minor Arch : Arch with maximum span of 6 ft and loads \r\n not exceeding 1000 lb. per ft. Typically known as jack arch, segmental \r\n arch or multicentered arch. Has rise to span ratio less than or equal \r\n to 0.15. \r\n \r\n Relieving Arch : One built over a lintel, flat arch, \r\n or smaller arch to divert loads, thus relieving the lower member from \r\n excessive loading. Also known as discharging or safety arch. \r\n Trimmer Arch : An arch, usually a low rise arch of brick, \r\n used for supporting a fireplace hearth. \r\n ASHLAR MASONRY : Masonry composed of rectangular units of burned \r\n clay or shale, or stone, generally larger in size than brick and properly \r\n bonded, having sawed, dressed or squared beds, and joints laid in mortar. \r\n Often the unit size varies to provide a random pattern, random ashlar. \r\n ASHRAE : American Society of Heating, Refrigerating and Air-Conditioning \r\n Engineers, Inc. \r\n ASTM : American Society for Testing and Materials. \r\n BACK FILLING : \r\n 1. Rough masonry built behind a facing or between two faces. \r\n 2. Filling over the extrados of an arch. \r\n 3. Brickwork in spaces between structural timbers, sometimes called brick \r\n nogging. \r\n BACKUP : That part of a masonry wall behind the exterior facing. \r\n BAT : A piece of brick. \r\n BATTER : Recessing or sloping masonry back in successive courses; \r\n the opposite of corbel. \r\n BED JOINT : The horizontal layer of mortar on which a masonry unit \r\n is laid. \r\n BELT COURSE : A narrow horizontal course of masonry, sometimes \r\n slightly projected such as window sills which are made continuous. Sometimes \r\n called string course or sill course . \r\n BLOCKING : A method of bonding two adjoining or intersecting walls, \r\n not built at the same time, by means of offsets whose vertical dimensions \r\n are not less than 8 in. \r\n BOND : \r\n 1. Tying various parts of a masonry wall by lapping units one over another \r\n or by connecting with metal ties. \r\n 2. Patterns formed by exposed faces of units. \r\n 3. Adhesion between mortar or grout and masonry units or reinforcement. \r\n BOND BEAM : Course or courses of a masonry wall grouted and usually \r\n reinforced in the horizontal direction. Serves as horizontal tie of wall, \r\n bearing course for structural members or as a flexural member itself. \r\n BOND COURSE : The course consisting of units which overlap more \r\n than one wythe of masonry. \r\n BONDER : A bonding unit. See Header. \r\n BREAKING JOINTS : Any arrangement of masonry units which prevents \r\n continuous vertical joints from occurring in adjacent courses. \r\n BRICK : A solid masonry unit of clay or shale, formed into a rectangular \r\n prism while plastic and burned or fired in a kiln. \r\n \r\n Acid-Resistant Brick : Brick suitable for use in \r\n contact with chemicals, usually in conjunction with acid-resistant mortars. \r\n \r\n Adobe Brick : Large roughly-molded, sun-dried clay \r\n brick of varying size. \r\n \r\n Angle Brick : Any brick shaped to an oblique angle \r\n to fit a salient corner. \r\n \r\n Arch Brick : 1. Wedge-shaped brick for special \r\n use in an arch. 2. Extremely hard-burned brick from an arch of a scove \r\n kiln. \r\n \r\n Building Brick : Brick for building purposes not \r\n especially treated for texture or color. Formerly called common \r\n brick. See ASTM Specification C 62. \r\n \r\n Clinker Brick : A very hard-burned brick whose shape \r\n is distorted or bloated due to nearly complete vitrification. \r\n \r\n Common Brick : See Building Brick. \r\n Dry-Press Brick : Brick formed in molds under high pressures \r\n from relatively dry clay (5 to 7 percent moisture content). \r\n \r\n Economy Brick : Brick whose nominal dimensions are \r\n 4 by 4 by 8 in. \r\n \r\n Engineered Brick : Brick whose nominal dimensions \r\n are 4 by 3.2 by 8 in. \r\n \r\n Facing Brick : Brick made especially for facing purposes, \r\n often treated to produce surface texture. They are made of selected clays, \r\n or treated, to produce desired color. See ASTM Specification C 216. \r\n \r\n Fire Brick : Brick made of refractory ceramic material \r\n which will resist high temperatures. \r\n \r\n Floor Brick : Smooth dense brick, highly resistant \r\n to abrasion, used as finished floor surfaces. See ASTM Specification C \r\n 410. \r\n \r\n Gauged Brick : 1. Brick which have been ground or \r\n otherwise produced to accurate dimensions. 2. A tapered arch brick. \r\n \r\n Hollow Brick : A masonry unit of clay or shale whose \r\n net cross-sectional area in any plane parallel to the bearing surface \r\n is not less than 60 percent of its gross cross-sectional area measured \r\n in the same plane. See ASTM Specification C 652. \r\n \r\n Jumbo Brick : A generic term indicating a brick larger \r\n in size than the standard. Some producers use this term to describe oversize \r\n brick of specific dimensions manufactured by them. \r\n \r\n Norman Brick : A brick whose nominal dimensions are \r\n 4 by 2 2/3 by 12 in. \r\n \r\n Paving Brick : Vitrified brick especially suitable \r\n for use in pavements where resistance to abrasion is important. See ASTM \r\n Specification C 7. \r\n \r\n Roman Brick : Brick whose nominal dimensions are \r\n 4 by 2 by 12 in. \r\n \r\n Salmon Brick : Generic term for under-burned brick \r\n which are more porous, slightly larger, and lighter colored than hard-burned \r\n brick. Usually pinkish-orange color. \r\n \r\n \"SCR Brick\" (Reg U.S. Pat Off., SCPI (BIA)): See \r\n SCR (Reg U.S. Pat. Off., SCPI (BIA)). \r\n \r\n Sewer Brick : Low absorption, abrasive-resistant \r\n brick intended for use in drainage structures. See ASTM Specification \r\n C 32. \r\n \r\n Soft-Mud Brick : Brick produced by molding relatively \r\n wet clay (20 to 30 percent moisture). Often a hand process. When insides \r\n of molds are sanded to prevent sticking of clay, the product is sand-struck \r\n brick. When molds are wetted to prevent sticking, the product is water-struck \r\n brick. \r\n \r\n Stiff-Mud Brick : Brick produced by extruding a stiff but \r\n plastic clay (12 to 15 percent moisture) through a die. \r\n BRICK AND BRICK : A method of laying brick so that units touch \r\n each other with only enough mortar to fill surface irregularities. \r\n BRICK GRADE : Designation for durability of the unit expressed \r\n as SW for severe weathering, MW for moderate weathering, or NW for negligible \r\n weathering. See ASTM Specifications C 216, C 62 and C 652. \r\n BRICK TYPE : Designation for facing brick which controls tolerance, \r\n chippage and distortion. Expressed as FBS, FBX and FBA for solid brick, \r\n and HBS, HBX, HBA and HBB for hollow brick. See ASTM Specifications C \r\n 216 and C 652. \r\n BUTTERING : Placing mortar on a masonry unit with a trowel. \r\n CAPACITY INSULATION : The ability of masonry to store heat as a \r\n result of its mass, density and specific heat. \r\n C/B RATIO : The ratio of the weight of water absorbed by a masonry \r\n unit during immersion in cold water to weight absorbed during immersion \r\n in boiling water. An indication of the probable resistance of brick to \r\n freezing and thawing. Also called saturation coefficient . See \r\n ASTM Specification C 67. \r\n CENTERING : Temporary formwork for the support of masonry arches \r\n or lintels during construction. Also called center(s). \r\n CERAMIC COLOR GLAZE : An opaque colored glaze of satin or gloss \r\n finish obtained by spraying the clay body with a compound of metallic \r\n oxides, chemicals and clays. It is burned at high temperatures, fusing \r\n glaze to body making them inseparable. See ASTM Specification C 126. \r\n CHASE : A continuous recess built into a wall to receive pipes, \r\n ducts, etc. \r\n CLAY : A natural, mineral aggregate consisting essentially of hydrous \r\n aluminum silicate; it is plastic when sufficiently wetted, rigid when \r\n dried and vitrified when fired to a sufficiently high temperature. \r\n CLAY MORTAR-MIX : Finely ground clay used as a plasticizer for \r\n masonry mortars. \r\n CLEAR CERAMIC GLAZE : Same as Ceramic Color Glaze except \r\n that it is translucent or slightly tinted, with a gloss finish. \r\n CLIP : A portion of a brick cut to length. \r\n CLOSER : The last masonry unit laid in a course. It may be whole \r\n or a portion of a unit. \r\n CLOSURE : Supplementary or short length units used at corners or \r\n jambs to maintain bond patterns. \r\n COLLAR JOINT : The vertical, longitudinal joint between wythes \r\n of masonry. \r\n COLUMN : A vertical member whose horizontal dimension measured \r\n at right angles to the thickness does not exceed three times its thickness. \r\n COPING : The material or masonry units forming a cap or finish \r\n on top of a wall, pier, pilaster, chimney, etc. It protects masonry below \r\n from penetration of water from above. \r\n CORBEL : A shelf or ledge formed by projecting successive courses \r\n of masonry out from the face of the wall. \r\n COURSE : One of the continuous horizontal layers of units, bonded \r\n with mortar in masonry. \r\n CULLS : Masonry units which do not meet the standards or specifications \r\n and have been rejected. \r\n DAMP COURSE : A course or layer of impervious material which prevents \r\n capillary entrance of moisture from the ground or a lower course. Often \r\n called damp check. \r\n DAMPPROOFING : Prevention of moisture penetration by capillary \r\n action. \r\n DOGS TOOTH : Brick laid with their corners projecting from the \r\n wall face. \r\n DRIP : A projecting piece of material, shaped to throw off water \r\n and prevent its running down the face of wall or other surface. \r\n EBM : See Engineered Brick Masonry. \r\n ECCENTRICITY : The normal distance between the centroidal axis \r\n of a member and the parallel resultant load. \r\n \r\n e 1 /e 2 : Ratio of virtual eccentricities occurring \r\n at the ends of a column or wall under design. The absolute value is always \r\n less than or equal to 1.0. \r\n \r\n EFFECTIVE HEIGHT : The height of a member to be assumed for calculating \r\n the slenderness ratio. \r\n EFFECTIVE THICKNESS : The thickness of a member to be assumed for \r\n calculating the slenderness ratio. \r\n EFFLORESCENCE : A powder or stain sometimes found on the surface \r\n of masonry, resulting from deposition of water-soluble salts. \r\n ENGINEERED BRICK MASONRY : Masonry in which design is based on \r\n a rational structural analysis. \r\n FACE : 1. The exposed surface of a wall or masonry unit. \r\n 2. The surface of a unit designed to be exposed in the finished masonry. \r\n FACING : Any material, forming a part of a wall, used as a finished \r\n surface. \r\n FIELD : The expanse of wall between openings, corners, etc., principally \r\n composed of stretchers. \r\n FILTER BLOCK : A hollow, vitrified clay masonry unit, sometimes \r\n salt-glazed, designed for trickling filter floors in sewage disposal plants. \r\n See ASTM Specification C 159. \r\n FIRE CLAY : A clay which is highly resistant to heat without deforming \r\n and used for making brick. \r\n FIRE RESISTIVE MATERIAL : See Non-combustible Material. \r\n FIREPROOFING : Any material or combination protecting structural \r\n members to increase their fire resistance. \r\n FLASHING : 1. A thin impervious material placed in mortar joints \r\n and through air spaces in masonry to prevent water penetration and/or \r\n provide water drainage. 2. Manufacturing method to produce specific color \r\n tones. \r\n FROG : A depression in the bed surface of a brick. Sometimes called \r\n a panel. \r\n FURRING : A method of finishing the interior face of a masonry \r\n wall to provide space for insulation, prevent moisture transmittance, \r\n or to provide a level surface for finishing. \r\n GROUNDS : Nailing strips placed in masonry walls as a means of \r\n attaching trim or furring. \r\n GROUT : Mixture of cementitious material and aggregate to which \r\n sufficient water is added to produce pouring consistency without segregation \r\n of the constituents. \r\n \r\n High-Lift Grouting : The technique of grouting masonry \r\n in lifts up to 12 ft. \r\n \r\n Low-Lift Grouting : The technique of grouting as \r\n the wall is constructed. \r\n HACKING : 1. The procedure of stacking brick in a kiln or on a \r\n kiln car. 2. Laying brick with the bottom edge set in from the plane surface \r\n of the wall. \r\n HARD-BURNED : Nearly vitrified clay products which have been fired \r\n at high temperatures. They have relatively low absorptions and high compressive \r\n strengths. \r\n HEAD JOINT : The vertical mortar joint between ends of masonry \r\n units. Often called c ross joint. \r\n HEADER : A masonry unit which overlaps two or more adjacent wythes \r\n of masonry to tie them together. Often called bonder. \r\n Blind Header : A concealed brick header in the interior \r\n of a wall, not showing on the faces. \r\n \r\n Clipped Header : A bat placed to look like a header \r\n for purposes of establishing a pattern. Also called a false header. \r\n Flare Header : A header of darker color than the field of \r\n the wall. \r\n HEADING COURSE : A continuous bonding course of header brick. Also \r\n called header course. \r\n INITIAL RATE OF ABSORPTlON : The weight of water absorbed expressed \r\n in grams per 30 sq. in. of contact surface when a brick is partially immersed \r\n for one minute. Also called suction. See ASTM Specification C 67. \r\n IRA : See Initial Rate of Absorption. \r\n KILN : A furnace oven or heated enclosure used for burning or firing \r\n brick or other clay material. \r\n \r\n Kiln Run : Brick from one kiln which have not been \r\n sorted or graded for size or color variation. \r\n KING CLOSER : A brick cut diagonally to have one 2 in. end and \r\n one full width end. \r\n LATERAL SUPPORT : Means whereby walls are braced either vertically \r\n or horizontally by columns, pilasters, cross walls, beams, floors, roofs, \r\n etc. \r\n LEAD : The section of a wall built up and racked back on successive \r\n courses. A line is attached to leads as a guide for constructing a wall \r\n between them. \r\n LIME, HYDRATED : Quicklime to which sufficient water has been added \r\n to convert the oxides to hydroxides. \r\n LIME PUTTY : Hydrated lime in plastic form ready for addition to \r\n mortar. \r\n LINTEL : A beam placed over an opening in a wall. \r\n MASONRY : Brick, stone, concrete, etc., or masonry combinations \r\n thereof, bonded with mortar. \r\n MASONRY CEMENT : A mill-mixed cementitious material to which sand \r\n and water must be added. See ASTM C 91. \r\n MASONRY UNIT : Natural or manufactured building units of burned \r\n clay, concrete, stone, glass, gypsum, etc. \r\n \r\n Hollow Masonry Unit : One whose net cross-sectional \r\n area in any plane parallel to the bearing surface is less than 75 percent \r\n of the gross. \r\n \r\n Modular Masonry Unit : One whose nominal dimensions \r\n are based on the 4 in. module. \r\n \r\n Solid Masonry Unit : One whose net cross-sectional \r\n area in every plane parallel to the bearing surface is 75 percent or more \r\n of the gross. \r\n MORTAR : A plastic mixture of cementitious materials, fine aggregate \r\n and water. See ASTM Specifications C 270, C 476 or BIA M1-72. \r\n \r\n Fat Mortar : Mortar containing a high percentage \r\n of cementitious components. It is a sticky mortar which adheres to a trowel. \r\n \r\n High-Bond Mortar : Mortar which develops higher bond \r\n strengths with masonry units than normally developed with conventional \r\n mortar. \r\n \r\n Lean Mortar : Mortar which is deficient in cementitious \r\n components, it is usually harsh and difficult to spread. \r\n NOMINAL DIMENSION : A dimension greater than a specified masonry \r\n dimension by the thickness of a mortar joint, but not more than 1/2 \r\n in. \r\n NON-COMBUSTIBLE MATERIAL : Any material which will neither ignite \r\n nor actively support combustion in air at a temperature of 1200 F when \r\n exposed to fire. \r\n OVERHAND WORK : Laying brick from inside a wall by men standing \r\n on a floor or on a scaffold. \r\n PARGETING : The process of applying a coat of cement mortar to \r\n masonry. Often spelled and/or pronounced parging. \r\n PARTITION : An interior wall, one story or less in height. \r\n PICK AND DIP : A method of laying brick whereby the bricklayer \r\n simultaneously picks up a brick with one hand and, with the other hand, \r\n enough mortar on a trowel to lay the brick. Sometimes called the Eastern \r\n or New England method. \r\n PIER : An isolated column of masonry. \r\n PILASTER : A wall portion projecting from either or both wall faces \r\n and serving as a vertical column and/or beam. \r\n PLUMB RULE : This is a combination plumb rule and level. It is \r\n used in a horizontal position as a level and in a vertical position as \r\n a plumb rule. They are made in lengths of 42 and 48 in., and short lengths \r\n from 12 to 24 in. \r\n POINTING : Troweling mortar into a joint after masonry units are \r\n laid. \r\n PREFABRICATED BRICK MASONRY : Masonry construction fabricated in \r\n a location other than its final inservice location in the structure. Also \r\n known as preassembled, panelized and sectionalized brick masonry. \r\n PRISM : A small masonry assemblage made with masonry units and \r\n mortar. Primarily used to predict the strength of full scale masonry members. \r\n QUEEN CLOSER : A cut brick having a nominal 2 in. horizontal face \r\n dimension. \r\n QUOIN : A projecting right angle masonry corner. \r\n RACKING : A method entailing stepping back successive courses of \r\n masonry. \r\n RAGGLE : A groove in a joint or special unit to receive roofing \r\n or flashing. \r\n RBM : Reinforced brick masonry \r\n REINFORCED MASONRY : Masonry units, reinforcing steel, grout and/or \r\n mortar combined to act together in resisting forces. \r\n RETURN : Any surface turned back from the face of a principal surface. \r\n REVEAL : That portion of a jamb or recess which is visible from \r\n the face of a wall. \r\n ROWLOCK : A brick laid on its face edge so that the normal bedding \r\n area is visible in the wall face. Frequently spelled rolok . \r\n SALT GLAZE : A gloss finish obtained by thermochemical reaction \r\n between silicates of clay and vapors of salt or chemicals. \r\n SATURATION COEFFICIENT : See C/B Ratio . \r\n SCR (Reg U.S. Pat Off., SCPI (BIA)): Structural Clay Research \r\n (trademark Of the Structural Clay Products Institute, BIA). \r\n \r\n \"SCR acoustile \" (Reg U.S. Pat Off., SCPI (BIA) Pat. \r\n No 3,001,6O2): A side-construction two-celled facing tile, having a perforated \r\n face backed with glass wool for acoustical purposes. \r\n \r\n \"SCR brick \" (Reg U.S. Pat Off., SCPI (BIA)): \r\n Brick whose nominal dimensions are 6 by 2 2/3 by 12 in. (Reg U.S. \r\n Pat Off., SCPI (BIA)): \r\n \r\n \"SCR building panel \" (Reg U S. Pat Off., SCPI (BIA) \r\n Pat. No. 3,248,836): Prefabricated, structural ceramic panels, \r\n approximately 2 1/2 in. thick. \r\n \r\n \"SCR insulated cavity wall \" (Reg U.S. Pat Off., \r\n SCPI (BIA)): Any cavity wall containing insulation which meets \r\n rigid criteria established by the Structural Clay Products Institute (BIA). \r\n \r\n \"SCR masonry process \" (Reg. U.S. Pat Off., SCPI \r\n (BIA)): A construction aid providing greater efficiency, better \r\n workmanship and increased production in masonry construction. It utilizes \r\n story poles, marked lines and adjustable scaffolding. \r\n SHALE : Clay which has been subjected to high pressures until it \r\n has hardened. \r\n SHOVED JOINTS : Vertical joints filled by shoving a brick against \r\n the next brick when it is being laid in a bed of mortar. \r\n SLENDERNESS RATIO : Ratio of the effective height of a member to \r\n its effective thickness. \r\n SLUSHED JOINTS : Vertical joints filled, after units are laid, \r\n by \"throwing\" mortar in with the edge of a trowel. (Generally, not recommended.) \r\n SOAP : A masonry unit of normal face dimensions, having a nominal \r\n 2 in. thickness. \r\n SOFFIT : The underside of a beam, lintel or arch. \r\n SOFT-BURNED : Clay products which have been fired at low temperature \r\n ranges, producing relatively high absorptions and low compressive strengths. \r\n SOLAR SCREEN : A perforated wall used as a sunshade. \r\n SOLDIER : A stretcher set on end with face showing on the wall \r\n surface. \r\n SPALL : A small fragment removed from the face of a masonry unit \r\n by a blow or by action of the elements. \r\n STACK : Any structure or part thereof which contains a flue or \r\n flues for the discharge of gases. \r\n STORY POLE : A marked pole for measuring masonry coursing during \r\n construction. \r\n STRETCHER : A masonry unit laid with its greatest dimension horizontal \r\n and its face parallel to the wall face. \r\n STRINGING MORTAR : The procedure of spreading enough mortar on \r\n a bed to lay several masonry units. \r\n STRUCK JOINT : Any mortar joint which has been finished with a \r\n trowel. \r\n SUCTION : See Initial Rate of Absorption. \r\n TEMPER : To moisten and mix clay, plaster or mortar to a proper \r\n consistency. \r\n TIE : Any unit of material which connects masonry to masonry or \r\n other materials. See Wall Tie . \r\n TOOLING : Compressing and shaping the face of a mortar joint with \r\n a special tool other than a trowel. \r\n TOOTHING : Constructing the temporary end of a wall with the end \r\n stretcher of every alternate course projecting. Projecting units are toothers . \r\n TRADITIONAL MASONRY : Masonry in which design is based on empirical \r\n rules which control minimum thickness, lateral support requirements and \r\n height without a structural analysis. \r\n TUCK POINTING : The filling in with fresh mortar of cut-out or \r\n defective mortar joints in masonry. \r\n VENEER : A single wythe of masonry for facing purposes, not structurally \r\n bonded. \r\n VIRTUAL ECCENTRICITY : The eccentricity of a resultant axial load \r\n required to produce axial and bending stresses equivalent to those produced \r\n by applied axial loads and moments. It is normally found by dividing the \r\n moment at a section by the summation of axial loads occurring at that \r\n section. \r\n VITRIFICATION : The condition resulting when kiln temperatures \r\n are sufficient to fuse grains and close pores of a clay product, making \r\n the mass impervious. \r\n WALL : A vertical member of a structure whose horizontal dimension \r\n measured at right angles to the thickness exceeds three times its thickness. \r\n \r\n Apron Wall : That part of a panel wall between window \r\n sill and wall support. \r\n \r\n Area Wall : 1 . The masonry surrounding or \r\n partly surrounding an area. 2. The retaining wall around basement windows \r\n below grade. \r\n \r\n Bearing Wall : One which supports a vertical load \r\n in addition to its own weight. \r\n \r\n Cavity Wall : A wall built of masonry units so arranged \r\n as to provide a continuous air space within the wall (with or without \r\n insulating material), and in which the inner and outer wythes of the wall \r\n are tied together with metal ties. \r\n \r\n Composite Wall : A multiple-wythe wall in which at \r\n least one of the wythes is dissimilar to the other wythe or wythes with \r\n respect to type or grade of masonry unit or mortar \r\n \r\n Curtain Wall : An exterior non-loadbearing wall not \r\n wholly supported at each story. Such walls may be anchored to columns, \r\n spandrel beams, floors or bearing walls, but not necessarily built between \r\n structural elements. \r\n \r\n Dwarf Wall : A wall or partition which does not extend \r\n to the ceiling. \r\n \r\n Enclosure Wall : An exterior non-bearing wall in \r\n skeleton frame construction. It is anchored to columns, piers or floors, \r\n but not necessarily built between columns or piers nor wholly supported \r\n at each story. \r\n \r\n Exterior Wall : Any outside wall or vertical enclosure \r\n of a building other than a party wall. \r\n \r\n Faced Wall : A composite wall in which the masonry \r\n facing and backings are so bonded as to exert a common reaction under \r\n load. \r\n \r\n Fire Division Wall : Any wall which subdivides a \r\n building so as to resist the spread of fire. It is not necessarily continuous \r\n through all stories to and above the roof. \r\n \r\n Fire Wall : Any wall which subdivides a building \r\n to resist the spread of fire and which extends continuously from the foundation \r\n through the roof. \r\n \r\n Foundation Wall : That portion of a loadbearing wall \r\n below the level of the adjacent grade, or below first floor beams or joists. \r\n \r\n Hollow Wall : A wall built of masonry units arranged \r\n to provide an air space within the wall. The separated facing and backing \r\n are bonded together with masonry units. \r\n \r\n Insulated Cavity Wall : See \"SCR insulated cavity \r\n wall\" . \r\n \r\n Loadbearing Wall : A wall which supports any vertical \r\n load in addition to its own weight. \r\n \r\n Non-Loadbearing Wall : A wall which supports no vertical \r\n load other than its own weight. \r\n \r\n Panel Wall : An exterior, non-loadbearing wall wholly \r\n supported at each story. \r\n \r\n Parapet Wall : That part of any wall entirely above \r\n the roof line. \r\n \r\n Party Wall : A wall used for joint service by adjoining \r\n buildings. \r\n \r\n Perforated Wall : One which contains a considerable \r\n number of relatively small openings. Often called pierced wall or \r\n screen wall . \r\n \r\n Shear Wall : A wall which resists horizontal forces \r\n applied in the plane of the wall. \r\n \r\n Single Wythe Wall : A wall containing only one masonry \r\n unit in wall thickness. \r\n \r\n Solid Masonry Wall : A wall built of solid masonry \r\n units, laid contiguously, with joints between units completely filled \r\n with mortar or grout. \r\n \r\n Spandrel Wall : That part of a curtain wall above \r\n the top of a window in one story and below the sill of the window in the \r\n story above. \r\n \r\n Veneered Wall : A wall having a facing of masonry \r\n units or other weather-resisting non-combustible materials securely attached \r\n to the backing, but not so bonded as to intentionally exert common action \r\n under load. \r\n WALL PLATE : A horizontal member anchored to a masonry wall to \r\n which other structural elements may be attached. Also called head plate. \r\n WALL TIE : A bonder or metal piece which connects wythes of masonry \r\n to each other or in other materials. \r\n WALL TIE, CAVITY : A rigid, corrosion-resistant metal tie which \r\n bonds two wythes of a cavity wall. It is usually steel, 3/16 in. in diameter \r\n and formed in a \"Z\" shape or a rectangle. \r\n WALL TIE, VENEER : A strip or piece of metal used to tie a facing \r\n veneer to the backing. \r\n WATER RETENTIVITY : That property of a mortar which prevents the \r\n rapid loss of water to masonry units of high suction. It prevents bleeding \r\n or water gain when mortar is in contact with relatively impervious units. \r\n WATER TABLE : A projection of lower masonry on the outside of the \r\n wall slightly above the ground. Often a damp course is placed at the level \r\n of the water table to prevent upward penetration of ground water \r\n WATERPROOFING : Prevention of moisture flow through masonry due \r\n to water pressure. \r\n WEEP HOLES : Openings placed in mortar joints of facing material \r\n at the level of flashing, to permit the escape of moisture. \r\n WITH INSPECTION : Masonry designed with the higher stresses allowed \r\n under EBM. Requires the establishing of procedures on the job to control \r\n mortar mix, workmanship and protection of masonry materials. \r\n WITHOUT INSPECTION : Masonry designed with the reduced stresses \r\n allowed under EBM. \r\n WYTHE : 1. Each continuous vertical section of masonry one unit \r\n in thickness. 2. The thickness of masonry separating flues in a chimney. \r\n Also called withe or tier. \r\n \r\n \r\n \r\n \r\n \r\n\r\n "},{"TextID":60082,"ResultID":176314,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 20 - Cleaning Brick \r\n Masonry \r\n November 1990 \r\n \r\n Abstract : This Technical Notes \r\n addresses cleaning new buildings, removal of green (vanadium) and \r\n brown (manganese) stains, removal of stains from external sources \r\n and cleaning existing and historic buildings. Procedures included, \r\n if followed with good judgment, should result in successful applications \r\n of cleaning brick masonry. \r\n \r\n Key Words : brick, cleaning , efflorescence , \r\n existing masonry, historic structures, new masonry, stains . \r\n \r\n INTRODUCTION \r\n \r\n The final appearance of a brick masonry wall depends primarily \r\n on the attention given to masonry surfaces during construction and \r\n the cleaning process. Many of the problems of brick masonry, brought \r\n to the attention of the Brick Institute of America over the past \r\n years, have resulted from improper cleaning methods. Some walls \r\n have been irreparably damaged as a result of a lack of attention \r\n to cleaning details and procedures. \r\n Cleaning failures generally fall into one of three categories: \r\n \r\n 1. Failure to thoroughly saturate the brick masonry surface with \r\n water before and after application of chemical or detergent cleaning \r\n solutions. Dry masonry permits absorption of the cleaning solution \r\n and may result in \"mortar smear\", \"white scum\", or the development \r\n of efflorescence or \"green stain\". Saturation of the surface prior \r\n to cleaning reduces the absorption rate, permitting the cleaning \r\n solution to stay on the surface rather than be absorbed. \r\n 2. Failure to properly use chemical cleaning solutions. Improperly \r\n mixed or overly concentrated acid solutions can etch or wash out \r\n cementitious materials from the mortar joints. They have a tendency \r\n to discolor masonry units, particularly lighter shades, producing \r\n an appearance frequently termed \"acid burn\" and can also promote \r\n the development of \"green\" and \"brown\" stains. \r\n 3. Failure to protect windows, doors, and trim. Many cleaning agents, \r\n particularly acid solutions, have a corrosive effect on metal. If \r\n permitted to come in contact with metal frames, the solutions may \r\n cause pitting of the metal or staining of the masonry surface and \r\n trim materials, such as limestone and cast stone. \r\n \r\n GENERAL \r\n \r\n Before the actual cleaning of a project \r\n begins, all cleaning procedures and solutions should be applied \r\n to a sample test area of approximately 20 sq. ft. (1.9 m 2 ). The effectiveness of the \r\n cleaning agent should be judged by inspection of the sample test \r\n area after a period of not less than one week after application. \r\n The size of the test area may be larger, depending upon the cleaning \r\n procedure. The indiscriminate use of muriatic acid or the wrong \r\n proprietary compound can cause unsightly, difficult-to-remove stains. \r\n Reactions of brick and cleaning solutions are not always predictable \r\n and thus it is safer to use a trial-and-error method on a small \r\n test area before committing the entire project to a set procedure. \r\n Minute quantities of certain minerals found in some fired clay masonry \r\n units and materials, such as manganese, added to color brick may \r\n react with some solutions and cause staining. Sample testing should \r\n be performed under conditions of temperature and humidity that will \r\n closely approximate the conditions under which the brickwork will \r\n be cleaned. Chemical cleaning solutions are generally more effective \r\n when the outdoor temperature is 50 o F (10 o C) \r\n or above. \r\n \r\n It is always advisable for the mason to keep the brickwork as free \r\n from mortar smears as possible. However, in modern construction, \r\n where speed is important, even the most skilled of bricklayers may \r\n find this difficult. Some general precautions that can be taken \r\n to promote a cleaner wall are as follows: \r\n 1. Protect the base of the wall from rain-splashed mud and mortar \r\n splatter. Use straw, sand, sawdust, or plastic sheeting spread out \r\n on the ground, extending 3 to 4 ft. (0.9 to 1.2 m) from the wall \r\n surface and 2 to 3 ft. (0.6 to 0.9 m) up the wall. \r\n 2. Scaffold boards near the wall should be turned on edge at the \r\n end of the day to prevent possible rainfall from splashing mortar \r\n and dirt directly on the completed masonry. \r\n 3. Cover walls with a waterproof membrane at the end of the workday \r\n to prevent mortar joint wash out and entry of water into the completed \r\n masonry. \r\n 4. Protect site stored brick from mud. Store brick off the ground \r\n under protective covering. \r\n 5. Careful workmanship should be practiced to prevent excessive \r\n mortar droppings. Excess mortar should be cut off with the trowel \r\n as the brick are laid. Joints should be tooled when \"thumbprint\" \r\n hard. After tooling, excess mortar and dust should be brushed from \r\n the surface. Avoid any motion that will result in rubbing or pressing \r\n mortar particles into the brick faces. A medium soft bristle brush \r\n is preferable. \r\n \r\n CLEANING NEW MASONRY \r\n General \r\n \r\n Table 1 should be referred to as a general cleaning guide for new \r\n masonry. Present cleaning methods for new masonry may be classified \r\n into three categories: 1) Bucket and Brush Hand Cleaning, 2) Pressurized \r\n Water Cleaning, and 3) Sandblasting. Some chemicals or chemical \r\n compounds used to clean brickwork and the resulting fumes may be \r\n harmful. Protective clothing and accessories, proper ventilation \r\n and safe handling procedures must be exercised. The use and disposal \r\n of some chemicals or chemical compounds are regulated by federal, \r\n state or local laws and should be researched before use. Manufacturers \r\n material and handling requirements should be strictly observed. \r\n \r\n \r\n \r\n \r\n \r\n Bucket and Brush Hand Cleaning \r\n \r\n This is probably the most popular but most misunderstood of all \r\n the methods used for cleaning brick masonry. Its popularity is due \r\n to the simplicity of execution and the ready availability of proprietary \r\n cleaning compounds. A recommended general procedure using proprietary \r\n compounds, detergents or acid solutions is as follows: \r\n 1. Select the proper solution. \r\n \r\n \r\n \r\n a. For proprietary compounds, make sure that the one selected \r\n is suitable for the brick and follow the cleaning compound manufacturers \r\n recommended dilution instructions. Many proprietary cleaning \r\n solutions perform in a satisfactory manner for their intended \r\n cleaning jobs. However, their formulae are not generally disclosed \r\n and may be subject to change. It is suggested, therefore, that \r\n each product being considered be sample tested on a panel \r\n or inconspicuous wall area and judged on a trial basis before \r\n being used. \r\n \r\n b. Detergent or soap solutions may \r\n be used to remove mud, dirt and soil accumulated during construction. \r\n A suggested solution is 1/ 2 \r\n cup dry measure (0.14 L) of trisodium phosphate and 1/ 2 cup dry measure (0.14 L) \r\n of laundry detergent dissolved in one gallon (3.9 L) of clean \r\n water. \r\n \r\n c. For acid solutions, mix a 10% solution of muriatic acid \r\n (9 parts clean water to 1 part acid) in a non-metallic container. \r\n Pour acid into water. Do not permit metal tools to contact the \r\n acid solution. There is the temptation to mix acid solutions \r\n stronger than recommended in order to clean stubborn stains. \r\n The indiscriminate use of any acid solution may tend to cause \r\n further stains. \r\n \r\n \r\n \r\n 2. Schedule cleaning at least seven days after the brick masonry \r\n is completed. Mortar must be thoroughly set and cured. Prolonged \r\n time periods between the completion of the masonry work and the \r\n actual cleaning should be avoided when possible. Mortar smears and \r\n splatters left over a long period of time (6 months to 1 year) can \r\n cure on the wall surface and become very difficult to remove. \r\n 3. Remove larger mortar particles by hand with wooden paddles and \r\n non-metallic scrape hoes or chisels. \r\n 4. Protect metal, glass, wood, limestone and cast stone surfaces. \r\n Mask or otherwise protect windows, doors, and ornamental trim from \r\n cleaning solutions. \r\n 5. Presoak or saturate the area to be cleaned. Flush with water, \r\n from the top down. Saturated brick masonry will not absorb the cleaning \r\n solution or dissolved mortar particles. Areas below should also \r\n be saturated in order to prevent absorption of the run-off from \r\n above. \r\n 6. Starting at the top, apply the cleaning solution. Use a long \r\n handled stiff fiber brush or other type as recommended by the cleaning \r\n solution manufacturer. Allow the solution to remain on the brickwork \r\n 5 to 10 minutes. For proprietary compounds follow the manufacturers \r\n instructions for application and scrubbing. Wooden paddles or other \r\n non-metallic tools may be used to remove stubborn particles. Do \r\n not use metal scrapers or chisels. Metal marks will oxidize and \r\n cause staining. \r\n 7. Heat, direct sunlight, warm masonry and drying winds will affect \r\n the drying time and reaction rate of cleaning solutions. Ideally, \r\n the cleaning crew should be working on shaded areas to avoid rapid \r\n evaporation. \r\n 8. Rinse thoroughly!! Flush walls with large amounts of clean water \r\n from top to bottom before they can dry. Failure to completely flush \r\n the wall of cleaning solution and dissolve matter from top to bottom \r\n may result in the formation of \"white scum\". \r\n 9. Work on a small area. The size of the \"wash down\" area should \r\n be determined after a trial run. This will permit the cleaning crew \r\n to examine work for initial results. \r\n \r\n Pressurized Water Cleaning \r\n \r\n To cut labor costs, many cleaning contractors utilize pressurized \r\n water. Some pressure systems feature a pressure gun and nozzle equipped \r\n with a control switch. This setup permits the operator to apply \r\n solutions to a wall over 100 ft. (30.5 m) from the base unit. Other \r\n systems have two separate hoses - one with plain water and the other \r\n with a cleaning solution. Low pressure has been defined as 100 to \r\n 300 psi (700 to 2100 kPa), medium pressure as 300 to 700 psi (2100 \r\n to 4850 kPa) and high pressure as 700 psi (4850 kPa) or greater. \r\n A sand finish or a surface coating may be removed by pressurized \r\n water cleaning, resulting in a different appearance. Nozzle pressure \r\n in excess of 700 psi (4850 kPa) may damage brick units and erode \r\n mortar joints. \r\n Equipment should be as portable as possible. Units may be on wheels, \r\n skids, trailers, or pick-up truck beds. More elaborate systems include \r\n pumps, engines, acid containers, and water storage tanks fixed on \r\n truck beds. \r\n Cleaning compounds used with this method should be compatible with \r\n the equipment. Some equipment manufacturers are careful to recommend \r\n that only specific cleaning compounds be pumped through their equipment. \r\n Others build pumps that will resist hydrochloric acid solutions \r\n for reasonable lengths of time. \r\n The following procedure is suggested: \r\n 1. Select and test the cleaning solution on a sample area. Check \r\n the equipment for cleaning solution compatibility. For proprietary \r\n compounds, mix in accordance with the manufacturers instructions. \r\n 2. - 5. Presoak wall. Same as steps 2 through 5 of Bucket and \r\n Brush Hand Cleaning method. \r\n 6. Application of cleaning solutions may be by a low pressure sprayer, \r\n 30 to 50 psi (200 to 350 kPa), or through the high pressure cleaning \r\n unit. \r\n 7. Permit the cleaning solution to remain on the wall for approximately \r\n 5 minutes. \r\n 8. Starting at the top, flush the wall down, as in the previous \r\n procedure. \r\n Caution : It is possible for solutions to be driven into \r\n the masonry when applied under high pressure, and become the source \r\n of future staining. However, if the walls are sufficiently saturated \r\n with water before the solutions are applied, the risk of penetration \r\n is reduced. Experience has shown that this cleaning method has a \r\n high probability of changing the appearance of sand molded brick, \r\n sand- faced extruded brick, and brick with glazed coatings or slurries \r\n applied to the finished faces. The brick manufacturer should be \r\n consulted on the use of high pressure water cleaning of such brick. \r\n \r\n Sandblasting \r\n \r\n Dry sandblasting has been around for many years and is one method \r\n that may be used to clean brick masonry. However, there is also \r\n the possibility that, through improper execution, the face of brick \r\n units and mortar joints may be scarred. This method is sometimes \r\n preferred over conventional wet cleaning since it eliminates the \r\n problem of chemical reaction with vanadium salts and other materials \r\n used in manufacturing brick. Light and heavily sanded, coated, glazed \r\n and slurry finished brick should not be cleaned by sandblasting. \r\n \r\n \r\n Sandblasting by a qualified operator, in \r\n conjunction with proper specifications and job inspection, can be \r\n satisfactory. Basically, it involves a portable air compressor, \r\n blasting tank, blasting hose, nozzle, and protective clothing and \r\n hood for the operator. The air compressor should be capable of producing \r\n 60 to 100 psi (400 to 700 kPa) at a minimum air flow capacity of \r\n 125 cu ft. (3.5 m 3 ) per minute. The inside orifice \r\n or bore of the nozzle may vary from 3/16 to 5/16 in. (4.8 to 7.9 \r\n mm) in diameter. The sandblast machine (tank) should be equipped \r\n with controls to regulate the flow of abrasive materials to the \r\n nozzle at a minimum rate of 300 lb/h (0.004 kg/s). \r\n \r\n There are various degrees of cutting or cleaning desired and consequently \r\n many types of abrasive materials. They may be of mined silica sand, \r\n crushed quartz, granite, white urn sand (round particles), crushed \r\n nut shells, and other softer abrasives. Mined silica sands and crushed \r\n quartz should have a hardness of approximately 6 on Mohs Scale \r\n and be a Type \"A\" or \"B\" gradation. See Table 2. \r\n A suggested procedure for sandblasting is as follows: \r\n 1. Select sandblast materials that are clean, dust free and abrasive. \r\n 2. Brick masonry should be dry and well cured. \r\n 3. Remove all large mortar particles, as in previous methods. \r\n 4. Protect non-masonry surfaces adjacent to cleaning areas. Use \r\n plastic sheeting, duct tape or other covering materials. \r\n 5. Test clean several areas at varying distances from the wall \r\n and several angles that afford the best cleaning job without damaging \r\n brick and mortar joints. Workmen should be instructed to direct \r\n abrasive at the units and not on the mortar joints. \r\n \r\n \r\n TABLE 2 \r\n Typical Screen Analysis for Sandblasting Sand Abrasives a \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n a The screen analysis listed above is suggested \r\n primarily for mined silica sands and crushed quartz. Reference \r\n source: \"Good Practice for Cleaning New Brickwork\", produced \r\n by the Brick Association of North Carolina, 822 N. Elm St., \r\n Greensboro, NC 27415. \r\n b Type \"A\" gradation is suggested for very lightly \r\n soiled brick masonry or where very light, fine texturing \r\n of the masonry surface is permitted. \r\n c Type \"B\" gradation is suggested for heavy mortar \r\n stains, or where a medium texturing of the masonry surface \r\n is permitted. \r\n \r\n \r\n \r\n \r\n \r\n REMOVING EFFLORESCENCE \r\n \r\n The removal of efflorescent salts is relatively easy compared to \r\n some other stains. Efflorescent salts are water soluble and generally \r\n will disappear of their own accord with normal weathering. This \r\n is particularly true of \"new-building bloom\". White efflorescent \r\n salts can be removed by dry brushing or with clear water and a stiff \r\n brush. Heavy accumulation or stubborn deposits of white efflorescent \r\n salts may be removed with a proprietary cleaner. It is imperative \r\n that the wall be saturated before and after the solution is applied. \r\n Refer to Technical Notes 23 Series for more information on \r\n the cause and prevention of efflorescence. \r\n \r\n REMOVING \"GREEN STAIN\" (VANADIUM SALTS) \r\n \r\n Brick units can develop yellow or green stains resulting from vanadium \r\n salts. These stains can be found on red, buff or white brick. The \r\n vanadium salts responsible for these stains originate in the raw \r\n material used to manufacture certain brick units. \r\n As water travels through the brick, it dissolves the vanadium oxide \r\n and sulfates. Chloride salts of vanadium require highly acidic leaching \r\n solutions and are usually the result of washing brick masonry with \r\n acid solutions. Thus, the problem incurred with \"green staining\" \r\n often does not exist until the brickwork is washed down with an \r\n acid solution. For further information on \"green stain\" refer to \r\n Technical Notes 23 Series. \r\n To minimize the occurrence of green stain: \r\n 1. Store brick off the ground under protective covering. \r\n 2. Do not use acid solutions to clean light colored brick. \r\n 3. Follow the recommendations of the brick manufacturer for the \r\n proper cleaning compounds and procedures. \r\n Should the brickwork have been cleaned with an acid solution and \r\n \"green staining\" appears, the following procedure may be followed \r\n to neutralize the acid: \r\n 1. Immediately following the acid wash, flush brickwork with water. \r\n 2. Wash or spray the brickwork with a solution of potassium or \r\n sodium hydroxide, consisting of 1/2 lb (0.23 kg) hydroxide to 1 \r\n qt (0.95 L) water or 2 lb (0.91 kg) per gal (3.79 L). Allow this \r\n to remain for two or three days. \r\n 3. Use a hose to wash off the white salt remaining on the brickwork \r\n from the hydroxide. \r\n Various proprietary cleaning compounds have been developed to remove \r\n \"green stain\". Their effectiveness on a particular wall can only \r\n be determined by test. \r\n \r\n REMOVING \"BROWN STAIN\" (MANGANESE STAIN) \r\n \r\n Under certain special conditions this stain may occur on mortar \r\n joints of brickwork containing manganese colored units. It appears \r\n as a tan, brown, nearly black, or sometimes gray colored stain. \r\n The \"brown stain\" has an oily appearance and may streak down over \r\n the face of the brick. It appears to be running down from the brick-mortar \r\n interface and is the result of manganese used in some brick as a \r\n coloring agent. When the solution reaches the mortar joints, the \r\n salts are deposited upon neutralization by the cement or lime. See \r\n Technical Notes 23 Series. \r\n During firing in the manufacturing process of some brick, manganese \r\n coloring agents experience several chemical changes. This results \r\n in compounds that are not soluble in water, but are soluble in weak \r\n acid solutions. Since brick can take up acid by absorption, such \r\n weak acid solutions can prevail in brick washed with hydrochloric \r\n acid. Rainwater may also be acidic in some industrialized areas. \r\n To minimize this problem, do not use any acidic solutions \r\n on tan, brown, black or gray brick. There are special proprietary \r\n cleaning compounds available for cleaning brick containing manganese. \r\n These may be tested for effectiveness. The advice of the brick manufacturer \r\n should be requested and followed. \r\n The permanent removal of manganese stain may be difficult. After \r\n initial removal it often returns. The following method has been \r\n effective in removing \"brown stain\" and preventing its return. \r\n 1. Carefully mix a solution of acetic acid (80% or stronger), hydrogen \r\n peroxide (30-35%) and water in the following proportions by volume: \r\n 1 part acetic acid, 1 part hydrogen peroxide, and 6 parts water. \r\n Caution: Although this solution is very effective, it is a dangerous \r\n solution to mix and use. Acetic acid-hydrogen peroxide may also \r\n be available in a premixed form known as peracetic acid. This acid, \r\n a textile chemical, is also dangerous and may be difficult to purchase. \r\n 2. After wetting the brickwork, brush or spray on the solution. \r\n Do not scrub. The reaction is usually very rapid and the stain quickly \r\n disappears. After the reaction is complete, rinse the wall thoroughly \r\n with water. \r\n An alternate solution suggested for new and light colored \"brown \r\n stains\" is oxalic acid crystals and water. Mix 1 lb of crystals \r\n (0.45 kg) to 1 gal (3.79 L) of water. There are also proprietary \r\n compounds formulated to remove \"brown stains\". Their effectiveness \r\n should be judged only after testing. \r\n Proprietary compounds have been used and sometimes found to be \r\n effective in keeping the stain from re-appearing. Consult the recommendations \r\n and directions of the cleaning solution or brick manufacturer when \r\n applying proprietary solutions to remove manganese stains. \r\n \r\n REMOVAL OF EXTERNALLY CAUSED STAINS \r\n General \r\n \r\n These are stains caused by external materials being spilled, splattered \r\n on, and absorbed by the brick. Each is an individual case and must \r\n be treated accordingly. \r\n A large number of external stains can be removed by scrubbing with \r\n kitchen cleanser. Others can frequently be removed by bleaching \r\n with a household bleach. A combination, such as is found in some \r\n kitchen cleansers, may prove most effective. Table 3 lists sources \r\n of some materials suggested for this use. \r\n \r\n TABLE 3 \r\n Sources of Cleaning and Masking Agents a \r\n \r\n \r\n \r\n a Warning: Some chemicals and resulting fumes may \r\n be harmful. Protective clothing and accessories, proper ventilation \r\n and safe handling procedures must be exercised. The use and \r\n disposal of some chemicals are regulated by federal, state or \r\n local laws and should be researched before use. \r\n \r\n \r\n \r\n Poultice \r\n \r\n The use of a poultice is included in some of the recommendations \r\n that follow. A poultice is a paste, made with a solvent or reagent \r\n and an inert material. It works by dissolving the stain and leaching \r\n or pulling the solution into the poultice. The powdery substance \r\n is simply brushed off when dry. Repeated applications may be necessary. \r\n Poultices tend to prevent the stain from spreading during treatment \r\n and to pull the stain out of the pores of the brick. Poultices \r\n are normally used only for small stain spots. \r\n The inert material may be talc, whiting, fullers earth, diatomaceous \r\n earth, bentonite or other clay. The solution or solvent used will \r\n depend upon the nature of the stain to be removed. Enough of the \r\n solution or solvent is added to a small quantity of the inert material \r\n to make a smooth paste. The paste is smeared onto the stained area \r\n with a trowel or spatula and allowed to dry. When dried, the remaining \r\n powder is scraped, brushed or washed off. \r\n If the solvent used in preparing a poultice is an acid, do not \r\n use whiting as the inert material. Whiting is a carbonate which \r\n reacts with acids to give off carbon dioxide. While this is not \r\n dangerous, it will make a foamy mess and destroy the power of the \r\n acid. \r\n \r\n Paint Stains \r\n \r\n For fresh paint, apply a commercial paint remover, or a solution \r\n of trisodium phosphate in water at the rate of 2 lb. (0.91 kg) of \r\n trisodium phosphate in 1 gal (3.79 L) of water. Allow to remain \r\n and soften the paint. Remove with a scraper and a stiff bristle \r\n brush. Wash with clear water. There are also commercial paint removers \r\n in the form of a gel solvent. These should be applied on a small \r\n test area on a trial basis. For very old dried paint, organic solvents \r\n similar to the above may not be effective, in which case the paint \r\n must be removed by sandblasting or scrubbing with steel wool. \r\n \r\n Iron Stains \r\n \r\n Iron stains are quite common and, in some cases, cover large areas. \r\n These stains are easily removed by spraying or brushing with a strong \r\n solution 1 lb (0.45 kg) of oxalic acid crystals per gal (3.79 L) \r\n of water. Ammonium biflouride added to the solution 1/2 lb (0.23 \r\n kg) per gal (3.79 L) will speed up the reaction. The ammonium biflouride \r\n generates hydroflouric acid, a very dangerous material, which can \r\n etch the brick and glass. Etching will be evident on very smooth \r\n brick. Therefore, use this solution only with caution. \r\n Alternate method . Mix 7 parts lime-free glycerine with a \r\n solution of 1 part sodium citrate in 6 parts lukewarm water, and \r\n mix with whiting or diatomaceous earth to make a poultice. Apply \r\n a thick paste on stain with trowel. Scrape off when dry. Repeat \r\n until stain has disappeared and wash thoroughly with clear water. \r\n A poultice made from a solution of sodium thiosulfate and an inert \r\n powder (talc) has also been used for the removal of iron rust stain. \r\n \r\n Copper or Bronze Stains \r\n \r\n Mix together in dry form 1 part ammonium chloride (sal ammoniac) \r\n and 4 parts powdered talc. Add ammonia water and stir until a thick \r\n paste is obtained. Place this over the stain and leave until dry. \r\n When working on glazed brick use a wooden paddle to remove the paste. \r\n An old stain of this kind may require several applications. Aluminum \r\n chloride is sometimes used in the above procedure instead of the \r\n sal ammoniac. \r\n \r\n Welding Splatter \r\n \r\n A problem related to iron staining is welding splatter. When metal \r\n is welded too close to a pile of brick or completed brickwork, some \r\n of the molten metal may splash onto the brick and melt into the \r\n surface. The oxalic acid-ammonium biflouride mixture, recommended \r\n for iron stains, is particularly effective in removing welding splatters. \r\n Scrape as much of the metal as possible from the brick. Apply the \r\n solution in a poultice. Remove the poultice when it is dried. If \r\n the stain has not disappeared, use sandpaper to remove as much as \r\n possible and apply a fresh poultice. For stubborn stains, several \r\n applications may be necessary. \r\n \r\n Smoke \r\n \r\n Smoke is a difficult stain to remove. Scrub with scouring powder \r\n (particularly one containing bleach) and a stiff bristle brush. \r\n Some alkali detergents and commercial emulsifying agents, brush \r\n or spray applied, given sufficient time to work, also perform well. \r\n They should be tested on a small area, before use on a large area. \r\n They have the added advantage that they can be used in steam cleaners. \r\n For small, stubborn stains, a poultice using trichloroethylene will \r\n pull the stain from the pores. Exercise caution when using trichloroethylene \r\n in confined spaces. Ventilate the fumes. \r\n \r\n Oil and Tar Stains \r\n \r\n Oil and tar stains may be effectively removed by commercial emulsifying \r\n agents. For heavy tar stains, mix the agents with kerosene to remove \r\n the tar, and then water to remove the kerosene. After application, \r\n they can be hosed off. When used in a steam cleaning apparatus, \r\n they have been known to remove tar without the use of kerosene. \r\n Where the area to be cleaned is small, or where a mess cannot be \r\n tolerated, a poultice using naphtha or trichloroethylene is most \r\n effective in removing oil stains. \r\n \r\n Also, dry ice or compressed CO 2 may be applied to make tar \r\n brittle. Light tapping with a small hammer and prying with a putty \r\n knife generally will be enough to remove thick tar splatters. \r\n \r\n Dirt \r\n \r\n Dirt is sometimes difficult to remove, particularly from a textured \r\n brick. Scouring powder and a stiff bristle brush are effective if \r\n the texture is not too rough. Scrubbing with an oxalic acid-ammonium \r\n biflouride solution, recommended for iron stains, has proven effective \r\n on some moderately rough textures. For very rough textures, pressurized \r\n water cleaning appears to be a most effective method. \r\n \r\n Straw and Paper Stains \r\n \r\n Straw and paper stains sometimes result from wet packing materials. \r\n Not all packing materials stain brick, but those that do can produce \r\n very stubborn stains. Such stains can be removed by applying household \r\n bleach. Allow time to dry. Several applications may be required \r\n before the stains disappear. The solution of oxalic acid-ammonium \r\n biflouride, recommended for iron stain, cleans the stain much more \r\n rapidly. \r\n \r\n Plant Growth \r\n \r\n Occasionally an exterior masonry surface, not exposed to sunlight, \r\n remains in a constantly damp condition, thus exhibiting signs of \r\n plant growth, i.e., moss. Application of ammonium sulfamate or weed \r\n killer, in accordance with directions furnished with the compound, \r\n has been used successfully for the removal of such growths. \r\n \r\n Ivy \r\n \r\n Avoid pulling the vines away from the masonry since this may damage \r\n the brick or mortar. Carefully cut away a few square feet of vine \r\n in an inconspicuous area and examine how much they have rooted into \r\n the brickwork. Inspect the exposed area for condition and appearance. \r\n There will be some deposits left on the masonry. These are the \"suckers\" \r\n that attached and held the vines. Do not use acids or chemicals \r\n to remove the suckers. Leave in place until they dry and turn dark. \r\n Remove with a stiff bristle brush and detergent. \r\n \r\n Egg Splatter \r\n \r\n Brick walls vandalized with raw eggs have been successfully cleaned \r\n with a saturated solution of oxalic acid crystals dissolved in water. \r\n Mix in a non-metallic container and apply with a brush after saturating \r\n the surface with water. \r\n \r\n White Scum \r\n \r\n White scum is a grayish-white haze on the face of brick. It is \r\n sometimes mistaken for efflorescence, but technically is silicic \r\n acid scum. This condition results from the failure to saturate the \r\n wall before application or thoroughly rinsing acid solutions after \r\n cleaning. Generally, it is a film of material that is insoluble \r\n in acid solutions except for hydroflouric acid, which is very dangerous \r\n and not generally recommended for this use. Proprietary compounds \r\n formulated to remove this condition may be tested and their effectiveness \r\n judged. \r\n If removal is too difficult, masking of the haze may be considered. \r\n In time, weathering will remove both the masking solution and white \r\n scum. \r\n Masking solutions may consist of paraffin oil and Varsol, or linseed \r\n oil and Varsol, applied by brush to the affected brick units. Linseed \r\n oil and Varsol (10-25% linseed oil) or paraffin oil and Varsol (2 \r\n to 50% paraffin oil) will darken light colored brick. Several batches \r\n of solutions with various concentrations should be mixed and tested. \r\n Generally, solutions of 2 to 25% paraffin oil will be satisfactory. \r\n Allow 4 to 5 days of warm drying weather to pass, preferably at \r\n 70 o F (21 o C) minimum, before a judgment is \r\n made on the effectiveness of the solutions. \r\n \r\n Stains of Unknown Origin \r\n \r\n Stains of unknown origin can be a real challenge. Laboratory tests \r\n of unknown stains maybe necessary to determine their composition. \r\n Then the appropriate method may be implemented to clean the brickwork. \r\n The indiscriminate use of any cleaning agent may aggravate the initial \r\n stain and cause further staining. The application of a cleaning \r\n agent without identifying the initial stain may result in other \r\n stains which are difficult to remove. However, appearance of the \r\n stain may be the first clue. \r\n Rust-colored stains may actually be rust. Such stains are quite \r\n common and have been known to come from mortar ingredients, wall \r\n ties or joint reinforcement with inadequate cover, welding splatter \r\n on the brick, or something placed on the pile of brick prior to \r\n being laid in the wall. \r\n \"Green stains\" may be grass, moss or vanadium efflorescence. \"Brown \r\n stains\" may also be vanadium efflorescence, or possibly manganese \r\n staining. \r\n One test useful in narrowing down the list of possible causes of \r\n a stain involves a substance ordinarily not placed on brick masonry. \r\n Concentrated sulfuric acid in contact with an organic material, \r\n will turn it black. This is a quick and easy way to identify stains \r\n originating from such a material. Organic stains can usually be \r\n removed with household bleach or oxalic acid. \r\n \r\n CLEANING EXISTING MASONRY \r\n \r\n The paper, \"Cleaning Masonry - A Review of the Literature\", by \r\n Clayford T. Grimm, lists various methods of cleaning exterior masonry \r\n walls. They are: high-pressure steam, sandblasting, hand washing, \r\n pressurized water and chemicals with steam. \r\n \r\n High-Pressure Steam \r\n \r\n This method lends itself readily and satisfactorily to various \r\n types of masonry and is generally not injurious to most masonry \r\n surfaces. Buildings with smooth hard brick or brick with glazed \r\n surfaces should always be cleaned with steam. The more impervious \r\n a brick unit, the easier it should clean. Steam cleaning without \r\n chemical additives is usually at pressures less than 60 psi (400 \r\n kPa). \r\n In most cases, buildings may be cleaned satisfactorily with plain \r\n high-pressure steam. For stains it is sometimes necessary to use \r\n a chemical or detergent solution. \r\n \r\n Sandblasting \r\n \r\n The dry method of sandblasting should be employed only when brick \r\n will not be damaged and when certain types of brick cannot be successfully \r\n cleaned with high-pressure steam. See the section on Sandblasting \r\n under Cleaning New Masonry . \r\n \r\n Wet Sand Cleaning \r\n \r\n The wet sand cleaning method is used on hard brick and depends \r\n on a water-cushioned abrasive action for its effectiveness. It is \r\n suggested for removal of paint or other surface coatings, where \r\n abrasion of the surface is permissible. Wet sand cleaning employs \r\n water in the cleaning action to eliminate dust. \r\n \r\n Wet Aggregate Cleaning \r\n \r\n The wet aggregate cleaning method is a special process for use \r\n on soft brick and soft stone materials, and is particularly effective \r\n on surfaces with flutings, carvings and other ornamentation. It \r\n is a gentle but thorough process, employing a mixture of water and \r\n a friable aggregate free from silica, delivered at low pressure \r\n through a special nozzle with a \"scouring\" action which cleans effectively \r\n without damage to the surface. \r\n \r\n Hand Washing \r\n \r\n Many buildings of smaller size have been cleaned successfully by \r\n hand washing. It is a bit slower method and does not give the added \r\n advantage of heat as in high-pressure steam. Usually this work is \r\n done by using soap or detergent with cold water. The method is generally \r\n more costly because it is slower, does not lend itself to a job \r\n of any size, and may need to be repeated more often. See the section \r\n on Bucket and Brush Hand Cleaning . \r\n \r\n High-Pressure Cold Water \r\n \r\n This method usually results in a satisfactory job. An ample water \r\n supply is necessary. However, disposing of large volumes of water \r\n used is sometimes a problem. \r\n On hard burned brickwork, water at very high pressure can be effective \r\n but requires careful application by experienced operators. Pressure \r\n should not exceed that which would damage the brickwork being cleaned. \r\n Nozzle pressure in excess of 700 psi (4850 kPa) can damage brick \r\n and mortar joints. \r\n \r\n Chemicals and Steam \r\n \r\n Mr. Grimm points out that chemicals and high-pressure steam are \r\n used primarily to remove applied coatings to masonry, such as paint. \r\n This is a highly specialized field and frequently the proper cleaning \r\n agent can be determined only after an analysis of the various factors \r\n involved in a particular project. \r\n \r\n CLEANING HISTORIC STRUCTURES \r\n \r\n This type of cleaning endeavor should be referred to a restoration \r\n specialist. There are comprehensive papers and publications available \r\n on the subject of restoration. Before an old structure is to be \r\n cleaned, several questions should be asked before making a final \r\n decision, such as: (1) Why clean?, (2) What is the dirt? and (3) \r\n What is the construction of the building? \r\n The query \"Why Clean?\" is posed in the publication \"The Cleaning \r\n and Waterproof Coating of Masonry Buildings\" - Preservation Briefs \r\n No. 1 , by Robert C. Mack, AIA. \r\n \r\n SUMMARY \r\n \r\n Cleaning brick masonry still remains, for the most part, a trial-and-error \r\n procedure. Therefore, it is strongly suggested that any cleaning \r\n procedure and chemical cleaning solution be tested as suggested \r\n in this Technical Notes . Such testing should be performed \r\n under conditions of temperature and humidity that will closely approximate \r\n those conditions under which the brick masonry will be cleaned. \r\n Cleaning compounds recommended by the brick or cleaning agent manufacturer \r\n should also be trial tested before being committed to the entire \r\n project. \r\n If general suggestions and recommendations contained in this Technical \r\n Notes are followed with good judgment and common sense, successful \r\n cleaning of brick masonry should be possible and practical. Due \r\n to the diverse nature of cleaning solutions, procedures and problems, \r\n the Brick Institute of America cannot accept responsibility for \r\n the final success or effectiveness of these procedures. \r\n In conclusion, nothing is quite as effective as careful attention \r\n exercised during construction to keep brick walls relatively clean. \r\n If this is successful, it will eliminate the need for costly cleaning \r\n procedures. \r\n \r\n REFERENCES \r\n \r\n More detailed information on subjects discussed here can be found \r\n in the following publications: \r\n \r\n \r\n 1. Grimm, \r\n C.T., \"Cleaning Masonry - A Review of the Literature\", Construction \r\n Research Center, University of Texas at Arlington, 1988. \r\n 2. Mack, \r\n R.C., \"The Cleaning and Waterproof Coatings of Masonry Buildings\", \r\n Preservation Briefs No. 1 , National Park Service, \r\n Washington, D.C., 1975. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60083,"ResultID":176315,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 21 - BRICK MASONRY CAVITY WALLS \r\n August 1998 \r\n \r\n \r\n Abstract: This Technical Notes covers brick masonry \r\n cavity walls. Description of the properties of cavity walls, \r\n including structural properties, water penetration resistance, \r\n fire resistance, and thermal and sound transmission properties \r\n are included. Theories for structural design are introduced. Recommendations \r\n for cavities, flashing, expansion joints, ties and other related \r\n subjects are covered. \r\n \r\n Key Words: brick, cavity wall, design, expansion joints, \r\n fire resistance, flashing, structural, thermal resistance, ties, \r\n veneer. \r\n \r\n INTRODUCTION \r\n \r\n Brick masonry cavity walls consist of two wythes of masonry \r\n separated by an air space connected by corrosion-resistant metal \r\n ties (see Fig.1). The exterior masonry wythe can be solid or \r\n hollow brick, while the interior masonry wythe can be solid \r\n brick, hollow brick, structural clay tile, or hollow or solid \r\n concrete masonry units. The selection for each wythe depends \r\n on the required wall properties and features. A cavity \r\n of 2 to 4 1/2 in. (50 to 114 mm) between the two wythes may \r\n be either insulated or left as an air space. The interior \r\n surface of the cavity wall may be left exposed or finished in \r\n conventional ways. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Cavity walls, long common in Europe, were first built in the United \r\n States as early as 1850. However, it was not until 1937 \r\n that this type of construction gained official acceptance by any \r\n building code or construction agency in the U.S. Since then, \r\n interest in and use of cavity walls in this country has increased \r\n rapidly. Extensive testing and research and empirical evidence \r\n of existing cavity wall construction has been used to determine \r\n cavity wall properties and performance. Cavity walls are \r\n often regarded as the premier masonry wall system. \r\n \r\n The early use of cavity walls in this country was limited primarily \r\n to exterior load-bearing walls, one and two-stories in height. \r\n In the 1940s, designers of high-rise buildings began to recognize \r\n the advantages of cavity walls and used them as curtain and panel \r\n walls in structural frame buildings. Today, masonry cavity \r\n walls are used extensively throughout the United States in all \r\n types of buildings. See Fig. 2. The primary reasons for \r\n their popularity are: excellent rain penetration resistance, fire \r\n resistance, thermal capabilities and sound transmission resistance. \r\n \r\n A brick cavity wall is differentiated from a brick veneer with masonry \r\n backing by how the designer considers load resistance by the exterior \r\n wythe. The exterior wythe of a cavity wall is designed to \r\n resist loads by stresses developed in that wythe. Further, \r\n both wythes resist out-of-plane loads by stresses in each wythe. \r\n These stresses, whether axial, flexural or shear, must be less than \r\n the corresponding allowable stresses. The exterior wythe of \r\n a brick veneer wall transfers out-of plane loads to the backing \r\n and is not subject to limitations of the allowable stress values. \r\n No axial loads are applied to the veneer wythe. Out-of plane \r\n lateral loads are transferred by metal ties to the backing which \r\n is designed for the full load. Shear stresses generated by \r\n the veneers weight are ignored. Other design issues, such \r\n as water penetration resistance, fire resistance, thermal, and sound \r\n transmission, are the same for either brick masonry cavity walls \r\n or brick veneer over a masonry backing; therefore, such information \r\n in this Technical Notes is appropriate for both types of \r\n wall systems. \r\n \r\n Some parts of the country use the term \"reinforced cavity walls\" \r\n to denote a multi-wythe masonry wall with grout placed between \r\n the wythes. This should actually be considered a multiwythe grouted \r\n masonry wall. Since the definition of a cavity wall includes an \r\n air space, this type of wall is not truly a cavity wall. \r\n \r\n This Technical Notes discusses the properties of cavity walls, \r\n and the proper design to achieve these properties. Other issues \r\n in this Technical Notes series deal with materials, detailing \r\n and proper construction practices for cavity walls. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Camegie \r\n Hall Tower \r\n New York City \r\n Fig. 2 \r\n \r\n \r\n \r\n \r\n PROPERTIES OF CAVITY WALLS \r\n \r\n Structural Properties \r\n \r\n Properly designed, detailed and constructed cavity walls may be \r\n used in any building requiring load-bearing or non-loadbearing \r\n walls. The increased flexibility by the separation of the \r\n wythes and the use of metal ties permits more freedom from differential \r\n movement between the wythes. This is extremely important \r\n in todays construction which makes use of many combinations of \r\n dissimilar materials. \r\n \r\n The structural behavior of cavity walls is complex because of the \r\n interaction of the wythes, ties and support conditions. Typically, \r\n the inner wythe of a cavity wall is designed to support the weight \r\n of floors, roofs are transferred by metal ties to the backing which \r\n is designed for the full load. Shear stresses generated by \r\n the veneers weight are ignored. Other design issues, such \r\n as water penetration resistance, fire resistance, thermal, and sound \r\n transmission, are the same for either brick masonry cavity walls \r\n or brick veneer over a masonry backing; therefore, such information \r\n in this Technical Notes is appropriate for both types of \r\n wall systems. \r\n Some parts of the country use the term \"reinforced cavity walls\" \r\n to denote a multi-wythe masonry wall with grout placed between \r\n the wythes. This should actually be considered a multiwythe grouted \r\n masonry wall. Since the definition of a cavity wall includes an \r\n air space, this type of wall is not truly a cavity wall. \r\n \r\n This Technical Notes discusses the properties of cavity walls, \r\n and the proper design to achieve these properties. Other issues \r\n in this Technical Notes series deal with materials, detailing \r\n and proper construction practices for cavity walls. \r\n \r\n PROPERTIES OF CAVITY WALLS \r\n \r\n Structural Properties \r\n \r\n Properly designed, detailed and constructed cavity walls may be \r\n used in any building requiring load-bearing or non-loadbearing \r\n walls. The increased flexibility by the separation of the \r\n wythes and the use of metal ties permits more freedom from differential \r\n movement between the wythes. This is extremely important \r\n in todays construction which makes use of many combinations of \r\n dissimilar materials. \r\n \r\n The structural behavior of cavity walls is complex because of the \r\n interaction of the wythes, ties and support conditions. Typically, \r\n the inner wythe of a cavity wall is designed to support the weight \r\n of floors, roofs and live loads. The outer wythe is mainly \r\n non-loadbearing. Out-of plane loads are shared by the wythes in \r\n proportion to their stiffnesses and the stiffness of the connecting \r\n ties. Walls tied together by brick headers (masonry bonded \r\n hollow walls or utility walls) behave differently from walls tied \r\n together by metal ties. Therefore, this Technical Notes \r\n addresses only metal-tied walls. Information on masonry bonded \r\n hollow walls (utility walls) can be found in other technical literature \r\n [1]. \r\n \r\n Resistance to Moisture Penetration \r\n \r\n One of the major functions of an exterior wall is to resist \r\n moisture penetration. A brick masonry cavity wall, properly designed \r\n and built, is virtually resistant to water penetration through the \r\n entire wall assembly. The outside wythe may permit some moisture \r\n penetration, but the overall design of the cavity wall assembly \r\n accommodates this expected infiltration. It should be assumed \r\n that wind-driven rain will penetrate the exterior wythe of brick \r\n masonry. A cavity wall is designed as a drainage wall system, \r\n so that any moisture which does penetrate the exterior wythe will \r\n run down the back face of the exterior wythe to the bottom of the \r\n cavity where it is diverted to the outside by flashing and weep \r\n holes. For further discussion of moisture penetration, refer \r\n to the Technical Notes 7 Series. \r\n \r\n Rain Screen Walls \r\n Cavity walls can also be designed as pressure-equalized rain \r\n screen walls. This wall system provides compartmented air \r\n spaces with vents at the top and bottom of the cavity allowing wind \r\n pressures to equalize between the cavity and the exterior. \r\n In theory, the outer wythe is essentially an open rain screen that \r\n eliminates water penetration due to air pressure differences. \r\n Although pressure-equalized rain screen walls can provide increased \r\n resistance to water penetration, they are more difficult to design, \r\n detail and construct. They are typically used in projects \r\n located in areas which receive high volumes of wind-driven rain \r\n and when resistance to water penetration is of prime concern. \r\n Refer to Technical Notes 27 \r\n for more information on pressure-equalized rain screen walls. \r\n \r\n Condensation \r\n Although moisture penetration due to wind-driven rain may be a major \r\n concern, condensation may also be a problem in certain climates \r\n and occupancies. Differences in humidity between inside and \r\n outside air will cause vapor flow within the wall and, unless controlled, \r\n this vapor may condense within the wall under certain temperature \r\n conditions. This condensation may contribute to efflorescence \r\n when soluble salts are present, corrosion of metal ties or disintegration \r\n of the masonry units. A condensation analysis, as described \r\n in Technical Notes 7D , will \r\n help determine the points in a wall system where condensation may \r\n occur. Information found in the Air Barriers and Vapor Retarders \r\n section of this Technical Notes and Technical Notes \r\n 7C should be used for the design against \r\n condensation. \r\n Thermal Properties \r\n \r\n \r\n \r\n \r\n \r\n \r\n Heat losses and heat gains through masonry walls can be minimized \r\n by the use of cavity wall construction. The separation of \r\n the exterior and interior wythes by the cavity eliminates or reduces \r\n thermal bridging and allows a large amount of heat to be absorbed \r\n and dissipated in the outer wythe and cavity before reaching the \r\n inner wythe and the building interior. The cavity provides \r\n an excellent location to incorporate insulation in the wall assembly. \r\n Insulation can be placed in the air space by using a rigid board \r\n attached to the backing or by completely filling the air space \r\n with granular fill or foam. Insulation may also be placed \r\n in the cores of the backing wythe, such as granular fill in concrete \r\n block. Finally, the interior side of the cavity wall may \r\n be finished with insulation and gypsum board. \r\n ,br>Steady-state U-values can range from 0.33 BTU/ (hr o \r\n F o ft 2 ) [1.9 W / m 2 o K ] for an 8-in. (200 mm) uninsulated \r\n cavity wall to 0.06 BTU/ (hr o F o ft 2 ) \r\n [0.34 W / m 2 o K) for a 16 in. (400 mm) cavity \r\n wall with 2-in. (50 mm) polyisocyanurate board insulation. \r\n Table 1 lists R-values for typical cavity walls. Table 2 lists \r\n R-values of the materials used in brick masonry cavity walls. Table \r\n 3 lists thermal properties of interior finishes used in combination \r\n with cavity walls. For example, using Table 3, combine a 12 \r\n in. (300 mm) brick and block cavity wall with extruded polystyrene \r\n in the cavity (R-value of 9.5), with 11/2 in. (38 mm) extruded \r\n polystyrene insulation between metal furring strips at 16 in. (400 \r\n mm) o.c. (R-value of 4.6) resulting in a total R-value of 14.1. \r\n Thermal properties are further enhanced when considering the mass \r\n effect of masonry. Thus, considerable energy savings can be \r\n realized by the use of cavity walls. Refer to Technical \r\n Notes 4 Series for U-values of \r\n materials and assemblies. \r\n \r\n Thermal Mass \r\n Brick masonry exhibits superior thermal mass, that is, \r\n the ability to store and slowly release heat at a later time. \r\n These properties help shift the peak heating or cooling loads to \r\n off-peak times and reduce the peak temperatures. Current energy \r\n codes take thermal mass into account by requiring a lower R-value \r\n for mass walls, such as brick cavity walls (see Technical Notes \r\n 4B ). \r\n Passive solar design can be used in conjunction with cavity wall \r\n construction to take full advantage of masonrys thermal mass properties. \r\n Solar design techniques, such as the use of building orientation, \r\n daylighting and thermal mass, can provide both comfort and energy \r\n savings for the owner and occupants. It is best to incorporate \r\n passive solar techniques in a building during the preliminary design \r\n phase. Technical Notes 43 \r\n Series has information on passive solar design techniques. \r\n Other references are available to assist in design [4, 8]. \r\n \r\n Fire Resistance \r\n \r\n The results of fire resistance tests clearly show that brick masonry \r\n cavity walls have excellent fire resistance. Fire resistance \r\n ratings of brick masonry cavity walls range from 2 to 4 hr, depending \r\n upon the wall thickness and other factors (see Table 4). Due \r\n to their high fire resistance properties, brick walls make excellent \r\n fire walls or building separation walls for compartmentation in \r\n buildings. By using compartmentation, the spread of fire can \r\n be halted. Technical Notes 16 \r\n Series describes fire ratings and applicable design conditions. \r\n \r\n An alternative way of determining the fire resistance of a cavity \r\n wall assembly is by using the calculated fire resistance method. \r\n This approach is approved by the model building codes for determining \r\n fire ratings of walls that are not physically tested by ASTM E 119 \r\n Test Methods for Fire Tests of Building Construction and Materials. \r\n The fire rating of cavity walls can be calculated using Technical \r\n Notes 16B . \r\n \r\n Sound Transmission \r\n \r\n Resistance to transmission of sound in masonry construction is \r\n accomplished in two ways: the use of heavy massive walls or the \r\n use of discontinuous construction. The cavity wall employs \r\n both techniques, i.e., the massiveness of the two masonry wythes \r\n plus the partial discontinuity of the cavity. \r\n \r\n In cavity wall construction, the air space provides a partial isolation \r\n of the two wythes. Sound on one side of a cavity wall causes \r\n vibration of a wythe. Because of the separation and cushioning \r\n effect of the air space and the massiveness of the masonry, the \r\n vibration is dampened and greatly reduced. A 10-in. (250 mm) \r\n brick cavity wall with brick backing has a Sound Transmission Class \r\n (STC) rating of 50, which is usually sufficient for substantially \r\n reducing typical outside noises entering the building through the \r\n wall. For more information on sound transmission, see Technical \r\n Notes 5A . \r\n \r\n DESIGN OF CAVITY WALLS \r\n \r\n The successful design of cavity walls depends on proper attention \r\n to four elements: appropriate design, proper detailing, selection \r\n of quality materials and execution of good workmanship. \r\n All four elements must be satisfied to produce a successful cavity \r\n wall. \r\n \r\n Structural Design \r\n \r\n There are many various design procedures for cavity walls. \r\n Both rational and empirical design methods are used. Rational \r\n design methods currently use working stress analysis. Limit \r\n states or strength design methods are now being written. \r\n Other methods such as a modified yield line approach, fracture \r\n line approach and elastic performance of cracked panels have been \r\n proposed for the design of unreinforced walls. However, \r\n insufficient data and lack of recognition by model building codes \r\n relegate these methods to use as special systems for design. \r\n The structural design of cavity walls should follow either rational \r\n or empirical methods. The rational design method is based \r\n on the properties of the wall materials and engineering analysis. \r\n This method may be used for any structure where high loads are \r\n likely or where tall walls are a necessity. The empirical \r\n method is generally satisfactory for one and two-story buildings \r\n consisting of light construction with limited floor spans and \r\n wall heights; and for multistory buildings where unsupported wall \r\n heights are not excessive. \r\n \r\n Rational Design \r\n . The design of cavity walls is governed by model building codes. \r\n Most of these reference the ACI 530/ASCE 5/TMS 402 Building Code \r\n Requirements for Masonry Structures, also known as the Masonry Standards \r\n Joint Committee (MSJC) Code [2]. The Uniform Building Code \r\n incorporates similar design requirements for cavity walls [9]. \r\n Seismic design requirements are also stipulated in these building \r\n codes based on site location. A detailed design of cavity \r\n walls is not covered in this Technical Notes . For design \r\n aids and examples of design procedures, several books listed in \r\n the REFERENCES section should be consulted [5, 7]. \r\n \r\n The MSJC Code requirements differentiate between multiwythe walls \r\n as those with composite or non-composite action. Composite \r\n action requires a transfer of shear stress between wythes so that \r\n the wythes act as a single element in resisting loads. The \r\n wythes must be bonded with a filled collar joint and metal ties \r\n or with masonry headers. Therefore, all cavity walls are \r\n classified as non-composite walls and must be designed using those \r\n requirements. When non-composite action occurs, each wythe \r\n is designed to individually resist the effects of imposed loads. \r\n In order for both wythes to carry part of the vertical load, the \r\n floor or roof system must bear on both wythes or on a spreader \r\n beam bearing on both wythes. Typically, the wythe closest \r\n to the center of the span of horizontal members resists the resulting \r\n vertical load and the associated shear forces. Out-of plane \r\n loads are apportioned to wythes based upon their relative stiffnesses. \r\n \r\n The rational design method used in the MSJC Code is allowable stress \r\n design. Individual wythes may be either reinforced or unreinforced. \r\n See the Technical Notes 3 Series for more information on \r\n the MSJC Code. \r\n \r\n \r\n \r\n \r\n \r\n Empirical Design \r\n Chapter 9 of the MSJC Code presents empirical requirements \r\n for masonry structures. These requirements are based on past proven \r\n performance and pre-dates rational design methods. According to \r\n the 1995 edition of the MSJC Code, the empirical requirements \r\n in Chapter 9 may be applied to the following masonry elements: \r\n 1.The main lateral force resisting system for buildings in Seismic \r\n Performance Category (SPC) A and all other masonry elements for \r\n buildings in SPC A, B and C. \r\n 2.Buildings subject to a wind velocity pressure not exceeding \r\n 25 psf (1.2 kPa). \r\n 3.Buildings not exceeding 35 ft (10.7 m) in height when \r\n the masonry walls are part of the main lateral load resisting \r\n system. \r\n The empirical requirements may not be applied to structures resisting \r\n horizontal loads other than those due to wind or seismic events. \r\n The MSJC Code contains limits on the ratios of wall thickness \r\n to distance between lateral supports. These limits provide \r\n controls on the flexural tensile stresses within the wall and \r\n limit possible buckling under axial loads. Maximum h/t or \r\n 1/t ratios and minimum thicknesses used for determining distances \r\n between lateral supports are consistent with past masonry standards. \r\n Definitions for height (h), length (1) and thickness (t) for use \r\n in the lateral support ratios for cavity walls are as follows: \r\n \r\n h =the vertical distance or height between lateral \r\n supports; \r\n 1 =the horizontal distance or length between lateral supports; \r\n and \r\n t =the sum of the nominal thicknesses of the inner and outer \r\n wythes. \r\n \r\n Further information on empirical design of brick masonry is provided \r\n in Technical Notes 42 Revised. \r\n \r\n Seismic Issues \r\n As with other loading, the seismic loads from other elements \r\n applied to the wythes are resisted by the loaded wythes. \r\n This requires each loaded wythe to meet prescriptive seismic reinforcement \r\n requirements. For seismic loading due to wall weight, if \r\n the tie spacing and stiffnesses are adequate, the wythes will \r\n share the out-of-plane load in proportion to their relative rigidities. \r\n In such instances, the seismic force can be resisted by just one \r\n wythe. In many cases, the inner wythe is reinforced according \r\n to the minimum reinforcement requirements prescribed by the code \r\n and the brick exterior wythe is treated as a veneer. Proper \r\n ties, reinforcement or isolation joints may be required in specific \r\n seismic performance categories (zones). \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Architectural Design \r\n \r\n Cavity \r\n The cavity or air space between wythes should be between \r\n 2 in. (50 mm) and 41/2 in. (114 mm). Air spaces less than \r\n 2 in. (50 mm) can not practically be kept free from mortar bridging. \r\n Air spaces greater than 41/2 in. (114 mm) do not allow the normally \r\n prescribed ties to properly transfer lateral loads. Air \r\n spaces different from these can be used, but care in design and \r\n construction would be required. If larger air spaces are \r\n used additional ties and/or thicker ties may be necessary. \r\n When rigid board insulation is placed in the air space, the clear \r\n distance from the back side of the brick to the exterior side \r\n of the insulation must be no less than 1 in. (25 mm). This \r\n allows the mason to lay the brick properly and for the wall to \r\n still function as a drainage wall. Mortar protrusions should \r\n not contact the insulation as this is a direct path for water. \r\n These air space requirements also allow for tolerances in construction. \r\n \r\n Since it is assumed that water never crosses the air space, parging \r\n of the cavity face of either wythe is neither necessary, nor recommended. \r\n In cases where mortar could bridge the cavity, where mortar droppings \r\n fill the bottom of the cavity due to poor workmanship, or when \r\n a pressure-equalized rain screen wall is designed, a coating or \r\n membrane on the exterior face of the masonry backing may be prudent. \r\n To be effective, the coating or membrane must be continuous over \r\n the backing and be sealed at interfaces with other elements or \r\n materials. Consideration must be given to the effects of \r\n movement on the coating or membrane. \r\n \r\n Flashing and Weep Holes \r\n Flashing and weep holes collect water that enters a wall \r\n and directs it back to the exterior. Flashing should be \r\n provided at the base of the wall, above and below all wall openings, \r\n at the tops of walls, beneath copings, and any other discontinuities \r\n in the air space, such as recessed courses or shelf angles. \r\n Fig. 3 shows typical flashing locations. \r\n Since flashing is a bond break, the tensile strength of the wall \r\n at that location is assumed to be zero. The shear stress \r\n will also be reduced. The structural design of the building \r\n should address these issues appropriately. \r\n \r\n Flashing and weep holes should be located above grade level. \r\n If the wall continues below the flashing at the base of the wall, \r\n the space between the exterior wythe and the interior wythe should \r\n be filled with mortar or grout to the elevation of the flashing. \r\n \r\n \r\n Flashing should be securely fastened to the interior wythe and extend \r\n through the face of the exterior brick wythe. The flashing should \r\n be turned up at least 8 in. (200 mm) and embedded in the inner wythe. \r\n Flashing should be carefully installed with no punctures or tears. \r\n Where flashing is required to be lapped, the ends of the flashing \r\n should be overlapped a minimum of 6 in. (150 mm) and the laps properly \r\n sealed to avoid water running between the sections. Where the flashing \r\n is not continuous, such as over and under openings in the wall, \r\n the ends of the flashing should be turned up approximately 1 in. \r\n (25 mm) into a head joint in the exterior wythe to form an end dam. \r\n Prefabricated flashing pieces may be available to help form the \r\n detail. Typical flashing details are shown in Technical \r\n Notes 21B Revised and 7 Revised. \r\n \r\n Weep holes must be located immediately above all flashing. \r\n Open head joint or vent weep holes should be spaced no more than \r\n 24 in. (600 mm) o.c. Weep holes formed with wick materials \r\n or with round tubes should be spaced at a maximum of 16 in. (400 \r\n mm) o.c. \r\n \r\n Drainage materials, such as pea gravel or plastic mesh, can be \r\n used at the base of the cavity when mortar droppings are a high \r\n probability. Although these drainage materials are not always \r\n necessary, they may help keep the cavity and the weep holes from \r\n being totally blocked by mortar. However, the use of these \r\n materials does not negate the importance of good workmanship and \r\n keeping the cavity clean from mortar droppings. When pea \r\n gravel is used, its depth should not exceed 2 to 3 in. (50 to \r\n 75 mm). Consideration should be given to the weight of the \r\n gravel on the flashing, the presence of salts in the gravel and \r\n the size of the pea gravel to keep it from flowing out of open \r\n weep holes. These types of materials may interfere with \r\n walls that are designed for air circulation in the cavity. \r\n \r\n Ties \r\n Wall ties provide a connection between the inner and outer wythes \r\n of a cavity wall, and may accommodate differential movements between \r\n the wythes. Tie spacing requirements for cavity walls differ \r\n slightly from those of brick veneer with masonry backing. \r\n Non-composite walls (cavity walls) designed in accordance with \r\n the MSJC Code permit a maximum spacing of 36 in. (910 mm) o.c. \r\n horizontally and 24 in. (610 mm) o.c. vertically. In addition, \r\n the spacing for W1.7 size ties must be no more than one tie for \r\n every 2.67 ft 2 (0.25 m 2 ); and for W2.8 size ties, no more than one \r\n tie for every 4.5 ft 2 (0.42 m 2 ). Adjustable \r\n ties must be spaced at no more than 16 in. (400 mm) o.c. in each \r\n direction and no more than one tie for every 1.77 ft 2 \r\n (0.16 m 2 ). \r\n \r\n When designing the exterior wythe as a veneer, the tie spacing depends \r\n on the type of tie. For adjustable two-piece ties and ties \r\n with a wire size of W 1.7, the spacing should be no more than one \r\n tie for every 2.67 ft 2 (0.25 m 2 ); and for \r\n all other ties, no more that one tie for every 3.5 ft 2 \r\n (0.33 m 2 ). The maximum spacing for ties in a brick \r\n veneer are 32 in. (810 mm) o.c. horizontally and 18 in. (460 mm) \r\n o.c. vertically. Drips in the ties reduce the strength of \r\n the tie, therefore, the wall area per tie must be reduced by 50 \r\n percent. More information on ties can be found in Technical \r\n Notes 44B . \r\n \r\n Foundations \r\n Foundations of brick, concrete masonry or concrete are used to \r\n support brick masonry cavity walls. It is recommended that \r\n the thickness of the foundation or foundation wall supporting \r\n the cavity wall be at least equal to the total thickness of the \r\n cavity wall less 2 in. (50 mm). The brick exterior wythe \r\n may be corbeled out over the top of the foundation; however, the \r\n overhang may not be more than one-third of the bricks thickness \r\n nor more than one-half its height per course. \r\n \r\n A bond break is recommended between the exterior brick wythe and \r\n the foundation. Differential movement between the brick \r\n and concrete or concrete masonry foundation and cracks emanating \r\n from the foundation can be avoided by placing a bond break, such \r\n as a flashing material, on top of the foundation. However, \r\n it must also be remembered that the flashing or bond break changes \r\n the end condition of the wall. The wythes separated from \r\n the foundation by flashing should be designed as a simply-supported \r\n or pinned end walls, not as a fixed end condition. If the \r\n exterior brick wythe is designed as a veneer then this is not \r\n a concern. \r\n \r\n The exterior brick wythe should start above grade. Brick \r\n used below grade must be properly waterproofed with a waterproof \r\n membrane or coating. Weep holes should not be placed below \r\n grade. \r\n \r\n Shelf Angles \r\n Shelf angles are used in buildings to accommodate vertical \r\n movement by allowing an expansion joint to be placed beneath the \r\n angle. Shelf angles must be accompanied with horizontal \r\n expansion (soft) joints, as shown in Fig. 4. The need for \r\n shelf angles in a building depends on the type of structure, height \r\n of building, location of windows, window size and other factors. \r\n The decision to use shelf angles should be based on the effects \r\n of differential movement, type of tie system and connection of \r\n the exterior brick wythe to other building components. The \r\n MSJC Code gives no limits for the placement of shelf angles in \r\n cavity walls or in brick veneer with backings of concrete or concrete \r\n masonry. For low-rise structures, less than 30 ft (9.1 m), \r\n it is advisable to have the brick wythe bear on the foundation \r\n wall. For multi-story structures the effects of differential \r\n movement should be considered. The local building code may \r\n dictate the placement of shelf angles and their required height \r\n from the foundation. \r\n \r\n Care should be taken to ensure proper anchorage and shimming of \r\n the angles to prevent excessive deflection or rotation. \r\n These movements may create problems in construction and induce \r\n concentrated loads in the masonry below. The maximum deflection \r\n and rotation should be no more than the size of the space below \r\n the angle. \r\n \r\n Shelf angles should not be installed as one continuous member. \r\n Spaces should be provided at intervals to permit thermal expansion \r\n and contraction of the steel to occur without causing distress \r\n to the masonry. Shelf angles must provide continuous support \r\n around corners. As at the foundation, at least 2/3 of the \r\n brick wythe thickness must bear on the shelf angle. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Expansion Joints \r\n All building materials change dimension with changes in temperature. \r\n Most building materials, with the exception of glass and metals, \r\n change dimension with changes in their moisture content. \r\n Brick undergoes a permanent moisture expansion. All materials \r\n will deform when subjected to loads. And, some materials, \r\n notably those with cement matrices, will deform plastically (creep) \r\n when loaded. Building frames are subject to movements from \r\n applied vertical and horizontal loads. Concrete and concrete \r\n masonry frames and members, in addition to the above, are subject \r\n to drying shrinkage. Since many cavity walls are built of \r\n dissimilar materials, there will be differential movement between \r\n these materials. All of these movements must be considered \r\n in the design and construction of the wall system. Problems, \r\n such as cracking, can arise if these movements are not recognized \r\n and accommodated. \r\n \r\n In order to prevent distress in the masonry, vertical of differential \r\n movement should be considered. The local building code may \r\n dictate the placement of shelf angles and their required height \r\n from the foundation. \r\n \r\n Care should be taken to ensure proper anchorage and shimming of \r\n the angles to prevent excessive deflection or rotation. \r\n These movements may create problems in construction and induce \r\n concentrated loads in the masonry below. The maximum deflection \r\n and rotation should be no more than the size of the space below \r\n the angle. \r\n \r\n Shelf angles should not be installed as one continuous member. \r\n Spaces should be provided at intervals to permit thermal expansion \r\n and contraction of the steel to occur without causing distress \r\n to the masonry. Shelf angles must provide continuous support \r\n around corners. As at the foundation, at least 2/3 of the \r\n brick wythe thickness must bear on the shelf angle. \r\n \r\n Expansion Joints \r\n All building materials change dimension with changes in \r\n temperature. Most building materials, with the exception \r\n of glass and metals, change dimension with changes in their moisture \r\n content. Brick undergoes a permanent moisture expansion. \r\n All materials will deform when subjected to loads. And, \r\n some materials, notably those with cement matrices, will deform \r\n plastically (creep) when loaded. Building frames are subject \r\n to movements from applied vertical and horizontal loads. \r\n Concrete and concrete masonry frames and members, in addition \r\n to the above, are subject to drying shrinkage. Since many \r\n cavity walls are built of dissimilar materials, there will be \r\n differential movement between these materials. All of these \r\n movements must be considered in the design and construction of \r\n the wall system. Problems, such as cracking, can arise if \r\n these movements are not recognized and accommodated. \r\n \r\n In order to prevent distress in the masonry, vertical and horizontal \r\n expansion joints are used to accommodate movements. No single \r\n recommendation for the positioning and spacing of vertical and horizontal \r\n expansion joints can be applicable to all structures. Each \r\n building must be analyzed to determine the potential movements, \r\n and provisions must be made to permit such movement or to resist \r\n stresses resulting from such movements. Expansion joints must \r\n also be designed, located and constructed so not to impair the integrity \r\n of the wall. The movement of the exterior brick wythe due \r\n to thermal and moisture expansion may be greater than the movement \r\n in solid or composite walls exposed to the same environment. \r\n This is due to the greater temperature differences between wythes \r\n and the absence of vertical loads. For further information, \r\n see Technical Notes 18 Series. \r\n \r\n A distinction should be made between the use of the terms expansion \r\n joint and control joint. An expansion joint is used \r\n to separate brick masonry into segments to prevent cracking due \r\n to an increase in size. The joints are formed of highly \r\n elastic materials placed in a continuous, unobstructed opening \r\n through the brick wythe, see Fig. 5. This allows the joints \r\n to close as a result of an increase in size of the brickwork. \r\n A control joint is used in concrete or concrete masonry \r\n to create a plane of weakness which, used in conjunction with \r\n reinforcement or joint reinforcement, controls the location of \r\n cracks due to a reduction in volume resulting from shrinkage and \r\n creep. A control joint is usually a vertical opening through \r\n the concrete masonry wythe and may be formed of inelastic materials. \r\n A control joint will open rather than close. This distinction \r\n is made so that the wrong type of joint is not used in either \r\n material. These vertical movement joints do not have to \r\n be placed at the same location in a wall. \r\n \r\n Horizontal Expansion Joints \r\n - If the brick is supported on shelf angles attached \r\n to the structural frame, horizontal expansion (soft) joints should \r\n be placed immediately beneath each angle. This is particularly \r\n important in reinforced concrete frame buildings because of frame \r\n shortening. Horizontal expansion joints may be constructed \r\n by leaving an air space or by placing a compressible material \r\n under the shelf angle. Using a compressible pad, such as \r\n a preformed foam pad may assist in keeping debris out of that \r\n space. Mortar should never be placed in this space. \r\n In either case, the joint must be sealed at the exterior face \r\n with a suitable elastic sealant and backer rod. \r\n \r\n Parapets \r\n Of all the masonry elements used in buildings, probably \r\n the most difficult to adequately detail is the parapet wall. \r\n Designers have tried many different ways to design parapets to \r\n minimize cracking, leaking and displacement. Some experts \r\n believe that the only sure way to avoid parapet problems is to \r\n eliminate the parapet altogether. However, they are frequently \r\n required by building codes or for architectural or fire safety \r\n considerations. \r\n The detail shown in Fig. 6 is suggested as one method of building \r\n a parapet. For cavity wall construction, it is recommended \r\n that the cavity continue up through the parapet, thereby maintaining \r\n the separation between the outside wythe and the inner wythe. \r\n In addition, the backing wall of the parapet may be need to be \r\n reinforced and attached to the structural frame. Expansion \r\n joints should extend up through the parapet. Expansion joints \r\n should also be placed near corners to avoid displacement of the \r\n parapet. \r\n Parapet copings should provide a drip on at least one side of \r\n the wall. Metal, stone, and fired clay copings of various \r\n designs usually provide this feature. The back side of the \r\n parapet should be constructed of durable materials, preferably \r\n the same material that is used in the front side of the parapet. \r\n They should not be painted or coated, but must be left free to \r\n \"breathe.\" Unless copings are impervious with watertight \r\n joints, place through-wall flashing in the mortar bed immediately \r\n beneath them and firmly attach the coping to the wall below with \r\n mechanical anchors. The joints between precast concrete \r\n and stone copings should be raked out to two times the width of \r\n the joint and filled with a backer rod and sealant. \r\n \r\n \r\n \r\n \r\n \r\n Thermal Design \r\n \r\n Since energy costs to heat and cool a building over its life are \r\n greater than the initial construction cost of the building, good \r\n energy design is important. Local climate and building codes \r\n may dictate the level of thermal performance necessary for a particular \r\n building. Depending on these requirements, insulation may \r\n need to be included in the cavity wall. Heavy-weight walls, \r\n such as cavity walls, have good thermal mass properties; therefore, \r\n required R-values are less than those required for lighter-weight \r\n walls. \r\n \r\n When insulation is necessary in brick masonry cavity walls, several \r\n locations can be used. Insulation can be placed: 1) in the cavity; \r\n 2) in the cells of hollow unit backing; or 3) on the inside of \r\n the interior wythe using studs or furring strips. The location \r\n of the insulation influences the energy performance of the building \r\n and the drainability and constructability of the wall. \r\n \r\n Newer types of insulation strategies, such as foam-filled cavities, \r\n drainage mats attached to insulation and drainable mineral fiber \r\n insulation used in the air space should have a good track record \r\n of in-place performance before they are considered. Manufacturers \r\n technical data should be carefully reviewed. \r\n \r\n Thermal Bridges \r\n A thermal bridge is a component or assembly through which \r\n heat (or cold) is transferred at a substantially higher rate than \r\n through the surrounding wall. A thermal bridge can degrade \r\n a walls thermal performance or allow condensation to occur more \r\n easily. Examples of thermal bridges in cavity wall construction \r\n are slab edge details, corner columns and roof parapets (see Fig. \r\n 7). Metal ties can be considered a thermal bridge; however, \r\n the effect of ties are negligible. Insulation placement is usually \r\n the easiest way to avoid thermal bridging. \r\n \r\n Air Barriers and Vapor Retarders. \r\n Air leakage through the building envelope can severely \r\n degrade the thermal performance of a wall, and increase space \r\n conditioning loads and the chance for condensation. Air \r\n leakage carries heat and moisture between the inside and outside \r\n of the building. Infiltrating air is not filtered or conditioned, \r\n and its rate can not be controlled. The control of air leakage \r\n is important to the thermal performance of the building. \r\n The need for air barriers and vapor retarders is dependent upon \r\n climate, building use and the construction assembly. What \r\n works in one situation may not be appropriate for another. \r\n Therefore, each building must be examined on a case-by-case basis. \r\n Typically, extreme climates that have very cold winters or very \r\n humid summers are candidates for air retarders and vapor barriers. \r\n Moderate climates are less likely to require these membranes. \r\n In many cases, an air barrier may be more effective than a vapor \r\n retarder since air leakage can carry several hundred times more \r\n water vapor than vapor movement. \r\n \r\n Air barriers must provide continuity, airtightness, structural integrity \r\n and durability. Since the placement of an air barrier is usually \r\n not critical, it is often located on the exterior face of the inner \r\n wythe. This allows for a solid surface on which to attach \r\n (adhere) the air barrier, although there may be discontinuities \r\n at the structural frame or penetrations through the wall. \r\n For walls with insulation placed in the air space, the insulation \r\n protects the air barrier from temperature extremes. Continuity \r\n of the air barrier is of utmost importance. The air barrier \r\n must be kept free from punctures and tears, and it must be continuous \r\n over the entire wall assembly by sealing any penetrations. \r\n Materials include parging, elastomeric membranes or insulation. \r\n More information on materials is found in Technical Notes 21A \r\n Revised. \r\n \r\n Vapor retarders are used to slow or stop the rate of water vapor \r\n transmission through a wall. An effective vapor retarder decreases \r\n the potential for condensation in a wall. A low vapor permeance \r\n classifies the material as a vapor barrier. Although this \r\n value is usually taken as less than 1 perm (57 ng/Pa o \r\n s o m 2 ), the perm rating should be based on \r\n the entire wall design and the vapor pressure difference across \r\n the wall. A vapor retarder should have the same characteristics \r\n as an air barrier, i.e. continuity, low permeance, structural integrity \r\n and durability. The preferred location of the vapor retarder \r\n is on the high vapor pressure side of the wall. Most people \r\n know the saying \"on the warm side of the wall.\" In climates \r\n dominated by heating, the vapor retarder would be located on the \r\n inside of the wall and in cooling climates near the exterior. \r\n These rules are often too simplistic and do not cover many parts \r\n of the country. Therefore, it is suggested that a condensation \r\n analysis be run on the wall in question based on the local climate. \r\n This will provide an accurate depiction of any potential problem. \r\n Technical Notes 7C and 7D \r\n discuss condensation and analysis procedures. \r\n \r\n A potential problem can occur where the construction materials \r\n and their location may create a double vapor retarder. This \r\n may trap water between the two barriers with no chance for evaporation. \r\n When specifying materials, such as interior wall coverings, make \r\n sure the permeance is high enough to avoid the entrapment of vapor. \r\n A membrane may serve as both an air barrier and vapor retarder. \r\n This is true of many elastomeric coatings used in cavity wall \r\n construction. In this case, use the more critical design \r\n requirement and apply that to that material. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes provides an introduction to brick masonry \r\n cavity walls and discusses their various properties. Information \r\n is provided for the proper design of cavity walls. Cavity \r\n wall use will continue and recommendations found in this Technical \r\n Notes will improve building performance. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering \r\n staff of the Brick Industry Association. The information contained \r\n herein must be used in conjunction with good technical judgment \r\n and a basic understanding of the properties of brick masonry. \r\n Final decisions on the use of the information contained in this \r\n Technical Notes are not within the purview of the Brick Industry \r\n Association and must rest with the project architect, engineer and \r\n owner. \r\n \r\n REFERENCES \r\n \r\n 1. An Inside Look at the Utility Brick Wall , Brick Association \r\n of the Carolinas, Charlotte, NC. \r\n \r\n 2. Building Code Requirements for Masonry Structures (ACI \r\n 530/ASCE 5/TMS 402), The Masonry Society, Boulder, CO, 1995. \r\n \r\n 3. Catalog of Thermal Bridges in Commercial and Multi-Family \r\n Residential Construction , Oak Ridge National Laboratory, Oak \r\n Ridge, TN, December 1989. \r\n \r\n 4. Designing Low-Energy Buildings: Passive Solar Strategies & \r\n Energy 10 Software , Passive Solar Industries Council, Washington, \r\n D.C., June 1996. \r\n \r\n 5. Drysdale, R.G., Hamid, A.A., Baker, L.R., Masonry Structures: \r\n Behavior and Design , Prentice Hall, Englewood Cliffs, NJ, 1994. \r\n \r\n 6. Handbook of Fundamentals , American Society of Heating, \r\n Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA, \r\n 1997. \r\n \r\n 7. Masonry Designers Guide , The Masonry Society, Boulder, \r\n CO, 1993. \r\n \r\n 8. Thermal Mass Handbook , Concrete and Masonry Design Provisions \r\n Using ASHRAE/IES 90.1-1989, Eley Associates, San Francisco, CA, \r\n 1994. \r\n \r\n 9. Uniform Building Code , International Council of Building \r\n Officials, Whittier, CA, 1997. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60084,"ResultID":176316,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 21A -BRICK MASONRY CAVITY WALLS -SELECTION OF MATERIALS \r\n Feb. 1999 \r\n \r\n Abstract: The selection of quality materials is essential to the \r\n successful performance of brick masonry cavity walls. Careful evaluation \r\n of materials is required in order to obtain the high performance level \r\n associated with these wall systems. This Technical Notes \r\n addresses selection of appropriate materials, referencing ASTM standards \r\n when applicable. \r\n \r\n Key Words: air retarder, brick, cavity wall, expansion joint, flashing, \r\n insulation, materials, mortar, ties, vapor retarder, weep holes. \r\n \r\n INTRODUCTION \r\n \r\n Brick masonry cavity walls have always been a popular choice with structural \r\n frames and as bearing walls, particularly for use in commercial construction. \r\n These wall types are selected for their superior in-service performance \r\n resulting from such properties as excellent moisture penetration resistance, \r\n thermal capabilities, sound transmission resistance and fire resistance. \r\n All of these qualities of brick masonry cavity walls depend on four key \r\n elements: design, material selection, detailing and construction. \r\n Proper design will not compensate for inadequate material selection or \r\n detailing. Conversely, superior design, material selection, or detailing \r\n will not compensate for poor construction practices. The use of \r\n quality materials in the construction of brick masonry cavity walls is \r\n of prime importance. The selection of materials is even more critical \r\n now that masonry design standards and model codes put greater emphasis \r\n on material properties for design requirements. This Technical \r\n Notes addresses proper material selection. Properties of brick \r\n masonry cavity walls, adequate detailing and construction are addressed \r\n in other Technical Notes in this series. \r\n \r\n GENERAL \r\n \r\n The standards of choice for quality construction materials are those developed \r\n by the American Society for Testing and Materials (ASTM). ASTM has \r\n developed standard specifications for virtually all construction-related \r\n building materials. These specifications are based on laboratory \r\n tests, field experience and, in the case of brick masonry units, are the \r\n result of the legacy of masonrys long successful performance. ASTM \r\n standards are consensus documents that set minimum acceptable requirements \r\n for materials of construction. ASTM standards allow for different \r\n performance levels and it may be necessary to choose a level in the project \r\n specifications to meet the particular requirements for an individual project. \r\n ASTM standards should be reviewed and understood before they are incorporated \r\n into a project specification. It must also be understood that the \r\n use of ASTM standards does not guarantee the desired performance, even \r\n though all materials may meet the specifications. \r\n There are additional materials available that are not addressed in this \r\n Technical Notes that would accomplish the goal of providing proper \r\n material selection. Lack of specific reference to a material does \r\n not preclude its use for brick masonry cavity walls. \r\n \r\n MASONRY UNITS \r\n \r\n The exterior wythe of a brick masonry cavity wall may be of solid or hollow \r\n brick. The interior wythe can be solid brick, hollow brick, structural \r\n clay tile or hollow or solid concrete masonry units. \r\n \r\n Brick \r\n \r\n Solid brick units should meet the requirements of ASTM C 216 Specification \r\n for Facing Brick when appearance is a factor or C 62 Specification for \r\n Building Brick when appearance is not important. Hollow brick units \r\n should meet the requirements of ASTM C 652 Specification for Hollow Brick. \r\n For these specifications, Grade SW should be specified for all exterior \r\n exposures in areas that experience freeze/thaw cycling. Grade MW \r\n units may be used for the interior wythe. Ceramic glazed solid brick \r\n used for both the exterior and interior wythe of cavity walls should meet \r\n the requirements of ASTM C 1405 Specification for Glazed Brick (Single \r\n Fired, Solid Brick). Other ceramic glazed units should conform to \r\n ASTM C 126 Specification for Ceramic Glazed Structural Clay Facing Tile, \r\n Facing Brick and Solid Masonry Units. Information on classification \r\n and selection of brick can be found in Technical Notes 9A \r\n and 9B , respectively. Further information \r\n on brick masonry material selection for adequate strength and compliance \r\n with the Masonry Standards Joint Committee (MSJC) Code and Specification \r\n can be found in Technical Notes 3 Series. \r\n \r\n Concrete Masonry Units \r\n \r\n Concrete masonry units are usually used for the interior wythe of a cavity \r\n wall in combination with a brick masonry exterior. They may also \r\n be used as accent bands in the exterior brick wythe. Hollow or solid \r\n concrete masonry units should conform to ASTM C 55 Specification for Concrete \r\n Building Brick, ASTM C 90 Specification for Loadbearing Concrete Masonry \r\n Units or ASTM C 129 Specification for Non-Loadbearing Concrete Masonry \r\n Units. Non load-bearing concrete masonry units are usually specified \r\n for the interior wythe when the brick and block cavity wall is used as \r\n infill walls for concrete or steel frame structural systems if shear loads \r\n are not transmitted to that wythe. \r\n \r\n Structural Clay Tile \r\n \r\n Structural clay tile has been used as a backing material for cavity wall \r\n construction. Structural clay tile for this purpose should conform to \r\n ASTM C 126, ASTM C 34 Specification for Structural Clay Load-Bearing Wall \r\n Tile or ASTM C 212 for Structural Clay Facing Tile. Clay tile units \r\n under ASTM C 126 and ASTM C 212 are commonly used for the interior wythe \r\n of a cavity wall when left exposed for architectural appearance reasons. \r\n \r\n MORTAR \r\n \r\n The strength and moisture penetration resistance of a brick masonry cavity \r\n wall are affected by the mortar selection and compatibility with the brick \r\n units. Portland cement-lime, mortar cement, or masonry cement mortars \r\n can be used. However, mortars with an air content less than 12 percent \r\n are recommended for their superior bond strength and resistance to moisture \r\n penetration. The MSJC Code requires that the allowable flexural \r\n tensile stresses be reduced by approximately 50 percent for assemblies \r\n constructed with masonry cement mortars or portland cement-lime mortars \r\n that have air entrainment. In addition, some building codes prohibit \r\n the use of masonry cement mortars and all Type N mortars in Seismic Performance \r\n Categories D and E (formerly Seismic Zones 3 and 4). \r\n Mortar should meet the proportion requirements of ASTM C 270 Specification \r\n for Mortar for Unit Masonry as shown in Table 1. Mortar type selection \r\n should be based on project requirements, such as strength and compatibility \r\n with a particular brick unit. Types N or S mortars are typically \r\n used in brick masonry cavity walls. See Technical Notes 8 \r\n Series for more detailed information on mortar types and selection. \r\n \r\n WALL TIES \r\n \r\n Wall ties must provide two important functions: 1) distribute lateral \r\n loads between wythes; and 2) accommodate differential movement between \r\n wythes. For a wall tie system to provide these functions, it must: \r\n 1) be securely attached and embedded in the masonry wythes; \r\n 2) be placed at the appropriate spacing; \r\n 3) have sufficient strength to transfer lateral loads with minimal deformations; \r\n 4) have a minimal amount of mechanical play, if an adjustable tie; \r\n 5) have sufficient corrosion resistance; \r\n 6) be easily installed without damage to the tie system or other wall \r\n components; and \r\n 7) not compromise expected wall performance. \r\n Although cost of the wall tie should be considered, this should not be \r\n the controlling factor since the cost of the wall tie system is small \r\n as compared to the total cost of the wall assembly. \r\n There are many different wall tie types available for use in brick masonry \r\n cavity walls. These include unit ties, horizontal joint reinforcement \r\n and adjustable ties. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Unit Ties \r\n \r\n Unit ties can be rectangular ties or \"Z\" ties as shown in Figure 1. \r\n These tie types are usually fabricated from cold-drawn steel wire in accordance \r\n with ASTM A 82 Specification for Steel Wire, Plain, for Concrete Reinforcement. \r\n They can also be fabricated from stainless steel conforming to ASTM A 167 \r\n Specification for Stainless and Heat-Resisting Steel Plate, Sheet and Strip \r\n for use in more corrosive environments. Corrugated sheet metal ties \r\n are not recommended for brick masonry cavity walls because they do not usually \r\n transfer loads properly between wythes. Wall ties with drips should \r\n not be used since they reduce the capacity of the ties significantly. \r\n Metal \"Z\" ties should only be used between wythes of solid masonry units \r\n in brick masonry cavity walls. Rectangular ties can be used for all \r\n brick masonry cavity walls are therefore recommended instead. Wire \r\n ties should be either wire size W1.7, [No. 9 gage, (0.148 in.) (3.8 mm)] \r\n or W2.8, [3/16 in. (4.8 mm)] in diameter. \r\n \r\n Horizontal Joint Reinforcement \r\n \r\n Continuous horizontal joint reinforcement should meet the requirements of \r\n ASTM A 951 Specification for Masonry Joint Reinforcements. Horizontal \r\n joint reinforcement is typically produced in 10 to 12 ft (3 to 4 m) lengths. \r\n Longitudinal wires are typically W1.7 [No. 9 gage, (0.148 in.) (3.8 mm)] \r\n or W2.8 [3/16 in. (4.8 mm)] diameter wire. Cross wires are W1.7 or \r\n W2.8 diameter wire and should be spaced at a maximum of 16 in. (400 mm) \r\n on center horizontally. Cross wires without drips should be used. \r\n The total thickness of the wires should not exceed one-half the joint thickness. \r\n Horizontal joint reinforcement configurations available are the ladder, \r\n truss and tab types as shown in Fig. 2. \r\n Tests indicate that brick masonry cavity walls tied by the use of horizontal \r\n joint reinforcement perform similar to that of the same wall systems tied \r\n together with metal unit ties. These tests also indicate that truss-type \r\n joint reinforcement used in brick cavity wall construction helped to develop \r\n a degree of composite action in the horizontal span, but did not contribute \r\n to any composite action in the vertical span. This restraint in the \r\n horizontal direction will reduce the amount of in-plane movement and possibly \r\n result in bowing of the masonry walls. Thus, truss-type joint reinforcement \r\n is not recommended for brick and block cavity walls. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Adjustable Ties \r\n \r\n Use of adjustable ties has increased for several reasons: 1) the structure \r\n can be enclosed faster since the exterior brick wythe can be erected later \r\n in the construction process; 2) adjustable ties compensate for the height \r\n differences between wythes and construction tolerances; and 3) they can \r\n accommodate larger differential movement between wythes. \r\n When specifying adjustable ties, there are certain conditions which must \r\n be considered. The model building codes limit the vertical offset \r\n between the eye and pintle components to 11/4 in. (31.8 mm). Maximum \r\n play within the connecting pieces is limited to 3/16 in. (1.6 mm). \r\n Once engaged, the pieces should not be able to separate. The strength \r\n and stiffness of adjustable ties are generally less than that of unit ties \r\n or horizontal joint reinforcement. Thus, more ties are required. \r\n Adjustable Unit Ties. Such ties available for brick masonry cavity \r\n walls are shown in Fig. 3. These ties typically have two-pieces consisting \r\n of a double eye and pintle configuration. Adjustable unit ties should \r\n be at least W2.8 [3/16 in. (4.8 mm)] in diameter and meet the conditions \r\n previously stated. \r\n Adjustable Joint Reinforcement Assemblies. Adjustable ties with ladder- \r\n and truss- type joint reinforcement are also produced. This type of \r\n tie consists of rectangular tie extensions connected to standard joint reinforcement, \r\n see Fig. 4. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Adjustable Unit Ties \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Corrosion Resistance \r\n \r\n Corrosion potential can be affected by the function of the structure, geographic \r\n location, presence of insulation or vapor retarders (alters the dew point \r\n within the wall), compatibility of construction materials, design and detailing \r\n of the wall system and workmanship used in construction. Resistance \r\n to corrosion can be provided by control of environmental factors or by selection \r\n of the tie material. \r\n \r\n There are three types of materials used for corrosion protection of wall \r\n ties: galvanizing (zinc coatings), stainless steel and epoxy coatings. \r\n Galvanizing provides resistance to corrosion in two ways. First, the \r\n zinc coating acts as a barrier to corrosion by shielding the underlying \r\n metal. Second, the zinc coating acts as a sacrificial element that \r\n is consumed by the corrosive environment before the base metal is attacked. \r\n Generally, as the thickness of the zinc coating increases, the period of \r\n protection increases. \r\n Two methods of galvanizing are available: mill galvanizing and hot-dip galvanizing. \r\n Mill galvanizing takes place after the steel wire has been drawn, but prior \r\n to fabrication of the tie. Therefore, the cut end of the tie will \r\n not be protected. Hot-dip galvanizing is performed by dipping the \r\n completed assembly into molten zinc until a specified amount of zinc is \r\n bonded to the base metal. Hot-dip coatings are typically thicker than \r\n mill galvanizing, and therefore, provide longer periods of protection. \r\n Minimum corrosion protection for galvanized ties should be according to \r\n ASTM A 153, Class B-2 (1.5 oz/ft ² ) (458 g/m²). \r\n Zinc coating requirements are related to the size of the element to be coated. \r\n \r\n \r\n Stainless steel can be used for unit ties or joint reinforcement to resist \r\n corrosion. Stainless steel materials should conform to ASTM A 167, \r\n Type 304. \r\n \r\n Another method recently developed for corrosion protection of metal ties \r\n is epoxy coating. The application of an epoxy coating is similar to \r\n that for reinforcing bars used in reinforced concrete or masonry construction. \r\n Epoxy coatings provide protection by acting as an impervious barrier. These coatings are applied \r\n to the base steel by an electrostatic spray method. The coating bonds \r\n to the steel by a heat-induced chemical reaction in which chemical and mechanical \r\n bonds form. This aids in preventing cracking of the coating due to \r\n handling and installation. This coating type is not sacrificial like \r\n zinc coatings. At present, an ASTM Standard governing this type of \r\n corrosion protection has not been developed. Some manufacturers have \r\n been using an adaption of ASTM A 775 Specification for Epoxy-Coated Reinforcing \r\n Steel Bars for metal tie purposes. At this time, hot-dip galvanizing \r\n is preferred over epoxy-coated ties since any nicks, voids or cuts of the \r\n epoxy coating could lead to corrosion of the base steel. \r\n \r\n THROUGH-WALL FLASHING \r\n \r\n Flashing is a necessary component of the wall assembly to assure the excellent \r\n moisture penetration resistance of brick masonry cavity walls. Its \r\n main purpose is to collect any moisture that penetrates the exterior wythe \r\n and divert it to the outside of the wall system. \r\n \r\n There are a variety of flashing materials that can be used with brick masonry \r\n cavity walls. Flashing for masonry construction generally fall into \r\n three categories: sheet metals, composite materials (combination flashing) \r\n and fabrics (plastic or rubber compounds). Materials such as polyethylene \r\n sheeting and asphalt-impregnated building felt should not be used as flashing \r\n materials. These materials can be easily torn or punctured during \r\n installation. \r\n \r\n Flashing must possess certain physical properties. Water resistance \r\n is the main attribute. However, flashing should also be durable and \r\n resistant to damage during installation. Resistance to puncturing \r\n or tearing and resistance to ultraviolet light must be evaluated in flashing \r\n selection. Flashing material should not be susceptible to corrosion \r\n in fresh mortar or react with adjacent materials such as rigid insulation. \r\n \r\n Flashing should be easily formed into the desired shape. Compatibility \r\n with materials such as sealants or adhesives should be reviewed. Expected \r\n life of the flashing materials should be the expected life of the structure, \r\n at a minimum. All of these qualities of the flashing material must \r\n be taken into consideration in selection because replacement is expensive. \r\n Table 2 describes the thickness and advantages and disadvantages of flashing \r\n materials that can be installed in brick masonry cavity walls. \r\n \r\n Sheet Metals \r\n \r\n Sheet metals used for flashing include stainless steel, copper, lead-coated \r\n copper and galvanized steel. Aluminum should not be used since it \r\n can corrode in fresh mortar. Stainless steel and copper materials \r\n are the most durable, but are also the most expensive. Galvanized \r\n steel has also been used in limited applications. These flashing materials \r\n have a greater life expectancy than composite or fabric flashing. \r\n Sheet metal flashing is bent and formed on site and sealed by soldering \r\n or with adhesives and rivets. This additional installation time can \r\n result in additional construction costs. Stainless steel materials \r\n should conform the ASTM A 167 Specification for Stainless and Heat-Resisting \r\n Steel Plate, Sheet and Strip. Copper flashing should comply with ASTM \r\n B 370 Specification for Copper Sheet and Strip for Building Construction. \r\n Solder should conform to ASTM B 32 Specification for Solder Metal. \r\n \r\n Composites \r\n \r\n Composite or combination flashings are typically less expensive than sheet \r\n metal and are easier to install. The most predominant type is a thin \r\n layer of metal sandwiched between one or two layers of another material. \r\n The metal layer is usually of aluminum, copper or lead. It is covered \r\n on one or both sides with various materials, such as asphalt coatings, kraft \r\n paper, fiberglass fabric or plastic films. Product literature should \r\n be reviewed to determine whether these materials are appropriate for use \r\n in brick masonry cavity walls. Consideration should be given to compatibility \r\n with adjacent sealants, delamination due to moisture penetration and movement \r\n of the wall system. \r\n \r\n Plastic and Rubber Compounds \r\n \r\n These flashing materials are usually the least expensive flashing suitable \r\n for brick masonry cavity walls. They are flexible and can make complex \r\n shapes, except in the heavier thicknesses. Polyvinyl chloride (PVC), \r\n Ethylene Propylene Diene Monomer (EPDM) and rubberized asphalt are the most \r\n common plastic flashings available. \r\n \r\n PVC deteriorates and breaks down when exposed to ultraviolet (UV) light. \r\n The material also becomes brittle and shrinks over time due to loss of plasticizers. \r\n Some PVC flashing is not compatible with polystyrene insulation and can \r\n cause the insulation to degrade. However, not all PVC flashings have \r\n experienced such problems. Appropriate quality, density and thickness \r\n of PVC flashings are paramount to successful performance and should be obtained \r\n from well-recognized manufacturers. \r\n \r\n EPDM was originally developed as a roofing membrane. However, this \r\n type of material has been gaining widespread use as through-wall flashing \r\n for masonry walls. It has increased resistance to weathering and performs \r\n better in low temperature environments than PVC. EPDM should be in \r\n a cured state. Junctures and laps of plastic flashing are usually \r\n sealed with plastics or adhesives. These materials may require a metal \r\n drip edge adhered to the flashing when exposed to exterior elements. \r\n EPDM should be talc free or the talc should be removed where laps are formed. \r\n \r\n Another type of fabric flashing is a self-adhering, rubberized asphalt. \r\n This flashing material easily adheres to itself at junctures, laps and interior \r\n wall surfaces and can be self healing to some extent. However, this \r\n material cannot be placed on damp, dirty or dusty surfaces. The adhesion \r\n properties may be reduced during cold weather. Rubberized asphalt \r\n can also degrade in the presence of UV light and therefore, requires the \r\n same type of drip edge as other plastic flashing materials. \r\n \r\n WEEP HOLES \r\n \r\n Weep holes channel moisture collected on the flashing to the exterior of \r\n the wall assembly. For best performance, weep holes should always be located \r\n directly on the flashing. If weep holes are installed one to two masonry \r\n courses above the flashing, they will not perform their intended function. \r\n Some types of weep holes may aid in drying out the wall system, although \r\n this is not their primary purpose. \r\n Weep holes can be formed in a number of ways. Some of the most common \r\n are: 1) omitting mortar in all or part of the head joint; 2) use of removable \r\n rods or ropes; 3) plastic or metal tubes; and 4) use of a wicking material. \r\n There are also plastic and metal vents that cover weep holes used in lieu \r\n of mortar in vertical head joints. Open head joints are recommended \r\n as weep holes; however, as long as weep holes remain open for drainage and \r\n positioned at the required flashing locations with the appropriate size \r\n and spacing, the specific type of weep hole selected is not critical. \r\n \r\n DRAINAGE MATERIALS \r\n \r\n For brick masonry cavity walls to retard moisture infiltration, the air \r\n space separating the masonry wythes must be kept clean of mortar droppings \r\n or mortar that may bridge the air space. These obstructions can render \r\n flashing and weep holes ineffective. \r\n \r\n While it is important to keep cavities clear, there are a number of approaches \r\n available to keep open a drainage path to the weep holes. Drainage \r\n materials can be installed above flashing consisting of materials configured \r\n and installed to allow water to flow around any mortar droppings. \r\n The use of these materials does not negate the importance of good workmanship \r\n and may not be required in all situations. Use of drainage materials \r\n may result in the mortar bridging the air space at certain locations, possibly \r\n above the flashing level. This may lead to isolated spots of dampness \r\n on the interior or exterior wythe. At worst, it could lead to a path \r\n for water penetration. In all cases, the cavity size should be maintained. \r\n \r\n A layer of pea gravel with an approximate diameter of 3?8 in. (10 mm) can \r\n be placed on top of flashing installations within the wall system. \r\n This layer should be approximately 2 to 3 in. (50 to 75 mm) deep. \r\n This will help to keep mortar droppings from clogging weep holes. \r\n The smallest gravel size should be larger than the weep hole opening so \r\n as not to interfere with drainage. It is recommended that a bed of \r\n mortar, conforming to the curve of the flashing, be placed under the flashing \r\n for additional support of the pea gravel. Care must be exercised when \r\n installing pea gravel at bolted shelf angle locations. The weight \r\n of the gravel on the flashing may cause tearing or puncturing at the bolt \r\n head. Pea gravel at loose lintels needs to be contained so it does \r\n not flow off the end. Fig. 5 shows a typical detail for the use of \r\n pea gravel although it would apply to many of the drainage materials. \r\n \r\n Mesh materials are gaining popularity. These materials are usually \r\n manufactured from high density polyethylene or nylon strand and are available \r\n in 1 in. to 2 in. (25 mm to 50 mm) thicknesses. They keep weep holes \r\n open and permanently suspend the mortar above the flashing level. \r\n Many have unique patterns such as dovetail shapes which break up mortar \r\n droppings so moisture has open flow paths to flashing and weep holes. \r\n \r\n Another mortar dropping control device consists of staggered shelves inserted \r\n in the cavity such that they overlap each other. The individual pieces \r\n are fixed in place by tabs which are mortared into the outer wythe of masonry. \r\n This may collect mortar droppings above the flashing level and create a \r\n bridge for moisture to cross the cavity. \r\n \r\n Some manufacturers of rigid board insulation provide a grooved face with \r\n an adhered filter fabric that is positioned in the air space towards the \r\n exterior. The aligned grooves act as a channel which allow moisture \r\n to drain down to the flashing and weep holes in the wall system. The \r\n grooves are intended to provide drainage capabilities in the event of the \r\n air space being clogged during construction of the masonry wythes; however, \r\n the grooves must align vertically for proper drainage. Other rigid \r\n insulation boards have an adhered mesh material which behaves in a similar \r\n manner. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n EXPANSION JOINT MATERIALS \r\n \r\n Building materials and elements used in construction react differently to \r\n loading and environmental conditions. Thus, they are constantly moving. \r\n A system of movement joints is necessary to accommodate these expected movements. \r\n For wythes of brick masonry, placement of expansion joints is necessary \r\n to permit these movements without concern. \r\n \r\n Typical expansion joint details are shown in Fig. 6. A backer rod \r\n and sealant must always be installed to resist moisture penetration at the \r\n expansion joint location. A filler material may be used in the expansion \r\n joint behind the backer rod to keep debris out of the joint during construction. \r\n Common expansion joint filler materials are pre-molded foam pads and neoprene \r\n pads. The sealant, backer rod and filler material, if present, must \r\n be designed to allow the expected movement; therefore, the movement potential \r\n of these materials must be included when determining expansion joint size \r\n and spacing. Expansion joint fillers should conform to ASTM D 1056 \r\n Specification for Flexible Cellular Materials - Sponge or Expanded Rubber, \r\n Class 2A1. \r\n \r\n Sealants come in many varieties and usually consist of polyurethanes, polysulfides \r\n or silicone. Sealants which exhibit the highest movement capabilities \r\n should be specified. Sealants should conform to ASTM C 920 Specification \r\n for Elastomeric Joint Sealants. For adequate sealing of expansion \r\n joints the sealant must bond well to the adjacent brickwork, flashing, windows, \r\n etc. Sealant manufacturers should be consulted to determine whether \r\n priming is necessary based on the sealant material selected. Oil-based \r\n caulking compounds should not be used as sealants for masonry wall assemblies \r\n be cause most lack the necessary flexibility and durability needed for in-service \r\n use. \r\n \r\n Backer rods are used to keep the sealant at the appropriate depth, provide \r\n a suitable shape for the sealant and act as a bond breaker to prevent back-adhesion. \r\n The backer rod should be slightly larger than the joint. Closed cell \r\n polyethylene rods are recommended and should be free from punctures. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n STEEL SHELF ANGLES AND LINTELS \r\n \r\n Several different types of steel members can support either the exterior \r\n or interior wythe of a brick masonry cavity wall. They generally fall \r\n into two categories: shelf angles and lintels. Shelf angles are used \r\n in panel wall systems to support the exterior wythe of brick masonry at \r\n floor levels. Shelf angles are anchored to floor slabs or beams and \r\n break the exterior wall facade into sections. Loose angle lintels \r\n are generally used over wall openings to support the masonry above. \r\n Typical loose angle lintels bear on the masonry at each end of the opening \r\n and are not attached to the frame or backing. \r\n Steel for shelf angles and lintels should conform to ASTM A 36 Specification \r\n for Carbon Structural Steel. Steel angles should be at least 1?4 in. \r\n (6 mm) thick with a horizontal leg of at least 31?2 in. (89 mm) for use \r\n with nominal 4 in. (100 mm) brick wythes and 3 in. (75 mm) for use with \r\n nominal 3 in. (75 mm) thick brick wythes. Further information on the \r\n design of steel lintels can be found in Technical Notes 31B \r\n Revised. \r\n \r\n The use of galvanized steel shelf angles or lintels may be necessary in \r\n areas subject to severe corrosion. Steel lintels, if not galvanized, \r\n should be painted before installation. These steel members support \r\n the weight of the masonry and must remain in good condition. Repair \r\n or replacement of shelf angles or lintels is time consuming and costly so \r\n the selection of adequate materials is critical to long service life. \r\n \r\n INSULATION MATERIALS \r\n \r\n In cavity wall construction, the prescribed air space acts as an insulating \r\n layer in addition to the masonry units. Thermal performance of the \r\n system can be further enhanced by placing insulation materials in the cavity. \r\n Insulation materials used in brick masonry cavity walls include inorganic \r\n cellular materials such as perlite and vermiculite, and organic cellular \r\n materials such as polystyrene, polyurethane, polyisocyanurate and foams. \r\n These insulation types are manufactured in the form of rigid boards, granular \r\n fills and foams. Each of these types, if properly used, will result \r\n in a more thermally efficient wall system. \r\n \r\n Although the most important characteristic for insulation is its thermal \r\n resistance, other properties should be considered including water absorption, \r\n combustibility, density, insect resistance and ease of installation. \r\n The following criteria can be used for the selection of insulation materials \r\n for brick masonry cavity walls: \r\n 1.The insulation must permit the air space to perform its function as a \r\n barrier to moisture penetration by allowing moisture to drain without passage \r\n to the interior wythe. \r\n 2.Thermal insulating efficiency must not be impaired nor degrade over time \r\n due to retained moisture from any source, i.e., wind-driven rain or vapor \r\n condensation. \r\n 3.Insulating materials must be long lasting, resisting rot due to moisture \r\n or dryness, offering no food value to vermin and meeting the building code \r\n requirements for flame resistance. \r\n 4.Granular fill materials must be capable of supporting their own weight \r\n without settlement to assure that no portion of the wall is without insulation \r\n and allow moisture to drain from the cavity. \r\n 5.Foam insulation materials must not shrink with age to assure that no portion \r\n of the wall is without insulation and that moisture does not have a path \r\n to migrate to the interior wythe. \r\n 6.Rigid boards must be firmly attached to the backing so as not to become \r\n dislodged in the cavity and allow air or water movement around the insulation. \r\n 7.Consider environmental concerns regarding off gassing and recycling of \r\n insulation materials. \r\n Properties of insulation materials vary widely. Table 3 shows various \r\n properties of insulation materials used in brick masonry cavity walls. \r\n The thermal conductivity (k) and thermal resistance (R) provide a means \r\n of comparing the insulating properties of insulation materials. These \r\n are determined in accordance with ASTM C 177 Test Method for Steady-State \r\n Heat Flux Measurements and Thermal Transmission Properties by Means of the \r\n Guarded-Hot-Plate Apparatus measured at various temperatures. Due \r\n to the large number of types of insulation, and even larger number of manufacturers, \r\n Table 3 lists only a few representative values of physical properties. \r\n For some materials, an aged or stabilized value is given. In all cases, \r\n the aged or stabilized value is the one that should be used in design. \r\n Individual manufacturers should be consulted for design values and other \r\n properties of their specific materials and their applications. \r\n \r\n Rigid Boards \r\n \r\n There are many rigid board insulation materials that can be installed in \r\n the air space of brick masonry cavity walls. Among the most common \r\n are: expanded and molded polystyrene, extruded polystyrene, expanded polyurethane, \r\n polyisocyanurate, mineral fibers and perlite board. \r\n \r\n Composition. Rigid board insulations are many and varied. \r\n They include the various mineral fiber boards and cellular insulation including \r\n polystyrenes, polyurethanes and polyisocyanurates. Air, or other gases, \r\n introduced into the material expands the material by as much as 40 times. \r\n Cells are formed in various patternsΓÇöopen (interconnected) or closed (unconnected). \r\n Most rigid insulation is expanded with hydrogenated chlorfluorocarbons (HCFC), \r\n pentane or other hydrogenated gases used as blowing agents. Gradual \r\n air leakage into the cells may replace some of the original gas and eventually \r\n reduce the thermal insulating quality. Some types of insulation use \r\n foil facers. These facers keep air leakage to a minimum and must not \r\n be punctured during construction. Aged R-values should be used when \r\n comparing different types of insulation. \r\n \r\n Fibrous insulation materials include wood, cane, or vegetable fibers \r\n bonded with plastic binders. To make them moisture resistant, \r\n they are sometimes impregnated with asphalt. Fibrous glass insulation \r\n consists of a core board of non-absorbent fibers held together by phenolic \r\n binders and a surface coating of asphalt-saturated organic material reinforced \r\n with glass-fiber. \r\n \r\n Properties. Water entrapped in insulation can destroy its thermal \r\n insulating value. Water vapor can flow wherever air can flowΓÇöbetween \r\n fibers, through interconnected open cells, or where a closed cell structure \r\n breaks down. Wherever water replaces air, the insulating value drops \r\n drastically since waters thermal conductivity exceeds that of air by 20 \r\n times. \r\n \r\n Fibrous organic insulations are especially vulnerable to moisture damage. \r\n Free water will eventually damage any fibrous organic material or organic \r\n binder. Fiberboard exposed to moisture for long periods of time may \r\n warp or buckle and eventually decay. The expansion and contraction \r\n that accompanies the changing moisture content may lead to problems. \r\n \r\n Though less vulnerable to moisture, inorganic materials are not immune. \r\n Water penetrating into fiberglass insulation not only impairs the insulating \r\n value, but may also dissolve the binder. Some types of cellular insulation \r\n may also break down under repeated freeze/thaw cycles. \r\n \r\n Rigid board insulation should conform to one of the following: ASTM C 208 \r\n Specification for Cellulosic Fiber Insulating Board, ASTM C 552 Specification \r\n for Cellular Glass Thermal Insulation, ASTM C 578 Specification for Rigid, \r\n Cellular Polystyrene Thermal Insulation, ASTM C 1224 Specification for Reflective \r\n Insulation for Building Applications, ASTM C 1289 Specification for Faced \r\n Rigid Cellular Polyisocyanurate Thermal Insulation Board, ASTM D 3490 Specification \r\n for Flexible Cellular Materials - Bonded Urethane Foam and ASTM D 3770 Specification \r\n for Flexible Cellular Materials - High Resilience Polyurethane Foam. \r\n There may be other products available for rigid foam products; therefore, \r\n manufacturers literature should be reviewed before selection. \r\n \r\n Granular Fills \r\n \r\n Granular fills are typically used in the hollow cells of concrete block \r\n backing. However, they can be used in the cavity. One advantage \r\n of granular fills is that they can be installed after wall sections have \r\n been completed. This permits the mason to work uninterrupted thus \r\n shortening construction time and lowering costs. However, the water \r\n resistance of the fill is of utmost importance. Settling of the fill \r\n material could lead to thermal bridging in the wall system. \r\n \r\n Two types of granular fill insulation have been found to meet the objectives \r\n of cavity wall insulation. These are water-repellent vermiculite and \r\n silicone-treated perlite insulation. \r\n \r\n Vermiculite is an inert, lightweight, granular insulating material manufactured \r\n by expanding an aluminum magnesium silicate mineral, which is a form of \r\n mica. The raw material is made up of approximately one million separate \r\n layers per inch, with a minute amount of water between each layer. \r\n When particles of the mineral are suddenly exposed to temperatures in the \r\n range of 1800°F to 2000°F (982°C to 1093°C), the water changes \r\n to steam, causing the vermiculite to expand into cellular granules of vermiculite \r\n insulation about 15 times their original size. \r\n \r\n Perlite is a white, inert, lightweight, granular insulation material made \r\n from volcanic siliceous rock. When the crushed stone is heated to \r\n approximately 1800°F (982°C), it expands or pops much like popcorn \r\n as the combined water vaporizes and creates countless, tiny bubbles in the \r\n heat-softened, glassy particles. Perlite can be expanded up to 20 \r\n times its original volume. \r\n Water-repellent vermiculite and silicone-treated perlite should conform \r\n to ASTM C 516 Specification for Vermiculite Loose Fill Thermal Insulation \r\n and C 549 Specification for Perlite Loose Fill Insulation, respectively. \r\n Each of these specifications contains limits on density, grading, thermal \r\n conductivity and water repellency. Some properties of these materials \r\n is given in Table 3. \r\n \r\n Foamed-in-place Insulation \r\n \r\n Foamed-in-place insulations have traditionally been used to fill the \r\n cells of hollow masonry units. However, new technology has now produced \r\n foamed-in-place insulations that can completely fill the air space between \r\n the two wythes of a brick masonry cavity wall. One advantage of these \r\n foamed-in-place insulations is that they can be installed after wall sections \r\n have been completed. However, the water resistance of brick cavity \r\n walls with these types of insulation materials are unproven in the field. \r\n Shrinkage of the foam material could lead to moisture drainage paths through \r\n the wall system. In addition, mortar bridging in the cavity may not \r\n allow the foam to flow around it properly. These materials used in \r\n the cavity contradict the drainage system and should be considered a barrier \r\n wall system. \r\n Most foams are a two component system. They are formed by a chemical \r\n reaction of two liquids. They are placed under pressure, so newly \r\n constructed walls must be cured long enough to resist the pressures. \r\n Typical compositions of these foams are urethane, polyicynene, magnesium \r\n oxychloride cement and ceramic talc and amino-plast resin. Since most \r\n of these products are proprietary, there are no ASTM standards at this time \r\n to verify quality. Therefore, manufacturers literature should be consulted \r\n for technical information on applications and usage. \r\n \r\n AIR AND VAPOR RETARDERS \r\n \r\n Sheets or layers of materials which effectively retard or reduce the flow \r\n of air and water vapor are called air retarders and vapor retarders, respectively. \r\n In recent years, there has been much confusion pertaining to the functions \r\n of each within a masonry wall system. Air retarders limit the amount \r\n of air flow through the wall system. Vapor retarders are intended \r\n to control transmission of water vapor through building assemblies. \r\n A vapor retarder can also serve as an air retarder. An air retarder \r\n may or may not serve as a vapor retarder. It is sometimes difficult \r\n to ensure that either retarder performs only one function. For example, \r\n polyethylene films will function as a vapor retarder, but it will also resist \r\n the passage of air. \r\n \r\n To provide effective air and vapor retarders, it is necessary to seal joints \r\n in these materials so that continuity is provided. It is also necessary \r\n to seal around the edges of wall openings such as windows, doors and access \r\n for utility services. Adhering or taping of the joints should be specified. \r\n The adhesive or tape used must be compatible with the material composition \r\n of the retarder in addition to performing adequately when exposed to moisture. \r\n \r\n Air Retarders \r\n \r\n Masonry cavity walls can appear to be relatively air tight, but may experience \r\n high air leakage rates. Parging the exterior or interior face of the \r\n interior masonry wythe with mortar is one method to reduce air leakage, \r\n but it will crack if the wythe cracks. Membranes or liquid-applied \r\n materials usually provide superior performance. Special attention \r\n must be given to adjacent materials or structural members intersecting the \r\n interior wythe and the membrane. Permanent fixtures in the interior \r\n wythe and movement joints at the top and sides of the wythe must provide \r\n a continuous air seal to perform successfully. \r\n \r\n For improved air retarder performance, the air and vapor retarders can be \r\n included in combination with mortar parging. The parging provides \r\n a base for the application of the vapor retarder. The vapor retarder \r\n must be able to span possible movement cracks in the interior wythe. \r\n \r\n Interior or exterior insulation boards applied to the interior wythe can \r\n also form part of the air retarder system. For insulation to work \r\n effectively as a retarder, proper adhesion to the interior wythe by the \r\n use of full grid of adhesive will eliminate air spaces between the insulation \r\n and the interior wythe. Mechanical anchorage may provide a tight fit \r\n of the insulation to the interior wythe. Joints between insulation \r\n boards must be sealed with a moisture resistant tape or sealant. \r\n \r\n Interior gypsum board finish materials can be used as air retarders when \r\n joints are properly sealed. Even when the interior wall covering is \r\n not intended to serve as the main air retarder, it is suggested that steps \r\n be taken to provide good air tightness in order to reduce possible air circulation \r\n in air spaces in the interior wythe. \r\n \r\n Vapor Retarders \r\n \r\n There are many materials that can be used to effectively provide vapor transmission \r\n resistance. However, the installation methods vary just as much as \r\n the materials themselves. Selection should consider the material \r\n and ease of application for the best results. \r\n \r\n The vapor retarder selection depends on the type and location of insulation \r\n in the brick masonry cavity wall and the interior and exterior climate. \r\n While some materials and methods of application may be successful in the \r\n cavity or on the interior side of the interior wythe, there are certain \r\n vapor retarders which perform better on one side that the other. \r\n \r\n Suitable vapor retarders consist of two coats of oil-based or alkyd emulsion \r\n paint on the interior side of the wall finish; a 15-mil thick polyethylene \r\n sheet over the insulation; or the insulation itself if it is highly impermeable \r\n to water vapor transmission and has taped or sealed joints. Foil-faced \r\n insulation and extruded polystyrene insulation boards meet these criteria. \r\n \r\n When the vapor retarder is installed within the cavity space, other material \r\n options are available. Paints or suitable coatings can be applied \r\n to the outside face of the interior wythe, but must have the ability to \r\n span or bridge small cracks. The vapor retarder can also consist of \r\n torched-on or spray-applied bituminous coatings, self-adhesive plastic sheets \r\n or plastic materials. \r\n \r\n The material must be continuous and be able to accommodate possible movement \r\n cracks that may form in the masonry. For long term performance, vapor \r\n retarder materials must remain firmly affixed as vapor pressure differentials \r\n occur. These materials must be chemically compatible with any insulation \r\n placed in the cavity. \r\n \r\n If the insulation is used as the vapor retarder, it must be held firmly \r\n in place by adhesives or mechanical anchorage. In addition, the joints \r\n between the insulation boards must be fully sealed with moisture resistant \r\n sealant or tape. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes is the second in a series dealing with brick \r\n masonry cavity walls. It is concerned primarily with recommended properties \r\n and selection of materials. Other Technical Notes in this series \r\n discuss cavity walls in general, design, detailing and construction. \r\n \r\n \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering staff \r\n of the Brick Industry Association. The information contained herein \r\n must be used in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonry. Final decisions on the use of \r\n the information contained in this Technical Notes are not within \r\n the purview of the Brick Industry Association and must rest with the project \r\n architect, engineer and owner. \r\n \r\n REFERENCES \r\n \r\n 1.\"Brick Masonry Cavity Walls,\" Technical Notes 21 \r\n Revised, Brick Industry Association, Reston, VA, August 1998. \r\n \r\n 2. Handbook of Fundamentals , American Society of Heating, Refrigeration \r\n and Air Conditioning Engineers, Inc., Atlanta, GA, 1997 Edition. \r\n \r\n 3.\"Thermal Insulation, Environmental Acoustics,\" Volume 04.06, Annual Book \r\n of ASTM Standards, American Society for Testing and Materials, West Conshohocken, \r\n PA, November 1998. \r\n \r\n 4.\"Through-Wall Flashing,\" Engineering and Research Digest, Brick Industry \r\n Association, Reston, VA, 1996. \r\n \r\n 5.\"Wall Ties for Brick Masonry,\" Technical Notes 44B , \r\n Brick Industry Association, Reissued Sept. 1988. \r\n \r\n 6.\"Water Resistance of Brick Masonry, Design and Detailing - Part I of III,\" \r\n Technical Notes 7 Revised, Brick Industry \r\n Association, Reston, VA, Reissued Feb. 1998. \r\n \r\n 7.\"Water Resistance of Brick Masonry, Materials - Part II of III,\" Technical \r\n Notes 7A Revised, Brick Industry Association, \r\n Reston, VA, Reissued Dec. 1995 . \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60085,"ResultID":176317,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 21B - Brick Masonry Cavity Walls - Detailing \r\n Jan./Feb. 1978 (Reissued Jan. 1987) \r\n \r\n INTRODUCTION \r\n \r\n This is the third in a series of Technical Notes devoted to \r\n brick masonry cavity walls. Other Technical Notes in this series \r\n cover areas of cavity walls in general, including properties, design, \r\n material selection, and insulation; this Technical Notes is \r\n concerned with proper detailing. \r\n The cavity wall can be correctly designed, and properly constructed \r\n using the best materials available, but if improperly detailed the \r\n wall will not function as it should. \r\n \r\n GENERAL \r\n \r\n Every structure must meet particular requirements and must be detailed \r\n accordingly. Details that are satisfactory on one structure may not \r\n be workable on another. However, certain details can usually be found \r\n that will minimize the possibility of damage to masonry walls from \r\n cracking, efflorescence, and water penetration. This Technical \r\n Notes will suggest some details which can be followed to achieve \r\n satisfactory cavity walls. \r\n \r\n BOND BREAKS \r\n Foundations \r\n \r\n In many areas there are significant foundation movements which can \r\n cause severe cracking in walls rigidly attached to the foundation. \r\n If these walls are left free of the foundation, they tend to span \r\n the low points and thus reduce the cracking. In general, differential \r\n movements in foundations supporting cavity walls must be kept to a \r\n minimum, or serious distress may result. Differential movement of \r\n 1/4 in. (6.4 mm) in 15 ft (4.572 m) has been considered sufficient \r\n to cause cracking in masonry walls. However, observations on cavity \r\n type and other masonry walls have shown that differential movements \r\n in the foundation of more than 1/2 in. (12.7 mm) in 15 ft (4.572 m) \r\n could occur and yet the walls remain in good shape and have no cracks. \r\n Figure 1 illustrates a typical foundation detail. In this case, the \r\n bond is broken between the base of the cavity wall and the top of \r\n the concrete beam by building paper. The transfer of movements in \r\n the foundation to the wall is thus minimized. Bond breaks also permit \r\n differential thermal and moisture movements without distress to either \r\n the brick wall or the concrete foundation. In addition, a bond beam \r\n or tie beam can be formed at the bottom of the wall by placing reinforcing \r\n bars and filling the cavity with grout. This will tie the inner and \r\n outer wythes of masonry together and distribute any strain over a \r\n longer length of wall. This can also be accomplished by a closer spacing \r\n of the horizontal joint reinforcement at the bottom of the wall. The \r\n above procedures will tend to contain any vertical cracks that may \r\n originate at the bottom of the wall. \r\n \r\n \r\n \r\n Foundation Detail \r\n FIG. 1 \r\n \r\n \r\n \r\n When it is necessary to anchor the masonry wall to the foundation, \r\n it is still possible to detail the wall in a manner which allows some \r\n differential movement. Such anchorage may be required for load-bearing \r\n structures of high slenderness ratio or in earthquake design areas \r\n \r\n Concrete Slabs \r\n \r\n Thermal strains or other movements are often blamed for cracking \r\n in masonry walls when the actual cause is the expansion or curling \r\n of the concrete slabs bearing on the walls. The curling of a concrete \r\n slab has even been known to pick up the brick bonded to it. Unfortunately, \r\n this behavior of concrete is frequently overlooked by the designer \r\n in detailing the structure. Figure 2 illustrates a typical detail \r\n that will relieve this condition. In this design, the bond is broken \r\n between the concrete slab and the brick wall by building paper. This \r\n permits the slab to have some freedom of movement with respect to \r\n the wall. In addition, it permits the longitudinal thermal and moisture \r\n movements to occur without distress. The slab is thickened into a \r\n beam over the interior wythe to help stiffen the slab and minimize \r\n curling. Under certain climatic conditions, provisions must be made \r\n for insulation which has not been shown. \r\n \r\n \r\n \r\n Concrete Roof Slab Detail \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n BEARING \r\n Structural Steel \r\n \r\n Steel has a coefficient of expansion approximately twice that of \r\n brick masonry. If the temperature difference in the materials is large, \r\n and the steel is firmly anchored to, or confined within, the masonry, \r\n then cracking of the masonry wall will probably occur. Normal practice \r\n has been to positively anchor the joists or steel in the masonry. \r\n This design can be improved by lubricating the bearing surfaces and \r\n providing slotted holes in the seats of the steel members. The anchor \r\n bolts should be only hand-tightened, or friction will prevent the \r\n necessary movement. \r\n Figure 3 illustrates a structural system using steel joists bearing \r\n on a masonry wall. \r\n \r\n \r\n \r\n Steel Joist Structural Floor Assembly \r\n FIG. 3 \r\n \r\n \r\n \r\n Wood Floor Joists \r\n \r\n Wood floor joists normally have a 3-in. fire cut end and bear only \r\n on the interior wythe of a cavity wall. If the ends project into the \r\n cavity, they can form a ledge which may create a moisture bridge across \r\n the cavity. \r\n All building codes require joists to be anchored to masonry walls \r\n at specified intervals in a prescribed manner. Codes generally require \r\n an anchor at the end of every fourth joist. Where the joists are parallel \r\n to a wall, anchors engage 3 joists at intervals not exceeding 8 ft \r\n (2.438 m). Cavity wall ties are usually required within 8 in. (203 \r\n mm) of joist bearing level. With such construction, the floor is considered \r\n to provide lateral support for the walls, see Fig. 4. \r\n \r\n \r\n \r\n Anchorage of Wood Floor to Cavity Wall \r\n FIG. 4 \r\n \r\n Wood Ratter Plates \r\n \r\n Wood roofs can be anchored to cavity walls by many methods. two of \r\n which are shown in Fig. 5. The detail on the left illustrates a method \r\n using solid units in both wythes. The detail on the right may be used \r\n with vertical cell back-up units. Anchor bolts are grouted into the \r\n hollow cells to provide positive anchorage. Regardless of the method, \r\n anchor bolts holding roof plates should extend into the masonry a \r\n minimum of 16 in. (406 mm), normally about six standard size brick \r\n courses. After the wood plate is installed, the nut should be hand-tightened. \r\n \r\n \r\n \r\n Anchorage of Wood Roof Framing to Cavity Walls \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n ANCHORAGE AND TIES \r\n \r\n When masonry walls are used to enclose skeleton-frame structures, \r\n care must be taken to anchor the masonry walls to the skeleton frame \r\n in a manner which will permit each to move relative to the other. \r\n Skeleton frames are more flexible than brick walls and will undergo \r\n greater deflections under load. The frame and enclosing wall differ \r\n in their reaction to moisture and in the magnitude of their thermal \r\n movement. \r\n Where anchors tie walls to the structural frame to provide lateral \r\n support, they should be flexible, resisting tension and compression, \r\n but not shear. This flexibility permits differential movements between \r\n the frame and the wall without cracking or distress. Figures 6 through \r\n 11 show typical methods for anchoring masonry walls to columns and \r\n beams with corrosion-resistant metal ties. These anchorage methods \r\n will permit both horizontal and vertical differential movements. \r\n \r\n \r\n \r\n Wall Anchorage to Concrete Beams \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n Wall Anchorage to Steel Beam \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Wall Anchorage to Concrete Columns \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n Wall Anchorage to Steel Columns \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Connection Details \r\n FIG. 10 \r\n \r\n \r\n \r\n Anchorage Detail Corner Concrete Column and Cavity Wall \r\n FIG. 11 \r\n \r\n \r\n \r\n \r\n MOVEMENT JOINTS \r\n Vertical Expansion Joints \r\n \r\n No single recommendation for the positioning and spacing of vertical \r\n expansion joints can be applicable to all structures. Each building \r\n must be analyzed to determine the potential horizontal movements, \r\n and provisions must be made to relieve excessive stress which might \r\n be expected to result from such movement. The extent to which precautions \r\n should be taken to prevent brick masonry from cracking will depend \r\n upon the exposure, character, and intended use of the structure. In \r\n some instances, it may be economically desirable to provide less than \r\n maximum protection as a calculated risk. See Technical Notes \r\n 18A for more specific suggestions. \r\n One additional consideration of extreme importance is the distinction \r\n between control joints and expansion joints. Control joints \r\n are placed in concrete or concrete masonry walls, along with suitable \r\n joint reinforcement, to control cracking by reducing restraint and \r\n accommodating wall movement from shrinkage due to initial drying. \r\n Shrinkage due to drying is not found in clay masonry construction. \r\n This becomes obvious when one considers the clay units, which comprise \r\n 70% or more of the total volume of a solid brick masonry wall, are \r\n manufactured by a firing process which drives off all moisture. As \r\n a result, control joints are not necessary to brick masonry \r\n walls. Expansion joints are placed to accommodate the movement \r\n of brick masonry walls due to change in temperature and moisture. \r\n Concrete masonry walls also experience expansion due to changes in \r\n temperature and moisture, but they experience their shrinkage due \r\n to initial drying first, then the control joints act in both \r\n contraction and expansion. Further information regarding expansion \r\n joints can be found in Technical Notes 18A . \r\n Typical details of expansion joints and their locations are \r\n shown in Figs. 12 and 13. \r\n \r\n \r\n \r\n Plan Views \r\n Fig. 12 \r\n \r\n \r\n \r\n \r\n \r\n Plan Views \r\n Fig. 13 \r\n \r\n Horizontal Expansion Joints \r\n \r\n Cavity walls are successfully used as curtain walls in concrete and \r\n steel-frame buildings. When cavity walls are so used, the inner masonry \r\n wythe is usually supported by the frame at each floor level and laid \r\n to the column faces. The outer wythe, supported by shelf angles, is \r\n tied to the structure by metal ties to the inner masonry wythe and \r\n the building frame. The shelf angle, which supports the outer wythe \r\n of masonry at each floor, can be secured to the spandrel in several \r\n ways. Care should be taken to insure proper anchorage and shimming \r\n of the angle to prevent deflections which might induce high concentrated \r\n stresses in the masonry. Angles should be designed so that total deflections \r\n are less than 1/16 in. (1.6 mm). Even if galvanized shelf angles are \r\n used, continuous flashing should be installed. Regardless of the type, \r\n shelf angles should not be installed as one continuous piece. Provide \r\n a space at intervals to permit thermal expansion and contraction to \r\n occur without damage to the wall. \r\n Where shelf angles are used in this manner, it is suggested that \r\n horizontal expansion joints be placed at shelf angles, see Fig. 8, \r\n Technical Notes 21 Revised. This \r\n is particularly important in concrete frame buildings. The joints \r\n should be sealed with a permanently elastic sealant of a color which \r\n will closely match the mortar joints. \r\n \r\n PARAPETS \r\n \r\n Of all the masonry elements used in buildings, probably the most \r\n difficult to adequately detail is the parapet wall. Designers have \r\n tried many different ways to design parapets to minimize cracking, \r\n leaking, and displacement. Experts generally agree that the only sure \r\n way to avoid parapet problems is to eliminate the parapet. However, \r\n they are frequently required by building codes, or architectural considerations. \r\n The detail shown in Fig. 14 is suggested as one method of building \r\n parapets. For cavity wall construction, it is recommended that the \r\n cavity continue up into the parapet, thereby providing some flexibility \r\n between the outside wythe and the inner wythe. Expansion joints should \r\n extend up through the parapet. In addition, the parapet wall should \r\n be reinforced and doweled to the structural frame or have an additional \r\n expansion joint spaced between those in the wall below. Expansion \r\n joints should also be placed near corners to avoid displacement of \r\n the parapet. Parapet copings should provide a drip on both sides of \r\n the wall. Metal, stone, and fired clay copings of various designs \r\n usually provide this feature. The back side of the parapet should \r\n be constructed of durable materials, preferably the same material \r\n that is used in the front side of the parapet. They should not be \r\n painted or coated, they must be left free to \"breathe.\" Unless copings \r\n are impervious with watertight joints, place through flashings in \r\n the mortar bed immediately beneath them and firmly attach the coping \r\n to the wall below with anchor bolts. \r\n \r\n \r\n \r\n Reinforced Parapet Wall \r\n FIG. 14 \r\n \r\n \r\n \r\n \r\n FLASHING AND WEEP HOLES \r\n \r\n Flashing is installed in masonry construction to divert moisture, \r\n which may enter the masonry at vulnerable spots, to the outside. In \r\n areas of severe or moderate exposures, flashing should be provided \r\n under horizontal masonry surfaces, such as roof and parapet, or roof \r\n and chimney; overheads of openings, such as doors and windows; and \r\n frequently at floor lines, depending upon the type of construction. \r\n To be most effective, the flashing should extend through the outer \r\n face of the wall and be turned down to form a drip. Weep holes should \r\n be provided at intervals of 16 in. (406 mm) to 24 in. (610 mm) maximum \r\n to permit water accumulated on the flashing to drain to the outside. \r\n If, for aesthetic reasons, it is necessary to conceal the flashing, \r\n the number and spacing of weep holes are even more important. In this \r\n case, the spacing should not exceed 16 in. (406 mm) o.c. Concealed \r\n flashing with tooled mortar joints can retain water in the wall for \r\n longer periods of time, thus concentrating the moisture at one spot. \r\n To prevent any possible moisture infiltration and to promote cavity \r\n drainage, place the bottom of the cavity wall above the finished grade, \r\n and avoid placing earth over the weep holes during landscaping. With \r\n basement construction, it is important to use through-wall flashing \r\n at the bottom of the cavity to prevent moisture from penetrating the \r\n inside surface of the basement wall, see Fig. 15. In basementless \r\n construction, the flashing at the dampproof course may also serve \r\n as a termite shield. \r\n \r\n \r\n \r\n Foundation Details \r\n FIG. 15 \r\n \r\n \r\n \r\n \r\n DOORS AND WINDOWS \r\n \r\n Stock sizes of windows and door frames are used in cavity walls, \r\n although sometimes additional blocking is needed for anchorage. Avoid \r\n solid masonry jambs at windows and doors in cavity walls. However, \r\n for steel windows, the jamb must be partially solid to accept most \r\n standard jamb anchors. Wood or steel surrounds must be used to adapt \r\n non-modular steel casement windows to modular cavity walls. Cavity \r\n wall ties spaced at 3 ft (914 mm) or less should be placed around \r\n all openings not more than 12 in. (305 mm) from the opening, see Figs. \r\n 16, 17 and 18. \r\n \r\n \r\n \r\n \r\n \r\n Double Hung Wood Window \r\n FIG. 16 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Metal Casement Window \r\n FIG. 17 \r\n \r\n \r\n \r\n \r\n \r\n Commercial Metal Window \r\n FIG. 18 \r\n \r\n \r\n \r\n \r\n Caulking and Sealants \r\n \r\n Too frequently, caulking is considered a means of correcting or hiding \r\n poor workmanship, rather than as an integral part of construction. \r\n It should be detailed and installed with the same care as the other \r\n elements of the structure. \r\n Joints at masonry openings for door and window frames, expansion \r\n joints, and other locations where caulking may be required, are the \r\n most susceptible areas for rain penetration. These areas should be \r\n given proper attention during detailing and construction Also, maintenance \r\n programs should be provided to inspect and replace sealants or caulking \r\n which may have dried out, or otherwise become ineffective, see \r\n Figs. 16, 17 and 18. In all cases, the use of a good grade polysulfide, \r\n butyl or silicone rubber sealant is recommended. Oil based caulks \r\n should not be used. Regardless of the type used, proper priming and \r\n backing are a must. \r\n \r\n \r\n \r\n CONDUIT \r\n \r\n It is possible to get double duty out of the cavity by using it to \r\n carry short runs of conduit. This feature must be used with caution \r\n so that a moisture bridge across the cavity is not formed. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes has discussed and illustrated the general \r\n principles that are involved in the proper detailing of brick masonry \r\n cavity walls. The information, recommendations, and detailed drawings \r\n contained in this Technical Notes are based on the available \r\n data and experience of the Institutes technical staff. They should \r\n be recognized as suggestions and recommendations for the consideration \r\n of the designers, specifiers, and owners of buildings when using brick \r\n masonry cavity walls. \r\n It is evident that all of the possible conditions and variations \r\n cannot be covered in a single Technical Notes. However, it \r\n is believed that the general principles and considerations are covered \r\n here. The final decision for details and materials to be used is not \r\n within the purview of the BIA and must rest with the project designer \r\n and/or owner. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60086,"ResultID":176318,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 21C - Brick Masonry \r\n Cavity Walls - Construction \r\n October 1989 \r\n \r\n Abstract : This Technical Notes \r\n describes proper techniques which should be used during the construction \r\n of brick masonry cavity walls. These techniques cover: storing materials, \r\n completely filling all mortar joints, placing wall ties, flashing \r\n and weep holes, keeping the cavity clean and protecting the wall \r\n from weather during construction. \r\n \r\n Key Words : brick, cavity walls , flashing , \r\n joints, mortar, ties, weep holes, workmanship . \r\n \r\n INTRODUCTION \r\n \r\n This fourth in the series of Technical Notes devoted to \r\n brick masonry cavity walls covers good construction practices. Other \r\n Technical Notes in this series are concerned with cavity \r\n walls in general, how to insulate them, and how to properly detail \r\n them. \r\n The proper construction of a brick masonry cavity wall is as important \r\n to proper performance as are the design, the use of quality materials, \r\n and proper detailing. Proper construction may not be achieved if \r\n it is considered of secondary importance by the designer. Adequate \r\n supervision may be necessary to ensure proper construction. \r\n \r\n GENERAL \r\n \r\n In the construction of a cavity wall there are no changes required \r\n in basic bricklaying techniques, only modifications of practices \r\n commonly used in the construction of any brick masonry wall. The \r\n fundamental principle in a cavity wall is that there shall be no \r\n bridge of solid material capable of carrying water across the minimum \r\n 2-in. (50 mm) cavity space. Therefore, the construction of two separate \r\n wythes, with a clean cavity, is of prime importance. This Technical \r\n Notes will discuss certain construction practices which are \r\n necessary for brick masonry cavity walls to perform successfully. \r\n \r\n WORKMANSHIP \r\n \r\n The importance of the workmanship used in constructing masonry \r\n has been stressed by many, sometimes to the point that it may appear \r\n that workmanship alone is responsible for the performance of masonry \r\n walls, regardless of the wall design, detailing, or the materials \r\n used. While this is by no means true, good workmanship is a very \r\n important factor in the construction of high performance masonry. \r\n See Technical Notes 7 Series for more information on moisture \r\n resistance of masonry walls. \r\n \r\n Complete Filling of All Mortar Joints \r\n \r\n Extensive laboratory tests at the National Institute of Standards \r\n and Technology, formerly the National Bureau of Standards, and elsewhere, \r\n as well as hundreds of observations of masonry buildings, indicate \r\n that to obtain good masonry performance, there is no substitute \r\n for the complete filling of all mortar joints that are intended \r\n to receive mortar. Partially filled mortar joints result in leaky \r\n walls, reduce the strength of masonry, and may contribute to spalling \r\n due to freezing and thawing in the presence of excessive moisture. \r\n Therefore, all joints intended to receive mortar in both the exterior \r\n and interior wythes should be completely filled as the brick are \r\n laid. \r\n \r\n Keeping the Cavity Clean \r\n \r\n It is vital that the cavity be kept clean of mortar droppings and \r\n other foreign materials. If mortar falls into the cavity, it may \r\n form \"bridges\" for moisture passage, or it may fall to the flashing, \r\n blocking the weep holes. \r\n Over the years many methods have been developed and considerable \r\n time and discussion have been devoted to the proper method to use \r\n in keeping the cavity clean. One method is to take a wooden or metal \r\n strip, slightly smaller than the cavity width, and place it in the \r\n air space. This strip rests on the wall ties as the wall is built. \r\n Wire or rope is attached to the strip. Then, as the brickmason builds \r\n the wall, this strip is easily lifted out. Before the next row of \r\n ties is placed, any mortar which may have fallen into the cavity \r\n is removed (Figure 1). \r\n \r\n \r\n \r\n \r\n Keeping the Cavity Clean \r\n FIG. 1 \r\n \r\n \r\n \r\n Another method is to place every third brick or so in the course \r\n above the flashing of the exterior wythe dry and wedge it into proper \r\n position so that it can be removed for final cleaning of the cavity. \r\n Mortar droppings at the base of the cavity can be easily removed \r\n and weep holes provided when the brick are mortared in the wall. \r\n \r\n In addition to the above mentioned methods of cleaning the cavity, \r\n the brickmason can use techniques that, if properly applied, should \r\n eliminate a considerable amount of mortar falling into the cavity \r\n in the first place (Figures 2 through 7). \r\n 1. After spreading the mortar bed, the brickmason should bevel \r\n the cavity edge with the flat of the trowel (Figure 2). When mortar \r\n is spread in this manner, very little will be squeezed out of the \r\n bed joints into the cavity when the units are laid (Figure 3). \r\n 2. The brick units are next rolled into place, keeping most of \r\n the mortar on the outside (Figures 4, 5 and 6). \r\n 3. After the brickmason has placed the unit on the bed joint any \r\n mortar fins protruding into the cavity should be flattened over \r\n the backs of the unit, not cut off (Figure 7). This prevents the \r\n mortar from falling into the cavity and provides a smooth surface \r\n which will not interfere with insulation materials which may be \r\n placed in the cavity. \r\n \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n Tooling \r\n \r\n Weather tightness and textural effect are the basic considerations \r\n of mortar joint finish selection and execution. Properly \"striking\" \r\n or \"tooling\" the joint helps the mortar and brick units bond together \r\n and seal the wall against moisture. Nine common joint finishes are \r\n shown in Figure 8 in order of their decreasing weather tightness. \r\n Compression of the mortar makes the concave, V, and grapevine joints \r\n the most weather tight and acceptable to use. The remaining six \r\n joint types are not recommended for exterior use. All holes in the \r\n mortar joints should be filled. Joints should be tooled when the \r\n mortar is \"thumbprint\" hard. \r\n \r\n \r\n \r\n \r\n Typical Mortar Joints \r\n FIG. 8 \r\n \r\n \r\n \r\n Weep holes \r\n \r\n Weep holes must be placed at the base of the cavity and at all \r\n other flashing levels. They provide a means of draining away any \r\n moisture that may have found its way into the cavity. Weep holes \r\n must provide a clear access to the cavity and must be placed directly \r\n on the flashing for proper drainage. \r\n Weep holes can be easily created or installed by various methods. \r\n In order of effectiveness these are: \r\n 1. Eliminating each second or third head joint. \r\n 2. Inserting oiled rods, rope or pins in the head joint at a maximum \r\n of 16 in. (410 mm) o.c. and removing before final set of the mortar. \r\n 3. Placing metal or plastic tubing in the head joint at a maximum \r\n of 16 in. (410 mm) o.c. \r\n 4. Placing sash cord or other suitable wicking material in the \r\n head joint at a maximum of 16 in. (410 mm) o.c. \r\n \r\n Insulation Placement \r\n \r\n \r\n The installation of insulation in a cavity wall is covered in Technical \r\n Notes 21A Revised. In addition, \r\n the literature of the insulation manufacturer should be consulted \r\n before beginning construction. \r\n \r\n Tie Placement \r\n \r\n In a properly constructed cavity wall, both wythes of masonry must \r\n be adequately and properly tied together. The main concern to the \r\n designer is assurance that all of the ties are in place and remain \r\n operative, firmly embedded in and bonded to the mortar. To achieve \r\n this, the two wythes of the cavity must be laid with completely \r\n filled bed joints, and the ties must be in the correct position \r\n so that later disturbance of the wall assembly is unnecessary. There \r\n exists extensive data showing that wall ties have excellent tying \r\n capacity if they are well embedded in the masonry, and also that \r\n the cavity wall is a weak structural member if few working ties \r\n must do the job of many (Figure 9). \r\n \r\n \r\n \r\n \r\n Cavity wall metal ties are embedded in bed joints \r\n as units are laid. \r\n FIG. 9 \r\n \r\n There must be at least one 3/16-in. (4.76 \r\n mm) diameter steel wall tie in every 4 1/2 sq ft (0.4 m 2 ) or #9 gauge wire for each \r\n 2 2/3 sq ft (0.25 m 2 ) for a cavity wall whose cavity is no greater than 4 in. (100 \r\n mm). If the cavity width is greater than 4 in. (100 mm), a wall \r\n tie analysis should be performed. The most common type of wall tie \r\n for brick masonry construction is the Z tie. In addition, there \r\n are the rectangular and U-shaped ties which are to be used when \r\n the backup units are hollow masonry units with cells laid vertically. \r\n \r\n From a performance standpoint, the most important factors for wall \r\n ties are: \r\n 1. Being corrosion resistant. \r\n 2. Placing ties at proper spacing. Spacing of ties should be reduced \r\n by one half for ties with drips. Crimping of the metal ties to form \r\n a drip is not necessary, and will decrease the strength of the tie. \r\n \r\n 3. Full bedding of the bed joint and placing the wall tie in the \r\n mortar 5/8 in. (16 mm) from either edge of the brick. \r\n Horizontal Joint Reinforcement . Prefabricated horizontal \r\n joint reinforcement may be used to tie the interior and exterior \r\n wythes. Truss type joint reinforcement should never be used to tie \r\n the wythes of a brick and block cavity wall together. Instead, ladder \r\n type reinforcement which allows for the in-plane movement between \r\n the wythes is recommended. \r\n Horizontal joint reinforcement is not usually required in brick \r\n masonry walls since they are not subject to shrinkage stresses. \r\n The use of horizontal joint reinforcement makes the placing of the \r\n cavity wall ties more convenient and there is less concern over \r\n omitting them. \r\n \r\n PROTECTION \r\n Storage of Materials \r\n \r\n The manner in which materials are stored at the construction site \r\n may have an influence on their future performance. Materials should \r\n be stored to avoid wetting by rain or snow, and also avoid contamination \r\n by salts or other matter which may contribute to efflorescence and \r\n staining. \r\n Masonry Units . Masonry units should be stored off the ground \r\n to avoid contamination by dirt and by ground water which may contain \r\n soluble salts. They should also be covered by a water-resistant \r\n membrane to keep them dry. \r\n Cementitious Materials . Cementitious materials for mortar \r\n should be stored off the ground and under cover. \r\n Sand . Sand for mortar should also be stored on high ground, \r\n or ideally, off the ground to prevent contamination from dirt, organic \r\n materials and ground water, any of which may contribute to efflorescence \r\n and may be deleterious to mortar performance. In addition, it is \r\n advisable to store sand and other aggregates under a protective \r\n cover. This will avoid saturation and freezing in cold weather. \r\n Flashing . Flashing materials should be stored in places \r\n where they will not be punctured or damaged. Plastic and asphalt \r\n coated flashing materials should not be stored in areas exposed \r\n to sunlight. Ultraviolet rays from the sun break down these materials, \r\n causing them to become brittle with time. Plastic flashing exposed \r\n to the weather at the site for months before installation should \r\n not be used. During installation, flashing must be pliable so that \r\n no cracks occur at corners or bends. \r\n \r\n Protection of Walls \r\n \r\n Rain . Masonry walls exposed to weather and unprotected during \r\n construction can become so saturated with water that they may require \r\n weeks, or even months (depending upon climatic conditions), to dry \r\n out. This prolonged saturation may cause many of the slightly soluble \r\n salts to go into solution, thus raising the possibility of efflorescence. \r\n Such conditions may also contribute to the contamination of the \r\n masonry with soluble salts from elsewhere in the construction (concrete, \r\n concrete block, plaster, trim, etc.). \r\n During construction, all walls should be kept dry by covering the \r\n top of the wall with a strong, water-resistant membrane at the end \r\n of each day or shutdown period. The covering should overhang the \r\n wall by at least 24 in. (610 mm) on each side, and should be secured \r\n against wind. The covering should remain in place until the top \r\n of the cavity wall is completed or protected by adjacent materials. \r\n Freezing . Leaky walls can sometimes be attributed to the \r\n freezing of mortar before it has set, or the lack of protection \r\n of materials and walls during cold weather construction. Therefore, \r\n when building in cold weather, all materials and walls should be \r\n properly protected against freezing. This involves the following \r\n items: storing of materials, preparation of mortar, heating of masonry \r\n units, laying precautions, and protection of work. Technical \r\n Notes 1 Series, \"Cold Weather Masonry Construction,\" contains \r\n recommendations for construction and protection of masonry during \r\n freezing weather. ACI-ASCE 530.1 Specifications for Masonry Structures \r\n also has requirements for cold weather construction. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes provides the basic information required \r\n for good construction of brick masonry cavity walls. \r\n The information and suggestions contained in this Technical \r\n Notes are based on the available data and the experience of \r\n the technical staff of the Brick Institute of America. The information \r\n and recommendations contained in this publication must be used in \r\n conjunction with good engineering judgment and a basic understanding \r\n of the properties of brick masonry and related construction materials. \r\n Final decisions on the use of the materials and recommendations \r\n contained in this publication are not within the purview of the \r\n Brick Institute of America and must rest with the project architect, \r\n engineer, owner or all. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60087,"ResultID":176319,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 23 - Efflorescence, \r\n Causes and Mechanisms, Part 1 \r\n May 1985 (Reissued Feb. 1997) \r\n \r\n Abstract : It is important for \r\n designers to understand the various types of efflorescence which \r\n can occur and to have at least a basic knowledge of the factors \r\n influencing the appearance of efflorescence on brick masonry. This \r\n Technical Notes covers the often very complicated mechanisms \r\n leading to the formation of efflorescence, including the probable \r\n sources of soluble salts as well as the sources of moisture needed \r\n to activate these salts. Information is presented as to the composition \r\n of each known type of stain, along with research references describing \r\n conditions necessary to cause these stains to appear. \r\n \r\n Key Words : admixtures , carbonates, chlorides, \r\n condensation , manganese, masonry \r\n units , mortar , rain water , \r\n silicates, soluble salts , sulfates, trim, vanadium. \r\n \r\n INTRODUCTION \r\n \r\n Efflorescence is a crystalline deposit of water-soluble salts on \r\n the surface of brick masonry. The principal objection to efflorescence \r\n is its unsightly appearance. Although efflorescence is unsightly \r\n and a nuisance to remove, it is usually not harmful to the brick \r\n masonry. \r\n Efflorescence is usually white in color; however, all white stains \r\n on brick masonry are not necessarily efflorescence. Also, certain \r\n vanadium and molybdenum compounds, present in some ceramic units, \r\n may produce a green deposit, commonly referred to as \"green stain\". \r\n Occasionally, \"brown stain\" may occur, resulting from deposits of \r\n manganese compounds. \r\n Under certain specific circumstances and conditions, it is possible \r\n for the crystals of efflorescence to form within the bodies of the \r\n units. When this occurs, it is possible that the pressure of crystallization \r\n and growth of the crystals may cause cracking and distress to the \r\n masonry. \r\n \r\n This Technical Notes addresses the mechanisms of efflorescence, \r\n including possible sources of salts and of water. The purpose is to \r\n provide a basic understanding of the phenomenon of efflorescence for \r\n the design professional, specification writer, contractor or owner. \r\n Technical Notes 23A Revised \r\n will present recommendations on how to prevent the occurrence of efflorescence, \r\n and serve as a guide for its investigation, identification and elimination. \r\n \r\n MECHANISMS OF EFFLORESCENCE \r\n \r\n The mechanisms of efflorescence are many and often complicated. \r\n However, simply stated, water-soluble salts in solution are brought \r\n to the surface of the masonry and deposited there by evaporation. \r\n The salt solutions may migrate across surfaces of units, between \r\n the mortar and units, or through the pore structure of the mortar \r\n or the masonry units. \r\n There are certain simultaneous conditions which must exist in order \r\n for efflorescence to occur. Soluble salts must be present within \r\n or in contact with the masonry assembly. These salts may be present \r\n in the facing units, backup, mortar ingredients, trim, etc. There \r\n also must be a source of water and it must be in contact with the \r\n salts for sufficient time to permit them to dissolve. The masonry \r\n must be such that the migration of salt solutions to the surface, \r\n or other locations, occurs in an environment which is conducive \r\n to the evaporation of water. \r\n It is apparent, from the above discussion, that if masonry could \r\n be constructed to contain no water-soluble salts, or if no water \r\n were permitted to penetrate the masonry, efflorescence would not \r\n occur. However, in conventional masonry exposed to weather, neither \r\n of these conditions can exist. Consequently, the practical approach \r\n to the elimination of efflorescence is to reduce all contributing \r\n factors to a minimum \r\n \r\n Sources of Salts \r\n \r\n The chemical composition of efflorescent salts is usually alkali \r\n and alkaline earth sulfates and carbonates, although chlorides have \r\n also been identified. The most common salts found in efflorescence \r\n are sulfate and carbonate compounds of sodium, potassium, calcium, \r\n magnesium and aluminum. Chlorides may also occur as efflorescence. \r\n This is usually a result of the use of calcium chloride as a mortar \r\n accelerator, contamination of masonry units or mortar sand by sea \r\n water, or the improper use of hydrochloric acids in cleaning solutions. \r\n Efflorescence is further complicated by the many available sources \r\n of soluble salts. Soluble salts may be present in the masonry units, \r\n in the mortar, or may result from rain water or ground water, or \r\n other sources as discussed hereafter. \r\n Masonry Units . Since efflorescence appears on the face of \r\n the wall, it is often erroneously assumed to be the fault of the \r\n brick. This is not usually the case. There are, however, soluble \r\n salts present in many of the units that make up a wall assembly. \r\n \r\n Brick - Because of the composition of the raw materials \r\n and the high temperatures associated with the manufacturing process, \r\n it is possible for soluble phases to exist within the finished brick. \r\n If water is absorbed by such products, the soluble salts enter into \r\n solution and efflorescence may be formed as evaporation takes place \r\n from the surface of the brick. \r\n In regard to brick which contain water-soluble salts formed during \r\n firing, Brownell (W.E. Brownell, \"The Causes and Control of Efflorescence \r\n on Brickwork\", Research Report No. 15, Structural Clay Products \r\n Institute, 1969) states: \"Products such as these will show efflorescence \r\n when placed in distilled water, even though all precautions are \r\n taken to eliminate outside contamination.\" \r\n Brick units with low efflorescence potential are readily available \r\n in all parts of the United States and Canada. The potential for \r\n masonry units to effloresce may be easily assessed by the efflorescence \r\n test in ASTM C 67, Standard Methods of Sampling and Testing Brick \r\n and Structural Clay Tile. \r\n \r\n Backup - Masonry materials used as backup \r\n or inner wythes of masonry walls may contain large quantities of \r\n soluble salts. These units may contribute to efflorescence on the \r\n face of the wall, if sufficient water is present to dissolve the \r\n salts and pathways are provided for the solution to reach the masonry \r\n surface. \r\n A comparison of the various types of concrete masonry units with \r\n structural clay tile was made by Young (J.E. Young, \"Backup Materials \r\n as a Source of Efflorescence\", Journal , American Ceramic \r\n Society, 40 (7), 1957). Young measured the soluble salts content \r\n and efflorescent tendencies of each of the various units in his \r\n experiments. It was found that concrete products contain two to \r\n seven times as much soluble material as the fired clay material. \r\n Figure 1 illustrates the transfer of soluble salts from backup \r\n units to facing brick. This result was obtained by placing the backup \r\n block in pans of water with five brick on top of each block, as \r\n shown. The brick had previously been subjected to the efflorescence \r\n test and showed no efflorescence. The potential for backup units \r\n to effloresce can be determined by using the same efflorescence \r\n test method which is used for facing brick. \r\n \r\n \r\n \r\n \r\n Showing Migration of Soluble Salts from Backup to \r\n Facing Brick \r\n FIG. 1 \r\n \r\n \r\n \r\n Trim \r\n - Building trim, such as caps, coping, sills, lintels, keystones, \r\n etc., are often of materials other than fired clay products. These \r\n items can be natural stone, cast stone, precast concrete, etc., \r\n which may contain soluble salts. Such materials may contribute significantly \r\n to efflorescence on the face of adjacent brickwork. \r\n \r\n Mortar . Mortar can be a significant contributor to efflorescence. \r\n As Brownell states: \r\n \"The primary and most obvious source of contamination of otherwise \r\n efflorescence-free brick is the mortar used in wall construction. \r\n The mortar is in intimate contact with the brick on at least four \r\n and sometimes five sides. It is applied to the brick in a wet, paste-like \r\n condition which provides ample moisture for the transfer of soluble \r\n salts from the mortar to the brick. If any appreciable soluble material \r\n is present in the mortar, it will be carried into the brick proportionately \r\n to the amount of moisture transferred. \r\n \"The simplest case of soluble salt contamination of efflorescence-free \r\n brick is the migration of free-alkali solutions from the mortar \r\n to the brick. This situation is not only the simplest mechanism, \r\n but it is also the most common. In the trade, it is known as new \r\n building bloom.\" \r\n \r\n Cement - The water-soluble alkalies common \r\n in mortars are sodium and potassium. Alkalies available in portland \r\n cements vary from one source to another, ranging from approximately \r\n 0.02 percent to 0.90 percent by weight of the cement. A survey of \r\n masonry cements indicates a range of alkali from 0.03 to 0.27 percent \r\n by weight of the cement. \r\n It is suspected that the sulfate content of the cement may be as \r\n significant as the alkali content in contributing to efflorescence. \r\n Modern cement manufacturing methods which attempt to achieve energy \r\n conservation may result in larger quantities of sulfates in the \r\n finished products. \r\n Lime - Various investigators disagree as to the possible \r\n contribution of lime to efflorescence. It has been demonstrated \r\n that lime, clay or sand additions to a mortar mix-do not generally \r\n contribute to efflorescence (T.J. Minnick, \"Effect of Lime on Characteristics \r\n of Mortar in Masonry Construction\", Bulletin, American Ceramic Society, \r\n 38 (5), 1959.) In fact, these ingredients tend to dilute the deleterious \r\n effects of a high alkali cement. \r\n On the other hand, lime is relatively soluble. Its presence may \r\n serve to neutralize sulfuric acids generated within the masonry. \r\n However, a cleaning solution containing hydrochloric acid can produce \r\n very soluble calcium chloride which can migrate to the surface. \r\n Nevertheless, lime in mortar is very important in establishing good \r\n bond to brick units, and thereby increases the water resistance \r\n of the masonry. \r\n \r\n Sand - Sands used in mortar are primarily silica, \r\n and as such they are not water-soluble. Sands, however, may be contaminated \r\n with material which will contribute to efflorescence. This contamination \r\n may include: sea water, soil runoff, plant life and decomposed organic \r\n compounds, among others. Any of these may contribute to efflorescence. \r\n Miscellaneous Sources of Salts . In addition to the mortar \r\n and units placed in the masonry, there are other outside sources \r\n of soluble salts that may contribute to efflorescence. Some of these \r\n are discussed here. \r\n \r\n Admixtures - A wide variety of admixtures \r\n for masonry mortars is available to the masonry industry. Most of \r\n these products are proprietary and their compositions are not disclosed. \r\n In general, they are classified as grinding aids, air-entraining \r\n agents, water repellents, wetting agents and accelerators. \r\n The effects of these admixtures on the properties of mortar are \r\n generally limited to flow, water retentivity and strength. Little \r\n information is available as to their effect on bond, either between \r\n mortar and brick or between mortar and reinforcing. In addition, \r\n there is some evidence, based largely on field experience, that \r\n certain admixtures may reduce the bond between mortar and brick. \r\n This reduction in bond may make masonry walls more vulnerable to \r\n water penetration. \r\n For these reasons, admixtures with unknown compositions are not \r\n recommended for use in mortars unless it has been established by \r\n experience or laboratory tests that they will neither materially \r\n impair mortar bond nor contribute to efflorescence. \r\n \r\n Calcium Chloride - Calcium chloride is sometimes \r\n added to mortar as an accelerator as permitted by ASTM C 270, Specification \r\n for Mortars for Unit Masonry. Calcium chloride and compounds containing \r\n calcium chloride should not be permitted in masonry containing metal \r\n anchors or reinforcing, as corrosion of metal embedded in mortar \r\n will occur when exposure conditions are favorable. \r\n \r\n If calcium chloride is used, it should be limited to an amount not \r\n to exceed 2 percent by weight of the portland cement or 1 percent \r\n of the masonry cement (usually about 50 percent portland cement) content \r\n of the mortar. See Technical Notes 1 . \r\n Normally, this amount of calcium chloride will not contribute materially \r\n to efflorescence. \r\n \r\n Ground Water - Soluble salts in soil are dissolved \r\n by water which penetrates the ground. Consequently, most ground \r\n water contains a high concentration of these salts. When the earth \r\n is in contact with the masonry, ground water may be absorbed by \r\n the masonry and may rise, through capillary action, several feet \r\n above the ground. An accumulation of salts in the masonry is then \r\n possible. \r\n \r\n Atmosphere - It has been reported by some investigators \r\n that sulfurous gases in the atmosphere may contaminate the brickwork. \r\n (F.O. Anderegg, \"Efflorescence\", ASTM Bulletin No. 195, 1952). This \r\n situation over a period of time will cause disintegration of the \r\n mortar joint surfaces. These acids may also attack the components \r\n of the brick itself. The reports of such instances are infrequent \r\n and are limited to highly industrial areas and coastal regions. \r\n \r\n Sources of Moisture \r\n \r\n As previously discussed, the mechanism of efflorescence is dependent \r\n upon the presence of free water in the masonry to dissolve the available \r\n soluble salts. Some of the sources of free water are discussed in \r\n the following paragraphs. \r\n \r\n Rain Water . The primary source of moisture for the occurrence \r\n of efflorescence is rain water which penetrates or comes in contact \r\n with masonry. The exposure of masonry to rain water varies greatly \r\n throughout the United States. Rain water exposure is very severe on \r\n the Atlantic Seaboard and Gulf Coast where rains of several hours \r\n duration may be accompanied by high winds. Rain water exposure is \r\n moderate in the Midwest and Mississippi Valley where wind velocities \r\n are lower. Rain water exposure is slight in arid areas of the West. \r\n Exposure area may be defined roughly in terms of wind pressure and \r\n annual precipitation. The maps in Fig. 2 indicate geographic areas \r\n of high wind pressures and heavy precipitation. A Driving Rain Index, \r\n which differs from the maps in Fig. 2, has recently been proposed. \r\n See Table 1 and Fig. 2 of Technical Notes 7 \r\n Revised. \r\n \r\n \r\n \r\n \r\n FIG. 2a \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 2b \r\n \r\n \r\n Rain water will penetrate all masonry walls to some degree, especially \r\n if they are improperly designed or improperly detailed. The craftsmanship \r\n employed in the construction of a masonry wall also has a significant \r\n effect on the amount of water penetrating the wall. Brick masonry \r\n with workmanship characterized by partially filled joints, deep furrowing \r\n of the mortar beds and improper execution of flashing and caulking \r\n details will be more subject to rain penetration. See Technical \r\n Notes 7 Revised, 7A \r\n Revised and 7B Revised. \r\n Condensation . In addition to rain water and ground water, \r\n water may accumulate within the wall as a result of condensation \r\n of water vapor. Frequently, efflorescence that appears on masonry \r\n walls protected from rain is due to this accumulation of condensed \r\n water. \r\n Condensation is usually due to moisture originating inside buildings. \r\n Cold outside air, entering a building and heated for comfort purposes, \r\n is invariably low in moisture content. Moisture released from cooking, \r\n bathing, washing and other operations employing water or steam, \r\n and moisture released by exhalation and perspiration of the occupants \r\n humidify this air. This gain in moisture content increases the vapor \r\n pressure of the inside air substantially above that existing outdoors. \r\n This increased pressure tends to drive the vapor outwardly from \r\n the building interior through any vapor-porous materials that may \r\n comprise the enclosing surfaces. \r\n \r\n When vapor passes through porous and homogeneous materials, which \r\n may be warm on one side and cold on the other, it may pass through \r\n the zone of its dew point temperature without condensing into water. \r\n But, if the flow of vapor is impeded by vapor-resistant surfaces at \r\n a temperature below the dew point temperature, the vapor will condense \r\n on such cold surfaces. This condensed moisture can contribute to efflorescence \r\n on the wall surface. See Technical Notes 7C \r\n and 7D . \r\n Construction . Another source of moisture which may cause \r\n \"new building bloom\" and contribute to future occurrences of efflorescence \r\n in a building is the water which enters the assembly during construction. \r\n The improper protection of a building during construction may significantly \r\n contribute to future problems, including efflorescence. It is at \r\n this stage, when interior assemblies are exposed, joints are open \r\n and foreign materials are present on the project, that the construction \r\n is highly vulnerable to the entry of considerable moisture. Also, \r\n in some cases, additional soluble salts from other sources may contaminate \r\n the masonry wall assembly. \r\n \r\n OTHER STAINS \r\n \r\n Stains will occasionally occur on the surfaces of masonry structures \r\n other than the fairly common white efflorescence previously discussed. \r\n These are carbonate deposits (\"lime run\"), silicate deposits (white \r\n \"scum\"), \"green stains\" and \"brown stains\". \r\n \r\n Carbonate Deposits (Lime Run) \r\n \r\n Carbonate deposits, if they occur, usually appear as a gray-white, \r\n crusty spot in the form of a vertical \"run-down\" shape on the face \r\n of the wall. These deposits are sometimes referred to as \"lime run\". \r\n This is not really correct, and may be misleading, as \"lime run\" \r\n is not directly a result of lime in the mortar. Carbonate deposits \r\n nearly always occur at a small hole or opening in the face of the \r\n masonry. \r\n The mechanisms of this type of stain are not clearly understood, \r\n but are often compared with the formation of stalactites in limestone \r\n caves. It is apparent that this deposit/stain requires a great deal \r\n of water traveling a similar path over an extended period of time. \r\n The water takes any of several calcium compounds into solution, \r\n and brings them to the surface of the masonry through the hole. \r\n The source of the calcium compounds may be trim, mortar, backup, \r\n etc. At the surface, it is thought that the solution reacts with \r\n carbon dioxide in the air, thus forming the crusty deposit. \r\n \r\n These carbonate stains can be removed using a weak solution of hydrochloric \r\n acid, applied directly to the deposit. Care must be taken to properly \r\n wet the wall area first and rinse it thoroughly after cleaning. This \r\n is especially true when removing carbonate deposits from light-colored \r\n brick. See Technical Notes 20 \r\n Revised. The deposit is likely to reappear unless the water source \r\n is stopped. \r\n \r\n Silicate Deposits (Scumming) \r\n \r\n Silicate deposits, sometimes called \"scumming\", \r\n sometimes occur as a general white or gray discoloration on the \r\n face of brick masonry. The discoloration may occur over all of the \r\n face of the masonry or sometimes in specific locations of 100 to \r\n 200 sq ft (9 to 19 m 2 ) in area, irregular \r\n in shape. Silicate stain/deposits may also occur adjacent to trim \r\n elements, precast concrete and occasionally large expanses of glass. \r\n \r\n These silicate deposits on brick masonry should not be confused \r\n with the \"scumming\" that occasionally occurs on brick in the manufacturing \r\n process. This \"scum\" will be evident on the brick units in storage \r\n before they are placed in the wall. \r\n It is known that there is any number of mechanisms that may precipitate \r\n silicate deposits on brickwork. Their specific chemistry, however, \r\n is not totally clear. Many of these stains are related to the cleaning \r\n of brick masonry with hydrochloric acid solutions, especially if \r\n proper cleaning procedures are not carefully followed, i.e., thoroughly \r\n wetting the wall, method of applying the cleaning solution and thoroughly \r\n rinsing the wall with clear water. \r\n \r\n Silicate deposits are very difficult, if not impossible, to remove \r\n from brick masonry. They are insoluble in most acids. Often the only \r\n practical method of dealing with a silicate deposit is to disguise \r\n it and permit it to weather away over time. See Technical Notes \r\n 20 Revised. \r\n \r\n Vanadium (Green or Yellow Stains) \r\n \r\n Some structural clay products develop yellow or green efflorescent \r\n salts when they come in contact with water. These stains are usually \r\n vanadium salts. They may be found on red, buff or white clay products; \r\n however, they are most objectionable and more readily apparent on \r\n the lighter-colored units. The vanadium salts responsible for these \r\n stains have their origin in the raw materials used for the manufacture \r\n of the clay products. The yellow and green stains are usually vanadyl \r\n salts, consisting of sulfates and chlorides, or hydrates of these \r\n salts. \r\n The mechanisms of this type of stain are as follows: as water travels \r\n through the brick, it dissolves both the vanadium oxide and sulfates. \r\n In this process, the solution may become quite acidic. As the solution \r\n evaporates from the surface of the product, the salts are deposited. \r\n The chloride salts of vanadium require highly acidic leaching solutions, \r\n and are usually the result of washing brickwork with acid cleaning \r\n solutions. Vanadyl chloride, one of the most prominent stain compounds, \r\n forms almost exclusively as a result of washing with hydrochloric \r\n acid. As stated by Brownell: \"A highly acid condition in the water \r\n leaching through a brick is necessary for the promotion of the colored \r\n vanadyl salts.\" \r\n Preventing green stain caused by vanadium is important, since subsequent \r\n efforts at cleaning may turn it into a brown, insoluble deposit \r\n that is very difficult to remove. \r\n To minimize the occurrence of green stain, the following steps \r\n are recommended: \r\n 1. Store brick off the ground and under protective covers. \r\n 2. Never use or permit the use of acid solutions to clean light-colored \r\n brick. \r\n 3. Seek and follow the recommendations of the brick manufacturer \r\n for cleaning procedures, for all types and colors of brick. \r\n \r\n Green vanadium stains can be difficult to remove. Some methods and \r\n procedures for the removal of green stain are described in Technical \r\n Notes 20 Revised. Never attempt \r\n to remove green stain with acids. \r\n \r\n Manganese (Brown Stain) \r\n \r\n Under certain conditions, tan or brown, and sometimes gray staining \r\n may occur on the mortar joints of brickwork. Occasionally, the brown \r\n stain will streak down onto the faces of the brick. This type of \r\n stain is the result of the use of manganese dioxide as a coloring \r\n agent in the units. This staining problem is closely related to \r\n the general efflorescence problem, since it is the sulfate and chloride \r\n salts of manganese that travel to the surface of the brick and are \r\n deposited on the mortar joints. \r\n During the brick firing process, the manganese coloring agents \r\n undergo several chemical changes, resulting in manganese compounds \r\n that are insoluble in water. They have varying degrees of solubility \r\n in weak acids. As previously discussed, acid solutions can occur \r\n in the brick in a wall. Also, the brick can absorb hydrochloric \r\n acid during the masonry cleaning process. It is also possible that \r\n in some areas rain water may be acidic (T.J. Minnick, \"Effect of \r\n Lime on Characteristics of Mortar in Masonry Construction\", Bulletin , \r\n American Ceramic Society, 38 (5), 1959.) \r\n \r\n According to Brownell: \"The manganese sulfate \r\n or chloride solutions from the brick will migrate across the mortar \r\n joints especially during a period of drying. These acidic manganese \r\n solutions will be neutralized by the inherent basic nature of the \r\n mortar. Upon neutralization, insoluble manganese hydroxide is precipitated \r\n on the mortar joints, and this is converted to brown Mn 3 O 4 on drying.\" \r\n \r\n To minimize or eliminate manganese staining, the following are \r\n suggested: \r\n 1. When a building is under construction using brick colored with \r\n manganese, it should not be cleaned with hydrochloric acid without \r\n neutralizing the acid during the rinsing operation. Such neutralization \r\n will tend to reduce the amount of manganese taken into solution. \r\n \r\n 2. Application of silicones to brick (if otherwise unobjectionable, \r\n see Technical Notes 6A ) may \r\n prevent staining by retarding water penetration of the brick while \r\n stored or in service. \r\n 3. Always request and follow the advice of the brick manufacturer \r\n in cleaning a brown or manganese-colored brick. \r\n \r\n The removal of manganese stain is a fairly simple operation, and \r\n is described in Technical Notes 20 \r\n Revised. However, the permanence of the removal is often in doubt. \r\n Hence, the prevention of the occurrence of brown manganese stain is \r\n of paramount importance. \r\n \r\n SUMMARY \r\n \r\n \r\n This Technical Notes has presented a brief description of \r\n the causes, mechanisms and sources of efflorescence. Technical \r\n Notes 23A Revised will address \r\n the prevention of efflorescence, a guide for analysis of efflorescence \r\n problems and the removal of efflorescent salts from the face of masonry. \r\n The information contained in this Technical Notes is based \r\n on the available data and experience of the technical staff of the \r\n Brick Institute of America. This information should be recognized \r\n as recommendations which, if followed with good judgment, should \r\n result in brick masonry that performs successfully. \r\n Final decisions on the use of information, suggestions and recommendations \r\n as discussed in this Technical Notes are not within the purview \r\n of the Brick Institute of America and must rest with the project \r\n owner, designer or both. \r\n \r\n REFERENCES \r\n \r\n For further information on the subject of efflorescence, its causes \r\n and mechanisms, the following publications may be consulted: \r\n \r\n \r\n 1. T. \r\n Ritchie, \"Study of Efflorescence Produced on Ceramic Wicks by \r\n Masonry Mortars\", Journal, American Ceramic Society, 38 \r\n (10) 1955. \r\n 2. W. \r\n F. Brownell, J. L. Kenna, and P. P. Wilko, Jr., \"Staining of Mortar \r\n by Manganese Colored Brick\", Bulletin, American Ceramic \r\n Society, 45 (12) 1966. \r\n \r\n 3. Technical \r\n Notes on Brick Construction \r\n 20 Revised, Brick Institute of America, \r\n McLean, Virginia, Sept/Oct 1977. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60088,"ResultID":176320,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 23A - Efflorescence, Causes and Mechanisms, Part 2 \r\n June 1985 (Reissued Jan. 2000) \r\n \r\n Abstract : Designers must not only understand the causes and \r\n mechanisms of the various types of efflorescence which can occur \r\n on brick walls, but should be aware of means to prevent efflorescence \r\n and to control it if it does appear. This Technical Notes presents \r\n a discussion on the importance of design, details, selection of \r\n materials, the use of caulking and sealants as well as the importance \r\n of good construction practices. An analysis procedure, consisting \r\n of a seven-point checklist, is suggested for use in examining problem \r\n structures. The concluding discussion addresses methods for the \r\n removal of efflorescence. \r\n \r\n Key Words : admixtures, analysis \r\n procedure , backup , brick, caulking and sealants \r\n coatings, construction practices , design, efflorescence, \r\n mortar , prevention , removal . \r\n \r\n INTRODUCTION \r\n Efflorescence, the normally harmless deposit \r\n of white crystals of salts on the face of brick masonry, can be \r\n prevented. An understanding of the nature and mechanisms of efflorescence, \r\n as well as the possible sources of soluble salts and moisture, is \r\n essential to the prevention of efflorescence. \r\n A detailed discussion of these mechanisms, \r\n soluble salts and moisture sources is contained in Technical \r\n Notes 23 Revised, \"Efflorescence-Causes \r\n and Mechanisms\". This discussion is recommended reading prior to \r\n the use of this issue of Technical Notes. \r\n This Technical Notes addresses \r\n recommendations for prevention and control of efflorescence, an \r\n analysis checklist for efflorescence problems and procedures for \r\n removal of efflorescence. \r\n \r\n PREVENTION OF EFFLORESCENCE \r\n It is not practical to attempt to preclude \r\n all soluble salts and all moisture from contact with masonry. However, \r\n the reduction of each of these contributing factors is highly practicable \r\n and will usually reduce or prevent the occurrence and severity of \r\n efflorescence. \r\n \r\n Selection of Materials \r\n Selecting materials, i.e., facing brick, \r\n backup, trim and mortar for minimum content of soluble salts and \r\n maximum performance for a watertight structure is the first step \r\n in the prevention of efflorescence. The following recommendations \r\n are presented to assist the designer in the selection of materials \r\n to limit the occurrence of efflorescence. \r\n Brick Units . As stated in Technical \r\n Notes 23 Revised, brick units \r\n which do not contain soluble salts or contribute to efflorescence \r\n are available throughout the United States and Canada. It is recommended \r\n that all solid and hollow facing brick be tested for a tendency \r\n to effloresce by the efflorescence test contained in ASTM C 67, \r\n Standard Methods of Sampling and Testing Brick and Structural Clay \r\n Tile. \r\n This test consists of partially immersing \r\n representative samples of brick in distilled water for a period \r\n of 7 days. At the end of this period, the units are allowed to dry, \r\n examined for efflorescence and compared to control samples which \r\n were not immersed. Brick should be rated at not more than \"slightly \r\n effloresced\" to be acceptable. \r\n Backup . Many backup materials contain \r\n relatively high percentages of alkali which may contribute to efflorescence \r\n on the face of a masonry wall. It is suggested, therefore, that \r\n backup units be tested for their salt content by the efflorescence \r\n test, as described by W. E. Brownell (W.E. Brownell,\" The Causes \r\n and Control of Efflorescence on Brickwork\", Research Report No. \r\n 15, Structural Clay Products Institute, 1969. \r\n When backup materials containing soluble \r\n salts are used, it is recommended that the wall details and design \r\n be such that the materials containing salts are separated from the \r\n facing brick. This design practice avoids through-the-wall migration \r\n of water-soluble salts solutions which lead to efflorescence. This \r\n can be done by using cavity-type walls, for example. \r\n Mortar . In Technical Notes \r\n 23 Revised, it is noted that the principal \r\n contribution to efflorescence in mortars is the high alkali content \r\n of the portland cement. The tendencies of cement toward efflorescence \r\n may be predicted with reasonable accuracy from a chemical analysis \r\n of the cement. Cements high in alkaline content are more prone to \r\n produce efflorescence than cements of lower alkali content. \r\n ASTM Standard Specification for Portland \r\n Cement, C 150, contains the following note as part of Section 4, \r\n Chemical Resistance: \r\n \"Note 3. Cement containing not more than \r\n 0.60 percent alkali calculated as the percentage of Na 2 O plus 0.658 times the percentage of \r\n K 2 O \r\n may be specified when the cement is to be used in concrete with \r\n aggregates that may be deleteriously reactive. Reference should \r\n be made to the Specification for Concrete Aggregates (ASTM Designation: \r\n C 33) for suitable criteria of deleterious reactivity.\" \r\n The alkalies referred to are the total, \r\n i.e., acid-soluble, which includes the water-soluble fraction alkalies. \r\n In general, the water-soluble alkali content will be of the order \r\n of 60 percent of the total. It is stated by Brownell: \r\n \"Experience has shown that 0.1 percent \r\n free alkali in a portland cement used in common mortars will cause \r\n new building bloom; therefore, if such efflorescence is to be \r\n avoided, the free alkali of the cement should be less than this \r\n and should be specified as low as possible.\" \r\n This severe limitation on water-soluble \r\n alkali content can be met only by a few cements, other than portland \r\n blast-furnace slag cement and masonry cements made with slag cement. \r\n It should be stated, however, that all \r\n investigators do not agree. Many believe that Brownell is extremely \r\n conservative. \r\n Other ingredients for mortar, i.e., lime, \r\n sand and water, should also be selected with care, although their \r\n contribution to efflorescence may be less frequent (see Technical \r\n Notes 23 Revised). \r\n Mortar types and proportions should be \r\n selected on the bases of structural and exposure requirements for \r\n the particular project. Recommendations for mortar are contained \r\n in Technical Notes 8 Revised \r\n and Technical Notes 8B . \r\n Admixtures . Admixtures for mortar \r\n are generally not recommended because of their unknown ingredients \r\n and the lack of data on their effect on bond strength and, consequently, \r\n watertightness of masonry walls. \r\n \r\n Design \r\n The most meticulous design and detailing \r\n may be thwarted by the selection of inappropriate materials or by \r\n poor workmanship. The converse is also true; the use of the best \r\n possible materials and craftsmanship will not in themselves ensure \r\n a successful and permanent structure, if the design is improper. \r\n Wall Sections . The design of a \r\n masonry wall and the selection of materials for construction should, \r\n from the standpoint of resistance to rain penetration, be based \r\n upon the exposures to which the wall will be subjected. \r\n There are two principal methods employed \r\n for preventing penetration of wind-driven rain into the body of \r\n the masonry. One is to provide a cavity or airspace behind the exterior \r\n masonry wythe to channel water through weepholes back to the outside \r\n of the wall. A second method is to provide an internal barrier to \r\n water penetration in back of the exterior wythe. These two wall \r\n types are generally referred to as \"drainage\" and \"barrier\" wall \r\n types, respectively, and are discussed in detail in Technical \r\n Notes 7 Series. In general, the \"drainage\" type walls are recommended \r\n for maximum resistance to rain penetration and minimum efflorescence. \r\n Details . As previously stated, \r\n one of the necessary conditions for the occurrence of efflorescence \r\n is the presence of moisture in the wall assembly. The preclusion \r\n of this moisture will thwart the mechanisms for efflorescence. Therefore, \r\n much depends on the design and attention to certain critical details. \r\n Of primary importance are those details associated with the prevention \r\n of the entry of moisture into the masonry assembly. Also of importance \r\n are details that will direct water away from wall tops and horizontal \r\n surfaces. \r\n Design recommendations, wall types, workmanship \r\n characteristics, detailing, flashing, drips and weepholes are some \r\n of the points to which careful attention must be paid in order to \r\n prevent the occurrence of efflorescence. These subjects are discussed \r\n with recommendations in Technical Notes 7 Series. \r\n Caulking and Sealants . Too frequently, \r\n caulking is used as a means of correcting or hiding poor workmanship \r\n rather than as an integral part of construction which should be \r\n designed and installed in the same manner as other elements of the \r\n structure. \r\n Joints between masonry and door and window \r\n frames, expansion joints and other locations where caulking is required, \r\n are the most frequent sources of rain penetration into masonry. \r\n These vulnerable locations should be given careful attention during \r\n design and construction. Also, maintenance programs should be established \r\n to inspect and replace sealants or caulking which have dried, or \r\n become ineffective. It is noted that the expected life of the best \r\n available sealant material is only 4 to 10 years, depending on the \r\n exposure. \r\n \r\n Construction Practices \r\n As previously discussed, it is apparent \r\n that construction practices and workmanship employed in building \r\n masonry walls can seriously affect the walls tendency to effloresce. \r\n Some discussion and recommendations for proper construction practices \r\n follow. \r\n Workmanship . Workmanship characterized \r\n by the complete filling of all mortar joints intended to receive \r\n mortar is desirable, as is the need to keep all cavities clean and \r\n free of mortar droppings. Attention to both of these items is of \r\n primary importance in preventing moisture penetration to the interior \r\n of masonry. It is also of paramount importance in preventing the \r\n occurrence of efflorescence. Technical Notes 7B \r\n Revised discusses the workmanship practices which should be employed \r\n in the construction of masonry walls. \r\n Protection . Partially completed \r\n masonry walls exposed to rain and other elements during construction \r\n may become saturated with water and can require weeks, or even months \r\n (depending on climatic conditions), after the completion of the \r\n building for the masonry to dry. This prolonged saturation may cause \r\n many \"slightly\" soluble salts, as well as the highly soluble salts, \r\n to go into solution. Such conditions may also contribute to the \r\n contamination of the masonry with soluble salts from elsewhere in \r\n the construction (concrete, plaster, trim, etc.). \r\n During construction, all walls should \r\n be kept dry by covering with a strong, waterproof membrane at the \r\n end of each workday or shutdown period. Mortar boards, scaffold \r\n planks and light plastic sheets weighted with brick should not be \r\n accepted as suitable cover. Metal clamps, similar to bicycle clips, \r\n are commercially available in a variety of sizes to meet various \r\n wall thicknesses. These are used in conjunction with plastic sheets \r\n or water-repellent tarpaulin material and offer excellent protection \r\n for extended periods of time. For masonry construction during cold \r\n weather, see Technical Notes 1 Series for winter protection \r\n recommendations and construction procedures. \r\n Storage of Materials . The method \r\n of storing materials at a construction project site may influence \r\n future occurrence of efflorescence. Materials should be stored in \r\n such a manner as to avoid their saturation by rain, snow and ground \r\n moisture, as well as contamination from salts or other matter which \r\n may contribute to efflorescence. \r\n \r\n Masonry Units - Masonry \r\n units should be stored off the ground to avoid contamination by \r\n dirt and ground water which may contain soluble salts. They should \r\n also be covered by a waterproof membrane to keep them dry. \r\n \r\n Cementitious Materials - \r\n Cementitious materials for mortar should be stored off the ground \r\n and either inside or under cover. \r\n \r\n Sand - Sand for mortar should \r\n also be stored off the ground to prevent contamination from dirt, \r\n plant life, organic materials and ground water, any of which may \r\n be a contributor to efflorescence. In addition, it is advisable \r\n to store sand and other aggregates under a protective membrane cover, \r\n if possible. \r\n \r\n Analysis Procedure \r\n An examination of a problem structure \r\n using the following checklist may be sufficient to determine the \r\n cause and extent of the efflorescence problem, and to suggest methods \r\n for repair and alleviation. \r\n 1. Determine the age of the structure \r\n at the time when the efflorescence first appeared. If \"new building \r\n bloom\" is involved (structures less than one year old), the source \r\n of the salts is often the cement in the mortar, and the source of \r\n the moisture is usually the construction water. If, however, the \r\n building is over a year old, other sources must be considered. \r\n If the structure is over two years old, \r\n construction details should be examined for possible leaks in the \r\n wall or in the surrounding construction. The appearance of efflorescence \r\n on an established building, which has been free of efflorescence, \r\n is usually attributable to a new source of water in the masonry. \r\n 2. The location of the efflorescence, \r\n both on the structure and on the individual units or mortar \r\n joints, should also be carefully noted. The location on the building \r\n may offer some information as to where the water is entering. The \r\n location of salt crystals on the joints or the units may be of help \r\n in determining the source of the salts. The recent use or occupancy \r\n of the building should also be noted. For example, has it been vacant \r\n for some time or has there been new construction? In short, what \r\n has occurred that might cause, or trigger, the appearance of the \r\n efflorescence? \r\n 3. The condition of the masonry should \r\n be carefully examined. The profile of the mortar joints, the condition \r\n of the mortar, the quality of workmanship employed, the condition \r\n of caulking and sealant joints, the condition of flashing and drips, \r\n any deterioration or eroding of mortar joints in copings or in sills \r\n should all be carefully noted. This information should offer clues \r\n as to the entry paths of moisture into the construction. \r\n 4. The wall sections and details of \r\n construction should be examined for an indication of possible paths \r\n of moisture travel, and for possible sources of contamination by \r\n soluble salts. A careful examination of roof and wall juncture and \r\n flashing details should be made. A comparison of \"contract drawings\" \r\n with \"as built drawings\" may be helpful. This examination will also \r\n be useful for the later determination of steps for repair or alleviation \r\n of the efflorescence. \r\n 5 . Laboratory test reports on the \r\n materials of construction should be examined, if they are available. \r\n This will help determine the source of the soluble salts, and may \r\n be of use in analyzing and making repair judgments. \r\n 6. The identification of efflorescence \r\n is sometimes of use. This can be done by commercial testing \r\n laboratories. X-ray defection analysis is sometimes used. Petrographic \r\n analysis or chemical analysis is also possible. In some instances, \r\n it is useful to know both the type of salts present and their relative \r\n quantity. \r\n Table 1 is taken from Brownells report \r\n and is described as a table of most probable sources of salts. \r\n \r\n \r\n \r\n \r\n \r\n 7. Miscellaneous sources of water should \r\n also be considered if all other sources seem to be eliminated. Some \r\n of these sources are: condensation within the wall, leaky pipes, \r\n faulty drains and condensation on heating or plumbing pipes. Although \r\n somewhat rare, if a condensation analysis is necessary, the methods \r\n are described in Technical Notes 7C \r\n and 7D . \r\n \r\n Corrections and Solutions \r\n When the mechanisms causing the efflorescent \r\n salts to appear have been established and the sources of salts or \r\n moisture are identified (usually the latter). the problem of making \r\n suitable corrections must be addressed. Such solutions to efflorescence \r\n problems usually involve preventing the entry of water into the \r\n masonry and removing the efflorescence from the wall. \r\n Recommendations for the correction of \r\n water penetration in masonry walls are contained in Technical \r\n Notes 7 Series. \r\n \r\n Coatings \r\n Silicone or acrylic applications are among \r\n the solutions open suggested for prevention of efflorescence. The \r\n application of a coating to a masonry wall may prevent recurrence \r\n of efflorescence. However, the application of a coating to masonry \r\n which has a tendency to effloresce, without stopping the mechanisms \r\n causing the occurrence of that efflorescence, may lead to disintegration \r\n of the masonry. \r\n As stated in Technical Notes 6A , \r\n water gaining entrance into the masonry will still take soluble \r\n salts into solution. Then, as the water travels toward the treated \r\n surface, most of it will be stopped at the inner depth of the coating \r\n penetration (usually 1/8 to 1/4 in. [3 to 6 mm]) from the face. \r\n At this point, the water will evaporate, passing through the treated \r\n area as vapor and will present no problem. However, the soluble \r\n salts contained will be deposited within the masonry at the point \r\n where the water evaporates. The crystalline growth, at that point, \r\n can develop tremendous pressures which may result in brick spalling. \r\n It is for this reason that coatings are not recommended as a treatment \r\n for efflorescence problems. \r\n \r\n REMOVAL OF EFFLORESCENCE \r\n As a general rule, the removal of efflorescent \r\n salts from the face of masonry is a relatively easy operation. As \r\n stated, most efflorescent salts are water-soluble and many will \r\n disappear of their own accord with normal weathering. This is especially \r\n true of \"new building bloom\". \r\n It is usually not advisable to wash \r\n efflorescence off of the brickwork except in warm, dry weather, \r\n since this results in the availability of considerably more moisture \r\n which may bring more salts to the surface. Many efflorescent salts \r\n can be removed by dry brushing. \r\n For recommendations concerning the removal \r\n of the efflorescent salts and other stains on masonry walls, see \r\n Technical Notes 20 Revised. \r\n Special care should be exercised in the cleaning operation of new \r\n masonry, since improper procedures and errors can contribute to \r\n or cause efflorescence and/or other staining. \r\n \r\n SUMMARY \r\n As stated, the mechanisms for efflorescence \r\n require the presence of soluble salts and moisture. To prevent or \r\n stop the occurrence of efflorescence, the elimination of either \r\n will suffice. \r\n Recommendations have been offered in this \r\n Technical Notes for the proper selection of materials, wall \r\n sections and design details to reduce to a minimum the available \r\n salts and the opportunity for water penetration. A discussion of \r\n the sources of moisture and salts and the mechanisms of efflorescence \r\n is contained in Technical Notes 23 \r\n Revised. \r\n The information contained in this Technical \r\n Notes is based on the available data and the experience \r\n of the technical staff of the Brick Institute of America. This information \r\n should be recognized as recommendations which, if followed with \r\n good judgment, should result in brick masonry that performs successfully. \r\n Final decisions on the use of details \r\n and materials as discussed in this Technical Notes are not \r\n within the purview of the Brick Institute of America and must rest \r\n with the project designer, owner or both. \r\n \r\n REFERENCES \r\n Information beyond that discussed in this \r\n Technical Notes is contained in the following publications: \r\n 1. Selected \r\n ASTM Standards for Brick, compiled by ASTM for Brick Institute \r\n of America, August 1985. \r\n 2. Technical \r\n Notes on Brick Construction 1 \r\n Revised, \"Cold Weather Masonry Construction-Introduction\", Reissued \r\n July 1981. \r\n 3. Technical \r\n Notes on Brick Construction 7 Series on the subject \r\n of Water Resistance of Brick Masonry. \r\n 4. Technical \r\n Notes on Brick Construction 8 \r\n Revised, \"Portland Cement-Lime Mortars for Brick Masonry\", September \r\n 1972. \r\n 5. Technical \r\n Notes on Brick Construction 20 \r\n Revised, \"Cleaning Brick Masonry\", Sept.-Oct. 1977. \r\n 6. Technical \r\n Notes 23 Revised, \"Efflorescence, \r\n Causes and Mechanisms, Part I of II\", May 1985. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60089,"ResultID":176321,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 24 - The Contemporary Bearing Wall \r\n Feb. 1970 (Reissued Dec. 1986) \r\n \r\n INTRODUCTION \r\n \r\n It has only been during the past five years (since 1965) that it \r\n has been the practice in this country to base the design of loadbearing \r\n brick masonry structures on a rational analysis. Prior to this time, \r\n the design of buildings was based on the empirical requirements of \r\n building codes for minimum wall thickness and maximum height. As a \r\n result of this, bearing wall construction for buildings higher than \r\n three to five stories was uneconomical and other methods of support \r\n (steel or concrete skeleton frame) were generally used. Since 1965, \r\n there has been a renewed interest on the part of the design professional, \r\n architect and engineer, in modern bearing wall construction, wherein \r\n the design is based on a rational structural analysis rather than \r\n on outmoded arbitrary requirements. This interest was first stimulated \r\n by the work in Europe, where many loadbearing brick buildings exceeding \r\n ten stories in height have been constructed during the past two decades. \r\n \r\n EXAMPLES \r\n \r\n One of the worlds tallest thin-brick bearing wall structures built \r\n in 1957, is located near Zurich, Switzerland (Fig. 1). This 18-story \r\n apartment structure utilizes interior loadbearing brick walls of 5 \r\n to 10 in. in thickness. The exterior walls (Fig. 2) are 15-1/4 in. \r\n in thickness; the thickness in this instance being determined by the \r\n requirements for thermal insulation rather than by structural requirements. \r\n By using cavity walls, the Swiss have found a way to provide the required \r\n thermal insulation and still maintain relatively thin exterior walls. \r\n Figure 3 shows a 16-story apartment building in Grenchen, Switzerland \r\n which utilizes cavity wall construction. The exterior walls of this \r\n building (Fig. 4) are comprised of a 6-in. brick inner bearing wythe, \r\n a 1-1/2-in. cavity and a 5-in. exterior brick wythe. The floor loads \r\n are carried by the 6-in. inner wythe and 6-in. interior brick bearing \r\n partitions. The 5-in. exterior wythe of the exterior wall is self-supporting \r\n on the foundation and is tied only at each floor level, with 1/4-in. \r\n stainless steel wire anchors embedded in the edge of the slab at approximately \r\n 20 in. on center. \r\n \r\n \r\n \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Bearing Wall @ Floor Slab \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Cavity Wall @ Floor Slab \r\n FIG. 4 \r\n \r\n \r\n \r\n Many of the high-rise brick bearing wall buildings in Switzerland \r\n are stuccoed on the exterior; this being their traditional method \r\n of building. However, there is an increasing use of exposed clay masonry \r\n units. Another example (Fig. 5) is a 14-story structure in Lucerne. \r\n The exterior bearing walls of this structure are only 7-1/4 in. in \r\n thickness (Fig. 6). The resistance to water penetration is provided \r\n by parging on the interior of the exterior wall rather than stucco \r\n on the outside. \r\n \r\n \r\n \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Brick & Clay Tile Cavity Wall @ Floor Slab \r\n FIG. 6 \r\n \r\n Recent American examples of brick bearing wall construction are shown \r\n in Figs. 7, 9 and 11. Figure 7 is the 17-story Park Mayfair East building, \r\n in Denver, Colorado. The structural system in this building utilizes \r\n 11-in. reinforced brick masonry (RBM) walls for the full building \r\n height (165 ft). Fourteen-inch prestressed concrete twin-tee slabs \r\n were used for the floor spans, which vary from 32 to 37 ft (Fig. 8). \r\n \r\n \r\n \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Cavity Wall @ Precast Tee Floor \r\n FIG. 8 \r\n \r\n \r\n \r\n Figure 9 illustrates the 8-story Oakcrest Towers apartment building \r\n in Prince Georges County, Maryland near Washington, D. C. This building \r\n utilizes 8-in. brick exterior walls for the full height of the building, \r\n and 6-in. brick bearing corridor walls. The floor system, in this \r\n instance is steel joints with 2-1/2-in. concrete topping over metal \r\n deck for the 24-ft. apartment span, and a 5-in. flat concrete slab \r\n or the 6-ft corridor span. Figure 10 is the typical detail for the \r\n 8-in. exterior and the 6-in. corridor walls. \r\n \r\n \r\n \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Interior Bearing Wall @ Floor Truss & Concrete Slab \r\n FIG. 10a \r\n \r\n \r\n \r\n \r\n \r\n Exterior Bearing Wall @ Floor Truss & Concrete Slab \r\n FIG. 10b \r\n \r\n \r\n \r\n The Muskegon Retirement Apartments (Fig. 11) is an 11-story, 194-unit \r\n structure in Muskegon, Michigan. The structure consists of 8-in. solid \r\n brick bearing cross walls which support the 8-in. precast hollow core \r\n concrete plank floor system. Non-bearing exterior walls are 10-in. \r\n brick cavity walls, insulated with water-repellent vermiculite (Figs. \r\n 12 and 13). Exposed brick forms the interior finish on the bearing \r\n cross walls, which are also separation walls between units. These \r\n walls provide attractive low maintenance surfaces, fire resistance, \r\n structure, and excellent sound separation. \r\n \r\n \r\n \r\n FIG. 11 \r\n \r\n \r\n \r\n \r\n \r\n Interior Bearing Wall \r\n FIG. 12 \r\n \r\n \r\n \r\n \r\n \r\n Exterior Non-Bearing Wall \r\n FIG. 13 \r\n \r\n \r\n \r\n BUILDING CODES \r\n \r\n Working with a highly qualified Engineering Advisory Committee, consisting \r\n of practicing structural engineers from throughout the continent, \r\n the Structural Clay Products Institute published the first edition \r\n of a rational design standard for engineered brick masonry in May \r\n of 1966. This first Standard was based on laboratory research and \r\n historical performance data. In August 1969, the Institute (now the \r\n Brick Institute of America), also in cooperation and collaboration \r\n with the Engineering Advisory Committee, developed and published a \r\n second generation standard, Building Code Requirements for Engineered \r\n Brick Masonry, BIA, August 1969. This newer edition incorporates \r\n the findings of additional research and the experience of architects \r\n and engineers in their use of the 1966 Standard. \r\n To date (February 1970), provisions of the First or Second Edition \r\n of the BIA Standard have been accepted by reference, or incorporated \r\n into the masonry chapters, by all of the model building codes in the \r\n United States. In addition, the Standard is listed as an acceptable \r\n design standard for masonry in the Department of Defense-Construction \r\n Criteria Manual, and is used by the various agencies of the Department \r\n of Housing and Urban Development. \r\n For easy reference, the BIA Standard has been accepted in substance \r\n or by reference in the following model and state building codes: \r\n \r\n Model Building Codes \r\n \r\n 1. BOCA Basic/National Building Code, 1984 Edition; Appendix A. Referenced \r\n Standards. \r\n 2. Standard Building Code, 1985 Edition; Section 1403.6 - Structural \r\n Analysis of Unreinforced Masonry, and Section 1411-Reinforced Masonry. \r\n 3. Uniform Building Code, 1985 Edition; Chapter 24 - Masonry. \r\n \r\n State Building Codes \r\n \r\n 1. Pennsylvania; \"Building Regulations for Protection from Fire and \r\n Panic of the Pennsylvania Department of Labor and Industry\", pages \r\n 6, 10 and 106A, September 22, 1966. \r\n 2. North Carolina State Building Code, 1967 Edition; Section 1403.7, \r\n Engineered Designs, and Section 1411, Reinforced Masonry. \r\n 3. Ohio Building Code, as amended July 3, 1967; Section BB-35-19.05, \r\n Engineered Brick Masonry, General Design and Construction Requirements. \r\n 4. State of Connecticut Basic Building Code (Revision dated October \r\n 1, 1967); Appendix B, Accepted Engineering Practice Standards. \r\n In addition to the model building codes and state building codes \r\n listed above, many local municipal sub-divisions - cities, counties \r\n and townships - have also adopted, by reference or in principle, these \r\n engineered brick masonry provisions and requirements. \r\n \r\n ECONOMICS \r\n \r\n Experience to date indicates that brick masonry bearing wall construction \r\n is competitive with structural frame, and for many types of buildings \r\n can be constructed at less cost. This economic advantage is due in \r\n part to the increased efficiency of the use of materials. For example, \r\n in a brick bearing wall structure, the brick walls become enclosure, \r\n separation, structure, finish and fire protection. The economic position \r\n is also the result of the simplified and faster construction process. \r\n Mr. Harold Simpson, General Contractor and part owner of the Park \r\n Mayfair East project in Denver (see Figs. 7 and 8), stated these reasons \r\n for using the brick bearing wall structural system: \r\n \"...As an owner, the number one consideration is lower initial \r\n and future costs, which means we can charge lower rents and have lower \r\n vacancy rates. The next important single criterion of a good apartment \r\n is sound control. For this, the 11 - in. wall of brick and grout gave \r\n us a sound resistance of 58 decibels which is excellent. Another important \r\n aspect is the shorter construction time which allows earlier occupancy. \r\n This means lower interest payments on construction loans and earlier \r\n rent payments. In fact as the building was being topped out, some \r\n of the lower floor apartments were complete with carpets and draperies, \r\n and future tenants were visiting the fully furnished display apartments. \r\n \"As a contractor, I look at this brick bearing wall structural \r\n system much the same as an owner, but with some differences. The faster \r\n erection time is very important because time is money. Brick bearing \r\n walls give me lower costs and faster erection by being the structural \r\n system as well as the enclosure walls. When the bearing walls are \r\n complete and the floor slabs have been placed, we have only to insert \r\n the windows and (1) the floor is closed in, (2) the exterior walls \r\n are complete, (3) the structure is fireproof. In addition, we have \r\n fire walls between apartments and many of the interior walls are also \r\n complete. This is not true with a steel or concrete structure. This \r\n finished building, including appliances, draperies, carpeting and \r\n landscaping, cost $12.25 per sq. ft. of floor area. This total includes \r\n some costs that would not have to be duplicated if we constructed \r\n the buildings again, but, with labor and material cost increases expected \r\n in the future, a new building similar to this one would probably cost \r\n about the same. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Monk, \r\n Clarence B., Jr. and Gross, James G., European Clay Masonry Loadbearing \r\n Buildings, SCPI, 1964. \r\n 2. Proceedings \r\n - The First National Brick and Tile Bearing Wall Conference, SCPI, 1965. \r\n 3. \"Contemporary \r\n Brick Bearing Wall\" Case Study, BIA (a bimonthly publication). \r\n 4. Technical \r\n Notes on Brick and Tile Construction, \r\n BIA (a monthly series). \r\n 5. Building \r\n Code Requirements for Engineered Brick Masonry, BIA, August 1969 \r\n 6. Gross, \r\n James G.; Dikkers, Robert D.; and Grogan, John C., Recommended \r\n Practice for Engineered Brick Masonry, BIA. November 1969. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60090,"ResultID":176322,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 24C - The Contemporary \r\n Bearing Wall - Introduction to Shear Wall Design \r\n Sept./Oct. 1970 (Reissued May 1988) \r\n \r\n INTRODUCTION \r\n The general design concept of the contemporary \r\n bearing wall building system depends upon the combined structural \r\n action of the floor and roof systems with the walls. The floor system \r\n carries vertical loads and, acting as a diaphragm, lateral loads to \r\n the walls for transfer to the foundation. Lateral forces of wind and \r\n earthquake are usually resisted by shear walls which are parallel \r\n to the direction of the lateral load. These shear walls, by their \r\n shearing resistance and resistance to overturning, transfer the lateral \r\n loads to the foundation. See Fig. 1. \r\n \r\n Shear Wall Action \r\n \r\n \r\n FIG. 1 \r\n \r\n It is the purpose of this Technical Notes \r\n to discuss some of the factors involved in the design of brick \r\n masonry shear walls and to present some of the available test data \r\n regarding their strength. Other issues of Technical Notes will \r\n contain examples relating to the design of brick masonry shear walls. \r\n \r\n LATERAL FORCES \r\n The principal lateral forces to be considered \r\n in the design of shear walls are wind pressure and earthquake. Most \r\n building codes and engineering practice standards specify that wind \r\n and earthquake may be assumed never to occur simultaneously. \r\n Wind Pressure . Building codes usually \r\n specify design wind load requirements which should be considered minimum. \r\n For additional information on wind pressure, the designer may refer \r\n to the American Standard Building Code Requirements for Minimum \r\n Design Loads in Buildings and Other Structures, A58.1 - 1955, \r\n and \"Wind Forces on Structures\", ASCE Transactions, Vol. 126, \r\n Part II, 1961. \r\n Earthquake . Unlike wind pressure, \r\n earthquake forces on a structure are considered a function of the \r\n mass and stiffness of the structure. Generally speaking, subject to \r\n dynamic phenomena, the greater the weight and rigidity of the structure \r\n - the greater are the forces which must be resisted by the structure. \r\n It is, therefore, current engineering practice to design \"box systems\" \r\n (structures without complete vertical load-carrying space frames) \r\n to resist the greater lateral forces. In this type of structural system \r\n the lateral forces are resisted by the shear walls. The Uniform \r\n Building Code, 1970 edition, contains the following requirements \r\n pertaining to minimum earthquake forces for structures: \r\n Every structure shall be designed and constructed \r\n to withstand minimum total lateral seismic forces assumed to act nonconcurrently \r\n in the direction of each of the main axes of the structure in accordance \r\n with the following formula: \r\n \r\n \r\n V = Z K C W \r\n \r\n where: \r\n \r\n \r\n V = total lateral load or shear \r\n at the base \r\n Z = numerical coefficient dependent \r\n upon the zone of seismic activity: \r\n Z = 1/4 for Zone 1 (minor damage); \r\n \r\n Z = 1/2 for Zone 2 (moderate damage); \r\n Z = 1 for Zone 3 (major damage) \r\n K = numerical coefficient from Table \r\n 1 \r\n C = numerical coefficient dependent on \r\n fundamental period of vibration of the structure (in seconds) \r\n in the direction considered \r\n \r\n W = total dead load of the structure. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n For additional information on earthquake forces \r\n and design, the designer may refer to the following publications: \r\n 1 . Uniform Building Code, 1970 \r\n edition, International Conference of Building Officials. \r\n 2 . Reinforced Brick Masonry and Lateral \r\n Force Design, Harry C. Plummer and John C. Blume, Structural Clay \r\n Products Institute, 1953. \r\n 3 . Seismic Design for Buildings, (Department \r\n of the Army, TM 5-809-10; Department of the Navy, NAVDOCKS P-355; \r\n Department of the Air Force, AFM 88-3, Chapter 13), March 1966. \r\n 4. Earthquake Engineering Research, The \r\n Committee on Earthquake Engineering Research - Division of Engineering \r\n - National Research Council, National Academy of Engineering, National \r\n Academy of Sciences, 1969. \r\n \r\n DISTRIBUTION OF LATERAL FORCES \r\n Diaphragms . Horizontal distribution \r\n of lateral forces to shear walls is achieved by the floor and roof \r\n systems acting as diaphragms (see Fig. 2). \r\n \r\n \r\n \r\n \r\n Diaphragm Action \r\n FIG. 2 \r\n \r\n \r\n To qualify as a diaphragm, a floor and roof \r\n system must be able to transmit the lateral forces to the shear walls \r\n without exceeding a deflection which would cause distress to any vertical \r\n element. The successful action of a diaphragm also requires that it \r\n be properly tied into the supporting shear walls. The designer should \r\n insure this action by appropriate detailing at the juncture between \r\n horizontal and vertical structural elements of the building. \r\n Diaphragms may be considered as analogous \r\n to horizontal (or inclined, in the case of some roofs) plate girders. \r\n The roof or floor slab constitutes the web; the joists, beams and \r\n girders function as stiffeners; and the walls or bond beams act as \r\n flanges. \r\n Diaphragms may be constructed of materials \r\n such as concrete, wood or metal in various forms. Combinations of \r\n such materials are also possible. Where a diaphragm is made up of \r\n units such as plywood, precast concrete planks or steel deck units, \r\n its characteristics are, to a large degree, dependent upon the attachments \r\n of one unit to another and to the supporting members. Such attachments \r\n must resist shearing stresses due to internal translational and rotational \r\n actions. \r\n The stiffness of a horizontal diaphragm \r\n affects the distribution of the lateral forces into the shear walls. \r\n No diaphragm is infinitely rigid or flexible. However, for the purpose \r\n of analysis, diaphragms may be classified into three groups: rigid, \r\n semirigid or semiflexible, and flexible. \r\n A rigid diaphragm is assumed \r\n to distribute horizontal forces to the vertical resisting elements \r\n in proportion to their relative rigidities (see Fig. 3). \r\n \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n \r\n Semirigid or semiflexible diaphragms \r\n are those which have significant deflections under load, but which \r\n also have sufficient stiffness to distribute a portion of the load \r\n to the vertical elements in proportion to the rigidities of the vertical \r\n resisting elements. The action is analogous to a continuous beam system \r\n of appreciable stiffness on yielding supports (see Fig. 4). The support \r\n reactions are dependent upon the relative stiffness of both diaphragm \r\n and the vertical resisting element. \r\n \r\n \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n \r\n A flexible diaphragm is analogous \r\n to a shear deflecting continuous beam or series of beams spanning \r\n between supports. The supports are considered non-yielding, and the \r\n relative stiffness of the vertical resisting elements compared to \r\n that of the diaphragm is great. Thus, a flexible diaphragm is considered \r\n to distribute the lateral forces to the vertical resisting elements \r\n on a tributary area basis (see Fig. 5). \r\n \r\n \r\n \r\n \r\n \r\n FIG. 5 \r\n \r\n \r\n Where the center of rigidity of a shear \r\n wall system does not coincide with the center of application of the \r\n lateral force, the distribution of the rotational forces due to a \r\n torsional moment on the system must also be considered. Where rigid \r\n or semirigid diaphragms are used, it may be assumed that the torsional \r\n forces are distributed to the shear walls in direct proportion to \r\n their relative rigidities and their distance from the center of rigidity \r\n (see Fig. 6). In the design provisions for earthquake forces of the \r\n 1970 Uniform Building Code, shear resisting elements are required \r\n to resist an arbitrary torsional moment equivalent to the story shear \r\n acting with an eccentricity of not less than five per cent of the \r\n maximum building dimension at that level. A flexible diaphragm is \r\n not considered capable of distributing torsional stresses. \r\n \r\n \r\n \r\n \r\n \r\n Torsional Movement on a Shear Wall System \r\n FIG. 6 \r\n \r\n When dealing with a rigid diaphragm and \r\n distributing the horizontal forces to vertical resisting elements \r\n in proportion to the relative rigidities, the relative rigidity of \r\n the shear wall is dependent upon the shear and flexural deflections. \r\n However, for the proportions of the shear walls in most high-rise \r\n buildings, the flexural deflection greatly exceeds the shear deflection, \r\n in which case only flexural rigidity need be considered in determining \r\n the relative stiffness of the shear walls. For determination of relative \r\n shear and flexural deflections, see Fig. 7. \r\n \r\n \r\n \r\n \r\n \r\n Relative Shear and Flexural Deflections \r\n Determined \r\n for a Uniformly Loaded Cantilever Member \r\n of Rectangular Section \r\n FIG. 7 \r\n \r\n A rigorous analysis of the lateral load \r\n distribution to the shear wall is sometimes very time-consuming and \r\n frequently unjustified by the results. Therefore, in many cases a \r\n design based on reasonable limits may be used. For example, the load \r\n may be distributed by first considering the diaphragm as rigid and \r\n then by considering it flexible. If the difference is not great, the \r\n shear wall can then be safely designed for the maximum applied load. \r\n Diaphragm Deflection . As previously \r\n indicated, deflection is another factor that must be considered in \r\n designing a horizontal diaphragm. As shown in Fig. 8, diaphragm deflection \r\n should be limited to prevent excessive stresses in the walls which \r\n are perpendicular to the shear walls. The following formula has been \r\n suggested by the Structural Engineers Association of Southern California \r\n for allowable deflection of horizontal diaphragms in buildings having \r\n masonry or concrete walls: \r\n \r\n \r\n \r\n \r\n \r\n Diaphragm Deflection Limitation \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: D = allowable deflection between adjacent \r\n supports of wall, in inches \r\n \r\n \r\n \r\n h = height of wall between adjacent \r\n horizontal supports, in feet \r\n t = thickness of wall, in inches \r\n f = allowable flexural compressive \r\n stress of wall material, in pounds per square inch \r\n E = modulus of elasticity of wall \r\n material, in pounds per square inch \r\n \r\n \r\n \r\n The application of these limits on deflection \r\n must be used with engineering judgment. For example, continuity at \r\n floor level is assumed, which in many cases is not present due to \r\n through-wall flashing. In this situation the deflection may be based \r\n on the allowable compressive stress in the masonry, assuming a reduced \r\n cross section of wall. The effect of reinforcement which may be present \r\n in a reinforced brick masonry wall or as a tie to the floor system \r\n in a non-reinforced or partially reinforced masonry wall is not considered. \r\n It should also be pointed out that the limit on deflection is actually \r\n a limit on differential deflection between two successive floor or \r\n diaphragm levels. \r\n Maximum span-to-width or depth ratios for \r\n diaphragms are usually used to indirectly control diaphragm deflection. \r\n Normally, if the diaphragm is designed with the proper ratio, the \r\n diaphragm deflection will not be critical. As a guide for horizontal \r\n diaphragm proportions, Table 2, taken from the State of California \r\n Administrative Code, Title 21, Public Works, may prove useful. \r\n \r\n \r\n \r\n \r\n 1 The use of diagonal sheathed \r\n or unblocked plywood diaphragms for buildings having masonry or reinforced \r\n concrete walls shall be limited to one-story buildings or to the roof \r\n of a top story. \r\n \r\n Rigidity of Shear Walls . Where shear \r\n walls are connected by a rigid diaphragm so that they must deflect \r\n equally under horizontal load, the proportion of total horizontal \r\n load at any story or level carried by a perpendicular shear wall is \r\n based on its relative rigidity or stiffness. The rigidity of a shear \r\n wall is inversely proportional to its deflection under unit horizontal \r\n load. The total deflection of the shear wall can be determined from \r\n the sum of the shear and moment deflections. Equations for the deflection \r\n of fixed and cantilevered walls or piers are shown in Fig. 9. \r\n \r\n \r\n \r\n \r\n \r\n Calculation of Wall Deflections \r\n FIG. 9 \r\n \r\n Where a shear wall contains no openings, \r\n the computations for deflection and rigidity are quite simple. In \r\n Fig. 10(a), the shear walls are of equal length and rigidity, and \r\n each takes one half of the total load. In Fig. 10(b), wall C is one \r\n half the length of wall D and it, therefore, receives less than one \r\n eighth of the total load. Where shear walls contain openings such \r\n as doors and windows, the computations for deflection and rigidity \r\n are more complex. However, approximate methods have been developed \r\n which may be used. See Fig. 11. \r\n \r\n \r\n \r\n \r\n \r\n Distribution of Wind Load \r\n FIG. 10 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Calculation of Wall Rigidity \r\n FIG. 11 \r\n \r\n \r\n To increase the stiffness of shear walls \r\n as well as their resistance to bending, intersecting walls or flanges \r\n may be used. Very often in the design of buildings, Z, T, U, and I-shape \r\n sections develop as natural parts of the design. See Figs. 12 and \r\n 13. Shear walls with these shapes, of course, have better flexural \r\n resistance. The 1969 BIA Standard, Building Code Requirements for \r\n Engineered Brick Masonry, (Sec. 4.7.12A) limits the effective \r\n flange width that may be used in calculating flexural stresses. In \r\n the case of symmetrical T or I sections, the effective flange width \r\n may not exceed one sixth of the total wall height above the level \r\n being analyzed. In the case of unsymmetrical L or C sections, the \r\n width considered effective may not exceed one sixteenth of the total \r\n wall height above the level being analyzed. In either case, the overhang \r\n for any section may not exceed six times the flange thickness (see \r\n Figs. 14 and 15). It is, of course, necessary to insure that the shear \r\n stress at the intersection of the walls does not exceed the permissible \r\n shear stress. This will depend on the method used in bonding the two \r\n walls together. \r\n \r\n \r\n \r\n \r\n \r\n Shear Walls of Equivalent Stiffness \r\n FIG. 12 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Shear Walls With Flanges \r\n FIG. 13 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Effective Flange Width \r\n FIG. 14 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Effective Flange Width \r\n FIG. 15 \r\n \r\n \r\n Coupled Shear Walls . Another method \r\n that may be used to increase the stiffness of a bearing wall structure \r\n and reduce the possibility of tension developing in shear walls due \r\n to wind parallel to the wall is the coupling of collinear shear walls. \r\n Figures 16 and 17 indicate the effect of coupling on the stress distribution \r\n in the wall due to parallel forces. A flexible connection between \r\n the walls is assumed in Figs. 16(a) and 17(a), so that the walls act \r\n as independent vertical cantilevers in resisting the lateral loads. \r\n Figures 16(b) and 17(b) assume the walls to be connected with a more \r\n rigid member which is capable of shear and moment transfer so that \r\n a frame-type action results. This can be accomplished with a steel, \r\n reinforced concrete or reinforced brick masonry section. The plate \r\n type action, which is indicated in Figs. 16(c) and 17(c), assumes \r\n an extremely rigid connection between walls, such as full story height \r\n walls or deep rigid spandrels. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n End Shear Walls \r\n FIG. 16 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Interior Shear Walls \r\n FIG. 17 \r\n \r\n \r\n SHEAR STRENGTH \r\n Test Data . The present standard racking \r\n test, described in ASTM E 72-68, Method of Conducting Strength \r\n Tests of Panels for Building Construction, provides only a relative \r\n measure of the shearing or diagonal tension resistance of a wall. \r\n Results of this test method are consequently valid only for comparison \r\n purposes and are not suggested for determination of design values. \r\n \r\n In this method of test, horizontal movement \r\n of the wall specimen (8 by 8 ft), due to the horizontal racking load \r\n at the top of one end, is prevented by a stop block at the bottom \r\n of the other end. To counteract rotation of the specimen due to this \r\n overturning couple, tie rods are used near the loaded edge of the \r\n wall specimen. Under racking load these rods superimpose an indeterminate \r\n compressive force which suppresses the critical diagonal tensile stresses \r\n and increases the load required to rack the specimen. A summary of \r\n the racking data for non-reinforced brick masonry walls tested in \r\n accordance with ASTM E 72 is given in Table 3. A typical mode of failure \r\n for a 4-in. brick wall subject to racking is shown in Fig. 18. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Tested in accordance with \r\n ASTM E 72. \r\n 2 Walls not loaded to failure. \r\n 3 \"Structural Properties \r\n of Six Masonry Wall Constructions\", H. L. Whittemore, A. H. \r\n Stang and D. E. Parsons, National Bureau of Standards Report \r\n BMS5, 1938. \r\n 4 \"Structural Properties \r\n of a Brick Cavity-Wall Construction\". H. L. Whittemore. A. H. \r\n Stang, D. E. Parsons, National Bureau of Standards Report BMS23, \r\n 1939. \r\n 5 \"SCR brick* Wall Tests\", \r\n C. R. Monk, Jr., Structural Clay Products Research Foundation, \r\n Research Report No. 1, June 1953. \r\n 6 \"Compressive, Transverse \r\n and Racking Strength Tests of Four-Inch Brick Walls\", \r\n Structural Clay Products Research Foundation, Research Report \r\n No. 9, August 1965. \r\n *Reg. U.S. Pat. Off., SCPI \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Mode of Failure \r\n in Racking \r\n \r\n FIG. 18 \r\n \r\n \r\n Circular Shear Specimens. Based on \r\n experimental work done at the Balcones Research Center of the University \r\n of Texas by Professors Neils Thompson and Frank Johnson, the Research \r\n Division of the Structural Clay Products Institute conducted a series \r\n of diagonal tensile tests on circular brick masonry specimens. In \r\n these tests, a 15-in. diameter specimen is tested in compression with \r\n the line of load at 45 deg to the bed joints. As shown in Fig. 19 \r\n the diametrical stresses are largely tensile over the central 80 per \r\n cent of the specimen. The tensile stress is approximately constant \r\n for about 60 per cent of the diameter and may be calculated by the \r\n following equation: \r\n \r\n \r\n \r\n \r\n \r\n \r\n Stress Distribution in Tensile Splitting \r\n Test \r\n FIG. 19 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: P = load at rupture, in pounds \r\n \r\n \r\n \r\n D = diameter of specimen, in inches \r\n t = thickness of specimen, in inches \r\n \r\n \r\n \r\n \r\n The test results for 133 specimens built \r\n with 27 types of brick and type S portland cement-lime mortar of ASTM \r\n C 270, Specifications for Mortar for Unit Masonry, are summarized \r\n in Table 4. A typical mode of failure for a circular brick specimen \r\n is shown in Fig. 20. While there was no consistent relationship between \r\n diagonal tensile strength and brick properties, such as initial rate \r\n of absorption, it appeared that brick with the weakest bond characteristics \r\n as shown by flexural strength values also yielded the lowest diagonal \r\n tensile strengths. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 \"Small Scale Specimen \r\n Testing\", Progress Report No. 1, SCPI-SCPRF, October 1964. \r\n 2 All specimens built \r\n with type S mortar. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Small-Scale \r\n Diagonal Tension Test \r\n \r\n FIG. 20 \r\n \r\n The test results for 20 circular specimens \r\n built with one type of brick and four types of mortars are summarized \r\n in Table 5. As indicated, the mortar type had a marked effect on the \r\n diagonal tensile strength of circular back masonry specimens. \r\n \r\n \r\n \r\n 1 \"Small Scale Specimen Testing\", \r\n Progress Report No. 1. SCPI-SCPRF, October 1964. \r\n 2 C = portland cement; L = hydrated \r\n lime (type S); S = sand. \r\n 3 28-day briquets. \r\n 4 All specimens built with 3/8-in. \r\n joints and brick having an average compressive strength of 11,771 \r\n psi and an initial rate of absorption of 10.6 g per min per 30 sq \r\n in. \r\n Square Shear Specimens. The Brick \r\n Institute of America has continued to study the diagonal tensile or \r\n shear strength of brick masonry in an effort to develop both test \r\n methods and design information. Working with the National Bureau of \r\n Standards and the Research Division of John A. Blume and Associates \r\n (San Francisco), a test method has been developed that has several \r\n advantages over the ASTM E 72 racking test procedure. As previously \r\n stated, in the E 72 procedure the hold-down tie rods required to prevent \r\n overturning of the specimen under load produce an indeterminate bearing \r\n condition at the bottom edge of the specimen, thus preventing an analytic \r\n determination of the stress within the wall specimen itself. \r\n In the alternate test procedure, which will \r\n be submitted to ASTM as a proposed alternate to the ASTM E 72 procedure, \r\n the specimens are nominally 4 ft by 4 ft as opposed to the 8-ft square \r\n specimen in the E 72 procedure. In this method, the test results are \r\n susceptible to stress analysis. In addition, they are more reproducible \r\n and thus more reliable for comparison and design data purposes. \r\n The square specimen is placed in the testing \r\n frame so as to be loaded in compression along a diagonal, thus producing \r\n a diagonal tension failure with the specimen splitting apart along \r\n the loaded diagonal (see Figs. 21 and 22). The results of both small \r\n scale (2 ft square) and full scale (4 ft square) tests of 4, 6 and \r\n 8-in. thick brick masonry specimens are summarized in Table 6 and \r\n typical shear stress-strain curies are displayed in Fig. 23. All specimens \r\n were constructed with type S mortar. The shearing stress V m \r\n is determined by the equation \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: F = diagonal compressive force or load, in pounds \r\n \r\n \r\n \r\n t = thickness of wall specimen, in \r\n inches \r\n \r\n l = length of a side of a square \r\n specimen, in inches \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Wallette Shear Test Setup \r\n \r\n \r\n FIG. 21 \r\n \r\n \r\n \r\n \r\n \r\n Full Scale Shear Setup \r\n \r\n \r\n FIG. 22 \r\n \r\n \r\n \r\n \r\n \r\n Typical Shear Stress-Strain Curves for \r\n 6 and 8 Inch Walls \r\n \r\n FIG. 23 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 2 ft square. \r\n \r\n 2 4 ft square. \r\n \r\n \r\n Effects of Normal Loads . The Brick \r\n Institute of America has also investigated the effects of compressive \r\n loads normal to the bed joints on the shearing strength of plain (non-reinforced) \r\n brick masonry walls. Table 7 summarizes the results of these tests \r\n with the normal compressive load on the wall varying from 0 (unloaded) \r\n to 375 psi. The specimens were built with one type of brick utilizing \r\n type S mortar and inspected workmanship. All specimens were two wythes, \r\n 8 in. in thickness and bonded with metal ties. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1Built with type S mortar, \r\n inspected workmanship and metal-tied. \r\n fb = 11,100 psi \r\n IRA = 20.7 g/min/30 in2 \r\n \r\n \r\n Allowable Stresses . The allowable \r\n shear stresses for non-reinforced masonry provided in the 1969 SCPI \r\n Standard, Building Code Requirements for Engineered Brick Masonry, \r\n are shown in Table 8, and for reinforced masonry in Table 9. \r\n \r\n The Standard also provides a basis for the \r\n design of biaxially loaded shear walls. Section 4.7.12.1 states: \r\n \"In non-reinforced shear walls, the virtual \r\n eccentricity (e l ) about the principal axis which is normal to the length ( l ) of \r\n the shear wall shall not exceed an amount which will produce tension. \r\n In non-reinforced shear walls subject to bending about both principal \r\n axes, (e t l \r\n + e l t ) shall not exceed (t l \r\n / 3) where e t = virtual eccentricity about the principal axis which is normal to the \r\n thickness (t) of the shear wall. Where the virtual eccentricity exceeds \r\n the values given in this section, shear walls shall be designed in \r\n accordance with Section 4.7.9 or 4.7.11\". (Reinforced or partially \r\n reinforced walls.) \r\n \r\n Provision is also made in the standard for \r\n increasing the shear capacity of the wall by taking into consideration \r\n compressive loads on the wall. Section 4.7.12.3 states: \r\n \r\n \"The allowable shearing stresses in non-reinforced \r\n and reinforced shear walls shall be taken as the allowable stresses given \r\n in Tables 3 and 4 (Tables 8 and 9 of this Technical Notes ), \r\n respectively, plus one fifth of the average \r\n compressive stress due to dead load at the level being analyzed. In no \r\n case, however, shall the allowable shear stresses exceed the maximum values \r\n given in Tables 3 and 4. \r\n \"In computing the shear resistance of the \r\n wall, only the web shall be considered.\" \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n REFERENCES \r\n \r\n 1. Technical Notes on Brick Construction, BIA, (a monthly series). \r\n 2. Gross, J. G.; Dikkers, R. D.; and Grogan, J. C.; Recommended Practice \r\n for Engineered Brick Masonry , SCPI, November 1969. \r\n 3. Allen M. H. and Watstein, D.; Compressive, Transverse and Shear Strength \r\n Tests of Six and Eight-lnch Single-Wythe Walls Built with Solid \r\n and Heavy-Duty Hollow Clay Masonry Units , Research Report No. \r\n 16, SCPI, September 1969. \r\n 4. Blume, J. A. and Prolux, J.; Shear in Grouted Brick Masonry Wall Elements , \r\n Western States Clay Products Association, August 1968. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60091,"ResultID":176323,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 24F - The Contemporary Bearing Wall - Construction \r\n Nov./Dec. 1974 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n \r\n The Contemporary Bearing Wall concept as conceived and being applied \r\n today is based upon rational engineering design. This concept requires \r\n floors and walls to work together as a system, each giving support \r\n to the other. A building of high strength, in which the structure \r\n provides finish, closure, partition, sound control and fire resistance, \r\n is thereby provided. In order to achieve this end, it is necessary \r\n that proper attention be given to design details and construction \r\n procedures. It is of utmost importance that constructors follow \r\n the plans and specifications of the designers. \r\n Attention to detail and requirements for high quality materials \r\n and workmanship have not deterred the rapid acceptance and application \r\n of the Contemporary Bearing Wall concept. Numerous cases can be \r\n cited where bearing wall buildings have been built faster than scheduled \r\n or anticipated, and, in many cases, these buildings have been built \r\n at less than the estimated cost of alternate designs utilizing other \r\n materials and structural systems. \r\n \r\n SPECIAL REQUIREMENTS \r\n \r\n The design of these buildings may be based upon the Building \r\n Code Requirements for Engineered Brick Masonry, SCPI (BIA), \r\n August 1969, which contains various additional construction requirements \r\n not required by most other modern building codes. The following \r\n sections relating to both materials and workmanship are specifically \r\n called to the attention of the reader: \r\n \r\n \r\n 1.1 SCOPE \r\n \r\n 1.1.1 General \r\n This standard provides minimum requirements for the design and \r\n construction of brick masonry of solid masonry units, both plain \r\n (non-reinforced) and reinforced. It does not include requirements \r\n for construction using hollow masonry units nor requirements for \r\n fire protection. \r\n \r\n 1.1.2 Analysis The design of brick masonry shall be based \r\n on a general structural analysis and the requirements of this \r\n standard. \r\n 1.1.3 Special Structures For arches, garden walls, retaining \r\n walls, tanks, reservoirs and chimneys, the provisions of this \r\n standard shall govern so far as they are applicable. \r\n \r\n 1.2 PERMITS AND DRAWINGS \r\n \r\n 1.2.1 \r\n Copies of structural drawings and typical details showing the \r\n sizes and position of all structural members, steel reinforcement, \r\n design strengths, and live loads used in the design shall be filed \r\n with the building department before a permit to construct such \r\n work shall be issued. Calculations pertaining to the design shall \r\n be filed with the drawings when required by the building official. \r\n \r\n 1.3 INSPECTION \r\n \r\n 1.3.1 With Inspection When the design of brick masonry is based on the allowable stresses and \r\n other values given in Tables 1, 2, 3, 4 and 5 for \"With Inspection, \r\n the construction shall be inspected by an engineer or architect, \r\n preferably the one responsible for the design, or by a competent \r\n representative responsible to him. Such inspection shall be of \r\n a nature as to determine, in general, that the construction and \r\n workmanship are in accordance with the contract drawings and specifications. \r\n \r\n 1.3.2 Without Inspection When there is no engineering \r\n or architectural inspection as specified in Section 1.3.1, the \r\n allowable stresses and other values given in Tables 1, 2, 3, 4 \r\n and 5 for \"Without Inspection\" shall be used. \r\n \r\n 2.2.1 Brick \r\n \r\n 2.2.1.1 Brick and Solid Clay or Shale \r\n Masonry Units Standard Specification \r\n for Building Brick (Solid Masonry Units Made from Clay or Shale), \r\n ASTM C 62, or Standard Specification for Facing Brick (Solid Masonry \r\n Units Made from Clay or Shale), ASTM C 216. \r\n \r\n 2.2.1.2 Grades and Types Brick subject to the action of \r\n weather or soil, but not subject to frost action when permeated \r\n with water, shall be of grade MW or grade SW, and where subject \r\n to temperature below freezing while in contact with soil shall \r\n be grade SW. Brick used in loadbearing or shear walls shall comply \r\n with the dimension and distortion tolerances specified for type \r\n FBS of ASTM C 216. Where such brick do not comply with these tolerance \r\n requirements, the compressive strength of brick masonry shall \r\n be determined by prism tests. (See Section 4.2.2.1.) \r\n 2.2.1.3 Used Brick Used or salvaged brick shall not be \r\n permitted under the provisions of this standard. \r\n \r\n 2.2.2 Mortar and Grout \r\n \r\n 2.2.2.1 Non-Reinforced Brick Masonry \r\n Mortar for use in non-reinforced brick masonry shall conform to \r\n Standard Specification for Mortar for Unit Masonry, ASTM C 270, \r\n types M, S or N. except that it shall consist of a mixture of \r\n portland cement (type I, II or III), hydrated lime (type S) and \r\n aggregate where values given in Tables 1, 2 and 3 are used. \r\n \r\n 2.2.2.2 Reinforced Brick Masonry Mortar and grout for \r\n use in reinforced brick masonry shall conform to Standard Specification \r\n for Mortar and Grout for Reinforced Masonry, ASTM C 476, except \r\n that mortar shall consist of a mixture of portland cement (type \r\n I, II or III), hydrated Iime (type S ) and aggregate where values \r\n given in Tables 2 and 4 are used. \r\n 2.2.2.3 Air-entraining admixtures or hydrated lime containing \r\n air-entraining admixtures shall not be used in mortar. \r\n 2.2.2.4 Calcium chloride or admixtures containing calcium \r\n chloride shall not be used in mortar or grout in which reinforcement, \r\n metal ties or anchors are embedded. \r\n 2.2.2.5 Other mortars not specified in Sections 2.2.2.1 \r\n and 2.2.2.2 may be used when approved by the building of official, \r\n provided strengths for such masonry construction are established \r\n by tests made in accordance with Section 4.2.2.1 and Standard \r\n Methods of Conducting Strength Tests of Panels for Building Construction, \r\n ASTM E 72. \r\n 5.2.1 Mortar Joints All brick shall be laid with \r\n full head and bed joints and all interior joints that are designed \r\n to receive mortar shall be filled. (See Section 5.8.3. ) The average \r\n thickness of head and bed joints shall not exceed 1/2 inch. \r\n \r\n 5.2.3 Tolerances for Brick Masonry Construction Based on Actual \r\n Dimensions \r\n 5.2.3.1 Variation from the Plumb \r\n \r\n (1) In the lines and surfaces of columns, \r\n walls and arrises: in 10 feet-1/4 inch; in any story or 20 feet \r\n maximum-3/8 S inch; in 40 feet or more-1/2 inch.(2) For external \r\n corners, expansion joints and other conspicuous lines: in any \r\n story or 20 feet maximum-1/4 inch; in 40 feet or more-1/2 inch. \r\n \r\n 5.2.3.2 Variation from the Level or the Grades Indicated on the \r\n Drawings \r\n \r\n (1) For exposed lintels, sills, parapets, \r\n horizontal grooves and other conspicuous lines: In any bay or \r\n 20 feet maximum-1/2 inch; in 40 feet or more-3/4 inch. \r\n \r\n 5.2.3.3 Variation of the Linear Building Lines from Established \r\n Position in Plan and Related Portion of Columns, Walls and Partitions \r\n \r\n (1) In any bay or 20 feet maximum-1/2 \r\n inch; in 40 feet or more-3/4 inch. \r\n \r\n 5.2.3.4 Variation in Cross-Sectional Dimensions of Columns and \r\n in the Thickness of Walls \r\n \r\n (1) Minus 1/4 inch; plus 1/2 inch. \r\n \r\n 5.9 CHASES AND RECESSES \r\n \r\n 5.9.1 \r\n Chases and recesses shall be considered in the structural design \r\n and detailed on the building plans. Chases not shown on the plans \r\n shall be permitted only when approved in writing by the structural \r\n engineer and the building official. \r\n \r\n \r\n EXPERIENCE AND EXAMPLES \r\n \r\n Pennley Park . \r\n This complex of eight buildings was one of the first major U.S. \r\n projects utilizing rationally designed brick bearing walls as a \r\n major structural system, (Fig. 1). The cost was approximately $4,500,000 \r\n or $13.89 per sq ft of floor area including architectural and engineering \r\n fees, soil analysis and site work. The project was scheduled for \r\n 21 months of construction; it started May 1, 1964 and 12 months \r\n later was 98 per cent completed. The bearing wall structural system \r\n resulted in approximately a 10 percent savings of the cost over \r\n a structural steel frame alternate. Included in this savings of \r\n approximately $420,000 was $69,000 for fireproofing of the steel \r\n frame. Tenants occupied some of the buildings seven months after \r\n the start of construction. The construction superintendent of the \r\n project, Mr. A. M. DiFerio, attributed this low cost and speed of \r\n construction to a number of reasons, including the simplicity of \r\n construction, the use of fewer cranes and other heavy construction \r\n equipment, and a simple spread footing, which was used in lieu of \r\n caissons. \r\n \r\n \r\n \r\n \r\n Pennley Park North, Pittsburgh, Pennsylvania \r\n \r\n Tasso G. Katselas, Architect; R.M. Gensert, Structural \r\n Engineer \r\n \r\n FIG. 1 \r\n \r\n Penn Plaza . \r\n This project, quite similar to the above, consists of six buildings, \r\n (see Fig. 2). The masonry contractor for this project, Charles L. \r\n Cost, stated that his men \"enclosed a floor every two and a half \r\n days and the masons worked fast and efficiently. They were very \r\n enthusiastic about this construction. We went on the job with very \r\n little advance notice, and with more planning time we could have \r\n finished the masonry work in seventy-four working days, rather than \r\n ninety-four working days actually required.\" The cost per square \r\n foot of the Penn Plaza project was $13.15. \r\n \r\n \r\n \r\n \r\n Penn Plaza, Pittsburgh, Pennsylvania \r\n \r\n Tasso G. Katselas, Architect; R.M. Gensert, Structural \r\n Engineer \r\n \r\n FIG. 2 \r\n \r\n Oakcrest Towers . Oakcrest Towers is a series of 14 apartment buildings, eight stories \r\n in height, being constructed on a 50-acre site outside of Washington, \r\n D. C., (Fig. 3). Each building contains a total of 161,334 sq ft. \r\n In good weather, the contractors report construction of one story \r\n per week. Mr. Stanley Reed, Vice-President of L. F. Jennings Inc., \r\n the masonry contractor for Oakcrest Towers, said that, in their \r\n experience, bearing wall buildings were built faster than structural \r\n frame buildings and, typically, the time required to complete a \r\n bearing wall building and have it ready for occupancy was approximately \r\n equal to the time required to erect the structural frame and enclose \r\n the frame with masonry walls for a project of similar scope. Mr. \r\n Reed reported that savings on the Oakcrest buildings resulted from \r\n lower initial cost for bearing wall than for structural frame construction, \r\n and elimination of finishing and painting of interior exposed brick \r\n walls. \r\n \r\n \r\n \r\n \r\n Oakcrest Towers, Prince Georges County, Maryland \r\n \r\n Bucher-Meyers & Associates, Architects; Keller \r\n & Marchigiani, Structural Engineers \r\n \r\n FIG. 3 \r\n \r\n Some bearing wall thicknesses in the first buildings were in excess \r\n of 20 in. in thickness. Buildings built after the SCPI (BIA) standard \r\n was introduced had thicknesses reduced to 8 and 6 in. of brick masonry \r\n for exterior and corridor walls, respectively. \r\n Park Lane Towers . Park Lane Towers is a group of 20-story \r\n structures located in Denver, Colorado, (Fig. 4). Each building \r\n is 206 ft high containing 38 one-bedroom, 73 two-bedroom, 4 three-bedroom \r\n units and one penthouse. Fireplaces are featured in the two and \r\n three-bedroom units beginning at the 15th floor. \r\n Ground breaking for Park Lane Towers No. 1 began in May of 1969. \r\n The masonry work was started in the fall of 1969 and progressed \r\n through the winter. By March 1, the masonry construction was at \r\n the 16th story. By May of 1970, the first building was topped out. \r\n BIA recommendations for cold weather construction were followed. \r\n Total time sequence per floor averaged six to eight days, depending \r\n upon weather and other non-controllable factors. An average of three \r\n and one-half days was required to construct all walls per story. \r\n Twin tee floor slab erection averaged one day per floor. \r\n The unit cost of Park Lane Towers, based on an area on 156,280 \r\n sq ft. excluding the area of the basement, was $ 14.71 per sq ft. \r\n The total cost of the building was $2,300,000, including drapes, \r\n carpets, kitchens, parking garage, basement and landscaping (excluding \r\n land and professional fees). \r\n \r\n \r\n \r\n \r\n Park Lane Towers, Denver, Colorado \r\n \r\n Joseph T. Wilson, AIA, Architect; Sallada & Hanson, \r\n Structural Engineers \r\n \r\n FIG. 4 \r\n \r\n Woodlake Towers . Woodlake Towers is a group of ten-story, T-shaped buildings, each containing \r\n 215 units, which consist of efficiencies, one, two and three-bedroom \r\n units, (Fig. 5). \r\n \r\n Bearing walls consist of 8-in., single wythe, solid brick supporting \r\n a precast concrete floor system. The first building was completed \r\n in 1970 and contains 268,450 sq ft at a cost of $2,700,000 or $ \r\n 10.06 per sq ft (excluding land, interim financing, professional \r\n fees, builders fee and entrance lobby finishing). The cost figure \r\n of $2,700,000 includes all general construction, electrical and \r\n mechanical work, parking lot paving, landscaping, furnished kitchens \r\n and corridor carpeting. \r\n \r\n \r\n \r\n \r\n Woodlake Towers, Fairfax County, Virginia \r\n \r\n Collins & Kronstadt, Leahy, Hogan, Collins, Architects; \r\n Keller & Marchigiani, Structural Engineers \r\n \r\n FIG 5 \r\n \r\n Twin Tower Apartments . Twin Tower Apartments consist of two identical structures of 11 stories \r\n in height for elderly residents in Jacksonville, Florida, consisting \r\n of a total of 120 efficiency and 80 one-bedroom units, (Fig. 6). \r\n The 10-in. bearing walls were grouted cavity walls (4-2-4) with \r\n varying amounts of grout and reinforcement, depending on loading \r\n and location. A 6-in. cast-in-place concrete slab provided the floor \r\n system. The masons rotated between buildings so the walls could \r\n be built on one building while the floor was formed and poured on \r\n the other building. \r\n \r\n \r\n \r\n \r\n Twin Tower Apartments, Jacksonville, Florida \r\n \r\n Sheetz & Bradfield, Architects; Bennett & \r\n Pless, Structural Engineers \r\n \r\n FIG. 6 \r\n \r\n Episcopal House of Reading . It is 15 stories tall and contains 141 units for middle income, \r\n elderly residents in Reading, Pennsylvania, (Fig. 7). All the bearing \r\n walls are 8 in. thick, single wythe, non-reinforced, solid brick \r\n masonry with the exception of some walls on the first floor level \r\n which are 12 in. in thickness. \r\n \r\n \r\n \r\n \r\n Episcopal House of Reading, Reading, Pennsylvania \r\n \r\n Muhlenberg & Greene, Architects; Long & Tann, \r\n Structural Engineers \r\n \r\n FIG. 7 \r\n \r\n The floor system consists of two layers of concrete. The first \r\n is 2 1/4-in. precast concrete containing positive steel and the \r\n second is 5 3/4-in. poured concrete with polystyrene foam sections \r\n to create internal voids. \r\n The basic construction process consisted of building brick masonry \r\n walls and placing concrete floors in a \"leapfrog\" fashion. While \r\n a crew of 8 to 12 masons, using corner poles, erected walls on one \r\n side of the building, the 2 1/4 in. concrete floor slabs were placed \r\n by tower crane on the other side and were positioned and shored \r\n as required. \r\n Construction continued throughout the winter. All materials were \r\n stored off the ground and covered for protection from the elements. \r\n A mortar mixing station was constructed adjacent to the structure, \r\n complete with propane gas equipment to heat sand and water. A custom-made \r\n sand measuring device permitted rapid and accurate proportioning \r\n by volume of portland cement-lime and sand mortar. The quantity \r\n of sand held by this device was 9 cu ft. Figure 8 shows this simple \r\n but workable setup for mixing mortar. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Measuring Sand Automatically. \r\n FIG. 8 \r\n \r\n TECHNIQUES \r\n \r\n Sequence and Scheduling . Most Contemporary Bearing Wall buildings can be planned so that the floor \r\n erection crew will place the floor in about the same length of time \r\n as is required for the masons to build the walls. When the crews \r\n are balanced in this manner, it is usually possible to schedule \r\n the construction so that neither the floor crew nor the wall crew \r\n will be in the way of the other. An example is shown in Fig. 9 where \r\n a floor system of steel joists with concrete topping is used. The \r\n plan of the Oakcrest project is tee-shaped with a short leg. The \r\n masons are completing the walls on the leg of the building and the \r\n area immediately next to it. In the background, concrete is being \r\n poured; in the center, steel decking is being placed; and in the \r\n foreground, steel joists are being set and spaced. In this manner, \r\n the contractors built a story per week in good weather. \r\n \r\n \r\n \r\n \r\n Floor and Wall Construction of Oakcrest Towers. \r\n FIG. 9 \r\n \r\n \r\n \r\n Foundations . \r\n Studies have indicated that, in many cases, foundation costs are \r\n reduced by delivering the loads into the soil in a series of lines \r\n or paths which might utilize spread footings, rather than in a series \r\n of points, which may require piles or caissons. A case in point \r\n is the Oakcrest project in which spread footings for bearing walls \r\n resulted in a savings in cost and time, (Fig. 10). \r\n \r\n \r\n \r\n \r\n \r\n Corridor Bearing Walls at Oakcrest Towers. \r\n FIG. 10 \r\n \r\n Formwork . \r\n In the construction of Contemporary Bearing Wall structures with \r\n joists or plank floor systems, there is little or no need for formwork, \r\n thus permitting the other trades to work immediately below the level \r\n of the wall and floor crews. In the case of a cast-in-place concrete \r\n building, the formwork is often such that other trades cannot conveniently \r\n work for several stories below the level where concrete is being \r\n placed, (Fig. 11). \r\n \r\n \r\n \r\n \r\n Formwork for Cast-in-Place Concrete Frame. \r\n FIG. 11 \r\n \r\n Coordination . \r\n The space immediately below a floor system of plank or joist is \r\n available; therefore, mechanical and other trades can closely follow \r\n the wall and floor crews, so as to contribute to the overall speed \r\n of construction, (Fig. 12). \r\n \r\n \r\n \r\n \r\n Working Space is Provided for Other Trades at Oakcrest \r\n Project. \r\n FIG. 12 \r\n \r\n Scaffolding . \r\n The scaffolding requirements are simplified in bearing wall buildings, \r\n usually requiring only one lift per story, (Fig. 13). Scaffolding \r\n used for one and two-story construction is often applicable to high-rise \r\n loadbearing construction when the masons work overhand from the \r\n inside. All of the examples cited above were built in this manner. \r\n \r\n \r\n \r\n \r\n Scaffolding is Simple for Bearing Wall Construction. \r\n FIG. 13 \r\n \r\n \"SCR masonry process\" (Reg. U.S. Pat. Off., SCPI (BIA)). The \"SCR masonry process is a development \r\n of the Structural Clay Products Research Foundation (now a part \r\n of BIA). It consists of a continuously adjustable scaffold and corner \r\n poles which carry the lines. This provides a means whereby skilled \r\n masons can increase productivity and enhance the quality of their \r\n work, resulting in better masonry at lower cost. For the construction \r\n of a series of three-story barracks, at Ft. Gordon, Gal, bearing \r\n walls were selected under \"Contractors Option\" in lieu of a reinforced \r\n concrete frame with masonry curtain walls. The masonry contractor \r\n on the project, Phiffer and Goodwin, stated that, four weeks after \r\n installing the \"SCR masonry process\", their records indicated a \r\n 37 percent increase in overall production of the 75 masons working \r\n the project, (Fig. 14). \r\n \r\n \r\n \r\n \r\n Use of \"SCR masonry process\" (Reg. U.S. Pat. Off., \r\n SCPI (BIA)), For Gordon, Georgia. \r\n FIG. 14 \r\n \r\n Prefabricated Elements . Prefabricated stairs, door and window combinations and other elements \r\n which can easily be set in place prior to the masonry work will \r\n eliminate cutting and fitting after the masonry is complete. In \r\n many cases, the prefabricated elements can become guides for the \r\n masonry. In the case of the stairs, illustrated in Fig. 15, the \r\n landings become bench marks for the floors and the stairs themselves \r\n provide continuous access during construction. \r\n \r\n \r\n \r\n \r\n Prefabricated Metal Stairs Used in Bearing Wall Construction. \r\n FIG. 15 \r\n \r\n Keeping Walls Clean . Frequently it will be desirable to place concrete for various members \r\n supported on brick walls. In such cases, care should be exercised \r\n to prevent the dropping of concrete on brickwork to be left exposed. \r\n This can be prevented by covering the walls with polyethylene sheets \r\n under formwork to make them watertight, (Fig. 16). \r\n \r\n \r\n \r\n \r\n Polyethylene Sheets Under Corridor Formwork in Construction \r\n of Oakcrest Towers. \r\n FIG. 16 \r\n \r\n Building in Accessories . When cavity walls are used, conduit and other accessories are often built \r\n in place as the walls are constructed. Also, in multi-wythe walls, \r\n this is easily accomplished as the walls are built. In many cases, \r\n through-the-wall units are designed so that they can be slipped \r\n over or conveniently built around conduit and other such elements, \r\n (Figs. 17 and 18). \r\n \r\n \r\n \r\n \r\n Building in Conduit and Sleeves at Park Lane Towers. \r\n FIG. 17 \r\n \r\n \r\n \r\n \r\n Conduit in 4-in. Wall at Fort Gordon, Georgia. \r\n FIG. 18 \r\n \r\n \r\n Lintels . \r\n Frequently, in the construction of brick masonry buildings, it is \r\n convenient to build horizontal elements on shoring, with reinforcing \r\n steel to span openings, (Fig. 19). Reinforced brick lintels have several \r\n advantages, including built-in fire resistance and elimination of \r\n structural steel, which requires maintenance and is more expensive \r\n in many cases. For further information on reinforced brick lintels, \r\n see Technical Notes 17B . \r\n \r\n \r\n \r\n \r\n \r\n Construction of Reinforced Brick Lintel on Shoring. \r\n FIG. 19 \r\n \r\n Cold Weather . \r\n Complete enclosure of bearing wall structures is not always the \r\n most economical way of providing protection for winter construction. \r\n In severe climates contractors may enclose the particular walls \r\n being worked upon. \r\n \r\n Figure 20 shows Jayhawker Towers, a dormitory at the University \r\n of Kansas in Lawrence. Kansas, where a prefabricated wood-frame \r\n assembly covered with a polyethylene film was lowered over the work \r\n area to protect walls under construction during cold weather. \r\n \r\n \r\n \r\n \r\n Temporary Enclosure at Jayhawker Towers, Lawrance, \r\n Kansas. \r\n FIG. 20 \r\n \r\n Where the weather is not severe enough to enclose the construction, \r\n heating of materials and proper covering of walls may be all that \r\n is necessary. In all cold weather construction, the masonry should \r\n be constructed so strength will develop and the mortar will lose \r\n sufficient water to prevent expansion upon freezing. \r\n \r\n For further discussion of winter construction, see Technical Notes \r\n 1 Revised , \"Cold Weather Masonry \r\n Construction-Introduction\", December 1967. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60092,"ResultID":176324,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 24G - The Contemporary \r\n Bearing Wall - Detailing \r\n Dec. 1968 (Reissued Feb. 1987) \r\n \r\n INTRODUCTION \r\n The selection of a wall type and appropriate \r\n connection details is one of the most important decisions to be made \r\n in the design of a bearing wall building. In most cases, the primary \r\n consideration will be a system which satisfies the structural requirements \r\n of the building. Other considerations are also of importance, including \r\n the properties and performance of the walls and floors that will result \r\n in an economical, maintenance-free and easy-to-construct building. \r\n Bearing walls offer the designer the opportunity \r\n to develop a complete building system in which the floors and walls \r\n not only carry the vertical and lateral loads, but also provide separation, \r\n thermal and acoustical control, and fire-resistive and low maintenance \r\n construction. \r\n MATERIALS \r\n Materials used in constructing the walls \r\n for bearing wall buildings will have considerable influence on the \r\n satisfactory performance of the structure. In most cases, the compressive \r\n stresses will be relatively high, requiring medium to high strength \r\n masonry units and mortar. Materials selected should comply with the \r\n requirements contained in the standard, Building Code Requirements \r\n for Engineered Brick Masonry, BIA, 1969. \r\n Brick . A large percentage of the \r\n brick produced in the United States have unit compressive strengths \r\n in excess of 5000 psi, with some having compressive strengths as high \r\n as 25,000 psi. Units are readily available throughout the U.S. and \r\n Canada which have strengths of 10,000 psi and above. Esthetics, durability \r\n and economy should also be considered in the selection of a particular \r\n type of brick unit for a given bearing wall building. The two sizes \r\n of brick most widely used are often referred to as Standard (actual \r\n dimensions - 3-3/4 by 2-1/4 by 8 in.) and Standard Modular (actual \r\n dimensions for 3/8-in. joint 3-5/8 by 2-1/4 by 7-5/8 in.). There are \r\n many different sizes of brick made to suit local conditions. In some \r\n areas of the U.S., 3-in. bed depth brick are widely used. The sizes \r\n vary with the manufacturer and locality. The size that is most widely \r\n made and distributed is called King size, with actual bed dimensions \r\n of 3 by 9-5/8 in. and height of 2-5/8 in. (laying 4 courses to 12 \r\n in.) or 2-3/4 in. (laying 5 courses to 16 in.). Walls built with larger \r\n brick units usually provide greater economy than walls of smaller \r\n units. Table 1 lists a number of modular brick sizes. These are illustrated \r\n in Fig. 1. The local availability and strength of specific units should \r\n be ascertained prior to the design. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Also called Norman Economy, \r\n General and King Norman. \r\n 2 Reg. U.S. Pat. Off., \r\n SCPI. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Modular Brick \r\n \r\n \r\n FIG. 1 \r\n \r\n Mortar . There is no one mortar that \r\n is best for all purposes. Masonry mortar should be selected for the \r\n particular use. ASTM Specifications C 270, \"Mortar for Unit Masonry\", \r\n are recommended as a basis for mortar specifications. It is further \r\n recommended that the Proportion Specification be used rather than \r\n the Property Specification and that mortar be constituted of portland \r\n cement (type I, II or III), type S hydrated lime (non-air-entrained), \r\n or lime putty and sand. \r\n Building Code Requirements for Engineered \r\n Brick Masonry recognizes three mortar types: Types M, S and N. \r\n In general, type S mortar provides high bond and compressive strength \r\n with long durability and good workability. Type N is a mortar with \r\n good strength properties, durability and excellent workability. In \r\n most cases, either type S or N mortar will provide the desirable properties \r\n for loadbearing buildings. When high compressive stresses control \r\n the design, type M mortar may be required. Type S mortar is proportioned \r\n 1C:1/2 L:4 - 1/2 S, type N mortar is 1C:1L:6S and type M is 1C: 1/4 \r\n L:3S. See Technical Notes 8 Revised, \r\n Portland Cement-Lime Mortars for Brick Masonry\". \r\n Metal Ties and Joint Reinforcement . \r\n In years past, structural bonding of masonry walls was generally accomplished \r\n by overlapping masonry units. In so doing, various visual patterns \r\n were created; two traditional ones being English and Flemish bond. \r\n In the construction of the thinner masonry \r\n walls of today, when these patterns are not required by esthetic considerations, \r\n it is recommended that metal-tie bonding be used for multi-wythe solid \r\n walls in lieu of masonry bonding. Laboratory tests at the Structural \r\n Clay Products Institute and independent laboratories indicate that \r\n metal-tied walls are comparable to masonry-bonded walls in resisting \r\n compressive and transverse loads, as well as water transmission, when \r\n the collar joint is full of mortar. In addition, metal-tied walls \r\n generally cost slightly less than masonry-bonded walls. They also \r\n provide greater freedom in construction and pattern selection. \r\n Metal ties used in bonding masonry walls \r\n should be equal to those required for cavity walls; i.e., 3/16-in. \r\n diameter steel or metal ties of equivalent strength spaced so that \r\n at least one tie is provided for every 4-1/2 sq ft of wall area. Distance \r\n between ties should not be over 24 in. vertically and 36 in. horizontally. \r\n Metal ties should be of corrosion-resistant metal or protected with \r\n a corrosion-resistant metal. Ties may be shaped to form a Z, rectangle \r\n or continuous tie of either the ladder or truss type. In cavity wall \r\n construction, the Z and rectangular ties, which are often used, have \r\n depressions or drips in the middle of the ties. The drip is not necessary \r\n and reduces the strength of the tie; however, most of the ties on \r\n the market have sufficient strength with or without the drips. There \r\n are some advantages to the continuous ladder or truss type joint reinforcement, \r\n particularly where wythes are made of units with different physical \r\n properties or in wall areas subject to stress concentration. \r\n If stack bond masonry is used as a bearing \r\n wall, continuous joint reinforcement should be provided, spaced not \r\n more than 16 in. on center vertically, one 9-gage or larger longitudinal \r\n wire for each 6 in. of wall thickness or portion thereof. \r\n CONSTRUCTION DETAILS \r\n Even though the masonry details must be \r\n handled somewhat differently in bearing wall buildings than in structural \r\n frame buildings, the same major considerations are prevalent: \r\n 1. Structural requirements of the buildings \r\n must be met. Anchorage must be provided which will transmit stress \r\n where desired. Equally important are anchorage details which will \r\n not transmit unwanted forces. \r\n 2. Since the elements of the building are \r\n in a constant state of motion, such movement must be accommodated \r\n or distress will occur. \r\n 3. The opportunity for uncontrolled entrance \r\n or condensation of water must be avoided. The problem of keeping water \r\n out of the bearing wall building may be solved by using cavity or \r\n grouted walls. Where solid walls are used with or without furring, \r\n pargeting, waterproofing and systems of flashing and drainage can \r\n be provided. See Technical Notes 7A \r\n Revised, Water Resistance of Brick Masonry-Materials\", and 7B Revised, \r\n \"Water Resistance of Brick Masonry-Construction and Workmanship\". \r\n Structural Requirements . Because \r\n of their structural simplicity, it is possible to design loadbearing \r\n clay masonry buildings quite easily, using accepted theories. In some \r\n buildings, the floor plan will be such that the longitudinal exterior \r\n and corridor walls may be loadbearing. In others, it may be more advantageous \r\n to have transverse bearing walls. In both cases, horizontal forces \r\n are usually resisted by shear wall action. Since the transverse strength \r\n of non-reinforced masonry walls is relatively low, structural positioning \r\n of building parts are so arranged as to minimize this action and to \r\n exploit the compressive and shear resistance of the walls. \r\n By utilizing the floors and roof as horizontal \r\n diaphragms and the shear walls as vertical diaphragms, the horizontal \r\n forces are carried down into the foundation. Shearing stresses in \r\n bearing wall buildings will seldom control the wall type and thickness. \r\n Although flexural stresses in shear walls may control the design under \r\n certain conditions, it is the bearing stress that will generally govern. \r\n For additional information pertaining to structural design, see Technical \r\n Notes 24 Series, \"The Contemporary Bearing Wall\". \r\n Types of walls and floors used with bearing \r\n wall construction will depend on a number of factors, including economics, \r\n climate, building type, height and arrangement of walls, and the structural \r\n requirements. In most cases, clay masonry walls from 4 to 12 in. in \r\n thickness will satisfy the structural requirements. \r\n In developing construction details for bearing \r\n wall buildings, it is important to understand the potential condition \r\n of stress at junctures of horizontal and vertical elements. At connections, \r\n as a result of vertical and horizontal loads, compression, tension \r\n and shear may occur. Seldom is it desirable to transmit bending moments \r\n at junctures of floors and walls unless the walls are of reinforced \r\n masonry. It is relatively easy to develop details which will transmit \r\n tension and compression, as well as shear. Often, however, it is desired \r\n to transmit tension and compression alone, or shear alone. At times, \r\n it is desirable to take loads horizontally (produced by wind) but \r\n not vertically (due to gravity). For these reasons, it is important \r\n for the structural designer to take an active part in developing the \r\n construction details for a particular project. \r\n Where concentrated loads are imposed upon \r\n masonry walls, it is recommended that bearing pads be used to distribute \r\n the stress and to permit slight movement which may occur. Suitable \r\n materials for this use include 55-lb roofing felt, pads of Neoprene, \r\n tempered Masonite or vinyl floor tile. It is advisable to design the \r\n connection so as to position the resultant of the bearing stress in \r\n the middle two-thirds of the wall. If the vertical load develops an \r\n eccentricity which falls outside of the middle two-thirds of the wall, \r\n the possibility of excessive tensile bending stresses developing in \r\n the wall must be investigated. See detailed design requirements contained \r\n in the Building Code Requirements for Engineered Brick Masonry. \r\n Small amounts of reinforcing steel may be \r\n grouted in brick walls to provide extra strength. The designer may \r\n find it helpful to use steel in piers where loads are high. Bond beams \r\n are often desirable to distribute loads at floor levels. For information \r\n on the design and construction of reinforced brick masonry (RBM), \r\n see Technical Notes 17 series, \"Reinforced Brick Masonry\". \r\n Rigid anchorage of concrete floors to the \r\n masonry walls is seldom desired or needed. The friction will often \r\n meet the structural requirements. Coefficients of friction between \r\n various materials in a dry state will vary. Standard references indicate \r\n a range of values given in Table 2. In this table, masonry may be \r\n considered to be clay, stone or concrete. \r\n \r\n \r\n \r\n \r\n \r\n Differential Movement . All elements \r\n and materials which go into the makeup of the building are in a constant \r\n state of motion. All building materials move with changes in temperature, \r\n some move with changes in moisture content, some have plastic flow \r\n due to stress, and all have elastic deformation due to imposed loads. \r\n Provisions must be made to permit the various materials and elements \r\n to move so as not to distress any part. See Technical Notes , \r\n 18 series, \"Differential Movement\". \r\n The stress developed in restrained elements \r\n due to a change in temperature is equal to the modulus of elasticity \r\n multiplied by the coefficient of expansion and by the change in temperature. \r\n Table 3 lists coefficients of lineal thermal expansion for many commonly \r\n used building materials. \r\n \r\n \r\n \r\n \r\n Wood, masonry and concrete may expand with \r\n changes in moisture content. For concrete and wood products, these \r\n movements are reversible. For clay products masonry, in which the \r\n initial moisture expansion is not reversible at atmospheric temperatures \r\n and pressures, a moisture expansion design coefficient of 0.0002 is \r\n recommended for clay masonry. A shrinkage coefficient of 0.0005 is \r\n recommended for concrete. \r\n Elastic deformation due to stress in the \r\n elastic range is approximately linear and is equal to the stress divided \r\n by the modulus of elasticity of the material. \r\n When some materials are continuously stressed, \r\n there is a gradual yielding in the direction of the stress application. \r\n This is plastic flow, which is influenced not only by stress, but \r\n also by time and the physical properties of the material. A design \r\n value of 0.000001 per unit of length per psi is recommended for concrete. \r\n For example, a 100-ft long member, stressed to 1000 psi, would be \r\n expected to have a reduction in the length of 1.2 in. \r\n In brick masonry, the units themselves are \r\n not subject to flow, although the mortar joints are. The joints, however, \r\n seldom comprise more than 15 or 20 per cent of the volume in compression. \r\n Limited research on creep for brick masonry suggests a design value \r\n of 0.0000002 per unit of length per psi. \r\n Another major cause of movement in buildings \r\n is settlement and the action of unstable soil. Frequently, bearing \r\n wall buildings can be utilized to an advantage because the loads are \r\n delivered in lines rather than points, thus keeping the soil bearing \r\n stress low. Also, the walls can be designed as thin, deep beams which, \r\n when working with the footing, will be able to span weak spots or \r\n depressions in the subsoil. \r\n The spacing of expansion joints in bearing \r\n walls need not be as close as for non-bearing walls because bearing \r\n walls are usually of greater strength and mass. Also, they are under \r\n higher stress, which in many cases will tend to restrain the walls, \r\n thus reducing movement. Where expansion joints are required, it is \r\n important to be careful to maintain the structural integrity of the \r\n wall. \r\n Floor systems in bearing wall buildings \r\n will necessarily be influenced by structural requirements and by arrangements \r\n of bearing and shear walls. Joist systems and precast plank systems \r\n are satisfactory for most buildings, since they eliminate form work. \r\n Occasionally, two-way slabs, where the vertical load can be distributed \r\n in two directions, will offer a better floor system. \r\n Control of Moisture and Temperature . \r\n In many buildings, cavity walls will meet the structural requirements, \r\n as well as provide walls which are resistant to water penetration, \r\n because of their internal drainage channels. Similar drainage channels \r\n can be built into walls which are furred on the inside, if through-the-wall \r\n flashing is used to collect any water which might penetrate the wall \r\n and divert it back to the outside through weep holes. These air spaces \r\n also provide convenient spaces for thermal insulation. Two types of \r\n pouring-type wall insulation have been investigated and found to be \r\n suitable for cavity walls. These are water-repellent vermiculite loose-fill \r\n insulation and water-repellent perlite loose-fill insulation. See \r\n Technical Notes 21 Series. Cavity walls can often be used as \r\n interior bearing walls to accommodate mechanical equipment which may \r\n run horizontally and vertically in the walls. \r\n On exterior walls, care should be taken \r\n to avoid thermal bridges on which condensation may occur. In most \r\n climates, condensation will not occur on uninsulated masonry walls; \r\n however, through-the-wall metal elements may collect condensation \r\n on the inside. See Technical Notes 7C , \r\n \"Moisture Control in Brick and Tile Walls - Condensation\", and 7D , \r\n \"Moisture Control in Brick and Tile Walls-Condensation Analysis\". \r\n In bearing wall buildings, some of the detailing \r\n problems are more critical, while others are minimized. There are \r\n few absolute answers to these problems. The best solution will stem \r\n from a rational analysis of the situation. Good details require ingenuity \r\n and imagination. There are no standard details which should be used \r\n without question. Each juncture of floor and wall should be considered \r\n as a separate problem and an appropriate detail developed for the \r\n situation. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60093,"ResultID":176325,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 26 - Single Wythe Bearing \r\n Walls \r\n Sept. 1994 \r\n \r\n Abstract : Brick masonry bearing wall systems have been used for years \r\n for their strength, durability and other inherent values. Once widely \r\n used in single family residential construction, this application is experiencing \r\n a resurgence in interest. New designs possible with a single wythe of \r\n brick are discussed in this Technical Notes . Selection of materials \r\n and recommended details for one and two story designs are addressed. \r\n Key Words : bearing wall, brick, reinforced \r\n brick masonry, single wythe wall. \r\n INTRODUCTION \r\n The rising cost of wood framing members has \r\n created a renewed interest in alternative building systems for residential \r\n housing. The use of light-gage steel framing is one alternative. Another \r\n is the use of single wythe brick bearing walls. The use of brick masonry \r\n as the load-carrying element of a structure provides several benefits \r\n over other alternate systems. Using brick as both the buildings exterior \r\n skin and its structure capitalizes on brick masonrys strength and other \r\n inherent values. Brick gives a home permanence and beauty. Brick homes \r\n have lower maintenance costs and often lower insurance rates because of \r\n their fire resistant characteristics. Because of their thermal mass properties, \r\n brick homes are more energy efficient than comparably insulated vinyl- \r\n or wood-sided homes. For these reasons, brick homes have a higher resale \r\n value. \r\n In a single wythe brick bearing wall system, \r\n the brick masonry serves as both the structural system and the exterior \r\n facing. A wood, steel or masonry backing system is not necessary. The \r\n interior living space of a brick bearing wall home may be the same as \r\n that of a framed home. Floor and roof elements and interior partitions \r\n are constructed with the same materials as used in frame homes. Home plans \r\n may include one or two story structures, expansive master bedrooms and \r\n other popular amenities. In brick bearing wall homes, attractive features \r\n such as brick masonry fireplaces and special brick details can be readily \r\n incorporated to set the house apart. \r\n The design and construction of single wythe \r\n brick bearing wall systems are discussed in this Technical Notes . \r\n Typical details for residential applications are provided. Although this \r\n Technical Notes illustrates residential construction, single wythe \r\n brick bearing walls are equally appropriate in commercial construction, \r\n and many of the design and material considerations discussed in this Technical \r\n Notes are the same. \r\n DESIGN CONSIDERATIONS \r\n Single wythe brick loadbearing walls include \r\n the same design considerations as other types of wall systems. Model building \r\n codes dictate the minimum loads to be resisted by the structural system, \r\n the minimum thermal performance requirements and the necessary fire resistance \r\n of the wall system. Since a brick bearing wall system forms the building \r\n envelope, the designer must also consider resistance to moisture penetration \r\n and detailing of interior finishes. These concerns are addressed in the \r\n sections that follow. \r\n Structural Considerations \r\n The design of any structural system begins with \r\n the determination of the design loads. Design loads include vertical loads \r\n from the weight of the building materials and occupants and lateral (horizontal) \r\n loads from wind, soil and seismic forces. In most residential structures, \r\n the controlling forces are the expected vertical loads plus wind loads. \r\n In certain regions of the United States, predominantly the west coast, \r\n seismic loads may control the structural design. \r\n The model building codes and the associated \r\n structural loads will dictate the size of the buildings structural members. \r\n Model building codes have two methods of design: empirical and rational. \r\n In the case of loadbearing masonry, all model building codes specify the \r\n minimum wall thicknesses and maximum wall height or number of stories \r\n for empirical designs. Generally, these limitations are not applicable \r\n to buildings which have been rationally designed. However, the distinction \r\n in model building code limitations for engineered (rational) versus empirically \r\n designed masonry structures is not always clear. Furthermore, even a rational \r\n design will include some prescriptive detailing requirements. The masonry \r\n standard used for the structural design of brick bearing walls in this \r\n Technical Notes is the Building Code Requirements for Masonry \r\n Structures (ACI 530/ASCE 5/TMS 402) and its companion Specifications \r\n for Masonry Structures (ACI 530.1/ASCE 6/TMS 602) [4], referred to \r\n as the MSJC Code and Specifications, respectively. Other masonry design \r\n criteria, such as Chapter 21 of the Uniform Building Code, could also \r\n be used. \r\n The most widely used residential building code \r\n is the CABO One- and Two-Family Dwelling Code [5]. The CABO Code \r\n is an empirical code which specifies an 8 in. (200 mm) minimum nominal \r\n wall thickness for loadbearing masonry structures over one story in height. \r\n For single-story homes, a nominal 6 in. (150 mm) wall is permitted, so \r\n long as the wall height does not exceed 9 ft (2.7 m) and the gable height \r\n does not exceed 15 ft (4.6 m). In cases where these limits are applied, \r\n the minimum wall thickness requirements will influence the type and size \r\n of brick unit used. When rationally designed, these limits on wall size \r\n can be exceeded. Other model building codes have similar prescriptive \r\n restrictions, but permit rational design, not subject to these limits, \r\n when using approved masonry standards. \r\n Loadbearing brick masonry houses may be built \r\n with walls less than 6 in. (150 mm) in nominal thickness when rationally \r\n designed. These walls may require vertical steel reinforcing bars and \r\n horizontal reinforcing bars or wires. Typically, vertical steel reinforcing \r\n bars are used to resist lateral loads and horizontally reinforced bond \r\n beams are used to attach floor and roof members. Additional horizontal \r\n reinforcement is required over large openings and in areas of high seismicity. \r\n This Technical Notes provides details for location of vertical \r\n reinforcement and horizontal bond beams when used in brick bearing wall \r\n construction. \r\n The designer of a brick bearing wall must specify \r\n the properties of the materials necessary to meet the structural requirements \r\n of the design. The compressive strength of the brick masonry assembly, \r\n f m , must \r\n be specified. Mortar and grout type or properties should be identified. \r\n Type, size and grade of reinforcement, if used, should also be specified. \r\n See Technical Notes 3 Series for further information on the structural \r\n design of brick bearing walls using the MSJC Code. \r\n Energy Considerations \r\n The model building codes contain requirements \r\n to ensure acceptable thermal performance of the building envelope. Minimum \r\n levels of insulation are required, and in some cases, air leakage is addressed. \r\n Type and installation of insulation in a single wythe brick bearing wall \r\n system differ from those in other residential wall systems. In wood frame \r\n residential structures, batt insulation is typically placed between the \r\n wood studs. For brick bearing wall homes, rigid board insulation is often \r\n placed on the interior face of the brick wythe. Rigid board insulation \r\n has the advantages of being easy to install and providing high insulation \r\n values. Installation of the insulation board on the interior of the brick \r\n wythe is coordinated with the interior finish materials and with the flashing \r\n and drainage system used to control water penetration. Options for attaching \r\n rigid insulation include square, \"Z\" or other shaped furring strips, mechanical \r\n fasteners and adhesives. Alternately, insulation may be placed in the \r\n cells of hollow brick units. However, this application is limited to large \r\n hollow units most commonly used in commercial brick bearing wall buildings. \r\n Furthermore, such insulation is generally not as effective as a continuous \r\n layer of insulation placed on the inside face of the single wythe wall, \r\n due to the discontinuity of the insulation at the webs of the units. \r\n Air leakage through the building envelope may \r\n also be a concern. Although the brick wall provides an effective air barrier, \r\n there will be some leakage through weep holes and at the top of the brickwork. \r\n Building paper or sheet membrane materials, called \"house wraps\", are \r\n commonly installed over exterior sheathing materials in wood frame construction \r\n to prevent air leakage. However, these materials are not appropriate for \r\n direct application on brick bearing walls. Alternate approaches to further \r\n limit air leakage are the use of either foil-faced rigid board insulation \r\n or so-called \"air-tight drywall\". These approaches rely on the air penetration \r\n resistance of the paper or other films on the insulation or gypsum board. \r\n To achieve an impenetrable air barrier, the joints between the sheets \r\n of insulation or gypsum board should be sealed or taped. Joints between \r\n dissimilar materials, and joints around door and window frames, should \r\n also be sealed. \r\n Water Penetration Resistance \r\n Water penetration is one of the chief concerns \r\n in the performance of any exterior wall system. Resistance to water penetration \r\n of the brick masonry wythe is of utmost importance in single wythe construction. \r\n Full mortar joints and good extent of bond between units and mortar help \r\n to reduce water penetration. The head joints in hollow brick masonry should \r\n be laid full, not face-shell mortar bedded only. Technical Notes \r\n 7 Series provides further information on water penetration resistance \r\n of brick masonry wall systems. \r\n A single brick masonry wythe may not prevent \r\n water penetration entirely. Therefore, a drainage cavity with flashing \r\n and weep holes should be provided. If a drainage cavity is not used, a \r\n bituminous, damp-proof coating should be applied to the inside face of \r\n the brick bearing wall prior to installation of the insulation and finishes. \r\n Material compatibility of the coating with adjacent materials should be \r\n considered. In regions of the country which are subject to large amounts \r\n of rainfall or severe wind-driven rain, the use of a clear water repellent \r\n coating on a wall built with good workmanship and proper details may be \r\n appropriate with this wall type. \r\n Location of Interior Work and Finishes \r\n The installation of plumbing, heating and electrical \r\n systems in a loadbearing brick home will vary slightly from their placement \r\n in conventional frame construction. There is no cavity between studs for \r\n the placement of piping or conduit, and piping or conduit should not be \r\n placed within the brick wythe. Instead, the plumbing, heating and electrical \r\n piping or conduit can be installed between furring strips on the brick \r\n bearing wall, in the floor or ceiling or in interior frame walls. The \r\n type of foundation will influence the location of interior systems. In \r\n slab-on-grade construction, it is easiest to route the mechanical systems \r\n through the ceiling space. With basement or crawl space foundations, it \r\n is possible to locate mechanical systems between the first floor joists. \r\n The interior finish materials used in brick \r\n bearing wall homes are the same materials as those used in frame construction. \r\n However, the installation of interior finishes varies. In brick veneer \r\n construction, interior gypsum board is typically nailed or screwed to \r\n the studs. In brick bearing wall construction, gypsum board or other interior \r\n finishes may be nailed or screwed to furring strips or light-gage metal \r\n studs, anchored to the masonry with special clips or ties, nailed to special \r\n nailing inserts in the masonry or adhesively attached over the brick masonry \r\n wythe and insulation. Some common methods are discussed in Construction \r\n Details . \r\n Cabinets and other built-in items can be attached \r\n directly to the brick masonry walls or to furring strips attached to the \r\n masonry. Wood 2 by 4s, spaced to support the cabinets or other built-in \r\n items, can be attached to the brick masonry using anchor bolts placed \r\n in the masonry wall or by expansion anchors, adhesive anchors or other \r\n brick anchors and fasteners installed in the completed masonry. Technical \r\n Notes 44 and 44A \r\n provide a complete description of suitable brick anchors and fasteners. \r\n Insulation may be placed between the 2 by 4s, and cabinets then placed \r\n over insulation and attached to the furring using conventional techniques. \r\n Cabinets may also be supported by stud framing built inside the brick \r\n bearing wall, in a manner similar to brick veneer construction. \r\n \r\n MASONRY MATERIAL SELECTION \r\n Selection of masonry materials for a brick bearing \r\n wall system should consider structural, energy and other performance requirements \r\n as discussed in this Technical Notes . Further information on material \r\n selection for adequate strength and compliance with the MSJC Code and \r\n Specifications can be found in Technical Notes 3 Series. \r\n Brick \r\n Brick used in single wythe bearing wall structures \r\n may be either solid or hollow. Solid units should meet the requirements \r\n of ASTM C 216 Specification for Facing Brick. Hollow units should meet \r\n the requirements of ASTM C 652 Specification for Hollow Brick. Structural \r\n and model building code requirements, aesthetics, availability and cost \r\n will determine the minimum unit compressive strength, type and sizes of \r\n units used. Brick unit compressive strengths range from 1,700 psi to 36,000 \r\n psi (12 to 250 MPa), with a mean value of over 5,200 psi (36 MPa) for \r\n molded brick and over 11,300 psi (77 MPa) for extruded brick [1]. Brick \r\n unit strength is directly related to compressive strength of the brick \r\n masonry assembly. Technical Notes 3A \r\n should be reviewed for material properties of brick masonry. \r\n There are numerous brick sizes manufactured \r\n today. Solid units are commonly manufactured in nominal widths of 3, 4 \r\n and 6 in. (75, 100 and 150 mm). Hollow units, which are less than 75 percent \r\n solid, are manufactured in nominal widths of 4 in. (100 mm), 5 in. (125 \r\n mm), 6 in. (150 mm) and 8 in. (200 mm). See Technical Notes 10B \r\n Revised for a more complete listing of sizes currently manufactured. Nominal \r\n 5 and 6 in. (125 and 150 mm) wide hollow brick are the most common units \r\n used to build reinforced brick bearing wall homes. \r\n Hollow brick are prevalent in reinforced brick \r\n bearing walls because they have cells which can accommodate vertical reinforcement \r\n and grout. The minimum size of cells in hollow units intended to be reinforced \r\n is dictated by the MSJC Code and listed in Table 1. Larger bars, horizontal \r\n reinforcing bars and coarse grout require larger cell sizes. When reinforcement \r\n is required, solid brick may be cut to form grout pockets or incorporate \r\n pilasters to accommodate vertical reinforcement. For further information \r\n on grouting requirements see the MSJC Code and Specifications and Technical \r\n Notes 3B . \r\n Uniform spacing of vertical reinforcement is \r\n important in the design and construction of reinforced loadbearing masonry \r\n walls. Cell size and unit length should be coordinated to provide cells \r\n which align vertically for ease of grouting and uniform spacing of reinforcing \r\n bars. Most hollow brick designed to accommodate reinforcing bars have \r\n lengths equal to twice their width, so that cells align vertically when \r\n the masonry is laid in half running bond. Spacing of reinforcement should \r\n be selected with these dimensions in mind. \r\n \r\n \r\n \r\n \r\n \r\n 1 Metric dimensions are based on metric reinforcing bar sizes as specified \r\n in ASTM A 615M. \r\n 2 Area \r\n of reinforcing bar should not exceed 6 percent of cell void area. \r\n \r\n \r\n \r\n \r\n Mortar \r\n The strength and water penetration resistance \r\n of a brick bearing wall is dependent upon the mortar selected. Portland \r\n cement-lime mortars with an air content less than 12 percent are recommended \r\n for their superior bond strength and resistance to water penetration. \r\n In unreinforced loadbearing masonry, the MSJC Code allowable flexural \r\n tensile stresses are reduced approximately 50 percent for assemblies made \r\n with masonry cement mortars or portland cement-lime mortars with air content \r\n over 12 percent. In addition, some codes prohibit the use of masonry cement \r\n mortars and all Type N mortars in Seismic Performance Categories D and \r\n E (formerly Seismic Zones 3 and 4). Mortar should meet the proportion \r\n requirements of ASTM C 270 Specification for Mortar for Unit Masonry. \r\n Type S, M or N mortar may be used in loadbearing brick masonry, although \r\n Type S is recommended for use in reinforced brick bearing walls. \r\n \r\n Grout \r\n Grout is used in reinforced brick masonry to \r\n bond steel reinforcement to the surrounding brick masonry. Grout for masonry \r\n may be made from either fine or coarse aggregate, although fine grout \r\n is typically used for ease of grouting smaller cells. Aggregate type influences \r\n the size of grout space needed. (See Table 1.) Grout should meet the proportion \r\n requirements of ASTM C 476 Specification for Grout for Unit Masonry, and \r\n use of a shrinkage compensating admixture is recommended. The water/cement \r\n ratio of grout is not typically specified, but the water content should \r\n be sufficient to provide a mixture which has a slump of 8 to 11 in. (200 \r\n to 275 mm). Grout should be fluid enough to fill voids, but not separate \r\n into its constituents. \r\n Reinforcement \r\n \r\n Vertical steel reinforcement is often used in \r\n brick bearing walls to provide resistance to lateral loads. Size and spacing \r\n of reinforcement required are a function of design loads, unit size, compressive \r\n strength of the masonry assemblage and cell spacing. The MSJC Code limits \r\n the maximum size of reinforcement used in masonry to a No. I I reinforcing \r\n bar. As a rule-of-thumb, the maximum bar size should not exceed the nominal \r\n thickness of the wall in inches to ensure proper development of the reinforcement. \r\n For example, a maximum reinforcing bar size of No. 6 is recommended for \r\n nominal 6 in. (150 mm) walls. \r\n Steel reinforcing bars should conform to ASTM \r\n Specification A 615, A 615M, A 616, A 617 or A 706, depending upon the \r\n type of bar used. Joint reinforcement, if used, should comply with ASTM \r\n A 82 and be hot-dipped galvanized or made from stainless steel to reduce \r\n the possibility of corrosion. \r\n CONSTRUCTION DETAILS \r\n There are several features of a brick bearing \r\n wall system which differ from brick veneer wall systems. The construction \r\n of loadbearing brick masonry may incorporate reinforcement and must provide \r\n support and attachment of floors and the roof. Openings for windows and \r\n doors may be spanned by self-supporting reinforced or unreinforced brick \r\n masonry. Water penetration resistance and thermal resistance are generally \r\n provided by methods other than the traditional drainage cavity and insulation \r\n between wood studs. Possible details for construction of these features \r\n in a brick bearing wall system follow. The structural details and methods \r\n of attaching the insulation and interior finishes shown vary from figure \r\n to figure to illustrate the variety of options available. No single method \r\n is preferred in all cases, nor are all possible options shown. \r\n Solid Brick With Grout Pocket \r\n FIG. 1 \r\n Pilaster Built with Solid \r\n Brick \r\n FIG. 2 Reinforced \r\n Hollow Brick \r\n FIG. 3 \r\n Bearing Wall Reinforcement \r\n A loadbearing brick wall often contains vertical \r\n steel reinforcement uniformly spaced along the length of the wall and \r\n horizontal reinforcement in bond beams. Vertical reinforcement may also \r\n be necessary around openings and at building comers. Figure I illustrates \r\n one means of incorporating vertical reinforcing bars in a wall built of \r\n solid units. In this case, horizontal joint reinforcement may be required \r\n in bed joints, and formwork is necessary to contain the grout in the grout \r\n pocket until it has cured. The brick units \r\n will require special cutting to form the grout pocket within the wall \r\n thickness. \r\n Alternately, brick bearing walls built with \r\n solid units may incorporate pilasters, as shown in Fig. 2, to provide \r\n the necessary confinement of vertical reinforcement. The advantage of \r\n using pilasters is that no forms are required. They may, however, occupy \r\n a significant amount of floor space if located on the interior side of \r\n the wall. \r\n Masonry walls constructed with hollow units \r\n may be vertically reinforced as shown in Fig. 3. By providing the necessary \r\n reinforcement within the cells of the unit, hollow brick bearing walls \r\n can optimize the wall section. The design and detailing of reinforcement \r\n should follow the provisions of the MSJC Code and Specifications. In some \r\n cases, such as at terminations or splices of vertical reinforcing bars, \r\n special attention may be necessary to accommodate multiple or hooked reinforcing \r\n bars within the confines of the cells of hollow brick. Technical Notes \r\n 3B provides examples of common reinforced pilasters and reinforced hollow \r\n brick walls. \r\n Horizontally reinforced bond beams \r\n are used to anchor bolts for attaching ledgers and plates and to span \r\n wall openings. Bond beams are formed by removing part of the cross webs \r\n of hollow brick or by using special Ushaped units. Necessary anchor bolts \r\n and reinforcement are placed, and the bond beam is grouted solid. The \r\n depth of the bond beam required will depend on the design loads for the \r\n structure, the material properties of the masonry and the amount of reinforcement \r\n used. \r\n Connections \r\n Foundation. Brick bearing \r\n walls may be supported on poured concrete, concrete masonry or brick masonry \r\n foundation walls. If construction incorporates a slab on grade, the foundation \r\n wall may be built as shown in Fig. 4. When a crawl space or basement is \r\n present, the floor joist system may be supported directly on the foundation \r\n wall (Fig. 5), on corbeled brickwork (Fig. 6) or on a ledger joist bolted \r\n onto a bond beam (Fig. 7). The details of support will vary depending \r\n upon the size of foundation wall and the width of the brick bearing wall \r\n above the foundation. A minimum bearing of 3 in. (75 \r\n mm) should be provided for floor joists which bear on the foundation wall. \r\n Waterproofing should be provided for below-grade masonry. \r\n Slab-On-Grade Foundation \r\n FIG. 4 \r\n Basement or Crawl Space Foundation \r\n FIG. 5 \r\n Basement or Crawl Space Foundation \r\n Corbeled Support \r\n FIG. 6 \r\n Basement or Crawl Space Foundation \r\n Bond Beam Support \r\n FIG. 7 \r\n Floors . Floors above the first story \r\n may be anchored to the brick bearing walls or be supported on corbeled \r\n brickwork. In multi-story construction, anchor bolts cast into a continuous, \r\n reinforced, grouted brick bond beam at the floor support level are often \r\n used. A continuous wood ledger is bolted into place, and the floor joists \r\n are attached to the ledger with joist hangers as shown in Fig. 8 Floor \r\n Connection FIG. 8 Flashing should extend a minimum of 8 in. (200 mm) above \r\n the ledger and at least 3 in. (75 mm) below. \r\n Roof. The roof should be supported directly \r\n on top of the bearing wall to minimize eccentric loading. The roof must \r\n be anchored to the top of the brick bearing wall to resist uplift forces \r\n on the roof. A wood plate is attached to the top of the wall using anchor \r\n bolts embedded in a bond beam or masonry below. A reinforced concrete \r\n bond beam or a reinforced and grouted brick bond beam may be used, as \r\n illustrated in Fig. 9. In this case, the \r\n anchor bolts should extend a minimum of 12 in. (300 mm) into the grouted \r\n cells in the wall below and terminate with a standard hook. One alternative, \r\n for use in unreinforced bearing walls, is to thread anchor bolts through \r\n the core holes of the solid units and attach the bolts to a steel plate \r\n embedded in the masonry, as shown in Fig. 10. \r\n Roof Connection \r\n FIG. 9 \r\n Roof Connection \r\n FIG. 10 \r\n Window Detail With Steel Lintel \r\n FIG. 11 \r\n Soldier Course Lintel FIG. \r\n 12a Brick Bond Beam Lintel FIG. 12b \r\n Window and Door Openings \r\n Masonry over openings for windows and doors \r\n may be supported by loose steel linters, reinforced brick masonry linters \r\n or brick masonry arches. The design of steel linters is covered in Technical \r\n Notes 31B. When steel linters are used, flashing and weep holes should \r\n be provided over the lintel as shown in Fig. I 1. Alternate- ly, loadbearing \r\n brick masonry can be self-supporting over many wall openings. Horizontally \r\n reinforced brick masonry linters are one option. Design of reinforced \r\n brick linters should be in accordance with the MSJC Code or other approved \r\n masonry standard. Reinforcement may be incorporated into voids in a soldier \r\n course of brick or in a bond beam, as illustrated in Figs. 12a and 12b, \r\n respectively. Figure 13 provides required steel reinforcement for solidly \r\n grouted bond beam lintels based on the MSJC Code. Required reinforcement \r\n is determined by the total uniform dead and live loads on the lintel and \r\n the span of the opening. Figure 13 is applicable to hollow or solid units \r\n of 5 to 6 in. (125 to150 mm) in nominal width. Lintels made of hollow \r\n units are assumed to be grouted over their entire height, ht. Generally, \r\n for loads greater than 400 lb/ft (6 kN/m), the maximum span length is \r\n limited by shear strength of the lintel. Spans may be increased if shear \r\n reinforcement is provided in the lintel. Reinforced brick linters should \r\n be shored for a minimum of seven days after construction. Openings can \r\n also be spanned by reinforced or unreinforced brick masonry arches. Consult \r\n the Technical Notes 31 Series for guidance on the structural design of \r\n brick masonry arches. \r\n Flashing and Weep Holes \r\n For best performance, a drainage cavity with \r\n flashing and weep holes should be incorporated in the single wythe bearing \r\n wall system. The most common method to form a drainage cavity behind the \r\n brick wythe is to space the rigid board insulation a minimum of 1/2 in. \r\n (13 mm) from the inside face of the brick wythe using furring strips or \r\n other spacers. The interior finish is then attached directly over the \r\n insulation. Any materials in direct contact with the brick wythe should \r\n be rot and corrosion resistant for long-term durability. Alternately, \r\n rigid board insulation can be adhered to the brick wythe, and light-gage \r\n (non-bearing) metal stud framing can be attached to floor and ceiling \r\n joists with no direct contact with the brick wythe. This forms a cavity \r\n between the insulation and interior finish which can be flashed similar \r\n to that in brick veneer wall systems. A minimum 1/2 in. (13 mm) cavity \r\n is adequate for this wall system because the insulation and finishes are \r\n installed after the masonry is completed. Any voids in the mortar should \r\n be filled, and any mortar protrusions should be removed to provide a clear, \r\n open cavity. \r\n Flashing should be placed at the base of the \r\n cavity and at all interruptions in the wall, such as over window and door \r\n openings. The effect of flashing placement should be considered in the \r\n structural design. Splices in flashing must be sealed and discontinuous \r\n flashing must have end dams. Flashing should be turned up a minimum of \r\n 8 in. (200 mm) and attached with adhesive to the inside sur- face of the \r\n rigid board insulation or ou -tside surface of the gypsum board, or nailed \r\n or stapled to furring strips. The flashing should extend past or be cut \r\n flush with the exterior face of the brickwork. If the brick bearing wall \r\n is reinforced, the through-wall flashing at the base of the wall will \r\n be punctured by vertical reinforcing bars. Hashing must be sealed around \r\n all reinforcement with mastic at these locations. Suitable flashing materials \r\n are discussed in Technical Notes 7A Revised. Weep holes should be placed \r\n directly above all flashing locations. \r\n Weep holes should be located above grade and \r\n spaced a maximum of 24 in. (600 mm) on center when using open head joints \r\n or brick vents, or 16 in. (400 mm) on center when using wicks or plastic \r\n tubes. Open head joint weep holes are preferred over rope wicks or tubes. \r\n Vents, copper screening or stain- less steel wool can be placed in open \r\n head joint weep holes to prevent insects and rain from entering. If the \r\n brick bearing wall is treated with a clear water repellent, brick vents \r\n in head joints at the base and top of each story are recommended. \r\n Insulation and Finishes \r\n The attachment of insulation and interior finishes \r\n may be accomplished in several ways. One method is to attach treated wood \r\n or plastic furring strips to wall plugs inserted into mortar joints as \r\n shown in Fig. 14, at the top, bottom and mid-height of the wall. Rigid \r\n board insulation may be installed between furring strips or over them \r\n to form a cavity for drainage. Gypsum board or other interior finish is \r\n then placed over the insulation. Another option involves the use of a \r\n special \"Z\" clip. The clip is attached to the brick wythe at 16 or 24 \r\n in. (400 or 600 mm) o.c. horizontally or vertically. The leg of the clip \r\n extends beyond the rigid board insulation, and special hat channels (so-called \r\n because of their shape) are screwed onto the clip, as shown in Fig. 15. \r\n The interior finish is then screwed to the hat channels to finish the \r\n wall. A third alternative is light-gage (non- bearing) metal stud framing. \r\n The framing is used to form a drainage cavity and to apply insulation \r\n and/or finishes in a manner similar to that in brick veneer wall systems. \r\n Light-gage metal framing is installed by attaching a track to the floor \r\n and ceiling joists at the desired distance from the brick wythe. Rigid \r\n board insulation may be placed between the metal framing and brick bearing \r\n wall, or insulation may be placed between studs. The framing provides \r\n a level surface for applying the interior gypsum board or other interior \r\n finish. The framing does not provide support for the brick bearing walls. \r\n This permits a substantial reduction in the size of the metal framing \r\n members. One and onehalf inch (40 nun) studs are often used. \r\n CONSTRUCTION CONSIDERATIONS \r\n Quality Control \r\n The quality of construction of a brick bearing \r\n wall is important for several reasons. The masonry wall is the primary \r\n structural system for the building and must meet the rffinimum strength \r\n necessary for adequate performance. Without quality construction, the \r\n expected strength of the masonry may not be achieved. Good workmanship \r\n is also important in resisting water penetration. In a single wythe wall, \r\n the masonry is the primary barrier to water penetration, and good workmanship \r\n directly affects the water penetration resistance of the masonry. \r\n To ensure quality construction, the MSJC Code \r\n and Specifications contain several provisions regarding materials testing, \r\n inspection of masonry and workmanship. Brick units and mortar may have \r\n to be tested to verify compliance with applicable standards. Verification \r\n of assembly compressive strength may be determined by preconstruction \r\n testing of brick masonry prisms constructed from the same brick and mortar \r\n to be used on the project. Alternately, assembly compressive strength \r\n may be verified by the conservative unit strength method which requires \r\n knowledge of the brick unit compressive strength and mortar Type to estimate \r\n the masonry assemblages strength. Inspection of the ma- sonry during \r\n construction is required by the MSJC Code, and limits on the dimensional \r\n tolerances of masonry elements ensure expected structural performance. \r\n In reinforced brick masonry, maintaining clear \r\n grout spaces during construction and proper location of reinforcement \r\n are important. The cells of hollow brick intended to receive reinforcing \r\n bars and grout should be free of mortar protrusions and debris. One method \r\n of keeping the cells of hollow brick clean is to insert sponges into the \r\n cells to be grouted at the beginning of construction. The sponges are \r\n pulled upward by a handle, wire or string as construction progresses, \r\n leaving clean cells ready for grouting, as shown in Fig. 16. Another method, \r\n if sponges are not used, is to provide cleanout openings at the base of \r\n the wall at all grout locations. The cleanouts allow the mortar protrusions \r\n to be scraped off after construction and the debris removed at the wall \r\n base. See Fig. 17. The cleanouts are sealed prior to commencing with grouting. \r\n One method of closing cleanouts in hollow brick is to bevel cut the section \r\n of the face shell to be removed. When replaced, the cut piece is held \r\n in position by pressure from the grout. Cleanouts are seldom used in single \r\n wythe construction except with large cell hollow brick or at pilaster \r\n locations. For further information on grouting brick masonry walls, see \r\n Technical Notes 17C and the MSJC Code and Specifications. \r\n To resist water penetration, full head joints \r\n should be used with solid and hollow units, and full bed joints are recommended \r\n with solid units. Proper installation of flashing and weep holes and other \r\n moisture control measures will control water which does penetrate the \r\n brick masonry wythe. \r\n Sequence of Work \r\n In a loadbearing wall system, brick masonry \r\n is the primary structural element. The masonry work may begin as soon \r\n as the foundation is complete and property cured. Bearing walls should \r\n be braced during construction until lateral support is provided by the \r\n floors and roof. Once one story height is laid, construction of the floor \r\n or roof systems follow, possibly serving as a work platform for the remaining \r\n masonry work. The fasteners necessary for attachment of the cabinets, \r\n insulation and interior finishes should be incorporated during the construction \r\n of the masonry. Interior frame walls may be built simultaneously with \r\n the exterior loadbearing brick walls once the floor has been constructed, \r\n at the builders discretion. \r\n Brick bearing walls should attain sufficient \r\n strength before any loads are applied. The curing conditions will affect \r\n the rate of strength gain of loadbearing masonry. If sufficient moisture \r\n is maintained, the masonry walls should cure a minimum of three days before \r\n supporting floor or roof loads. Reinforced brick masonry beams require \r\n curing periods of at least seven days. Poor curing conditions, such as \r\n exposure to cold temperatures, may require longer curing times. Once the \r\n brick bearing walls are cured, the floors and roof may be attached. The \r\n windows, doors, plumbing, electrical and heating systems, insulation and \r\n interior finishes can be installed as soon as the masonry is complete. \r\n SUMMARY \r\n This Technical Notes covers the design and detailing \r\n of single wythe bearing walls. Selection of materials and rnetfiods of \r\n reinforcing and finishing brick bearing walls are discussed. The information \r\n provided illustrates a few of the many options available for a single \r\n wythe brick bearing wall system. Design and construction considerations \r\n presented are equally applicable to residential and commercial construction. \r\n Any design should be completed in accordance with the MSJC Code and Specifications \r\n and applicable model building and energy codes. The information and suggestions \r\n contained in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used \r\n in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonary. Final decisions on the use of the \r\n information contained in this Technical Notes are not within the purview \r\n of the Brick Institute of America and must rest with the project architect, \r\n engineer and owner. \r\n REFERENCES \r\n \r\n I .\"Brick Masonry Material Properties,\" \r\n Technical Notes on Brick Construction 3A, Brick Institute of America, \r\n Reston, VA, December 1992. \r\n \r\n 2. \"Brick Masonry Section Properties,\" Technical Notes on Brick Construction \r\n 3B, Brick Institute of America, Reston, VA, May 1993. \r\n \r\n 3. \"Building Code Requirements for Masonry Structures ACI 530/ASCE 5 \r\n and Specifications for Masonry Structures ACI 530.1/ASCE 6,\" Technical \r\n Notes on Brick Construction 3, Brick Institute of America, Reston, VA, \r\n February 1990. \r\n \r\n 4. Building Code Requirements for Masonry Structures and Commentary \r\n (ACI 530/ASCE 5/TMS 402) and Specifications for Masonry Structures and \r\n Commentary (ACI 530.1/ASCE 6/TMS 602), American Concrete Institute, \r\n Detroit, MI, 1992. \r\n \r\n 5. One-and Two-Family Dwelling Code, Council of American Building Officials \r\n (CABO), Falls Church, VA, 1992. \r\n \r\n 6. \"Structural Design of Brick Masonry Arches,\" Technical Notes on Brick \r\n Construction 31A Revised, Brick Institute of America, Reston, VA, July \r\n 1986. \r\n \r\n 7. \"Structural Steel Lintels,\" Technical Notes on Brick Construction \r\n 31B Revised, Brick Institute of America, Reston, VA, May 1987. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60094,"ResultID":176326,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 27 - Brick Masonry Rain \r\n Screen Walls \r\n August 1994 \r\n \r\n Abstract: Pressure equalization \r\n across the exterior wythe of brick veneer and cavity walls allows \r\n the rain screen principle to minimize the infiltration of rain into \r\n exterior walls. This Technical Notes \r\n focuses on the design and wall \r\n components that contribute to the pressure equalized rain screen wall. \r\n A compartmented air cavity behind the exterior brick wythe, a rigid \r\n air barrier system and adequate venting area of the exterior cladding \r\n in relation to the leakage area of the air barrier are necessary elements. \r\n \r\n Key Words: air barrier, air retarder, brick veneer, cavity \r\n wall, drainage wall, exterior cladding, pressure equalization, rain \r\n screen, wind loads. \r\n \r\n INTRODUCTION \r\n \r\n Rain penetration through walls can damage the building envelope. \r\n Corrosion of metal accessories in the exterior cladding, efflorescence \r\n of the masonry and damage to interior finishes and staining are just \r\n a few examples of problems related to moisture penetration. Water \r\n penetration affects the appearance and function of a variety of brick \r\n masonry wall systems. \r\n Over the years, many methods have been used to prevent moisture penetration \r\n of walls, some more successfully than others. Masonry barrier walls \r\n rely on the massive wall materials to deter water penetration. Drainage \r\n type walls, such as brick veneer and cavity walls, provide good moisture \r\n penetration resistance. It must be recognized that the exterior wythe \r\n can not be made watertight. Provisions for internal drainage are necessary \r\n for these wall systems to function as intended. \r\n The next step to provide better moisture penetration resistance for \r\n exterior brick walls is the use of the rain screen principle. This \r\n concept introduces air into the cavity of conventional drainage type \r\n walls to provide pressure equalization so that the cavity works in \r\n resisting wind-driven moisture penetration. \r\n Cladding researchers and investigators increasingly recognize air \r\n pressure as a major cause of water penetration problems. They are \r\n looking more carefully to the rain screen principle as a deterrent \r\n to moisture penetration. This Technical Notes discusses the \r\n design criteria of the rain screen wall, how to develop the pressure \r\n equalization feature within the cavity space and additional construction \r\n detailing needed to tailor conventional brick veneer and cavity wall \r\n systems to the pressure equalized rain screen principle. Other \r\n Technical Notes in this series will address construction considerations \r\n and material selection. \r\n \r\n HISTORY \r\n \r\n The rain screen principle has been used intuitively for many years. \r\n One of the first references to it was made in 1946 by C. H. Johansson \r\n entitled, \"The Influence of Moisture on the Heat Conductance for Brick\". \r\n It was not until sixteen years later that researchers began to understand \r\n how to apply the fundamental laws of physics to the development of \r\n the rain screen principle for practical use. \r\n In 1962, Birkeland of the Norwegian Building Institute wrote Curtain \r\n Walls in which he stated: \r\n \r\n \"The only practical solution to the problem of rain penetration is \r\n to design the exterior rainproof finishing so open that no super-pressure \r\n can be created over the joints or seams of the finishing. This effect \r\n is achieved by providing an air space behind the exterior finishing, \r\n but with connection to the outside air. The surges of air pressure \r\n created by the gusts of wind will then be equalized on both sides \r\n of the finishing.\" \r\n \r\n Birkeland noted six main sources of moisture leakage through wall \r\n systems. The processes discussed were: 1) wind-induced air pressure \r\n differences; 2) pressure assisted capillarity; 3) gravity; 4) kinetic \r\n energy; 5) air currents; and 6) updrafts. Conventional means such \r\n as internal wall flashing, proper design of openings and overhangs \r\n provide moisture resistance to items 2 through 6. But item 1 was the \r\n most difficult to counteract. He concluded that there was no practical \r\n method of obtaining total watertightness in wall systems composed \r\n of joints when a pressure gradient exists across the exterior rain \r\n barrier. These observations formed the basis of the rain screen principle. \r\n Prompted by Birkeland, researchers in Canada began an intensive study \r\n into wall leakage. In 1963, Canadian Building Digest (CBD) 40, \"Rain \r\n Penetration and Its Control\" was published by the Canadian National \r\n Research Councils Division of Building Research. This publication. \r\n which remains a prime reference source on the subject, popularized \r\n the term rain screen principle. G. K. Garden, who authored CBD 40 \r\n on wind-induced moisture penetration wrote: \r\n \r\n \"It is not conceivable that a building designer can prevent the exterior \r\n surface of a wall from getting wet nor that he can guarantee that \r\n no openings will develop to permit passage of water. It has, however, \r\n been shown that through-wall penetration of rain can be prevented \r\n by incorporating an air chamber into the joint or wall where the air \r\n pressure is always equal to that on the outside. In essence, the outer \r\n layer (wythe) is then an open rain screen that prevents wetting of \r\n the actual wall or air barrier of the building\". \r\n \r\n The critical features of the rain screen principle are: \r\n 1. An exterior barrier (rain screen) containing protected openings \r\n which permit the passage of air but not water. \r\n 2. A confined cavity behind the rain screen in which air pressure \r\n is essentially the same as the external air pressure. \r\n 3. Insulation fixed to the outer face of the interior wall system, \r\n if provided in design. \r\n 4. An interior barrier (wall) which substantially limits the passage \r\n of air and water vapor and is capable of withstanding all required \r\n design loads (e.g. wind and earthquake forces). \r\n Many field studies and laboratory tests have applied this principle \r\n to a variety of wall systems, including masonry. The developments \r\n made over the years can be effectively applied to conventional brick \r\n masonry drainage wall construction, with some modifications as discussed \r\n in this Technical Notes . \r\n \r\n DEFINITION AND PRINCIPLES \r\n \r\n Drainage wall types, such as anchored brick veneers and cavity walls, \r\n which provide a space for drainage of moisture that has penetrated \r\n the exterior wythe, are often confused with rain screen walls. When \r\n causes of rain leakage problems are debated, the question usually \r\n arises of whether the wall system utilizes the rain screen principle. \r\n Certainly, there is a cavity between the exterior wythe and interior \r\n wall which provides drainage of moisture which has entered the wall. \r\n The concept of drainage type walls has been around for decades. More \r\n information on brick veneer and cavity wall systems can be found in \r\n Technical Notes 28 Series and 21 , \r\n respectively. However, the basic premise of the rain screen principle \r\n is to control all forces that can drive moisture through the wall \r\n system. \r\n The term pressure equalized rain screen wall should be used. \r\n This emphasizes the difference from the more common drainage type \r\n wall. The pressure equalization in the cavity behind the exterior \r\n wythe is the major difference between a rain screen wall and a drainage \r\n wall. A pressure equalized rain screen wall provides the best means \r\n of resisting water penetration. As such, it should be used on projects \r\n located in areas which receive high volumes of wind-driven rain and \r\n when resistance to water penetration is of prime concern. \r\n \r\n Pressure Equalized Rain Screen Walls \r\n \r\n The difference in air pressures across the exterior cladding is a \r\n significant force which causes infiltration of air and water on windward \r\n facades. Air and moisture can infiltrate through units, mortar joints, \r\n hairline cracks, poorly bonded surfaces and other openings that exist \r\n or develop over the life of the structure. \r\n A rain screen wall is composed of two layers of materials separated \r\n by a cavity as shown in Figure 1. The exterior cladding as discussed \r\n in this Technical Notes is a brick masonry wythe. The interior \r\n wall or inner layer can be either the backing of an anchored brick \r\n veneer wall or the inner wythe of a cavity wall. When wind loads are \r\n imposed on the wall assembly, a pressure difference between the exterior \r\n wythe and the cavity space is created. This pressure difference forces \r\n water on the surface of the exterior cladding to penetrate any openings \r\n through the wall. If the exterior cladding has sufficient openings \r\n to permit air to flow to the cavity behind the cladding, the pressure \r\n in the cavity increases until it equals the pressure resulting from \r\n the wind load being applied. This is the phenomenon of pressure equalization \r\n design. To affect this air pressure transfer, the inner layer of the \r\n wall assembly must be airtight. This is achieved by applying an air \r\n retarder at some location on the backing or inner wythe. The air barrier \r\n seal at this location should last longer because it is not exposed \r\n to the exterior elements. Since the interior wall will be airtight, \r\n stack effect and mechanical ventilation generated inside the building \r\n are effectively controlled. Rain penetration through the exterior \r\n cladding should be reduced as the pressure difference on the exterior \r\n cladding which drives rain into the cavity is reduced. The resultant \r\n wind load will be imposed on the air barrier and interior wall. \r\n \r\n \r\n \r\n Rain Screen Wall Principle \r\n FIG. 1 \r\n \r\n \r\n Moisture Migration \r\n \r\n Exterior claddings primarily restrict the passage of water and wind \r\n and also function as part of a thermal barrier. The extent to which \r\n the exterior cladding can be relied upon to serve these functions \r\n is variable, and the exterior cladding is not considered to be the \r\n sole air or moisture barrier in the wall system. \r\n Rain screen walls using brick veneer and cavity wall systems should \r\n be designed as a two-stage barrier for moisture penetration resistance. \r\n The first stage is the exterior brick wythe. The backing assembly \r\n or the inner wythe is the second stage. The exterior brick wythe should \r\n be detailed and constructed to provide moisture resistance so that \r\n the second stage is not continually tested. If excess water penetrates \r\n the exterior brick wythe, the backing system may become a single stage \r\n in itself which can lead to failure of the rain screen principle as \r\n a whole. A typical brick masonry rain screen wall is shown in Fig. \r\n 2. \r\n \r\n \r\n \r\n Brick Rain Screen Wall \r\n FIG. 2 \r\n \r\n \r\n \r\n The exterior brick wythe is the first stage of the rain screen principle, \r\n and a majority of the rain water will run down the face of the brickwork. \r\n Some moisture in contact with the exterior wythe is absorbed by capillary \r\n action. If wind pressure is applied to the face of the exterior brick \r\n wythe, the moisture will be forced into the brickwork, particularly \r\n at mortar joints or openings. The use of dissimilar materials, the \r\n presence of mortar joints and the variations of workmanship make it \r\n difficult to ensure a fully waterproof exterior wythe. Some moisture \r\n will penetrate the brick wythe and infiltrate into the cavity space. \r\n If the cavity space is at the same air pressure as the exterior as \r\n a result of air flow through vent openings and weep holes, the only \r\n moisture which will reach the cavity space is due to gravity flow \r\n and capillary action. For the rain screen principle to work effectively, \r\n water which penetrates the exterior brick wythe travels down the interior \r\n side, is collected on flashing and transferred to the exterior through \r\n weep holes. \r\n It is not advisable to support the exterior cladding on the floor \r\n assembly with the backing system. If detailed in this manner, moisture \r\n which penetrates the exterior cladding and its flashing has direct \r\n access through the joint at the base of the interior wall to the interior \r\n of the building. Moisture can also flow under the flashing and penetrate \r\n directly into the building. To avoid the chances of moisture penetration \r\n at this location, the exterior cladding support should be lower than \r\n the support of the interior wall. \r\n The rain screen principle relies on the use of intentional openings \r\n in the exterior brick wythe to create pressure equalization in the \r\n cavity. The cavity pressure should be close to the external pressure. \r\n That depends upon the air leakage characteristics of the exterior \r\n brick wythe and that of the air retarder on the backing or the inner \r\n wythe. Sufficient openings in the exterior wythe to balance air pressures \r\n with the exterior of the wall system create the pressure equalized \r\n rain screen wall. The openings are created by the use of weep holes \r\n and vents. Vents near the top of the wall help permit air circulation \r\n through the cavity which helps in drying out the wall system. \r\n For the second stage to work effectively, both pressurization of \r\n the cavity and the provision for an airtight barrier are extremely \r\n important. The extent to which the cavity can be pressurized will \r\n reduce the amount of moisture carried through the exterior wythe by \r\n wind. It also tends to decrease the tendency for moisture that penetrates \r\n due to capillary action to bridge the cavity and contact the backing. \r\n Moisture may actually be transported through the wall system by air \r\n passing through weep holes and vents. Movement of air within the cavity \r\n can transfer moisture to the interior wall and distribute it along \r\n the wall area. Air leakage can then draw this moisture into and through \r\n the backing or inner wythe. Laboratory tests have shown that high \r\n air leakage through the backing or inner wythe can even cause moisture \r\n to climb up and extend the area of wall wetness. The backing or inner \r\n wythe should not permit air leakage to occur, thus vents will not \r\n have to be oversized which could permit excess rain penetration. \r\n \r\n Vapor and Air Retarders \r\n \r\n There has been much confusion in the building industry about the \r\n functions of vapor and air retarders. Vapor retarders are intended \r\n to control transmission of water vapor through building materials. \r\n A vapor retarder always serves as an air retarder. Air retarders limit \r\n the amount of air flow through wall assemblies. An air retarder may \r\n or may not serve as a vapor retarder. It is difficult that either \r\n retarder performs only one function. For example, polyethylene film \r\n is commonly used as a vapor retarder but will also act to resist the \r\n passage of air. Most types of sheathing used as air retarders tend \r\n to permit the passage of water vapor. This can result in a common \r\n problem: many wall systems essentially have a two-stage setup of retarders. \r\n In actual construction, this means that moisture may become trapped \r\n between the air and vapor retarder installations if both are provided \r\n at different locations in the wall assembly. The amount of moisture \r\n and the duration of wetness of certain critical elements may render \r\n the wall design vulnerable to premature deterioration and distress. \r\n Of concern is the potential for corrosion of metal accessories within \r\n the wall system, deterioration of sheathing materials and decrease \r\n in insulation capacity. \r\n Vapor retarders are normally placed on the warm side of insulation \r\n in the wall assembly. Air retarders on the other hand have no distinct \r\n position. If interior wall board or other finishes are used as retarders, \r\n concern arises over punctures for utility services and wall hangings. \r\n Further, the incomplete seal around the perimeter of the wall section, \r\n may render the air retarder ineffective. The use of the air retarder \r\n on the exterior side of the interior wall has additional liabilities. \r\n Inspection for proper installation may be difficult and corrective \r\n repair may be troublesome. When air exfiltration does occur, the exterior \r\n applied air retarder which has some vapor retarder qualities, may \r\n result in condensing water being trapped in the wall. Walls designed \r\n with rigid insulation on the exterior side of the air retarder can \r\n be designed so that the second (partial vapor retarder) barrier is \r\n at a temperature above the dew point so condensation problems can \r\n be eliminated. \r\n Generally, the mass of water which can penetrate into a wall assembly \r\n by air leakage, even through a very small opening, is several times \r\n larger than the amount of water which infiltrates by other means. \r\n When this airborne water condenses, it is unlikely that it can be \r\n removed by vapor transmission or evaporation to the exterior. Drying \r\n out of this water is more likely to occur by air moving through the \r\n wall system under different temperature and humidity conditions. \r\n The location of the air and vapor retarders will depend on the wall \r\n system in question and whether inspection is needed during construction. \r\n Construction not requiring inspection should have the air and vapor \r\n retarders placed on the interior side of the interior wall. Incorrect \r\n installation or faults can easily be repaired or maintained. Where \r\n inspection is employed on a project, the air and vapor retarders can \r\n be installed within the wall system. However, the long term performance \r\n is questionable because these installations are not easily accessible \r\n for repair. \r\n When detailing for both air and vapor retarders in pressure equalized \r\n rain screen walls, the following should be accounted for: \r\n 1. wall openings, \r\n 2. disruption of the retarders due to building services such as utilities, \r\n 3. concealed spaces such as areas above suspended ceilings, behind \r\n heating elements and at junctions of interior walls which connect \r\n with outer portions of the building envelope, \r\n 4. minimize and seal joints of interior finishes, \r\n 5. minimize and seal joints between interior finishes and interruptions \r\n such as interior partitions and wall openings. \r\n \r\n Most difficulties with installing the retarders occur at wall openings. \r\n A variety of materials intersect in one area, which can be complicated. \r\n Damage by subsequent trades may breach or puncture the air and vapor \r\n retarders. Openings must permit field construction tolerances which \r\n must be accommodated by field-fit and sealing of the retarders. Also, \r\n attention to details of the air and vapor retarders can help minimize \r\n direct heat loss and other detrimental effects due to exfiltration \r\n of air movement within the wall system. Figure 3 depicts the possibilities \r\n of exfiltrating air in wall construction. Air can circulate through \r\n spaces between studs and cells of masonry units and exit at leakage \r\n paths to the exterior. Where the components of a building assembly \r\n can be completely sealed to prevent air leakage and the interior finish \r\n material provides the vapor resistance needed, a separate vapor retarder \r\n is not usually required. \r\n \r\n \r\n \r\n Sources of Exfiltrating Air Movement \r\n FIG. 3 \r\n \r\n To provide effective air and vapor retarders, it is necessary to \r\n seal joints in these materials so that continuity is provided. It \r\n is also necessary to seal around the edges of wall openings such as \r\n windows, doors and access for utility services. Caulking or taping \r\n of the joints should be specified. The joints in the retarders should \r\n be detailed and dimensioned with consideration of the need to accommodate \r\n variations in joint dimensions, building deflections and differential \r\n movement of building materials. \r\n If the sealant materials are inaccessible after construction, they \r\n must have qualities which will provide satisfactory performance over \r\n the life of the structure. Even when the sealant material can be repaired \r\n or replaced, the sealant must be suitable for the construction materials \r\n and environmental conditions. Field experience, tests or manufacturers \r\n literature should be used as the basis for selecting sealant materials \r\n for compatibility with the air and vapor retarders selected. \r\n The successful performance of the joint seal over the life of the \r\n structure depends on the ability of the material to adhere to the \r\n surfaces and to deform without tearing, delamination or peeling under \r\n repeated cycles of expansion and contraction. Workmanship is also \r\n very important. Air bubbles in the sealant or air voids between the \r\n sealant and adjacent materials must be avoided. Sealant manufacturers \r\n information should be followed for proper installation. \r\n \r\n Axial and Lateral Loads \r\n \r\n Load application to the exterior brick wythe and the interior wall \r\n and load transfer are based on the type of wall design and its associated \r\n construction. The exterior wythe is treated differently in cavity \r\n wall design from that in veneer wall design. The treatment of the \r\n exterior wythe of a rain screen wall with respect to axial and lateral \r\n loads is no different from that of conventional construction. \r\n The exterior wythe of a veneer wall should not be subjected to any \r\n axial load other than its own weight. Veneers must be designed, detailed, \r\n and constructed so that no axial loads are imposed. The exterior wythe \r\n of a cavity wall can carry vertical loads and still perform as the \r\n exterior cladding in the rain screen wall. The imposed load depends \r\n on the anchorage of floor or roof components to the exterior wythe. \r\n Building codes state that the brick wythe of an anchored veneer wall \r\n does not resist lateral loads and that the backing must be designed \r\n to carry all lateral loads. In cavity wall design, both wythes share \r\n a portion of the lateral loads imposed. In fact, all lateral loads \r\n will initially be resisted by the exterior wythe and then transferred \r\n through the wall system to the building frame. For lateral load distribution \r\n to occur, the exterior wythe must be anchored to the backing or interior \r\n wythe with metal ties in a sufficient number and spacing. Design must \r\n consider lateral load distribution, tie stiffness and deflection of \r\n the wall system. See Technical Notes 21 Series and 28 Series \r\n for the proper design and construction of cavity walls and brick veneer \r\n over wood or steel backings, respectively. \r\n \r\n Thermal Insulation \r\n \r\n All wall components affect the thermal resistance of the assembly \r\n and contribute to the overall R-value. For masonry wall systems, the \r\n insulation provides most of the thermal resistance. The designer should \r\n choose the level of insulation required as part of the total wall \r\n design, considering its location. \r\n The type and location of the insulation has a significant impact \r\n on the design and installation of the air and vapor retarders. The \r\n possible locations for thermal insulation include: 1) in the cavity; \r\n 2) in the interior wall; and 3) on either face of the interior wall. \r\n The general types of insulation used in drainage type walls are rigid \r\n board insulation, fiberglass (batt) insulation or loose fill. \r\n It is important to eliminate any gap between the insulation and the \r\n floor or ceiling. With suspended ceilings or ceilings attached to \r\n the bottom chord of joist construction, the insulation should be continued \r\n above the ceiling to the bottom of structural slabs, not as detailed \r\n in Fig. 4. For the pressure equalization to occur, air and vapor retarders \r\n must also be continued to the floor or roof above the suspended ceilings. \r\n If the air retarder is not continued, the insulation may separate \r\n from the backing wall by air infiltration pressure. Proper abutment \r\n of the edges of the insulation must be considered to hinder air circulation \r\n from the interior of the building. \r\n \r\n \r\n \r\n Leakage Above Suspended Ceilings \r\n FIG. 4 \r\n \r\n Cavity Placement. Rigid board insulation should be used when insulation in the cavity is \r\n desired. In order to be effective, it must be adhered tightly to the \r\n exterior side of the interior wall. If any air is permitted to circulate \r\n behind the insulation, the pressure equalization of the cavity is \r\n weakened as is the insulation capacity. As a result, the method of \r\n securing the insulation is important. Generally, adhesives or mechanical \r\n fasteners are used. Consideration on selecting adhesives includes: \r\n 1) assuring clean surfaces under field conditions; 2) compatibility \r\n of the adhesive with the insulation; 3) long-term effectiveness of \r\n the adhesive; and 4) movement of the wall system. \r\n \r\n Use of dabs of adhesive is not recommended because it creates an \r\n air gap which allows free air movement. Use of a full adhesive bed \r\n is recommended, where the full adhesive bed acts as a vapor barrier. \r\n If a full adhesive bed is not desired, a grid set-up is recommended \r\n because it will compartmentize the air spaces behind the insulation \r\n board and retain the full insulation capacity. \r\n There are a variety of mechanical fasteners available to attach rigid \r\n board insulation to the backing wall. Use of mechanical fasteners \r\n is suggested where uneven surfaces or protrusion of mortar require \r\n bending of the insulation to avoid air-gaps between the insulation \r\n and the interior wall. Mechanical fasteners are more reliable in the \r\n long term than adhesively attached clips. Adhesively attached fasteners \r\n are more convenient, but the same considerations for selecting adhesives \r\n to attach the insulation must be evaluated. Mortar joints should be \r\n cut flush to remove fins or protrusions and provide as smooth a surface \r\n as possible for a tight fit of the insulation to the interior wall. \r\n The insulation must support its own weight and accommodate expected \r\n wall movements. Further, the insulation may be subjected to wind pressures. \r\n These wind pressures must be resisted by the insulation to avoid separation \r\n of the insulation from the interior wall. The choice of mechanical \r\n fasteners, adhesives or a combination of both should take into consideration \r\n the life of the structure, conformance with manufacturers specifications \r\n and possible failure of the fastener or adhesive. Thus, in some cases \r\n a combination of both may be advisable to ensure that costly repairs \r\n are not needed for the life of the structure. \r\n Loose granular fill insulation must not be placed in the cavity. \r\n This placement violates the rain screen principle. However, loose \r\n fill insulation, such as vermiculite and perlite, can be used in the \r\n unobstructed vertical cells of the masonry backing to increase thermal \r\n resistance. \r\n Stud Wall Placement. For stud wall backings, fiberglass (batt) \r\n insulation is placed in the stud cavities. The insulation is usually \r\n slightly larger than the stud depth to provide a friction fit. Stud \r\n spacing should be controlled so that friction will be effective in \r\n keeping the insulation in place. The fiberglass insulation must fill \r\n the entire stud cavity so that air circulation is minimized. If not \r\n completely filled, convection can greatly reduce the thermal resistance \r\n of the interior backing wall. \r\n Interior of Wall Placement. Insulation installed on the interior \r\n of the interior wall is usually limited to masonry backings. It provides \r\n easy installation and is available to inspection of placement. The \r\n insulation can be applied by many means, but the need to support interior \r\n finishes usually requires the use of metal or wood furring. \r\n \r\n Differential Movement \r\n \r\n All building materials change dimension with changes in temperature. \r\n Some building materials change dimension with moisture content. All \r\n materials will deform elastically when subjected to loads. Some materials \r\n with cement matrices will deform plastically (creep) when loaded. \r\n Adequate allowance for deformations of materials and building movements \r\n are critical to the successful performance of the pressure equalized \r\n rain screen wall. Problems can arise if these naturally occurring \r\n movements are not recognized and accommodated for in initial design. \r\n The air and vapor retarders must not be disrupted by building movements, \r\n whether it be material generated or the building as a whole. \r\n Sealing of movement joints is required to prevent the passage of \r\n water and air without restricting differential movement. The sealant \r\n acts as the primary resistance to the passage of water through joints \r\n in exterior elements. A backing material and, perhaps, a filler may \r\n be needed for large movement joints. \r\n Discussion of building movements is beyond the scope of this Technical \r\n Notes . The reader is directed to Technical Notes 18 Series \r\n for information on accommodating material and building movements, \r\n such as the building frame, exterior cladding and interior wall systems. \r\n Recommendations for other materials should be reviewed. \r\n \r\n PRESSURE EQUALIZED RAIN SCREEN DESIGN PARAMETERS \r\n \r\n The pressure equalized rain screen wall, whether a brick veneer or \r\n a cavity wall system, will be subject to both axial and lateral loads. \r\n In the design of these innovative wall systems, imposed loads must \r\n be taken into account for the rain screen wall to perform as intended. \r\n Other environmental loads, such as moisture leakage, thermal and air \r\n retarder performance, must also be considered. There are many parameters \r\n which affect the pressure equalized rain screen principle. These parameters \r\n include: 1) rate of applied wind load; 2) magnitude of applied wind \r\n load; 3) cavity volume; 4) stiffness of the interior wall and the \r\n exterior cladding; 5) compartmentation of the cavity; and 6) leakage \r\n areas of the air retarder and the exterior cladding. Many of these \r\n factors are interrelated. \r\n \r\n Wind Loads \r\n \r\n An advantage of the pressure equalized rain screen wall, in theory, \r\n is that no wind load should be imposed on the exterior cladding. However, \r\n wind is dynamic and variable so that the pressures applied to the \r\n wall are constantly changing. An ideal rain screen wall would pressure \r\n equalize instantly. In fact there is a time lag between the imposed \r\n wind load and pressure equalization in the cavity. As a result a pressure \r\n difference does occur across the exterior cladding. \r\n This pressure is normally positive, a driving force pushing air into \r\n the wall. However, the cavity pressure can exceed the positive wind \r\n pressure under gusting wind conditions. This situation occurs after \r\n the cavity pressure increases to match that of a high wind, and the \r\n wind suddenly decreases. Until pressure equalization occurs, the cavity \r\n pressure will exceed the exterior wind pressure which creates a negative \r\n load on the cladding. This negative loading will tend to force water \r\n out of openings in the exterior cladding, reducing the likelihood \r\n of further moisture penetration. Under the rain screen principle, \r\n wind loads on the exterior brick wythe may actually be reduced due \r\n to pressure equalization of the cavity space. However, the entire \r\n design wind load should be applied to the exterior cladding and the \r\n backing. \r\n \r\n Pressure Differences and Distribution \r\n \r\n Pressure differences are encountered in buildings from two main sources. \r\n The first is commonly referred to as stack effect, which is created \r\n by temperature differences between the exterior and interior of the \r\n building. The second is the wind forces that are imposed on the building \r\n envelope. The net pressure difference across a wall system at the \r\n top and sides may be a combination of both and is not the same for \r\n all parts of the building envelope. \r\n The stack effect which occurs mainly during the heating season results \r\n from warmer inside air rising as a result of a lower density than \r\n cooler outside air. This difference in density creates an outward \r\n positive pressure at the top of a building, while exerting negative \r\n pressure at the wall base. Thus, air will tend to infiltrate at the \r\n lower levels of the building and exfiltrate at the upper levels. \r\n Wind causes air infiltration on the windward side of buildings and \r\n exfiltration on the leeward side and also on the sides parallel to \r\n the wind direction. A flat roof will experience exfiltration because \r\n of negative uplift pressure caused by wind. Since wind velocity increases \r\n with height, the difference in pressure across the building envelope \r\n increases with height. \r\n Pressure distribution on the windward facade varies from a maximum \r\n at the center and decreases towards the corners of the building. Suction \r\n pressures on the leeward wall vary from a maximum at the corners of \r\n the building, diminishing towards the center. The pressure on the \r\n side walls parallel to the wind direction is normally negative, but \r\n may change rapidly to positive pressure as the wind changes directions. \r\n This is usually why wind pressures are normally higher at the top \r\n and corners of the building envelope. \r\n \r\n The rain screen wall minimizes the air pressure \r\n differences across the exterior brick wythe by transferring the pressure \r\n to the cavity space, see Fig. 1. Under the imposed wind load (P e ), air flows into the cavity causing the \r\n cavity pressure (P c ) to increase until P c = P e and P c = \r\n 0. When the entire wind load is imposed on the interior wall, pressure \r\n equalization will occur. The veneer backing or the interior cavity \r\n wall wythe is thus designed for the entire wind load. \r\n \r\n Cavity Volume \r\n \r\n When positive pressure is applied to the exterior cladding, movement \r\n of air into the cavity causes the pressure in the cavity to increase \r\n to match the external pressure applied. The volume of air required \r\n to achieve pressure equalization is dependent on the volume of the \r\n cavity. The rate at which pressure equalization occurs is dependent \r\n on the rate at which air can enter the cavity. Thus, as the cavity \r\n volume increases, the vent openings in the exterior brick wythe must \r\n be increased in order to permit more rapid pressure equalization. \r\n The driving force causing air to enter the cavity is the pressure \r\n difference across the exterior cladding. As air enters the cavity, \r\n this pressure difference decreases. The flow rate is proportional \r\n to the pressure difference, and as air flows into the cavity, the \r\n flow rate decreases. \r\n Both the exterior cladding and air retarder applied to the interior \r\n wall will deflect under applied loads. Stiffness of these elements \r\n will influence the volume of the cavity. Since these deflections also \r\n vary as the pressure differences vary, it becomes clear that this \r\n situation is very complex. \r\n \r\n Leakage of the Exterior Cladding and the Air Retarder \r\n \r\n The relative airtightness of the exterior cladding with respect to \r\n that of the air retarder applied to the interior wall is paramount \r\n for the cavity to pressure equalize with the exterior wind pressure. \r\n If the two layers have similar air leakage characteristics, each layer \r\n will transmit the same volume of air, and the pressure differences \r\n will not change. If the interior wall is made more airtight, a greater \r\n pressure difference will occur across it than that across the exterior \r\n cladding. In the ideal case, the air retarder would be completely \r\n airtight, and the pressure difference across the exterior cladding \r\n would be negligible. However, this is generally not the case. \r\n \r\n The effectiveness of the rain screen wall \r\n is decreased as greater amounts of air are permitted to penetrate \r\n through the air retarder. The Architectural Aluminum Manufacturers \r\n Association specifies that, for laboratory tests, air leakage through \r\n a curtain wall should not exceed 0.06 cfm/ft 2 \r\n (0.0003 m 3 /s/m 2 ) for a pressure difference equivalent to a 25 mph (11 m/s) wind. This \r\n value for air retarders is currently being considered in ASTM Committee \r\n E 6. However, in Canada, the acceptable rate is one-third of that \r\n currently being suggested in ASTM. It seems prudent to use the lower \r\n value for air leakage through the air retarder. \r\n \r\n Compartmentation \r\n \r\n The wind pressure flowing around a building creates a distribution \r\n of positive and negative pressures over the building exterior cladding \r\n as shown in Fig. 5. If the cavity of the rain screen wall is continuous, \r\n horizontally or vertically, lateral flow of air in the cavity will \r\n occur. \r\n If air is permitted to flow laterally in the cavity, pressure equalization \r\n will not occur. Moisture penetration into the wall assembly may not \r\n be reduced. \r\n \r\n To prevent lateral airflow, the cavity must \r\n be compartmented. The size of the compartments should be based on \r\n the pressure differences across the exterior cladding. The corners \r\n and tops of buildings experience the greatest pressure differences; \r\n hence, the compartments located in these areas should be small. Where \r\n pressure differences are small, such as the center of the exterior \r\n cladding, the compartments can be larger. Many researchers suggest \r\n that these compartments have closures no more than 4 ft (1.2 m) apart \r\n at the sides and top of the building in a 20 ft (6 m) wide perimeter \r\n zone, see Fig. 6. Compartment closures should be within this recommendation \r\n for the sides and top of the building. Based on the design wind pressure \r\n of the wall area in question, compartment dimensions outside the 20 \r\n ft (6 m) zone of the tops and corners of the building can be increased. \r\n For a design wind pressure less than 15 psf (718 Pa), compartment \r\n closures should be provided for every 400 ft 2 \r\n (37 m 2 ) \r\n of wall area. When the design wind pressure is between 15 psf (718 \r\n Pa) and 25 psf (1200 Pa), the compartment closures should be decreased \r\n to 250 ft 2 (23 m 2 ) of area. When the \r\n design wind pressure is greater than 25 psf (1200 Pa), the compartment \r\n closures should have a maximum area of 100 ft 2 (9 m 2 ). At the minimum, the cavity \r\n must be closed at all corners and at the roof to prevent air from \r\n the windward side of the building laterally flowing to the adjacent \r\n sides, as shown in Fig. 5. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Moisture Movement Caused by Wind \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Compartmentation of Rain Screen Walls \r\n FIG. 6 \r\n \r\n Research conducted by Canada Mortgage and Housing Corporation used \r\n wind tunnel testing to determine the effects of compartmentation in \r\n the cavity. One significant result of this testing was that the compartment \r\n closures experienced at least two times the applied wind load. This \r\n research concluded that compartment closures must be designed for \r\n high wind pressures and must be completely sealed to prevent lateral \r\n airflow from one compartment to the next. \r\n \r\n Exterior Cladding Openings \r\n \r\n To provide pressure equalization in the rain screen wall, there must \r\n be a series of openings to connect the cavity to the exterior of the \r\n wall system. The openings should be positioned at the top and bottom \r\n of each compartment. All openings at the top and bottom should be \r\n placed at the same height, respectively, to avoid airflow loops in \r\n the cavity. \r\n There are no definitive guidelines for the required amount of openings \r\n for each compartment. The area of openings depends on the airtightness \r\n of other components of the cavity, e.g., the air retarder system and \r\n the cavity closures. If completely sealed compartment closures are \r\n used, a 10:1 ratio for cladding air leakage to air retarder leakage \r\n is recommended. Most often, the cavity closures will not form an airtight \r\n seal of the individual compartments. To account for this the required \r\n opening area should be larger. Some studies suggest a ratio of 25 \r\n to 40 times more air flow volume through the openings in the exterior \r\n brick wythe than air leakage through the interior wall. Therefore, \r\n the tighter the compartment, the less the area of openings in the \r\n exterior cladding required for pressure equalization of the cavity. \r\n To obtain the airtightness value of the interior wall construction, \r\n testing of a mock-up wall compartment may be required since little \r\n information on the range of air tightness of various field-applied \r\n air retarder components is available. After having evaluated the air \r\n tightness of the interior wall, the openings in the exterior cladding \r\n should be established to fit the recommended ratio. \r\n The following recommendations should provide sufficient venting to \r\n achieve pressure equalization for the rain screen wall. Vents are \r\n installed at the top and bottom of each compartment. Open head joints \r\n should be spaced at a maximum of 24 in. (600 mm) o.c. horizontally \r\n in the exterior brick wythe. If clear, round openings are used, they \r\n should be at least 3/8 in. (10 mm) inside diameter, and the spacing \r\n should be reduced to 16 in. (400 mm) o.c. horizontally. Open head \r\n joints may be positioned at flashing locations in the exterior brick \r\n wythe and serve as weep holes. A minimum of two vents at both the \r\n top and bottom should be provided for each individual compartment. \r\n The suggested minimum cavity width is 2 in. (50 mm). If the cavity \r\n space width is greater than 2 in. (50 mm), open head joints should \r\n be used as vents. Vents should not be positioned at corners. Water \r\n drainage provisions in the wall assembly should be evaluated carefully \r\n to avoid placing vents at high flow areas such as sills and heads \r\n of openings in the wall system. It is imperative that the cavity have \r\n no blockage due to mortar bridging or mortar droppings that can collect \r\n at the bottom of the cavity closures in each compartment, thus blocking \r\n the vent openings. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes describes the pressure equalized rain \r\n screen principle as it applies to conventional brick veneer and cavity \r\n wall systems. This innovative wall design has been used extensively \r\n in Canada and Europe for many years. Pressure equalization across \r\n the exterior wythe of drainage type walls is the main emphasis of \r\n the rain screen principle. Design recommendations that cover the prominent \r\n aspects of the pressure equalized rain screen principle to minimize \r\n rain penetration through the exterior walls are described. \r\n The information and suggestions contained in this Technical Notes \r\n are based on available data and the experience of the engineering \r\n staff of the Brick Institute of America. The information contained \r\n herein must be used in conjunction with good technical judgment and \r\n a basic understanding of the properties of brick masonry. Final decisions \r\n on the use of the information contained in this Technical Notes are \r\n not within the purview of the Brick Institute of America and must \r\n rest with the project architect, engineer and owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Anderson, \r\n J.M. and Gille, J.R., \"Rain Screen Cladding -A Guide to Design Principles \r\n and Practice,\" Construction Industry Research and Information \r\n Association - Building and Structural Design Report , Butterworths, \r\n London, England, 1988. \r\n 2. \"A Study \r\n of The Rainscreen Concept Applied to Cladding Systems on Wood Frame \r\n Walls,\" Canada Mortgage and Housing Corporation, Report No. 39108.0R1 , \r\n Ottawa, Ontario, Canada, August 1990. \r\n 3. Drysdale, \r\n R.G. and Suter, G.T., \"Exterior Wall Construction in High-Rise Buildings \r\n -Brick Veneer on Concrete Masonry or Steel Stud Wall Systems,\" Canada \r\n Mortgage and Housing Corporation, Report NHA 5450, Ottawa, Ontario, \r\n Canada, 1991. \r\n 4. Fornoville, \r\n L., \"Rain Resistant Masonry Construction,\" Third North American \r\n Masonry Conference , Matthys, J.H. and Borchelt, J.G., Eds., \r\n University of Texas at Arlington, Arlington, Texas, 1985. \r\n 5. Piper, \r\n R.S. and Kenney, R.J., \"Brick Veneer Walls -Proposed Details to \r\n Address Common Air and Water Penetration Problems,\" Masonry: \r\n Design and Construction, Problems and Repair, ASTM STP 1180 , \r\n Melander, J.M. and Lauersdorf, L.R., Eds., American Society for \r\n Testing and Materials, Philadelphia, PA, 1993. \r\n 6. Rousseau, \r\n M.Z., \"Facts and Fiction of Rain Screen Walls,\" National Research \r\n Council of Canada, Construction Canada , Vol. 32, Number 2, \r\n March/April 1990. \r\n 7. Ruggiero, \r\n S.S. and Myers, J.C., \"Design and Construction of Watertight Exterior \r\n Building Walls,\" Water in Exterior Building Walls: Problems and \r\n Solutions, ASTM STP 1107 , Schwartz, T.A., Ed., American Society \r\n for Testing and Materials, Philadelphia, PA, 1991. \r\n 8. \"Structural \r\n Requirements for Air Barriers,\" Canada Mortgage and Housing Corporation, \r\n Report No. 30133.0RI , Ottawa, Ontario, Canada, August 1991. \r\n 9. Williams, \r\n M.F. and Williams, B.L., \"Water Intrusion in Barrier and Cavity/Rain \r\n Screen Walls,\" Water in Exterior Building Walls: Problems and \r\n Solutions, ASTM STP 1107 , Schwartz, T.A., Ed., American Society \r\n for Testing and Materials, Philadelphia, PA, 1991. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60095,"ResultID":176327,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 28 - Anchored Brick Veneer, \r\n Wood Frame Construction \r\n August 1991 \r\n \r\n Abstract: This Technical Notes deals with the prescriptive \r\n design of brick veneer with wood frame construction in buildings limited \r\n to three stories in height in new construction. The properties of \r\n the brick veneer/wood stud system are described, which lead to design \r\n considerations. Selection of materials, construction details, and \r\n workmanship techniques are included. The minimum requirements given \r\n have proven successful for this type of wall construction. \r\n Key Words: brick, flashing, foundations, \r\n lintels, ties, veneer, weepholes, wood frame. \r\n INTRODUCTION \r\n Anchored brick veneer construction consists \r\n of a nominal 3 in. (75 mm) or 4 in. (100 mm) thick exterior brick \r\n wythe anchored to a backing system with metal ties in such a way that \r\n a clear air space is provided between the veneer and the backing system. \r\n The backing system may be wood frame, steel frame, concrete or masonry. \r\n By definition, a veneer wall is a wall having a facing of masonry \r\n units, or other weather-resisting, noncombustible materials, securely \r\n attached to the backing, but not so bonded as to intentionally exert \r\n common action under load. The brick veneer is designed to carry loads \r\n due to its own weight, no other loads are to be resisted by the veneer. \r\n For many years brick veneer construction \r\n was limited principally to wood frame houses. It is now being used \r\n on low-rise commercial and institutional construction and is used \r\n frequently for high-rise buildings, especially with concrete masonry \r\n or steel stud backing systems. This Technical Notes discusses \r\n the prescriptive design of brick veneer on wood frame buildings three \r\n stories or less in height. Other Technical Notes in this series \r\n cover brick veneer with different backing systems. \r\n The minimum requirements given in this Technical \r\n Notes are based on successful past performance of brick veneer \r\n anchored to wood frame systems. The proper design, detailing and construction \r\n of anchored brick veneer walls ensure that these walls function as \r\n complete systems. It is important to understand that the failure of \r\n any part of the system, whether in design or construction, can result \r\n in improper performance of the entire system. Satisfactory performance \r\n of brick veneer wood frame systems is achieved with: (1) an adequate \r\n foundation, (2) a sufficiently strong, rigid, well-braced backing \r\n system, (3) proper attachment of the veneer to the backing system, \r\n (4) proper detailing, (5) the use of proper materials, and (6) good \r\n workmanship in construction. \r\n PROPERTIES OF BRICK VENEER \r\n Strength \r\n Factors that affect the strength of brick \r\n veneer are the type of brick and mortar used, the span of the veneer \r\n and the backing, the stiffness of the backing, and the tie system. \r\n Although the brick veneer is not designed to carry lateral load, it \r\n does carry a proportionate share. In fact, due to the relatively low \r\n stiffnesses normally achieved in wood frame construction, the brick \r\n veneer usually carries the majority of any lateral load. \r\n Support \r\n With wood framing the brick veneer must \r\n carry its own weight and transfer this weight to a noncombustible \r\n foundation. The weight of brick veneer should not be supported by \r\n wood framing or other types of wood construction. Table 1 contains \r\n empirical height limitations for brick veneer and wood frame construction. \r\n These limits, which are found in model building codes, are imposed \r\n because of the differences in relative stiffnesses of the brick veneer \r\n and the wood frame. Further, differences in movement resulting from \r\n wood shrinkage and brick expansion are controlled by these limits. \r\n \r\n \r\n \r\n Fire Resistance \r\n Brick veneer wall assemblies can attain \r\n fire ratings of up to 2 hr. Figure 1 shows a brick veneer wall assembly \r\n with a 2 hr fire rating. The combustible wood stud must be protected \r\n from fire on each side by noncombustible materials which meet the \r\n required fire rating. A 4 in. (100 mm) nominal brick wythe provides \r\n a 1 hr fire rating. \r\n \r\n \r\n \r\n \r\n 2 Hr Fire Rated Brick Veneer Wall Assembly \r\n FIG. 1 \r\n \r\n Moisture Resistance \r\n Brick veneer wall assemblies are classified \r\n as drainage type walls. Walls of this type provide good resistance \r\n to rain penetration. It is essential to maintain the clear air space \r\n between the brick veneer and the backing to ensure proper drainage. \r\n Flashing and weepholes work with the air space to provide moisture \r\n penetration resistance. Refer to Technical Notes 7 Series for \r\n more information. Brick veneer with wood frame backing has historically \r\n been built with a 1 in. (25 mm) minimum air space. The protection \r\n provided by roof overhangs and the relatively low wall heights aid \r\n in reducing water penetration. \r\n Resistance to Heat Transmission \r\n Brick veneer wall assemblies provide resistance \r\n to the transmission of heat and capacity insulation. The overall coefficient \r\n of heat transmission, U-value, of these walls can be easily calculated \r\n using the procedure given in Technical Notes 4 \r\n or the ASHRAE Handbook, Fundamentals Volume. The mass of the \r\n brick veneer provides capacity insulation. It effectively lowers and \r\n delays the peak heating and cooling loads. The overall U-value obtained \r\n for the wall assembly can be adjusted by the capacity insulation correction \r\n factor (M factor) given in Technical Notes 4B , \r\n Fig. 1. This adjustment of the overall U-value will help the designer \r\n to more accurately predict the performance of the building envelope. \r\n The actual performance of brick masonry buildings shows that this \r\n adjustment is very conservative, but it is an improvement over the \r\n steady-state assumptions normally used in calculating heat flow. \r\n Acoustical Properties \r\n Brick veneer wall assemblies reduce sound \r\n transmission by several means. The mass of the veneer reduces sound \r\n transmission by absorbing the energy of the sound vibrations. The \r\n discontinuity between the brick veneer and the wood backing prevents \r\n vibrations of the exterior brick wythe from directly vibrating the \r\n rest of the wall assembly, thereby retarding sound transmission to \r\n the interior. Further, a high percentage of the sound is reflected \r\n by the brick wythe. \r\n Although there are no specific data available \r\n on the sound transmission characteristics of brick veneer wall assemblies, \r\n the brick veneer wall system shown in Fig. 1 has an estimated Sound \r\n Transmission Class (STC) in excess of 45. See Technical Notes 5A \r\n for more information on the STC. \r\n DESIGN AND DETAILS \r\n Foundations for Brick Veneer \r\n Brick veneer with wood frame backing must \r\n transfer the weight of the veneer through the veneer to the foundation. \r\n Typical foundation details for brick veneer are shown in Fig. 2. It \r\n is recommended that the foundation or foundation wall supporting the \r\n brick veneer be at least equal to the total thickness of the brick \r\n veneer wall assembly. Many building codes permit a nominal 8 in. (200 \r\n mm) foundation wall under single-family dwellings constructed of brick \r\n veneer, provided the top of the foundation wall is corbeled as shown \r\n in Fig. 2(c). The total projection of the corbel should not exceed \r\n 2 in. (50 mm) with individual courses projecting beyond the course \r\n below not more than one-third the thickness of the unit nor one-half \r\n the height of the unit. The top course of the corbel should not be \r\n higher than the bottom of the floor joist and shall be a full header \r\n course. \r\n \r\n \r\n \r\n \r\n Typical Foundation Detail \r\n FIG. 2a \r\n \r\n \r\n \r\n \r\n \r\n Typical Foundation Detail \r\n FIG. 2b \r\n \r\n \r\n \r\n \r\n \r\n Typical Foundation Detail \r\n FIG. 2c \r\n \r\n \r\n \r\n \r\n \r\n Typical Foundation Detail \r\n FIG. 2d \r\n \r\n Foundations must extend beneath the frost \r\n line as required by the local building code. Design of the foundation \r\n should consider differential settlement and the effect of concentrated \r\n loads such as those from columns or fireplaces. Appropriate drainage \r\n must be provided in order to maintain soil bearing capacity and prevent \r\n washout. \r\n Brick walls which enclose crawl spaces must \r\n have openings to provide adequate ventilation. Openings should be \r\n located to achieve cross ventilation. \r\n Ties \r\n Ties typically used with wood framing are \r\n shown in Fig. 3. There should be one tie for every 2 2/3 sq. ft. (0.25 \r\n m 2 ) of wall area \r\n with a maximum spacing of 24 in. (600 mm) o.c. in either direction. \r\n The nail attaching a corrugated tie must be located within 5/8 in. \r\n (16 mm) of the bend in the tie. The best location of the nail is at \r\n the bend in the corrugated tie, and the bend should be 90 o . \r\n Wire ties must be embedded at least 5/8 \r\n in. (16 mm) into the bed joint from the air space and must have at \r\n least 5/8 in. (16 mm) cover of mortar to the exposed face. Corrugated \r\n ties must penetrate to at least half the veneer thickness and have \r\n at least 5/8 in. (16 mm) cover. Ties should be placed so that the \r\n portion within the bed joint is completely surrounded by the mortar. \r\n \r\n \r\n \r\n \r\n Unit Ties \r\n FIG. 3 \r\n \r\n Flashing and Weepholes \r\n Flashing and weepholes should be located \r\n above and as near to grade as possible at the bottom of the wall, \r\n above all openings, and beneath sills. Weepholes must be located in \r\n the head joints immediately above all flashing. Clear, open weepholes \r\n should be spaced no more than 24 in. (600 mm) o.c. Weepholes formed \r\n with wick materials or with tubes should be spaced at a maximum of \r\n 16 in. (400 mm) o.c. If the veneer continues below the flashing at \r\n the base of the wall, the space between the veneer and the backing \r\n should be grouted to the height of the flashing. Flashing should be \r\n securely fastened to the backing system and extend through the face \r\n of the brick veneer. The flashing should be turned up at least 8 in. \r\n (200 mm). Typical flashing details are shown in Figs. 2, 4 and 5. \r\n Flashing should be carefully installed to prevent punctures or tears. \r\n Where several pieces of flashing are required to flash a section of \r\n the veneer, the ends of the flashing should be lapped a minimum of \r\n 6 in. (150 mm) and the joints properly sealed. Where the flashing \r\n is not continuous, such as over and under openings in the wall, the \r\n ends of the flashing should be turned up into the head joint at least \r\n 2 in. (50 mm) to form a dam. \r\n \r\n \r\n \r\n \r\n Lintel Details \r\n FIG. 4 \r\n \r\n Lintels, Sills and Jambs \r\n Brick veneer backed by wood frame must always \r\n be supported by lintels over openings unless the masonry is self-supporting. \r\n Lintel design information may be found in Technical Notes 17B \r\n and 31B . Loose steel, stone or precast lintels should bear at least \r\n 4 in. (100 mm) at each jamb. All lintels should have space at the \r\n end of the lintel to allow for expansion. The clear span for 1/4 in. \r\n (6.3 mm) thick steel angles varies between 5 ft (1.5 m) and a maximum \r\n of 8 ft (2.4 m), depending on the size of the angle selected. Steel \r\n lintels with spans greater than 8 ft (2.4 m) may require lateral bracing \r\n for stability. The maximum clear span may be restricted by the fire \r\n protection requirements of some building codes. Concrete, cast stone \r\n and stone lintels must be appropriately sized to carry the weight \r\n of the veneer. \r\n Reinforced brick lintels are also a viable \r\n option. Some of the advantages of reinforced brick lintels are: more \r\n efficient use of materials; built-in fireproofing; elimination of \r\n differential movement which may occur with steel lintels and brick \r\n veneer; and no required painting or other maintenance. Typical residential \r\n construction details for a lintel, sill and jamb using wood stud backing \r\n are shown in Figs. 4 and 5. \r\n \r\n \r\n \r\n \r\n Jamb and Sill Details \r\n FIG. 5 \r\n \r\n Eave Details \r\n A typical residential eave detail is shown \r\n in Fig. 6. This detail is suggested for the area at the top of the \r\n veneer. The air space between the top of the brick veneer and wood \r\n framing is necessary to accommodate movement. Larger overhangs and \r\n gutters are helpful to keep water from contacting the wall below. \r\n \r\n \r\n \r\n \r\n Eave Detail \r\n FIG. 6 \r\n \r\n Movement Provisions \r\n Design provisions for movement which include \r\n bond breaks, expansion joints, and joint reinforcement are not usually \r\n required in residential and low-rise brick veneer construction. However, \r\n they may be required in specific situations and the designer should \r\n analyze the project to determine such need. \r\n Bond Breaks. Significant differential \r\n foundation settlement and horizontal movement may cause cracking in \r\n walls rigidly attached to the foundation. Bond breaks will help to \r\n relieve the stresses caused by these movements between the wall and \r\n the supporting foundation. Flashing at the base of the wall between \r\n the veneer and the foundation will provide sufficient break in the \r\n bond. \r\n Expansion Joints. Expansion joints \r\n to allow for horizontal movement may be required in brick veneer when \r\n there are long walls, walls with returns or large openings. The placement \r\n of expansion joints and the materials used should be in accordance \r\n with the information given in Technical Notes 18 Series. \r\n Horizontal Joint Reinforcement \r\n Masonry materials subject to shrinkage stresses, \r\n such as concrete masonry, require horizontal joint reinforcement for \r\n control of cracking from such movement. Brick is not subject \r\n to shrinkage, therefore horizontal joint reinforcement is never required \r\n in brick masonry for this purpose. It may be beneficial to use limited \r\n amounts of horizontal joint reinforcement in brick veneer for added \r\n strength at the corners of openings and at locations where running \r\n bond in the masonry is not maintained. \r\n Horizontal joint reinforcement should be \r\n used to add integrity to veneer constructed in locations with intermediate \r\n and higher seismic activity or when the units are laid in stack bond. \r\n It may be either single or double wire joint reinforcement. The wire \r\n should engage the veneer ties as shown in Fig. 3(e) in seismically \r\n active areas. When using horizontal joint reinforcement, it must \r\n be discontinuous at all movement joints. \r\n Sealant Joints \r\n Exterior joints at the perimeter of exterior \r\n door and window frames to be filled with sealant should be formed \r\n by the adjacent materials or be a reservoir type joint. The joint \r\n should be no less than 1/4 in. (6.3 mm) nor more than 1/2 in. (12.7 \r\n mm) wide and 1/4 in. (6.3 mm) deep. If wider joints are required, \r\n the sealant depth should be one-half of the joint width. A compressible \r\n backer rod or sealant bond break tape must be used. Fillet joints \r\n are not recommended, but if used, should be at least 1/2 in. (12.7 \r\n mm) across the diagonal. Fig. 7 shows typical sealant joints. These \r\n joints should be solidly filled with an elastic sealant forced into \r\n place with a pressure gun. All joints should be properly prepared \r\n before placing sealants. Appropriate primers should be applied as \r\n necessary. Expansion joints must be clear of all material for the \r\n thickness of the veneer wythe and closed with a backer rod and sealant. \r\n \r\n \r\n \r\n \r\n Sealant Joints \r\n FIG. 7 \r\n \r\n SELECTION OF MATERIALS \r\n Brick \r\n Brick should conform to ASTM C 62, C 216 \r\n or C 652 for Building Brick, Facing Brick and Hollow Brick, respectively. \r\n Grade SW is required where high and uniform resistance to damage caused \r\n by cyclic freezing is desired and where the brick may be frozen when \r\n saturated with water. Grade MW may be used where moderate resistance \r\n to damage caused by cyclic freezing is permissible or where the brick \r\n may be damp, but not saturated, when freezing occurs. \r\n The brick selected should have an average \r\n initial rate of absorption (suction) of not more than 30 grams per \r\n 30 in. 2 (1.5 kg/m 2 ) per minute at the time of laying. Units having average initial rates \r\n of absorption exceeding this value may be wetted immediately before \r\n they are laid. Alternately, the units may be wetted thoroughly 3 to \r\n 24 hours prior to their use so as to allow moisture to become distributed \r\n throughout the unit. With either method the units should be surface \r\n dry when laid. \r\n The use of salvaged brick is not recommended. \r\n In general, masonry constructed with salvaged brick contains some \r\n weaker and less durable units than masonry constructed with new brick. \r\n Salvaged brick and the reasons against its use are discussed in detail \r\n in Technical Notes 15 . \r\n Mortars \r\n Mortar materials should comply with the \r\n requirements of ASTM C 270 Standard Specification for Mortar for Unit \r\n Masonry. Two types of cementitious materials are permitted: portland \r\n cement-lime and masonry cement. portland cement-lime mortars made \r\n with non-air-entrained materials have greater strength than those \r\n made with air-entrained materials and masonry cement. Proprietary \r\n mortar mixes, masonry cements, are widely used because of their convenience \r\n and good workability. Masonry cements usually contain portland cement, \r\n ground limestone and additives which provide workability, water retentivity \r\n and air entrainment. See Technical Notes 8 \r\n for information on both portland cement-lime mortars and masonry cement \r\n mortars. \r\n Type N mortar is suitable for most brick \r\n veneer although Type S or Type M may be used. Type S mortar is recommended \r\n where a high degree of flexural resistance is required and may be \r\n required in areas of high seismic activity. Type M is recommended \r\n where the brick veneer is in contact with earth. For further information \r\n on the selection of mortar see Technical Notes 8B . \r\n Ties \r\n Brick veneer with wood frame backing is \r\n supported on the foundation with lateral support provided by the ties \r\n and backing system. The ties must be capable of resisting tension \r\n and compression resulting from forces perpendicular to the plane of \r\n the wall. More information on wall ties is found in Technical Notes \r\n 44B . \r\n Corrugated steel ties, at least 22 gage, \r\n 7/8 in. (22 mm) wide, 6 in. (150 mm) long, as shown in Fig. 3(d) have \r\n historically been used to attach brick veneer to wood frame backing. \r\n However, corrugated metal ties are more susceptible to corrosion than \r\n wire ties. Adjustable ties provide better load transfer and permit \r\n differential movement in taller structures. Wire for such ties is \r\n either wire gage W1.7, 9 gage, or wire gage W2.8, 3/16 in. (4.8 mm) \r\n diameter. Wire ties should be fabricated from wire conforming to ASTM \r\n A 82 Specification for Steel Wire, Plain, for Concrete Reinforcement. \r\n Plate portions of adjustable ties are normally 14 gage in thickness. \r\n Steel used to fabricate plate portions and corrugated ties should \r\n conform to ASTM A 366 Standard Specification for Steel, Carbon, Cold-Rolled \r\n Sheet, Commercial Quality. \r\n All tie components must be corrosion resistant. \r\n Zinc coating on steel must be at least 1.5 oz per square foot (458 \r\n g/m 2 ). This corresponds \r\n to ASTM A 153 Standard Specification for Zinc Coating (Hot-Dip) on \r\n Iron and Steel Hardware, Class B-2. \r\n Ties are usually fastened to the wood frame \r\n with corrosion-resistant nails that penetrate the sheathing and are \r\n driven a minimum of 1 1/2 in. (38 mm) into the studs. \r\n Flashing and Weepholes \r\n There are many types of flashing available \r\n which are suitable for use in brick veneer walls. Sheet metals, plastics, \r\n laminates or combinations of these have been used successfully. Plastic \r\n flashing should be at least 30 mil thick. Asphalt impregnated felt \r\n (building paper) or an air-infiltration barrier is not acceptable \r\n for use as flashing. These materials serve other purposes in the wall \r\n assembly. Building paper is applied as a moisture barrier to the sheathing. \r\n Air-infiltration barriers function as their name implies and may also \r\n serve as a moisture barrier. \r\n Selection of flashing is often determined \r\n by cost; however, it is recommended that only superior materials be \r\n used, as replacement in the event of failure is exceedingly expensive. \r\n Weepholes can be made in several ways. Some \r\n of the most common ways are leaving head joints open, using removable \r\n oiled ropes or rods, using plastic or metal tubes, or using rope wicks. \r\n There are also plastic or metal vents which are installed in lieu \r\n of mortar in a head joint. Clear openings without obstructions produce \r\n the best weepholes. For further discussion on flashing and weepholes \r\n see Technical Notes 7A . \r\n Horizontal Joint Reinforcement \r\n Horizontal joint reinforcement should be \r\n fabricated from wire conforming to ASTM A 82. It should have a corrosion-resistant \r\n coating which conforms to ASTM A 153, Class B-2. \r\n Lintel Materials \r\n Lintels may be reinforced brick masonry, \r\n reinforced concrete, stone or steel angles. Reinforcement for reinforced \r\n brick masonry lintels should be steel bars manufactured in accordance \r\n with ASTM A 615, A 616 or A 617, Grades 40, 50, or 60 and should be \r\n at least No. 3 bar size. Joint reinforcement can also be used in reinforced \r\n brick masonry lintels. \r\n Steel for lintels should conform to ASTM \r\n A 36 Standard Specification for Structural Steel. Steel angle lintels \r\n should be at least 1/4 in. (6.3 mm) thick with a horizontal leg of \r\n at least 3 1/2 in. (89 mm) for use with nominal 4 in. (100 mm) thick \r\n brick veneer, and 3 in. (75 mm) for use with nominal 3 in. (75 mm) \r\n thick brick veneer. Steel lintels should be painted before installation. \r\n Sealants \r\n There are numerous types of sealants available \r\n that are suitable for use with brick veneer. The material selected \r\n should be flexible and durable. Superior sealants may have a higher \r\n initial cost, but their high flexibility and increased durability \r\n result in savings of maintenance costs due to the reduced frequency \r\n of reapplication. Good grades of polysulfide, butyl or silicone rubber \r\n sealants are recommended. Oil-based caulking compounds are not \r\n recommended since most lack the desired flexibility and durability, \r\n see Technical Notes 7A . Regardless \r\n of the type of sealant chosen, proper primers and backer rods must \r\n be selected. Follow the recommendations of the sealant manufacturer. \r\n CONSTRUCTION \r\n Protection of Materials \r\n Masonry. Prior to and during construction, \r\n all materials should be stored off of the ground to prevent contamination \r\n by mud, dust or other materials likely to cause stains or defects. \r\n The masonry materials should also be covered for protection against \r\n the elements. \r\n To limit water absorption, it is recommended \r\n that all brick masonry be protected by covering at the end of each \r\n workday and for shutdown periods. The cover should be a strong, weather-resistant \r\n membrane securely attached to and overhanging the brickwork by at \r\n least 24 in. (600 mm). Partially completed masonry exposed to rain \r\n may become so saturated with water that it may require months after \r\n the completion of the building to dry out. This saturation may cause \r\n prolonged efflorescence. See Technical Notes 23 Series for \r\n more information. \r\n Flashing. Flashing materials should \r\n be stored in places where they will not be punctured or damaged. Plastic \r\n and asphalt coated flashing materials should not be stored in areas \r\n exposed to sunlight. Ultraviolet rays from the sun break down these \r\n materials, causing them to become brittle with time. Plastic flashing \r\n exposed to the weather at the site for months before installation \r\n should not be used. During installation, flashing must be pliable \r\n so that no cracks occur at corners or bends. \r\n Workmanship \r\n Good workmanship is as essential in constructing \r\n brick veneer as it is in all types of brick masonry construction. \r\n All joints intended to receive mortar, including head joints with \r\n hollow brick, should be completely filled. Joints or spaces not intended \r\n to receive mortar should be kept clean and free of droppings. Courses \r\n of brick laid on foundations or lintels must have at least two-thirds \r\n of the brick thickness on the support. \r\n The joints should be tooled with a jointer \r\n as soon as the mortar has become thumbprint hard. The types of joints \r\n recommended for exterior use with brick veneer are concave, \"V\" and \r\n grapevine. These joints firmly compact the mortar against the edges \r\n of the adjoining brick. Other joints are not recommended because they \r\n do not provide the necessary resistance to moisture penetration. See \r\n Technical Notes 7B Revised \r\n for further information. \r\n It is essential when constructing brick \r\n veneer, to keep the 1 in. (25.4 mm) minimum air space between the \r\n veneer and the backing clean and free of all mortar droppings, so \r\n that the wall assembly will perform as a drainage wall. If mortar \r\n blocks the air space, it may provide a bridge for water to travel \r\n to the interior. In addition, all flashing, weepholes, ties and other \r\n accessories must be properly installed and kept clean. \r\n SUMMARY \r\n This Technical Notes is concerned \r\n primarily with the prescriptive design and conventional applications \r\n of anchored brick veneer in new wood frame buildings limited to three \r\n stories in height. Other Technical Notes in this series consider \r\n brick veneer applied to existing structures, brick veneer with different \r\n backing materials for mid-and high-rise structures, and adhered thin \r\n brick veneer. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of \r\n America. The information and recommendations contained herein must \r\n be used in conjunction with good technical judgment and a basic understanding \r\n of the properties of brick masonry and related construction materials. \r\n Final decisions on the use of the information contained in this Technical \r\n Notes are not within the purview of the Brick Institute of America, \r\n and must rest with the project architect, engineer, owner or all. \r\n REFERENCES \r\n For more detailed information on materials, \r\n design and construction procedures, the individual Technical Notes \r\n referred to herein should be consulted. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60096,"ResultID":176328,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 28A - Brick Veneer, Existing \r\n Construction \r\n Sept./Oct. 1978 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n The application of brick veneer to existing \r\n construction is popular because it enhances the appearance and improves \r\n the performance of existing walls. Its most common application is \r\n in refinishing the exterior of one and two-family dwellings, and also \r\n in refacing the fronts of commercial buildings. \r\n Brick veneer over existing construction \r\n consists of a nominal 3-in. (75 mm) or 4-in. (100 mm) thick brick \r\n wythe attached to an existing wall with metal ties in such a way that \r\n a 1-in. (25 mm) air space is maintained between the new brick veneer \r\n and the existing wall. New brick veneer can be applied to wood frame, \r\n metal, concrete or masonry structures. \r\n This Technical Notes considers the \r\n application of brick veneer to various types of existing construction. \r\n The illustrations, however, show only brick veneer applied to existing \r\n wood frame structures. This is the most common application. Details \r\n for brick veneer applied to other types of construction are similar, \r\n the method of attachment varying with the type of existing construction. \r\n PROPERTIES \r\n In addition to improving the appearance \r\n of the existing structure, the application of brick veneer may also \r\n enhance many of the performance properties of the wall and structure \r\n to which it is applied. \r\n Thermal Properties \r\n The thermal properties of a wall are improved \r\n by the addition of brick veneer in two ways - the addition of mass \r\n and the reduction of infiltration. The application of brick veneer \r\n also provides an opportunity to add insulation if desirable. \r\n Additional information on the thermal properties \r\n of brick veneer and brick masonry in general may be found in Technical \r\n Notes 28 Revised, and Technical \r\n Notes 4 Series. \r\n Moisture Resistance \r\n The moisture resistance of a wall can also \r\n be improved by the application of properly detailed and installed \r\n brick veneer. See Technical Notes 28 \r\n Revised, 7 Series and 21C for further \r\n information. \r\n Fire Resistance \r\n Constructing brick veneer over existing \r\n walls of combustible materials will decrease the possibility of externally \r\n initiated fires. Typical brick veneer wall assemblies have fire resistance \r\n ratings up to 2 hr. \r\n Acoustical Properties \r\n The addition of brick veneer to an existing \r\n wall will improve the sound transmission loss of the wall. This is \r\n due to the addition of mass and the discontinuity of the system. Further \r\n information is given in Technical Notes 28 \r\n Revised and Technical Notes 5A . \r\n DESIGN AND DETAILING \r\n Proper design and detailing of brick veneer \r\n applied to existing construction is very important to ensure that \r\n the wall assembly acts as it is intended. Areas of concern in design \r\n and detailing are structural performance, supporting the veneer, attaching \r\n the veneer to the existing structure, flashing and weepholes, movement \r\n provisions, framing around openings, and the top of the veneer. \r\n Structural Design \r\n Brick veneer is a non-loadbearing component \r\n of the wall assembly. In addition to its own weight, the only load \r\n that the brick veneer should carry is a proportionate share of any \r\n lateral loads. The wide differences between the stiffness characteristics \r\n of the brick veneer and those of the existing wall that usually occur \r\n result in the brick veneer carrying a disproportionate share of the \r\n lateral loads not considered in the design. \r\n The height limitations for brick veneer \r\n are based on the past history of successful performance. Empirical \r\n height limitations are provided in Table 1. \r\n \r\n \r\n Supporting Brick Veneer \r\n Brick veneer may be supported directly on \r\n either existing or new concrete foundations. Alternatively, it may \r\n be supported on steel angles anchored to existing concrete or masonry \r\n walls. \r\n Foundations . The brickwork should \r\n extend down to the existing foundation where possible, as shown in \r\n Fig. 1a. If the existing foundation is not sufficiently wide to support \r\n the entire thickness of the brick wythe, a new foundation, as shown \r\n in Fig. 1b, can be installed at the same depth as the existing foundation. \r\n A bond break should be installed between the existing and new foundations \r\n to allow for any differential movement. \r\n \r\n \r\n Typical Foundation Details \r\n \r\n \r\n FIG. 1a \r\n \r\n \r\n \r\n \r\n Typical Foundation Details \r\n \r\n \r\n FIG. 1b \r\n \r\n \r\n \r\n \r\n Typical Foundation Details \r\n \r\n \r\n FIG. 1c \r\n \r\n Steel Angles . An alternate method \r\n of supporting the brick veneer is shown in Fig. 1c. This requires \r\n attaching a continuous corrosion-resistant steel angle to the existing \r\n foundation or basement wall. The angle should be installed at or slightly \r\n below grade. Installing the angle below the frost line will decrease \r\n the possibility of deleterious effects resulting from freeze-thaw \r\n actions. The angles should be attached to existing basement or foundation \r\n walls constructed of concrete or masonry. Angles should never be \r\n anchored to wood plates or framing members. \r\n This method of support should be used with \r\n caution. A careful analysis of the loads being applied to the \r\n angle should be made. Special consideration should be given to the \r\n eccentricities of the applied loads. The sizing and spacing of bolts \r\n must be carefully computed, taking into account not only the loads \r\n to be carried, and their resulting eccentricities, but also the strength \r\n of the foundation wall itself. In general, this method of support \r\n should be confined to one-story structures where the total height \r\n to the plate does not exceed approximately 14 ft (4.3 m). \r\n Attachment \r\n The brick veneer must be securely attached \r\n to the existing construction. Provide one tie for each 2 2/3 sq ft \r\n (0.24 m 2 ) of wall area. \r\n The maximum spacing of ties, either horizontally or vertically, should \r\n not exceed 24 in. (600 mm) o.c. This tie spacing applies above and \r\n below grade. The above-grade spacing may be reduced to one tie for \r\n each 3 1/4 sq ft (0.30 m 2 ) \r\n of wall area for one and two-family dwellings not exceeding one story \r\n in height. \r\n Flashing and Weepholes \r\n Good flashing details, similar to those \r\n shown in Figs. 1c, 2, and 3 are essential to brick veneer construction. \r\n In order to divert the moisture out of the air space through the weepholes, \r\n continuous flashing should be installed at the bottom of the air space. \r\n The flashing must be at or above grade. Where the veneer continues \r\n below grade, the space between the veneer and the existing construction \r\n should be completely filled with mortar or grout. Flashing should \r\n also be installed at the heads and sills of all openings, and wherever \r\n the air space is interrupted. The flashing should extend through the \r\n face of the brick veneer to form a drip. Where the flashing is not \r\n continuous, such as at heads and sills, the ends should be turned \r\n up approximately 1 in. (25 mm). \r\n \r\n \r\n \r\n \r\n Base Detail \r\n \r\n \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Lintel, Jamb, and Sill Details \r\n FIG. 3a \r\n \r\n \r\n \r\n Typical Lintel, Jamb, \r\n and Sill Details \r\n \r\n FIG. 3b \r\n \r\n Weepholes should be located in the head \r\n joints immediately above all flashing. The maximum spacing of the \r\n weepholes should be 24 in. (600 mm) o.c. When wick materials are used \r\n in the weepholes or when the flashing does not extend through the \r\n face of the brick veneer, the spacing of the weepholes should not \r\n exceed 16 in. (400 mm) o.c. Additional discussion of flashing and \r\n weepholes may be found in Technical Notes 7 Series. \r\n Movement Provisions \r\n Provisions to accommodate differential movement \r\n due to temperature, moisture, shrinkage, and creep are not ordinarily \r\n required in small brick veneer buildings. For structures larger than \r\n single-family houses, the design should include considerations of \r\n potential differential movements and proper details to accommodate \r\n them. \r\n Design and details for differential movement \r\n may include: expansion joints, flexible anchorage, joint reinforcement, \r\n bond breaks, and sealants. These items and their applications are \r\n discussed in Technical Notes 18 Series, 28 \r\n Revised and 21 Series. \r\n Framing Around Openings \r\n Typical lintel, jamb, and sill details are \r\n shown in Fig. 3. New brick sills can usually be constructed so that \r\n the existing sill overlaps the new brick sill. \r\n New moulding installed at the existing jambs \r\n and heads of openings should extend the framing enough so that the \r\n air space between the brick veneer and the existing construction can \r\n be properly sealed. \r\n Lintels may be of reinforced brick masonry, \r\n steel angles, or precast concrete. Reinforced brick masonry and steel \r\n angle lintels are the most commonly used in brick veneer construction. \r\n The minimum required bearing length for \r\n steel angle lintels is 4 in. (600 mm). The spans and sizes of steel \r\n angle lintels may be modified by fireproofing requirements in local \r\n building codes. \r\n Further information on the design, detailing \r\n and material selection of lintels may be found in Technical Notes \r\n 17B and Technical Notes 31B \r\n Revised. \r\n Top of the Veneer \r\n A typical detail for the top of the brick \r\n veneer at an existing cave is shown in Fig. 4. There should be at \r\n least a 1/8 - in. (3.2 mm) clear space between the top of the last \r\n course of brick and the bottom of the soffit. This space should be \r\n covered with a new moulding strip and sealant or caulking. If there \r\n is insufficient eave to properly cover the top of the veneer, provisions \r\n must be made to extend the cave. \r\n \r\n \r\n Typical Eave Detail \r\n \r\n \r\n FIG. 4 \r\n \r\n SELECTION OF MATERIALS \r\n The proper selection of quality materials \r\n is essential to the satisfactory performance of a brick veneer wall \r\n assembly. No amount of design, detailing or construction can compensate \r\n for the improper selection of materials. \r\n Brick \r\n Nominal 3-in. (75 mm) or 4-in. (100 mm) \r\n thick brick, conforming to ASTM C 62 or ASTM C 216, should be used \r\n for brick veneer. Grade SW brick is recommended because the brick \r\n wythe is isolated from the remainder of the wall by the air space, \r\n thus exposing it to the maximum temperature extremes. \r\n Salvaged brick should not be used because \r\n they may not provide the strength and durability necessary for satisfactory \r\n performance. The use of salvaged brick is discussed in Technical \r\n Notes 15 . \r\n Mortar \r\n The use of the correct mortar is very important \r\n to the successful performance of brick veneer. Portland cement-lime \r\n mortars are recommended because they have a long history of proven \r\n performance. Portland cement-lime mortars for brick masonry are discussed \r\n in Technical Notes 8 Series. \r\n Type N portland cement-lime mortar is recommended \r\n for brick veneer, except that Type M portland cement-lime mortar should \r\n be used for brick veneer below grade, where the brickwork is in contact \r\n with earth \r\n Ties \r\n The type of tie system which should be used \r\n with brick veneer will depend on the construction of the existing \r\n wall. Corrugated metal ties may be used with wood frame backup. Metal \r\n wire ties should be used elsewhere. Several types of ties which may \r\n be used in brick veneer applied to existing construction are shown \r\n in Figs. 2a through 2d in Technical Notes 28 \r\n Revised. \r\n Corrugated Metal Ties . Corrugated \r\n metal ties should be corrosion-resistant. They should be at least \r\n 22 gage, 7/8 in. (22 mm) wide and 6 in. (150 mm) long. \r\n Metal Wire Ties . Metal wire ties \r\n should be at least 9 gage and corrosion-resistant. It is recommended \r\n that 3/16 -in. (4.7 mm) diameter metal wire ties be used to fasten \r\n the brick veneer to a structural frame. Metal wire ties should comply \r\n with ASTM A 82 or A 185. \r\n Corrosion Resistance . Corrosion resistance \r\n is usually provided by copper or zinc coating, or by using stainless \r\n steel. To ensure adequate resistance to corrosion, coatings or materials \r\n should conform to: \r\n Zinc-Coating of Flat Metal-ASTM A 153, \r\n Class B-3; \r\n Zinc-Coating of Wire-ASTM A 116, Class \r\n 3; \r\n Copper Coated Wire-ASTM B 227, Grade 30 \r\n HS; \r\n Stainless Steel-ASTM A 167, Type 304. \r\n \r\n Tie Fasteners \r\n The type of fastener used to attach the \r\n ties to the existing wall will also depend on the construction of \r\n the existing wall. \r\n Wood Frame . Corrosion-resistant nails \r\n should be used to attach the corrugated metal ties to wood frame construction. \r\n The nails should penetrate at least 1 1/4 in. (40 mm) into the wood \r\n studs. \r\n Metal . Corrosion-resistant, self-tapping \r\n metal screws should be used to attach metal wire ties to metal construction. \r\n The screws should penetrate at least 1/2 in. (13 mm) into the metal. \r\n Concrete or Masonry . There are several \r\n methods of attaching the metal wire ties to existing concrete or masonry \r\n walls. The ties may be attached with lag bolts and expansion shields \r\n or masonry nails. The fasteners and anchors should be corrosion-resistant. \r\n Steel Angles \r\n When a continuous steel angle is used to \r\n support the new brick veneer at the foundation wall, it should be \r\n of steel conforming to ASTM A 36, and should be treated or coated \r\n to resist corrosion. Bolts or other fasteners should also be corrosion-resistant. \r\n The sizing of the angle, and the sizing \r\n and spacing of the bolts should be determined by structural analysis. \r\n Steel angles for lintels should be a minimum \r\n 1/4 in. (6.2 mm) thick with at least 3-in. (75 mm) legs and the steel \r\n should conform to ASTM A 36. For information on steel lintels for \r\n brick masonry, see Technical Notes 31B \r\n Revised. \r\n Flashing \r\n Flashing materials for use with brick veneer \r\n may be bituminous membranes, plastics, sheet metals, or combinations \r\n of these. It is best to select only superior materials because replacement \r\n in the event of failure will be costly, if not impossible. Asphalt \r\n impregnated felt paper should not be used as a flashing material. \r\n For a more complete discussion on the various types of flashing, see \r\n Technical Notes 7A Revised. \r\n Weepholes \r\n Weepholes are formed by inserting a material \r\n into the mortar joint, or by omitting all or part of the head joint. \r\n Forming materials, such as well-oiled rods, are removed to leave an \r\n unobstructed opening. Other forming materials, such as plastic tubes \r\n or rope wicks, may be left in place. Sometimes metal screening, fibrous \r\n glass, or other materials, are placed in open weepholes, but this \r\n should not be done indiscriminately. Materials such as metal screening \r\n can corrode and cause staining of the masonry. \r\n CONSTRUCTION \r\n Supports \r\n Foundations . Supporting brick veneer \r\n on new or existing foundations requires excavating down to the existing \r\n foundation. The excavation must be sufficiently wide for the brickmason \r\n to work. Prior to placing the masonry on an existing foundation, the \r\n foundation should be brushed clean of loose soil and debris. \r\n Angles . When constructing brick veneer \r\n on continuous corrosion-resistant steel angles, the first course of \r\n brick should be laid in a mortar setting bed. This provides a means \r\n to compensate for any variations and misalignment of the steel angles. \r\n Installing Additional Insulation \r\n Applying brick veneer over existing construction \r\n offers an opportunity to better insulate the existing exterior walls. \r\n The insulation materials used should comply to the criteria discussed \r\n in Technical Notes 21A . \r\n Rigid insulation may be installed directly \r\n over the existing finish prior to erecting the new brick veneer. A \r\n 1-in. (25 mm) air space should be maintained between the brick veneer \r\n and the rigid insulation. If the existing wood frame or metal stud \r\n walls contain little or no insulation, the existing siding of the \r\n wall may be removed so that insulation can be installed within the \r\n wall. The materials removed from the existing wall may be reapplied. \r\n Workmanship \r\n Good workmanship is necessary to achieve \r\n satisfactory performance of brick veneer. The veneer must be properly \r\n constructed if the expected performance of the masonry is to be obtained. \r\n Mortar Joints . There is no substitute \r\n for the complete filling of all mortar joints that are intended \r\n to receive mortar. Partially filled mortar joints result in leaky \r\n walls, reduced strength of the masonry, and may contribute to cracking \r\n and spelling due to freezing and thawing in the presence of moisture. \r\n All joints intended to receive mortar should be completely filled \r\n as the brick are laid. \r\n Keeping the Air Space Clean . It is \r\n essential to maintain a 1-in. (25 mm) air space between the brick \r\n veneer and the existing wall, and to keep it clean of mortar protrusions, \r\n droppings, and other foreign materials. If mortar falls into the air \r\n space, it may form \"bridges\" for moisture and thermal transfer, or \r\n it may fall onto the flashing and block the weepholes. \r\n Tooling of Joints . Weather tightness \r\n and textural effect are the basic considerations of mortar joint finish \r\n selection and execution. Tooling the joint properly helps the mortar \r\n adhere to the edges of the brick units and seal the wall against moisture \r\n penetration. The use of concave, V, or grapevine joints is recommended. \r\n The joints should be tooled when the mortar is \"thumb-print\" hard. \r\n Additional information on joints may be found in Technical Notes \r\n 21C . \r\n Flashing and Weepholes . Flashing \r\n materials must be carefully installed to prevent punctures or tears. \r\n The flashing must be securely attached to the existing wall and should \r\n extend through the face of the brick veneer. Weepholes should be installed \r\n in the head joints immediately above all flashing. \r\n Tie Placement . Secure attachment \r\n of the ties to the existing wall is a necessity. The ties must be \r\n of sufficient length to provide a minimum 2-in. (50 mm) embedment \r\n into the bed joints. Ties should be placed in the bed joints and should \r\n be completely surrounded by mortar. \r\n Caulking or Sealants . Caulking joints \r\n at the perimeter of exterior door and window frames should not be \r\n less than 1/4 in. (6 mm) nor more than 3/8 in. (10 mm) wide. They \r\n should be cleaned for a depth of 3/4 in. (20 mm). The joints should \r\n be properly primed before placing caulking compound or sealant. The \r\n caulking or sealant should be placed with a pressure gun. \r\n Cleaning . If the brick veneer is \r\n properly and carefully constructed, cleaning the brickwork can be \r\n kept to a minimum. Most of the cleaning can be done by dry cleaning \r\n methods or by washing the wall with plain water. Refer to Technical \r\n Notes 20 Revised for information \r\n on cleaning brick masonry. \r\n Protection \r\n Storage of Materials . Masonry units \r\n should be stored off the ground to avoid contamination by dirt and \r\n ground water, which may contain soluble salts. They should be covered \r\n by a weather-resistant membrane to keep them dry. \r\n Mortar materials should also be stored off \r\n the ground and under cover. If these materials are exposed to moisture, \r\n they may become useless for constructing the brick veneer. Flashing, \r\n ties and other materials should also be protected from the weather. \r\n Protection of Walls . Partially completed \r\n walls must be protected from the elements. This can be done by securely \r\n attaching a strong, weather-resistant membrane to the existing structure \r\n and allowing it to overhang the brickwork by at least 2 ft \r\n (0.61 m). This will prevent the wall from becoming saturated, thus \r\n decreasing the possibility of efflorescence, and other deleterious \r\n effects caused by moisture in brick masonry. \r\n SUMMARY \r\n This Technical Notes provides the \r\n basic information required to properly select materials, design, detail, \r\n and construct brick veneer over existing construction. Further information \r\n about the properties of brick veneer and concepts not unique to brick \r\n veneer over existing construction is discussed in Technical Notes \r\n 28 Revised. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the technical staff of the Brick Institute of America. \r\n This information should be recognized as recommendations and suggestions \r\n which, if followed with good judgment, will result in brick veneer \r\n wall assemblies that perform successfully. Final decisions on the \r\n use of details and materials as discussed are not within the purview \r\n of the Brick Institute of America, and must rest with the project \r\n designer, or owner, or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60097,"ResultID":176329,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 28B - Brick Veneer, Steel \r\n Stud Panel Walls \r\n Feb. 1987 \r\n \r\n Abstract: This Technical Notes addresses the considerations and recommendations \r\n for the design, detailing, materials selection and construction of \r\n brick veneer/steel stud panel walls. All previous issues of this Technical \r\n Notes are superseded. The information presented pertains to behavior \r\n of veneer, differential movement, ties and anchors, air space, detailing, \r\n selection of materials and construction techniques. The recommendations \r\n are more detailed than in earlier issues and in some instances differ, \r\n based on testing and experience. \r\n \r\n Key Words: brick , brick veneer, buildings, design, \r\n elastic properties, fasteners , masonry , permeability, \r\n stability, stiffness , walls. \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes is one of four in a series dealing with \r\n brick veneer. The other issues are Technical Notes 28 \r\n Revised, \"Brick Veneer-New Construction\", Technical Notes 28A ,\"Brick \r\n Veneer-Existing Construction\" and Technical Notes 28C , \r\n \"Thin Brick Veneer-Introduction\". \r\n This issue of Technical Notes addresses brick veneer as used \r\n in commercial construction or wherever the spans are longer (taller) \r\n than 8 ft (2.44 m) high, the walls are not as frequently braced by \r\n cross walls, and the design does not afford the usual protection of \r\n residential construction (overhangs, gutters, etc.). Generally, the \r\n buildings in question are taller than three-story structures prescribed \r\n by the building codes for residential brick veneer; hence the wind \r\n loads are greater, the occupancy loads are higher and the expected \r\n deflections are larger. These buildings are usually of structural \r\n steel or reinforced concrete frame. This Technical Notes specifically \r\n addresses brick veneer over steel stud backup used as panel walls \r\n in other than one and two-family residential structures (see Figures \r\n 1 and 2). It does not address seismic design. \r\n \r\n \r\n \r\n Brick Veneer/Steel Stud Wall \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Wall Section at Foundation \r\n FIG. 2 \r\n \r\n BRICK VENEER \r\n General \r\n \r\n A veneer wall is, by definition, \"a wall having a facing of masonry \r\n units, or other weather-resisting, noncombustible materials, securely \r\n attached to the backing, but not so bonded as to intentionally exert \r\n common action under load\", (see Technical Notes 2 \r\n Revised). A brick veneer wall consists of an exterior wythe of brick \r\n isolated from the backup by a minimum prescribed air space and attached \r\n to the backup with corrosion-resistant metal ties. The backup for \r\n brick veneer can be any of several construction materials, i.e., brick, \r\n concrete block, concrete, wood or other materials. The general recommendations \r\n for design and construction of the brick veneer remain essentially \r\n the same. \r\n \r\n Behavior of Veneer \r\n \r\n General. Brick veneer is subject to numerous imposed loads, \r\n both axial and lateral. In the design of the veneer, all of these \r\n must be taken into account for the system to perform as intended. \r\n Axial Loads. Brick veneer should not be subjected to any axial \r\n loading other than its own weight. Therefore, it should be designed, \r\n detailed and constructed as non-loadbearing, so that no axial loads \r\n are imposed on the veneer. \r\n Lateral Loads. Many codes imply that the veneer backup should \r\n be designed to carry all lateral loads. This will only work when the \r\n veneer material is applied directly to the backup, as in the case \r\n of thin brick or mosaic tile. The brick veneer and the backup system \r\n are separate and consequently, must share the lateral load, though \r\n not necessarily equally. \r\n \r\n BRICK VENEER/STEEL STUDS \r\n General \r\n \r\n The past two decades have seen the exterior walls of buildings become \r\n thinner and more vulnerable to the elements. One particular wall system, \r\n brick veneer/steel studs, has become quite popular with many designers. \r\n This wall system is relatively new as brick masonry wall systems go; \r\n and, as such, is still evolving. For this reason, some of the suggestions \r\n and considerations are changing as experience is gained. \r\n Brick veneer, however, is certainly not new. It has been successfully \r\n used for residential structures for many decades. In such instances, \r\n the design has been entirely empirical. The spans are relatively small \r\n and residential design generally provides many cross walls for bracing, \r\n as well as overhangs and gutters for a modicum of protection from \r\n the weather. Also, maximum heights and minimum thicknesses are closely \r\n controlled by standards. See Technical Notes 28 \r\n Revised. \r\n The brick veneer/steel stud wall, however, has been and is being \r\n used in other types of buildings, i.e., commercial, industrial and \r\n institutional structures such as office buildings, schools, churches, \r\n hospitals, etc. These buildings are usually of structural steel and/or \r\n reinforced concrete frames, and are frequently beyond the three-story \r\n limit in height prescribed for brick veneer walls of houses. \r\n The brick veneer/steel stud wall system is an adaptive and innovative \r\n application of the conventional brick veneer with wood stud backup \r\n used in houses. For adequate performance of this wall system, it is \r\n necessary to have an understanding of the nature and behavior of the \r\n materials involved. Problems can and have occurred with the application \r\n of this system. Careful attention is required for design, detailing \r\n and field execution to realize satisfactory performance. This Technical \r\n Notes provides information and suggestions for design, detailing \r\n and construction procedures that can assist the designer in attaining \r\n the expected and required level of performance. \r\n The brick veneer/steel stud wall system is somewhat less \"forgiving\" \r\n than most other brick masonry walls. That is, it may not tolerate \r\n even minor errors in detailing, material selection and construction. \r\n However, this wall system, when properly designed, detailed and constructed, \r\n will perform quite satisfactorily. This wall system offers several \r\n advantages: 1) It provides space in the stud wythe for insulation. \r\n 2) It permits the construction to get into the \"dry\" and the \r\n brickwork to follow at a convenient time. 3) It provides the desirable \r\n appearance and attributes of a brick masonry building. 4) It fits \r\n a schedule. \r\n \r\n Observations \r\n \r\n As the use of the system has grown, there has been much written and \r\n spoken criticism of the system. Some of these criticisms have their \r\n foundation in competitive concerns, and others are genuine concerns. \r\n It is the position of the Brick Institute of America that so long \r\n as design professionals and owners are selecting and using this brick \r\n masonry wall system, it is the ethical and professional duty of the \r\n Institute to provide the best available information about the design \r\n and construction of the system, to ensure that it has the best possible \r\n chance to perform as desired and expected. \r\n Based on observations and experience, satisfactory performance of \r\n this system can be achieved by careful attention to: \r\n 1. The movements that can be expected with the materials and the \r\n system. \r\n 2 . The forces involved and the behavior of the brick veneer. \r\n 3. The proper type of ties and their adequate spacing. \r\n 4. The design and detailing factors to prevent water penetration \r\n of the wall: a) flashing and weepholes, b) sealant joints, c) clean, \r\n open air spaces. \r\n 5. Strength and stiffness (deflection characteristics) of the wall \r\n system. \r\n 6. Corrosion resistance and protection for the several metal components \r\n of the wall. \r\n 7. Selection of proper materials for strength, durability, and ease \r\n of construction. \r\n 8. Climatic conditions and exposures, as well as interior conditions. \r\n 9. Good field practices and construction techniques. \r\n Each of these considerations is addressed in this Technical Notes, \r\n along with suggestions and recommendations. \r\n \r\n STRUCTURAL DESIGN \r\n General \r\n \r\n The brick veneer/steel stud wall system should not be designed \r\n using the allowable flexural tensile stresses as contained in the \r\n structural design standards for masonry. These allowables are generally \r\n based on factors of safety of three or more, i.e., ratio of ultimate \r\n flexural strength to allowable flexural stress. However, accurate \r\n calculation procedures to predict the behavior of this wall system, \r\n and thereby to determine the expected stresses, do not exist. \r\n \r\n Clemson University Research Study \r\n \r\n In early 1981, the Metal Lath/Steel Framing Association and the Brick \r\n Institute of America jointly sponsored a research study at the Department \r\n of Civil Engineering at Clemson University in Clemson, South Carolina. \r\n The purpose of the project was to determine the behavior and performance \r\n of laterally loaded brick veneer/steel stud walls. The project included \r\n testing of full-scale wall specimens and an analytical study of their \r\n behavior. \r\n The final report was issued in April of 1982, and is entitled \"Performance \r\n Evaluation of Brick Veneer With Steel Stud Backup\", by J. O. Arumala \r\n and R. H. Brown. \r\n The experimental investigation consisted of two phases: The first \r\n phase involved the testing of two different types of metal tie systems \r\n to determine their suitability. The second phase involved testing \r\n six simple span brick veneer walls with steel stud backup to measure \r\n their deflection characteristics under lateral load. The purpose of \r\n Phase Two was \". . .to establish approximately the performance of \r\n walls designed in accordance with metal stud industry standards\". \r\n The analytical aspect of the study included the development of models \r\n to simulate the behavior of the wall system under wind pressures and \r\n for different boundary conditions and tie stiffnesses. \r\n Conclusions. Among the conclusions to the Research Report, \r\n the authors stated: \r\n \"The walls tested were very complex in their behavior. Even with \r\n the substantial data obtained during the experimental program, the \r\n system remained difficult to explain. The loads carried by the system \r\n exceeded values predicted by conventional analysis.\" \r\n \"The compressible filler material at the top of the brick veneer \r\n allowed appreciable movement of the top of the brick veneer. This \r\n movement relieved the stresses in the brick and enabled the system \r\n to resist more load than it would have done without the movement. \r\n The load capacity of the walls during the tests is attributable, in \r\n part, to these brick veneer top movements. The analytical results \r\n show that if the top of the wall is not permitted to move laterally, \r\n the brick veneer will develop cracks at lower loads.\" \r\n \"The mathematical model developed predicted failure loads to a good \r\n degree of accuracy. The brick veneer behaved as if it were restrained \r\n at the base and free at the top, and the drywall behaved as pinned \r\n at both ends. The composite action obtained between the stud and the \r\n gypsum wallboard did not appear to be significant.\" \r\n \"Forces in the wall ties are nonuniform, even when wind pressure \r\n is uniformly distributed. The practice of distributing force to ties \r\n uniformly in design appears to substantially underestimate maximum \r\n tie forces.\" \r\n \"The use of flexural rigidity as measured by the value EI as a means \r\n to distribute lateral load to each wythe is inaccurate. Such factors \r\n as tie stiffness, span difference between the two wythes, and boundary \r\n conditions have as much effect as flexural rigidity on distribution \r\n of lateral load.\" \r\n Based on this information, the rational design approach to this wall \r\n system is not valid. Therefore, the design of this wall system should \r\n be empirical, based on observation and experience. \r\n \r\n Lateral Loading \r\n \r\n All lateral loads, such as wind loads, are initially resisted by \r\n the exterior wall system, and then transferred to the building frame \r\n and eventually to the foundation. To satisfactorily accomplish this, \r\n several things must be considered: \r\n Load Distribution. The brick veneer must be connected to the \r\n backup with metal ties, in sufficient number and of sufficient stiffness \r\n that under lateral loading, the system deflects equally. The deflections \r\n of both the veneer and the backup must be equal. This is not to say \r\n that the loads will be equal. It is here that the load distribution \r\n defies accurate analysis, according to the research. Thus, the design \r\n is based on experience and judgment where the brick wythe is composed \r\n of a relatively rigid and brittle material compared to the more flexible \r\n steel stud backup. \r\n \r\n Stiffness Considerations. As the research \r\n indicates, the differences between the stiffness of the brick veneer \r\n and the steel stud backup, and the equal deflections, are not sufficient to rationally \r\n design this wall system. Therefore, to obtain a minimum backup stiffness, \r\n the allowable lateral deflection of the studs must be limited. Many \r\n design tables are based on a stud deflection of L/360. Using this \r\n stiffness of backup represented by an L/360 deflection may permit \r\n more deflection than the veneer is able to tolerate without cracking. \r\n \r\n Moment Resistance. In order to provide lateral support for \r\n the steel studs, and thus be able to use the full allowable stresses \r\n in the studs, there must be sheathing attached to both sides of \r\n the studs. If this is not properly detailed, specified and constructed, \r\n problems may arise. As an example, the practice of loading the scaffold \r\n from the inside of the building has often resulted in exterior sheathing \r\n being left out of the system in some locations. Proper attachment \r\n of the backup studs at both top and bottom is mandatory. \r\n \r\n Recommendations \r\n \r\n Support of Veneer. It is suggested that the brick veneer/ \r\n steel stud wall system be detailed as a panel wall, i.e., fully supported \r\n at each story height by the structural frame and shelf angles. A minimum \r\n of 2/3 of the brick thickness must bear on the shelf angles. Experience \r\n has indicated that the best performance is achieved when the brick \r\n wythe is divided into relatively small, discreet elements of the facade, \r\n and isolated by soft joints. \r\n Shelf Angles. The structural steel shelf angles must be sized \r\n and anchored to carry the imposed loads such that total deflection \r\n is limited to the lesser of L/600 or 0.3 in. (7.5 mm), and rotations \r\n are less than 1/16 in. (1.6 mm). For severe climates and exposures, \r\n consideration should be given to the use of galvanized or stainless \r\n steel shelf angles. Continuous flashing should be installed to cover \r\n the angle. Shelf angles are not to be attached to the steel \r\n studs. Shelf angles should be sized so that at least 2/3 of the thickness \r\n of the brick wythe is supported. \r\n Stiffness Requirements. Based on observations, experience \r\n and judgment, the Brick Institute of America suggests that in order \r\n to obtain the stiffness necessary for performance, the maximum deflection \r\n that should be permitted for the steel stud backup, when considered \r\n alone at full lateral design load, be L/600 to L/720. \r\n Steel Studs. There must be sheathing securely attached to \r\n both sides of the studs. This sheathing must be rigid, properly detailed \r\n and properly attached to be effective. Horizontal bracing of the studs \r\n at mid-height is recommended for added stiffness. Studs at all jambs, \r\n headers and sills of windows, doors and other openings should be designed \r\n with loads based on the tributary area of the opening, with adequate \r\n transfer of loads to the structure within the deflection/stiffness \r\n criteria. \r\n \r\n Ties. The minimum air space has been \r\n increased to 2 in. (50 mm), therefore, ties must be spaced closer. \r\n There should be one tie for each 2 sq ft (0.18 m 2 ) of wall area, spaced a maximum of 24 in. (600 mm) o.c., as shown in Fig. \r\n 3. These should be minimum 3/16 in. (9 mm) diameter, corrosion-resistant \r\n wire ties of the type shown in Fig. 4. In addition, they should be \r\n limited to strength and deformation as stated in the SELECTION OF \r\n MATERIALS section. Corrugated metal veneer ties should not be used. \r\n All ties must be embedded at least 2 in. (50 mm) into the bed \r\n joints of the brick veneer. They must be securely attached to the \r\n steel studs through the sheathing, and not to the sheathing \r\n alone. Additional ties should be installed at approximately 8 in. \r\n (200 mm) o.c., at jambs and near edges. \r\n \r\n \r\n \r\n \r\n Spacing of Metal Ties \r\n FIG. 3 \r\n \r\n \r\n \r\n Tie Assemblies \r\n FIG. 4 \r\n \r\n Mortar. \r\n Mortar has an important effect on the flexural strength of a brick \r\n veneer wythe. Transverse strength tests of full-scale walls indicate \r\n that the bond between mortar and brick units is the most important \r\n single factor affecting wall strength when the load is applied such \r\n that failure occurs through a horizontal joint. These tests indicate \r\n that portland cement-lime mortars, conforming to ASTM C 270 or BIA \r\n M1-72, Type S, provide maximum bond between masonry units and mortar. \r\n Type S mortar is recommended for use in brick veneer walls at locations \r\n where wind loads are expected to exceed 25 psf (1.2 kPa). For other \r\n locations, Type N mortar is recommended. In any case, a designer should \r\n select the lowest compressive strength mortar that is compatible with \r\n the structural requirements of a project. Only portland cement-lime \r\n mortars, as discussed in Technical Notes 8 Series, should be \r\n used with brick veneer/steel stud panel walls. \r\n \r\n Parapet Walls. Parapet walls should be avoided unless absolutely \r\n required (see Fig. 5). If they must be used, they should be properly \r\n designed, detailed and constructed (see Fig. 6). Steel studs should \r\n not be used as backup for parapet walls. \r\n \r\n \r\n \r\n Non-Parapet Wall \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Reinforced Parapet Wall \r\n FIG. 6 \r\n \r\n DIFFERENTIAL MOVEMENT \r\n General \r\n \r\n All building materials change dimension with changes in temperature. \r\n Some building materials, with the exception of metals, change dimension \r\n with changes in their moisture content. All materials will deform \r\n elastically when subjected to loads. And, some materials, notably \r\n those with cement matrices, will deform plastically (creep) when loaded. \r\n Problems can arise if these naturally occurring movements are not \r\n recognized and accommodated. \r\n Building Frame Movements. Building frames are subject to many \r\n movements. Steel frames and members are subject to deflection, thermal \r\n movements, and elastic shortening due to imposed loads. Concrete frames \r\n and members, in addition to the above, are subject to creep, shrinkage \r\n and moisture movements. These movements must be considered in the \r\n design of the wall system. \r\n Veneer Movements. The brick veneer wythe is also subject to \r\n various natural movements, as discussed in Technical Notes \r\n 18 Series. \r\n \r\n The brick veneer may be subject to minor \r\n moisture movements. A coefficient of 0.0005 is suggested for design. \r\n Also, thermal movements will probably occur. The design coefficient \r\n for thermal movement is 0.000004 per degree Fahrenheit (7.0 x 10 -6 per degree C). The general design formula \r\n to provide for these is: \r\n \r\n \r\n \r\n w = \r\n [0.0005 + 0.000004 (T max -T min )] L \r\n \r\n \r\n \r\n where: w = the total expected movement \r\n of the brick veneer, in. (mm), \r\n \r\n \r\n \r\n T max = the maximum mean temperature of the brick veneer, degree Fahrenheit (C), \r\n T min = the minimum mean temperature of the brick veneer, degree Fahrenheit (C), \r\n L = \r\n the length of the brick veneer wall, in.(mm) \r\n \r\n \r\n \r\n \r\n It should be noted that in a brick veneer system, the movement should \r\n be calculated for the brick wythe alone. Since the brick veneer wythe \r\n is separated from the backup, it is essentially unrestrained, is thermally \r\n isolated from the stabilizing interior, and may have movements greater \r\n than expected. \r\n Backup System Movements. Since the backup system is built \r\n between floors and securely attached both top and bottom, any shortening \r\n of the frame will be directly transferred into the backup. As the \r\n frame shortens, it will produce axial loads on the steel stud system. \r\n As these loads are increased, the backup may deflect laterally. This \r\n bowing of the stud system, whether inward or outward, will produce \r\n a similar deflection in the brick veneer as the movement is transferred \r\n through the metal ties. The additional flexural tensile stress in \r\n the veneer caused by this deflection, along with the stress caused \r\n by the external lateral loading from wind, may become excessive. \r\n \r\n Recommendations \r\n \r\n Movement Joints. In order to prevent distress in the masonry, \r\n provision must be made for the movements described. The use of vertical \r\n and horizontal expansion joints best provides for these movements. \r\n Provisions must be made for the total differential movement, i.e., \r\n the shortening and/or deflection of the structural frame, the growth \r\n from thermal changes and the possibility of moisture growth of the \r\n brick masonry. \r\n No single recommendation for the positioning and spacing of expansion \r\n joints can be applicable to all structures. Each building must be \r\n analyzed to determine the potential movements, and provisions must \r\n be made to relieve excessive stresses which might be expected to result \r\n from such movements. The movement of the brick veneer due to thermal \r\n and moisture expansion may be greater than the movement in solid or \r\n composite walls exposed to the same environment. This is due to the \r\n greater differences between the mean maximum and mean minimum temperatures \r\n of the brick veneer, and the absence of restraint. \r\n The isolated brick veneer will undergo maximum movements due to thermal \r\n changes and, as a result, the number of expansion joints required \r\n will be increased. Special care must be exercised in design, detailing \r\n and construction of expansion joints. For further information, see \r\n Technical Notes 18 Series. \r\n \r\n Expansion Joints- Expansion joints must be properly \r\n sized and located. In addition, they must be detailed and constructed \r\n to provide for the anticipated movements. Since most sealant materials \r\n are only about 50% efficient, the joints should be sized to accommodate \r\n twice the expected movement. \r\n Vertical Expansion Joints. Expansion joints in brick masonry \r\n oriented vertically are designed to accommodate potential horizontal \r\n movements in the masonry. The expansion joints must be of compressible \r\n material to permit the movement to occur without distress from excessive \r\n or concentrated stresses, see Fig. 7. Expansion joints must also be \r\n designed, located and constructed so as not to impair the integrity \r\n of the wall. \r\n \r\n \r\n \r\n Expansion Joint Fillers \r\n FIG. 7 \r\n \r\n Parapet Walls- All vertical expansion joints should be carried through parapet walls. \r\n Additional expansion joints through the parapets should be spaced \r\n approximately halfway between those running full wall height, unless \r\n the parapets are reinforced. \r\n \r\n Horizontal Expansion Joints. The veneer in these types of \r\n structures is supported on shelf angles attached to the structural \r\n frame. It is recommended that horizontal pressure-relieving (soft) \r\n joints be placed immediately beneath each angle, as shown in Fig. \r\n 8. This is particularly important in reinforced concrete frame buildings. \r\n Horizontal expansion joints may be constructed by leaving an air space \r\n or by placing a compressible material under the shelf angle. In either \r\n case, the joint must be sealed at the exterior face with a suitable \r\n elastic sealant and backer rod. \r\n \r\n \r\n \r\n Shelf Angle Detail \r\n FIG. 8 \r\n \r\n Joint Reinforcing. Horizontal joint reinforcing is not usually required in brick veneer \r\n since brick masonry is not subject to initial drying shrinkage stresses \r\n as is concrete masonry. However, single-wire, horizontal joint reinforcing \r\n in the brick veneer will improve continuity, tensile capacity and \r\n toughness at places such as corners, offsets and at intersecting walls. \r\n When using horizontal joint reinforcing it must be discontinuous \r\n at all movement joints. Also, all joint reinforcing must be adequately \r\n protected from corrosion. See Technical Notes 7A \r\n Revised and 44B . \r\n \r\n Anchorage. When brick veneer is used to enclose skeleton frame \r\n structures, care must be taken to anchor the masonry veneer to the \r\n skeleton frame in a manner that will permit each to move freely, in-plane, \r\n relative to the other. Skeleton frames are more flexible than brick \r\n veneer, and will undergo larger deflections. \r\n Anchors that connect the veneer to the structural frame to provide \r\n lateral support, should be flexible, resisting tension and compression, \r\n but not shear. This flexibility permits in-plane differential \r\n movements between the frame and the veneer without causing cracking \r\n or distress. See Technical Notes 18 Series. \r\n Shelf Angles. The veneer should be supported by shelf angles \r\n at each floor, as shown in Fig. 9. Care should be taken to insure \r\n proper anchorage and shimming of the angles to prevent excessive deflections \r\n and/or rotations which may induce concentrated stresses in the masonry. \r\n Shelf angles should not be installed as one continuous member. \r\n Spaces should be provided at intervals to permit thermal expansion \r\n and contraction of the steel to occur without causing distress to \r\n the masonry. \r\n \r\n \r\n \r\n Alternate Shelf Angle Detail \r\n FIG. 9 \r\n \r\n Windows. \r\n The proper framing and attachment of windows can be a problem if the \r\n differences in the movement between the brick veneer and the frame \r\n or backup are not taken into account. The window can be attached either \r\n to the brick veneer, or to the backup, but should not be attached \r\n to both, (see Fig. 10). \r\n \r\n \r\n \r\n Lintel, Jamb and Sill Details \r\n FIG. 10 \r\n \r\n WATER PENETRATION \r\n General \r\n \r\n One of the major concerns with the brick veneer/steel stud wall system \r\n has been that of water penetration. Prevention of water penetration \r\n of this wall system requires the same care and attention as do other \r\n brick masonry walls. \r\n There are three principal requirements for prevention of water penetration: \r\n 1) proper design and detailing, 2) selection of suitable materials \r\n and 3) good workmanship and construction techniques. Lack of attention \r\n to any one of these may result in leaky walls or other problems. Experience \r\n has shown that frequently the water and moisture found in these walls \r\n are the result of condensation. It is therefore recommended that condensation \r\n analyses be part of the design considerations. \r\n \r\n Recommendations \r\n \r\n General. The general recommendations for preventing water \r\n penetration of brick walls are covered in Technical Notes 7 \r\n Series. Many are repeated here as they specifically impact \r\n brick veneer/steel stud panel walls. It is suggested that the general \r\n recommendations also be consulted. \r\n Design and Detailing . Following are some of the critical factors \r\n of design and detailing of brick veneer/steel stud panel wall systems: \r\n \r\n Condensation- For specific projects, a condensation \r\n analysis should be made at the extremes of expected conditions. In \r\n this way, the potential for condensation can be assessed and suitable \r\n vapor-resistant layers can be properly placed in the wall to reduce \r\n and minimize this potential. See Technical Notes 7C \r\n and 7D . \r\n \r\n Flashing- Flashing must be placed at all points where \r\n the wall is interrupted, i.e., at window and door heads, louvers or \r\n other wall penetrations, sills, shelf angles, etc. Also, it should \r\n be installed at the top and bottom of the wall. It is imperative that \r\n flashing extend through the wall. It must not be stopped behind \r\n the face of the wall. See Fig. 10. \r\n \r\n Weepholes- Weepholes are placed at all flashing locations \r\n to permit any water that is collected on the flashing to exit the \r\n wall. Weephole spacing should not exceed 24 in. (600 mm) o.c., and \r\n if wicks are used, spacing should not exceed 16 in. (400 mm) o.c. \r\n See Fig. 11. \r\n \r\n \r\n \r\n Flashing and Weepholes \r\n FIG. 11 \r\n \r\n Air Space- It is recommended that the air space between the back of the brick and \r\n the sheathing be a minimum of 2 in. (50 mm). Air spaces larger than \r\n 3 in. (75 mm) require ties at closer spacing. \r\n \r\n Sheathing- Both sides of the studs must be sheathed \r\n with rigid sheathing material, i.e., exterior grade gypsum board, \r\n cement board, etc. Foam board or other rigid insulation is not recommended \r\n for use as sheathing. \r\n \r\n Moisture Barrier- It is recommended that a shingled \r\n layer of minimum 15-lb building paper, with the edges and ends lapped \r\n at least 6 in. (150 mm), be placed over the exterior sheathing as \r\n added protection against moisture entry. \r\n Selection of Materials . The selection of suitable and adequate \r\n materials for the successful performance of the brick veneer/steel \r\n stud wall system involves considerations other than just water penetration. \r\n Selection of suitable materials affects structural performance, durability, \r\n differential movement, construction techniques and maintenance, as \r\n well as water penetration concerns. Therefore, a separate section \r\n of this Technical Notes addresses selection of materials for \r\n this brick veneer/steel stud wall system. \r\n Construction Practices . The best design and detailing and \r\n the selection of the best materials can be subverted by poor construction \r\n practices in the field. These are some of the more important practices \r\n that should be followed: \r\n \r\n Storage of Materials- All materials at the jobsite \r\n should be stored off the ground and under adequate cover to prevent \r\n deterioration and contamination. \r\n \r\n Mortar Mixing- Mortar is the last jobsite manufactured \r\n material. It is recommended that some device for measuring sand be \r\n used in the batching of mortar. Proper sizing of the mortar mixer \r\n to use only full bags of portland cement and lime, and measuring the \r\n sand is the only manner in which consistency can be assured. See Technical \r\n Notes 8B for further information \r\n on controls for mixing mortar. \r\n \r\n Wetting of Units- It is important that brick \r\n which have an initial rate of absorption (suction) more than 30 g/30 \r\n sq in. be wetted and permitted to surface dry prior to laying. Otherwise, \r\n high suction units may not form proper bond to mortar, resulting in \r\n leaky walls. See Technical Notes 7B \r\n Revised. \r\n \r\n Filling of Mortar Joints- All mortar joints should \r\n be completely filled. This is especially true of head joints. Conversely, \r\n any joint or cavity not intended to receive mortar, i.e., air spaces, \r\n expansion joints, etc., should be kept clean and free of mortar and/or \r\n mortar droppings. \r\n \r\n Placement of Ties- Metal ties are an important part \r\n of the wall and help determine its strength, watertightness and general \r\n performance. Ties must be accurately spaced and fully embedded in \r\n mortar. \r\n \r\n Tooling of Mortar Joints- In addition to changing the \r\n appearance of the brickwork, the proper tooling of mortar joints enhances \r\n the watertightness of the wall. The tool should be slightly larger \r\n than the joint and should be of either Vee or Concave profile for \r\n the best results. A \"grapevine\" joint is also suitable, if struck \r\n with a proper jointer. \r\n \r\n Protection of the Work- Protection of the unfinished \r\n wall in place is extremely important. The entry of rain or snow into \r\n an unfinished brick wall may cause extreme cases of efflorescence \r\n and distress of the brick masonry. Of course, winter protection is \r\n mandatory. See Technical Notes 7 Series and 1 Series. \r\n \r\n \r\n CORROSION \r\n General \r\n \r\n There has been a great deal of discussion and debate about the occurrence \r\n of corrosion of the ties and other metal parts of the brick veneer/steel \r\n stud wall system. There is no definitive information on the life expectancy \r\n of ties and metal parts, nor on the amount of corrosion protection \r\n required. All masonry walls contain metal in one form or another. \r\n Further, corrosion is a natural occurrence in the often hostile environment \r\n of a masonry wall. \r\n \r\n Recommendations \r\n \r\n Considering this lack of definitive data on corrosion potential, \r\n and recognizing that corrosion is a naturally occurring phenomenon, \r\n the Brick Institute of America recommends the maximum available corrosion \r\n protection on all ties and fittings for this wall system, as indicated \r\n in the section SELECTION OF MATERIALS. Also, it is important to employ \r\n careful detailing and construction to reduce the entry of water into \r\n the wall system and drain it efficiently via flashing and weepholes. \r\n \r\n SELECTION OF MATERIALS \r\n General \r\n \r\n The selection of proper, suitable and adequate materials for the \r\n design and construction of brick veneer/steel stud wall systems is \r\n extremely important. Proper choices will affect many of the performance \r\n aspects of the wall, i.e., structural integrity, durability, differential \r\n movement, water penetration, corrosion resistance and ease of construction. \r\n For these reasons, detailed suggestions are made. \r\n \r\n Recommendations \r\n \r\n The following recommendations and cautions are offered for selecting \r\n materials and components for brick veneer/ steel stud wall systems: \r\n Brick. Brick are usually selected on the basis of their appearance, \r\n i.e., color, texture, scale, etc. Quality of brick units should be \r\n governed by the following ASTM standards: ASTM C 62 for Building Brick, \r\n ASTM C 216 for Facing Brick and ASTM C 652 for Hollow Brick. All \r\n brick units should be of Grade SW. Caution is suggested in selecting \r\n brick size. When tall units, i.e., over 4 in. (100 mm) nominal are \r\n used, it is more difficult to obtain full head joints. \r\n Mortar. Mortar should be limited to mixes containing portland \r\n cement, lime and sand. Admixtures and additives for workability are \r\n not recommended, nor are masonry cement mortars. Type N mortar should \r\n be used in all veneer except in areas of expected high wind loads, \r\n i.e., over 25 psf (1.2 kPa), in which case Type S mortar should be \r\n used. See Technical Notes 8 Series. \r\n Steel Studs. Steel studs should be of a configuration and \r\n gage to provide sufficient stiffness, as controlled by the maximum \r\n allowable deflection, under full wind load, of L/600. In addition, \r\n steel studs should be a minimum of 18-ga steel and should be zinc-coated \r\n to conform to ASTM A 525, Grade G-90. Field welding of studs should \r\n not be permitted. Welding of 14-ga studs as part of shop fabrication \r\n may be permitted. \r\n Sheathing. Exterior sheathing on steel studs should be rigid \r\n and suitably fastened with corrosion-resistant screws. The sheathing \r\n should be of exterior grade gypsum board or cement board, not less \r\n than 1/2 in. (12 mm) in thickness; or of exterior grade plywood, not \r\n less than 3/8 in. (9 mm) in thickness. The fire resistance rating \r\n may be affected by the use of combustible material. \r\n Screws. Screws used to attach the exterior sheathing and the \r\n ties should be as non-corrosive as possible. Screws are available \r\n which are cadmium-plated, hot-dipped galvanized, and composite zinc \r\n and polymer-coated. Although the polymer coatings do not have the \r\n self-healing properties of zinc or cadmium, they offer acceptable, \r\n long-term protection. The use of stainless steel or copper-coated \r\n screws is not recommended as these can react galvanically with zinc \r\n coatings or cadmium-coated steel. \r\n Ties. Flat, corrugated ties should not be used. Ties \r\n should be two-piece adjustable ties with wire embedded at least 2 \r\n in. (50 mm) into the brick wythe. Ties should be hot-dipped galvanized \r\n in accordance with ASTM A 153, Class B-3. In addition, ties should \r\n not have mechanical play in excess of 0.05 in. (1.2 mm) and \r\n should not deform over 0.05 in. (1.2 mm) for 100-lb load in \r\n either tension or compression. \r\n Shelf Angles. Shelf angles should be of structural steel, \r\n adequately designed for strength and properly attached to the structure \r\n and anchored so as to prevent excessive deflection or rotation. Limitation \r\n on shelf angle deflection should be L/600, but not to exceed 0.3 in. \r\n (7.5 mm). Galvanized steel shelf angles should be considered. \r\n Flashing. Flashing material should be sufficiently tough and \r\n flexible so as to resist puncture and cracking. In addition, it should \r\n not be subject to ultra-violet deterioration or other deterioration \r\n when in contact with metal parts, with mortar or with elastic sealants. \r\n Flashing materials are generally formed from sheet metals, bituminous-coated \r\n membranes, vinyls or combinations thereof. The selection is largely \r\n determined by cost and suitability. Acceptable bituminous membranes \r\n do not include asphalt-impregnated felt. The cost of flashing \r\n materials varies widely. It is suggested, however, that only superior \r\n materials be selected, since replacement in the event of failure is \r\n extremely expensive. See Technical Notes 7A \r\n Revised. \r\n Sealants. Sealants should be selected for their durability, \r\n extensibility, compressibility and their compatibility with other \r\n materials. In all cases, the use of good grade, polysulfide, butyl \r\n or silicone rubber sealants is recommended. Oil-based caulks should \r\n not be used. Regardless of the type of sealant selected, proper \r\n priming and backer rods are a must. Sealant materials should be selected \r\n to comply with ASTM C 920. See Technical Notes 7 Series. \r\n \r\n MAINTENANCE \r\n General \r\n \r\n Most brick masonry walls are virtually maintenance free. If they \r\n are properly designed, detailed and constructed, maintenance is of \r\n little concern. \r\n \r\n Recommendations \r\n \r\n Recognizing that the brick veneer/steel stud wall system is a relatively \r\n recent innovation, having a great deal of potential for problems and \r\n distress, it is suggested that the walls be inspected periodically \r\n to ascertain performance and identify any potential problems. The \r\n Brick Institute of America suggests a minimum of annual inspections \r\n and ideally, seasonal inspections (see Technical Notes 7F ). \r\n Such an inspection should address sealant joints, plumbness of \r\n the wall, cracking, etc. In this way, repairs and corrections can \r\n be instituted prior to the occurrence of severe problems. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes is one of a series which deals with brick \r\n veneer. This issue is primarily concerned with the design and construction \r\n of the brick veneer/steel stud wall system used as panel walls in \r\n other than residential construction. Other Technical Notes in \r\n this series address brick veneer as applied to low-rise new and existing \r\n residential buildings and to thin brick veneer. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and on the experience of the technical \r\n staff of the Brick Institute of America. The information and recommendations \r\n contained herein, if followed with the use of good technical judgment, \r\n will avoid many of the problems discussed. Final decisions on the \r\n use of the design, details and materials discussed are not within \r\n the purview of the Brick Institute of America and must rest with the \r\n project designer, owner, or both. \r\n \r\n REFERENCES \r\n \r\n The following publications were used in the preparation of this Technical \r\n Notes, and are suggested for more detailed information on specific \r\n subjects. \r\n \r\n \r\n 1. Technical \r\n Notes on Brick Construction 1 , \r\n \"Cold Weather Masonry Construction-Construction and Protection\", \r\n Brick Institute of America, McLean, Virginia, Reissued December \r\n 1982. \r\n 2. Technical \r\n Notes on Brick Construction 2 , \r\n \"Glossary of Terms Relating to Brick Masonry\", Brick Institute of \r\n America, McLean. Virginia. Reissued May 1987. \r\n 3. Technical \r\n Notes on Brick Construction 7 \r\n Series, dealing with the subject of Water Resistance of Brick Masonry, \r\n Brick Institute of America, Reston, Virginia, Feb. 1985, March 1985, \r\n April 1985, Reissued November 1981, November 1981, Reissued February \r\n 1987 and Reissued January 1987. \r\n 4. Technical \r\n Notes on Brick Construction 8 \r\n Series, dealing with the subject of Portland Cement-Lime Mortars \r\n for Brick Masonry, Brick Institute of America, McLean, Virginia, \r\n Reissued February 1987, Oct-Nov. 1972 and Reissued May 1987. \r\n 5. Technical \r\n Notes on Brick Construction 18 \r\n Series, dealing with the subject of Differential Movement, Brick \r\n Institute of America, McLean, Virginia, Reissued July 1984, Reissued \r\n December 1980 and Reissued December 1980 \r\n 6. Technical \r\n Notes on Brick Construction 21 \r\n Series, dealing with the subject of Brick Masonry Cavity Walls, \r\n Brick Institute of America, Reston, Virginia, Reissued May 1987, \r\n Reissued July 1986, Reissued January 1987 and May-June 1978. \r\n 7. \"Performance \r\n Evaluation of Brick Veneer With Steel Stud Backup\", J.O. Arumala \r\n and R.H. Brown, Clemson University, Clemson, South Carolina, 1982. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60098,"ResultID":176330,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 28C - Thin Brick Veneer \r\n - Introduction \r\n Jan. 1986 (Reissued Feb. 1990) \r\n \r\n Abstract : This Technical Notes is an introduction to thin \r\n brick veneer, and covers the brick units, several application procedures \r\n and its advantages and disadvantages. It is not the purpose of this \r\n Technical Notes to cover all aspects of the use \r\n of thin brick veneer, nor to make specific recommendations for installation. \r\n Future issues on the topic of thin brick veneer will address, in detail, \r\n design, detailing and construction requirements. \r\n \r\n Key Words : adhered veneer , brick, panels , \r\n prefabrication, thick set, thin brick , thin set. \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes addresses thin fired clay units, often \r\n referred to as thin brick, as interior or exterior wall coverings: \r\n Thin brick veneer is a relatively new product which is seeing increasing \r\n popularity in commercial, residential and do-it-yourself markets. \r\n The kinds of thin brick units discussed are formed from shale and/or \r\n clay, and are kiln-fired. These thin brick units are much like facing \r\n brick (ASTM C 216), except they are approximately 1/2 to 1 in. (12 \r\n to 25 mm) thick. The face sizes are normally the same as conventional \r\n brick and therefore, when in place, give the appearance of a conventional \r\n brick masonry wall. ASTM C 1088 Thin Veneer Brick Units made from \r\n Clay or Shale covers two grades for exposure conditions to weather \r\n which are defined as Exterior and Interior. The three types of thin \r\n veneer brick are based on appearance and are defined as TBS, TBX and \r\n TBA. Minimum compressive strengths are not required in C 1088 as there \r\n is no way to test thin brick in compression. \r\n There were early uses of thin brick. In the early 1950s, the Structural \r\n Clay Products Research Foundation (now the Brick Institute of America) \r\n began the development of \"SCR Re-Nu-Veneer\", a 3/4 in. (19 mm) thick \r\n fired clay unit which had Norman size nominal face dimensions (2 - \r\n 2/3 in. by 12 in. [68 mm by 305 mm]). The decision to begin development \r\n of this product was due to marketing research which recognized remodeling \r\n and reveneering areas as substantial markets for a thin clay veneer \r\n wall covering. In addition to developing the thin units, the Foundation \r\n developed special clips to attach the units to an existing wall, mortar \r\n for grouting the joints and a power-driven grouting gun. Locations \r\n were chosen to test the product, manufacturers were licensed to produce \r\n the units and applicators were licensed to install the \"Re-Nu-Veneer\". \r\n After approximately 4 years of effort, work was discontinued on the \r\n project. \r\n Today, thin brick are being installed using a variety of procedures. \r\n In Japan and in the United States, thin brick have been placed into \r\n forms and cast integrally with concrete, thus providing a very attractive \r\n architectural precast concrete panel. Another procedure involves bonding \r\n thin brick to a 16 in. by 48 in. (406 mm by 1220 mm) substrate, resulting \r\n in small, lightweight, easily installed modular panels. Ceramic tile \r\n installation techniques are often used to install the brick units, \r\n either at the jobsite or on prefabricated panels, and homeowners are \r\n renovating with do-it-yourself thin brick products. \r\n This Technical Notes addresses thin brick units, several methods \r\n for installing thin brick, as well as some of the advantages and disadvantages \r\n of thin brick veneer. \r\n \r\n THIN BRICK UNITS \r\n \r\n Thin brick are available in various sizes, colors and textures. The \r\n most commonly found face size is standard modular with nominal dimensions \r\n of 2-2/3 in. by 8 in. (68 mm by 203 mm). The actual face dimensions \r\n vary slightly among manufacturers, but are typically 3/8 in. to 1/2 \r\n in. (10 mm to 13 mm) less than the nominal dimensions. The economy \r\n size unit is 50% longer and higher, but this difference goes virtually \r\n unnoticed since the aspect ratio (length to height) is the same for \r\n both the standard and the economy modular units. The economy modular \r\n face size, 4 in. by 12 in. (102 mm by 305 mm), is popular for use \r\n in large buildings because productivity is increased, and the units \r\n size decreases the number of visible mortar joints, thus giving large \r\n walls a more pleasing appearance by reducing the visual scale of the \r\n wall. Other sizes, such as Norwegian, 3-in. (76 mm), non-modular, \r\n oversize, etc., may be available. Table 1 contains face sizes of several \r\n modular brick units; however, thin brick may not be available in each \r\n size. It is advisable to check with individual manufacturers or distributors \r\n regarding sizes available in a particular area. Figure 1 illustrates \r\n the various types of thin brick units. \r\n \r\n \r\n \r\n \r\n \r\n Thin Brick Units \r\n FIG. 1 \r\n \r\n As with all other fired clay or shale products, color depends on \r\n the chemical composition of the raw material, the intensity of firing \r\n and controls used in the firing. The color ranges for thin brick units \r\n are as unlimited as those for other fired clay brick. The texture \r\n of thin brick units depends on the method of manufacture and the surface \r\n treatment used prior to firing. Also, some manufacturers provide glazed \r\n thin brick units. \r\n The physical properties, such as modulus of rupture and compressive \r\n strength of the thin units, depend on the raw materials and methods \r\n of molding or forming the units. Fire resistance properties of thin \r\n brick construction have not been evaluated. But, because the units \r\n are made from fire clay or shale, it is likely that the overall performance \r\n of a wall system would be improved as compared to non-masonry sidings. \r\n Thermal resistivity of thin brick is probably not significantly different \r\n than that of solid face brick; however, because of the units thickness, \r\n the overall resistance would be very little. Likewise, because of \r\n the thickness, the units would contribute little mass for thermal \r\n storage. \r\n Primarily, thin brick functions as an architectural wall covering \r\n that has the maintenance-free benefits of conventional brick masonry. \r\n Secondarily, thin brick will provide some protection to the material \r\n over which it is applied. In comparison to conventional brick masonry, \r\n thin brick will have less fire resistance, sound resistance, structural \r\n strength, thermal mass or insulation properties. \r\n \r\n METHODS OF THIN BRICK INSTALLATION \r\n Adhered Veneer \r\n \r\n Adhered veneer relies on a bonding agent between the thin brick units \r\n and the backup substrate. Adhered veneer construction may be classified \r\n as either thin bed set or thick bed set. \r\n Thin Set . The thin bed set procedure typically utilizes an \r\n epoxy or organic adhesive, and is normally used on interior surfaces \r\n only. For areas subject to dampness, only clear and dry masonry surfaces \r\n or concrete surfaces should be used for backup. For dry locations, \r\n the backing material (substrate) may be wood, wallboard, masonry, \r\n etc. A cross-section depicting a wood frame wall upon which thin brick \r\n veneer (thin set procedure) is installed is shown in Fig. 2. \r\n \r\n \r\n \r\n \r\n \r\n Thin Set Interior Finish Over Wallboard \r\n FIG. 2 \r\n \r\n Thick Set . \r\n The thick bed set procedure is used on interior and exterior surfaces. \r\n The backing material may be masonry, concrete, steel or wood stud \r\n framing. The thick bed setting procedure over concrete masonry is \r\n illustrated in Fig. 3. The wire lath shown in Fig. 3 may be eliminated \r\n if the masonry wall is heavily scarified (sand-blasted). (Williams, \r\n Griffith, Jr., \"New Bricklike Tile Veneer\", Building Standards , \r\n July-August, 1982). For applications over steel studs, procedures \r\n are similar to those used for concrete or masonry backup; however, \r\n wallboard and building felt must be installed over the studs before \r\n the lath and mortar bed are placed. Thick bed setting of thin brick \r\n over steel studs is shown in Fig. 4. \r\n \r\n \r\n \r\n Thick Set Method Over Masonry \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n Thick Set Method Over Steel Stud Framing \r\n FIG. 4 \r\n \r\n \r\n \r\n Prefabrication \r\n \r\n Prefabrication, utilizing thin brick veneer units, has been accomplished \r\n using the \"casting\" method. This process involves the combination \r\n of thin brick, grout and/or concrete cast into a prefabricated panel \r\n (similar to architectural pre-cast concrete). This process requires \r\n the use of forms, a method of placing the units, and a system for \r\n grouting. The usual practice is to place the units face down into \r\n a form (or waffle mold), and place a very fluid grout over the back \r\n surface of the units. The grout flows into the space between the units, \r\n thus forming the appearance of mortar joints (see Fig. 5). Concrete \r\n and reinforcement are placed over the grout to provide structural \r\n support. The installation of a completed panel is shown in Fig. 6. \r\n \r\n \r\n \r\n Grouting Over Back Surface of Thin Brick Panel \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Erection of Panel \r\n FIG. 6 \r\n \r\n The use of steel studs and the thick bed setting procedure is another \r\n method of prefabrication with thin brick (see Figs. 4, 7 and 8). The \r\n use of thin brick for prefabrication of this type results in panels \r\n which are lighter than many of the conventional prefabricated panel \r\n systems. \r\n \r\n \r\n \r\n \r\n \r\n Positioning Prefabricated Panel \r\n FIG. 7 \r\n \r\n \r\n \r\n Electric Winch Used To Lower Panels Over Edge of Slab \r\n FIG. 8 \r\n \r\n There are several advantages of prefabrication over laid-in-place \r\n masonry. By using panelized construction, the need for on-site scaffolding \r\n is eliminated, which can be a significant cost savings in masonry \r\n construction. If an off-site plant is used, the work and storage areas \r\n for materials at the jobsite are reduced, resulting in a less congested \r\n jobsite. If proper scheduling of delivery is maintained, the panels \r\n can be erected as they are delivered, eliminating any need for panel \r\n storage at the site. One of the distinct advantages of the factory \r\n set-up is that it permits year-round work and multi-shift workdays. \r\n The use of prefabricated masonry may eliminate the need for, or actually \r\n provide, the means of winterizing the structure. \r\n The use of panelization makes possible the fabrication of complex \r\n wall shapes. These shapes can be accomplished with ease. Complicated \r\n shapes with returns, soffits, arches, etc., are accomplished by using \r\n jigs, forms and templates. Repetitive usage of these shapes can lower \r\n costs appreciably. \r\n Prefabrication allows for the use of stringent quality control. Mortar \r\n batching systems can be tightly controlled, and curing conditions, \r\n temperature and humidity can also be controlled. Panelization on some \r\n projects may save construction time. It is possible for the masonry \r\n panels to be built before ground-breaking for the project, thus keeping \r\n far enough ahead of the in-place construction work to permit panel \r\n erection when needed. \r\n As with any construction method, prefabrication has inherent advantages \r\n as well as disadvantages. The use of prefabricated brick masonry is \r\n limited to use with certain types of construction. The designer should \r\n be aware of the limitations of prefabricated masonry. The size of \r\n brick masonry panels is limited primarily by transportation and erection \r\n requirements. Architectural plan layout may, in some cases, preclude \r\n the use of prefabricated brick masonry. Another disadvantage of prefabricated \r\n brick masonry, as in other panel systems, is the absence of adjustment \r\n capabilities during the construction process. In-place masonry construction \r\n permits the craftsman to build masonry to fit the other elements of \r\n the structure by adjusting joint thicknesses over a large area so \r\n that they are not noticeable. This is not possible with prefabricated \r\n elements. The use of prefabricated elements sometimes requires that \r\n other trades build to accuracies beyond the standard construction \r\n tolerances of those trades. \r\n \r\n Modular Panels \r\n \r\n A relatively new method of thin brick application is becoming popular \r\n in the United States and Canada. Modular panels are produced by several \r\n different companies and each system differs slightly. Basically, thin \r\n brick units are adhered to modular panels in the factory, or at the \r\n jobsite. The modular panels have dimensions of approximately 16 in. \r\n by 48 in. (406 mm by 1220 mm), as shown in Fig. 9. The backing materials \r\n to which the brick units are adhered may consist of polystyrene, polyurethane, \r\n cementitious board, asphalt-impregnated fiber board, plywood, aluminum, \r\n or a combination of these materials, depending on the manufacturer. \r\n \r\n \r\n \r\n Thin Brick Panel \r\n FIG. 9 \r\n \r\n The panels weigh approximately 35 lb (16 Kg), which is light enough \r\n for one person to handle easily. Installation techniques vary only \r\n slightly among the different manufacturers. At the time of this writing \r\n (1985) most, but not all, systems require that the head and bed joints \r\n between the thin brick units be grouted after the panels are secured \r\n to the supporting wall. \r\n The application of the modular panels is illustrated in Fig. 10. \r\n Since the construction materials and application methods vary among \r\n manufacturers, the user must select the panel with installation techniques \r\n and materials which best fit the job requirements. Measures must be \r\n taken to prevent water penetration and subsequent corrosion, especially \r\n for multi-story buildings which are subjected to severe weather conditions. \r\n \r\n \r\n \r\n Modular Panels Over Frame Construction \r\n FIG. 10 \r\n \r\n BUILDING CODE ACCEPTANCE \r\n \r\n The model building codes (Building Officials and Code Administrators, \r\n International, 4051 West Flossmoor Road, Country Club Hills, Illinois; \r\n Southern Building Code Congress International, Inc., 900 Montclair \r\n Road, Birmingham, Alabama; International Conference of Building Officials, \r\n 5360 South Workman Mill Road, Whittier, California) do not specifically \r\n address the usage of thin brick veneer in all of the methods of installation \r\n mentioned in this Technical Notes. Thick set and thin set adhered \r\n veneer have been used for many years with thin brick units, ceramic \r\n tile and architectural terra cotta; therefore, these methods are addressed \r\n in the model codes. The other methods, such as prefabrication or modular \r\n panels, may have to be approved on a case-by-case basis, through research \r\n compliance reports from the various model code agencies, or through \r\n code changes. \r\n \r\n ADVANTAGES AND DISADVANTAGES OF THIN BRICK VENEER \r\n \r\n Some of the advantages of thin brick veneer are: \r\n 1. Interior thin brick veneer finishes can be applied by homeowners \r\n or other moderately skilled craftsmen. \r\n 2. Thin brick veneer is more durable and longer lasting than aluminum, \r\n wood or vinyl sidings. \r\n 3. Prefabrication with thin brick veneer is easily and economically \r\n done. \r\n 4. Better sound and fire resistance properties may be obtained using \r\n thin brick veneer than with some non-masonry sidings. \r\n 5. Thin brick units are more durable than imitation brick units made \r\n from gypsum, cement or plastics. \r\n 6. Walls built with thin brick units are lighter in weight than conventional \r\n masonry veneer. \r\n 7. Cleanup costs often incurred in conventional brick veneer construction \r\n may be reduced. \r\n 8. Year-round installation is possible. \r\n 9. May be used where structural support for conventional brick veneer \r\n is not available. \r\n \r\n Some of the disadvantages of thin brick veneer are: \r\n 1. The durability and overall quality of thin brick veneer systems \r\n may not be equivalent to conventional brick veneer. \r\n 2. Thin brick veneer does not provide the structural properties of \r\n conventional brick veneer. \r\n 3. Sound and fire resistance properties are less than those of conventional \r\n brick masonry veneer. \r\n 4. Thin brick veneer does not provide the thermal mass of conventional \r\n brick veneer. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes has discussed a relatively new product \r\n in the masonry industry - thin brick veneer. Walls faced with thin \r\n brick veneer may look like conventional brick masonry walls, yet weigh \r\n considerably less. Thin brick veneer is popular with homeowners for \r\n redecorating or renovating because the homeowners can obtain an attractive \r\n finish and may do the work themselves. \r\n Thin units are also used in commercial construction, applied one \r\n unit at a time, or applied in large prefabricated panels. Small, lightweight, \r\n interlocking modular panels are available and are installed as a siding. \r\n Thin brick veneer can provide the same architectural effects as conventional \r\n brick masonry, but does not have the same structural, thermal or fire \r\n resistance qualities. \r\n The information contained in this Technical Notes is based \r\n on the available data and the experience of the technical staff of \r\n the Brick Institute of America. Final decisions on the use of information, \r\n details and materials as discussed in this Technical Notes are \r\n not within the purview of the Brick Institute of America and must \r\n rest with the project designer, owner, or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60099,"ResultID":176331,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 29 - Brick in Landscape \r\n Architecture - Pedestrian Applications \r\n July 1994 \r\n \r\n Abstract : This Technical Notes \r\n describes brick paving systems used in landscape design. Landscape \r\n architecture and its relationship to brick masonry is covered. Master \r\n planning and environmental aspects of landscape architecture are briefly \r\n discussed. Applications covered include patios, walks, steps and ramps. \r\n Materials and methods of construction of flexible and rigid paving \r\n applications, citing the most critical requirements, are outlined. \r\n \r\n Key Words : landscape architecture, patios, pavements, ramps, \r\n steps, terraces. \r\n \r\n INTRODUCTION \r\n \r\n Landscape architecture is the planning and design of elements relating \r\n to the land, including trees, plants, paving, streets and sometimes \r\n structures. The design must take into account all of these elements \r\n and their relation to each other. Brick as a landscape material is \r\n an important design element. Brick paving applications can be used \r\n to create a pathway through the landscape, delineating pedestrian \r\n elements from natural elements. Since brick is made from the earth \r\n and is small in scale, it fits into many landscaping plans. \r\n This Technical Notes covers the topic of brick as it relates \r\n to landscape architecture. It also covers environmental issues concerning \r\n the use of brick and brick paving systems in landscaping. Paving applications \r\n addressed include patios, walks, steps and ramps. Design, installation \r\n and material selections are discussed. Other installation practices \r\n that must be considered, but are not included in this Technical \r\n Notes , are edging, expansion joints and membranes. Other Technical \r\n Notes in this series cover garden walls and other miscellaneous \r\n landscape applications. Paving systems and related issues are discussed \r\n in more detail in the Technical Notes 14 Series [5,6]. \r\n \r\n LANDSCAPE ARCHITECTURE \r\n \r\n The art of landscape architecture is more than the placement of trees \r\n and shrubs. Often it involves the development and planning of large \r\n areas within cities and suburban areas. This is typically organized \r\n through the development of a master plan. Alternately, landscaping \r\n may be on a much smaller scale, as in the design of a small garden. \r\n The landscape architect must always consider certain issues, including \r\n aesthetics, harmony, continuity/unity, accessibility, economy and \r\n other design parameters. Material and system selections are usually \r\n based on these issues. \r\n Materials can be broadly classified as either landscape materials \r\n or hardscape materials. Landscape materials include trees, plants, \r\n grasses, soil and gravel. Hardscape materials include brick, stone, \r\n concrete and other hard materials. A comprehensive landscape plan \r\n usually combines both landscape and hardscape features. \r\n \r\n Master Planning \r\n \r\n The landscape architect plays a much larger role with all land development \r\n issues today than in the past. Buildings and their relationship and \r\n integration into the site have become increasingly important design \r\n issues. This may apply to entire subdivisions and cities as well. \r\n A master plan is usually developed to incorporate all elements into \r\n a comprehensive land development design. Master plans will dictate \r\n where open spaces should be located and locations of buildings, pavements \r\n and walks. Brick can play an important part in the development of \r\n master plans since it can be used as a common thread throughout an \r\n entire project. This includes walls, pavements, fountains, planters, \r\n fences, steps and other miscellaneous landscape uses. Continuity throughout \r\n the project can be achieved by using brick in many of these applications. \r\n \r\n \r\n Environmental Issues \r\n \r\n There is now more pressure than ever to consider the environmental \r\n effects of a particular landscape plan. A movement, often termed \"sustainable \r\n development\", considers the environmental impact of land development \r\n before, during and after design. Environmental issues, such as storm \r\n water runoff and the lack of water, are becoming more important as \r\n landscape architects look more closely at potentially threatening \r\n issues. \r\n Sustainable Development . Sustainable development can be defined \r\n as development that meets the needs of the present without compromising \r\n the future. In the past, sites were often dramatically altered without \r\n adequate consideration of the environmental impact. As with all designs, \r\n compromises must be made to achieve the design requirements. Sustainable \r\n development takes into account the effects of materials used in the \r\n landscaping plan on the environment. The embodied energy and the effects \r\n of the manufacturing of the material on the environment are closely \r\n considered. Brick is a material made from clay and shale, some of \r\n the earths most abundant materials. The energy used to make brick, \r\n which is termed its embodied energy, is less than that of concrete, \r\n steel and many other materials [3]. Since brick is inert, it does \r\n not pose any long-term environmental threats. \r\n Water Issues . Environmental concerns have been raised regarding \r\n both storm water runoff and the lack of water in some areas. When \r\n many parts of the landscape are being covered by impermeable surfaces, \r\n storm water runoff becomes a larger problem. The amount of water that \r\n drains off of a shopping center parking lot, for example, can be quite \r\n large causing flooding or erosion. Thus, the size of storm sewers \r\n and catch basins must be increased in size accordingly, putting more \r\n stress on the infrastructure. Conversely, some areas of the country \r\n are so arid, they cannot support plant life. \r\n \r\n Porous Pavements - Most hardscaping materials, such \r\n as concrete or asphalt, will not allow water back into the ground. \r\n This is also true of rigid (mortared) brick pavements and some flexible \r\n (mortarless) brick pavements over an impermeable base. These systems \r\n can have a negative effect in urban areas which include trees as a \r\n part of the urban landscape. Trees can die due to lack of water and \r\n nutrients when surrounded by impervious hardscapes. In an effort to \r\n provide water for trees, grates have been used, but their small size \r\n can inhibit proper tree growth. Soil and mulch have also been used \r\n around trees, but usually become compacted and allow rain to evaporate \r\n away too quickly. When water infiltration into the ground is desired, \r\n a pavement which allows water to percolate back into the ground should \r\n be used [4]. One alternative that can help water infiltration and \r\n reduce storm water runoff is the use of porous pavements. \r\n A porous pavement allows water to filter through it, percolate back \r\n into the ground and replenish the ground water. In most cases, mortarless \r\n brick paving over an aggregate base can be constructed to allow water \r\n to percolate into the ground. However, to allow more percolation to \r\n occur, the pavement must have joints between the pavers at least 1/4 \r\n in. (6 mm) wide. The joints allow water to enter easily and permeate \r\n to the base. The base should be an open-graded aggregate, such as \r\n free- draining gravel or sand, to allow percolation. Although porous \r\n pavements allow storm water runoff to be directed back into the ground \r\n water system, it may go against usual pavement design practice. In \r\n a flexible brick pavement, it is desirable to have a dense base to \r\n resist loads from traffic above and from frost heave from below. Using \r\n an open-graded base may not provide the stable base that is needed. \r\n \r\n To use an open-graded base under brick paving, some simple recommendations \r\n must be followed. The open-graded base must be compacted appropriately. \r\n Guidelines exist for the proper construction of open-graded bases \r\n [6]. A membrane, such as a geotextile or filter fabric membrane, must \r\n be placed between the sand setting bed and the open-graded base to \r\n avoid settling of the sand into the voids of the base. A geotextile \r\n may also be required between the base and the soil or subgrade to \r\n prevent soil from pumping up into the base. The size of the joints \r\n can be problematic when large amounts of water constantly run across \r\n the pavement. Jointing sand may wash out in areas when the joints \r\n are larger than 1/4 in. (6 mm). Another issue to consider is that \r\n interlock of the pavers will not be achieved when the joints are larger \r\n than 1/4 in. (6 mm). Interlock of the pavement occurs when the pavers \r\n are compacted into the sand setting bed and the entire pavement - \r\n i.e. pavers, setting bed, and base - lock together and act to withstand \r\n the loads as a single element. A flexible brick paving system can \r\n be designed for improved percolation, but interlock of the pavement \r\n cannot be expected when sand-filled joints are larger than 1/4 in. \r\n (6 mm). \r\n \r\n Xeriscapes - Xeriscapes are defined as water-efficient \r\n landscapes which not only require less water to grow vegetation, but \r\n have a reduced need for mowing, fertilizing and pesticide application. \r\n They may be used in certain areas of the country, such as parts of \r\n Southern California, Arizona and Nevada, where water supplies are \r\n low or unreliable. Instead of introducing planting areas that require \r\n large amounts of water, it may be prudent to use brick in the place \r\n of plants. In this manner, reliance on the local water system, expensive \r\n watering systems and plant maintenance can be reduced. Wildfires in \r\n arid regions of the country are another concern which may require \r\n the use of non-combustible materials adjacent to homes. Brush and \r\n shrubs can act as fuel sources for wildfires. Brick paving adjacent \r\n to the house can act as a fire break. To offset the use of all of \r\n the hardscape materials, patterns are laid in the pavement to give \r\n the impression of plantings. Obviously, this must fit in with the \r\n entire landscaping plan. \r\n \r\n Aesthetics \r\n \r\n One of the most important features that a landscape architect faces \r\n is that of appearance. The look of any design can evoke strong feelings, \r\n good or bad. So it is important that the aesthetics of the project \r\n be examined closely. As in all architecture, form, color and pattern \r\n are the vehicles for achieving a certain aesthetic appeal. Brick paving \r\n utilizes its variety of size, shape, color and pattern to conform \r\n to the chosen theme. Brick pavers are produced in a variety of sizes. \r\n The most common sizes are shown in Table 1. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Check \r\n with manufacturer for availability of chamfers. \r\n \r\n \r\n \r\n \r\n Alternative sizes and shapes of pavers can also be manufactured or \r\n cut from standard units into the desired shape. For example, radial \r\n brick are often used to create curves or circles in the pavement, \r\n as shown in Figure 1. \r\n \r\n \r\n \r\n Special Brick Shapes \r\n FIG. 1 \r\n \r\n The color of brick pavers range from buffs to dark browns, pinks \r\n to deep reds. The pavers can be a uniform color or there can be a \r\n range of colors. The color of brick will not fade over time. Different \r\n colors can be arranged within a pavement to achieve a truly dramatic \r\n look. \r\n Almost any pattern is possible with brick. The pattern can be simple \r\n diagonals or more complicated cross or weave patterns. Different colored \r\n units can be used to create a flow pattern for pedestrian traffic. \r\n It may suggest a special theme used throughout the landscape plan. \r\n The more traditional brick paving patterns are shown in Fig. 2. Brick \r\n can also be cut to achieve a pattern; although in some cases, specially \r\n shaped pavers may be used. \r\n \r\n \r\n \r\n Brick Paving Patterns \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n BRICK PAVING SYSTEMS \r\n \r\n Brick paving can be classified by two basic systems; flexible and \r\n rigid. Flexible brick pavements usually consist of mortarless brick \r\n paving over a sand setting bed and an aggregate base. Rigid brick \r\n pavements consist of mortared brick paving over a concrete slab. Mortarless \r\n brick paving can be used over any base. Mortared brick paving must \r\n be supported by an adequate concrete slab or the mortar joints or \r\n pavers may crack if the base is not sufficiently rigid. Examples of \r\n flexible and rigid brick pavements are shown in Figs. 3 and 4, respectively. \r\n \r\n \r\n \r\n \r\n Flexible Brick Paving \r\n FIG. 3 \r\n \r\n \r\n \r\n Mortarted Brick Paving \r\n FIG. 4 \r\n \r\n Although a flexible brick paving system is generally recommended, \r\n there are certain applications where rigid brick paving is desired. \r\n An example is brick steps, which requires the edges to be mortared \r\n together to keep the brick in place. The major advantages of using \r\n a flexible pavement include easier repairs to utilities beneath the \r\n pavement and usually lower installation costs. \r\n The design of brick paving systems can be rather complex, depending \r\n on the size of the project. Technical Notes 14 Series discusses \r\n many of the design and construction parameters in more depth than \r\n in this Technical Notes . Only critical or unique information \r\n is contained here. \r\n \r\n Patios and Walks \r\n \r\n Some of the most widely used features of landscape design to which \r\n brick is adapted are patios and walks. Patios may be outdoor extensions \r\n of the indoor living space and supplement the activities of the occupant. \r\n Patios are often adjacent to living, family or dining rooms. Patios \r\n may be built as terraces, which are raised levels of earth supported \r\n on one or more sides by a wall or bank. A terrace is used to extend \r\n living space along a hillside. \r\n Walks are often effectively used to provide an interesting and inviting \r\n entrance path to a garden or home. Walks may be used to define pedestrian \r\n travel routes and can provide geometric patterns in formal garden \r\n layouts. They can also serve as a path through a natural or garden \r\n setting. \r\n Bases . The proper design and construction of the base is often \r\n the most critical element for long-term performance of the paving \r\n assembly. Insufficient base thickness or improperly compacted bases \r\n will lead to undulations (rutting) or cracking of the pavement. Appropriate \r\n base thickness depends on the type of loading and weathering it will \r\n receive. Most residential patios and terraces will only receive pedestrian \r\n traffic; therefore, the thickness may depend more on its resistance \r\n to frost heave. The minimum recommended base thickness is 4 in. (200 \r\n mm) for concrete, asphalt and aggregate bases. Thicker bases and the \r\n use of a subbase may be required in areas with poor soil conditions \r\n or soils that are constantly saturated. In these cases, the base should \r\n be increased in thickness based on local requirements. \r\n Drainage . Drainage is another key design feature which affects \r\n long-term performance. Poor drainage will allow water to stand on \r\n the pavement and saturate the brick pavement. Problems resulting from \r\n poor drainage include deterioration of the paving, moss and algae \r\n growth and slippery pavements. Therefore, it is important to slope \r\n the pavement to keep water from collecting. Primary drainage of all \r\n pavements should occur on the surface. Drainage should occur away \r\n from buildings or other walls. For brick pavements, a slope of 1/8 \r\n to 1/4 in. per foot (1 to 2 mm per 100 mm) is recommended. Lesser \r\n slopes will allow water to accumulate. Steps and ramps must also be \r\n sloped to avoid standing water. Treads of steps should slope 1/8 to \r\n 1/4 in. per foot (1 to 2 mm per 100 mm). Cross-slopes of the pavement \r\n help drain water off of the pavement, but the slope should not exceed \r\n 3 percent. Flexible brick pavements may allow some water to percolate \r\n down into the ground. In this case, subsurface drains may be necessary \r\n to remove water from the system. \r\n \r\n Steps and Ramps \r\n \r\n Steps and ramps are used to connect different levels for easy access. \r\n Steps have traditionally been used to allow movement up and down steep \r\n slopes or within structures. The size and configuration of steps is \r\n governed by a combination of physical human dimensions and aesthetics. \r\n Ramps are used on gentle slopes and are used to provide access for \r\n the physically impaired. Since ramps have low slopes, they will require \r\n more space than steps. Brick has been used successfully in all configurations \r\n of steps and ramps mainly because it is a small element which permits \r\n numerous configurations. Model building codes often dictate certain \r\n criteria for steps and ramps such as riser-tread relationships and \r\n minimum slip resistance. Other design issues that should be considered \r\n include structural support of the steps or ramps and other safety \r\n issues. Steps should be a minimum width of 60 in. (1.5 m) for public \r\n spaces, or 42 in. (1.1 m) for private residences. There should be \r\n at least two, preferably three or more steps, in a stepped walkway, \r\n since single steps can be overlooked and lead to trips. \r\n Step Riser - Tread Relationships . Riser-tread relationships \r\n have been studied for many years. Most steps are constrained to fit \r\n into a set elevation at the top and the bottom of the steps. For these \r\n steps, riser-tread relationships have been developed for safe and \r\n efficient use. In other areas, such as plazas, the tread dimension \r\n may not be constrained, which allows freedom of design. In these areas, \r\n riser and tread dimensions will be dictated by human dimensions and \r\n appearance. \r\n Most local building codes mandate the minimum and maximum riser dimension \r\n and minimum tread dimension. The 7-11 rule is used most frequently; \r\n that is, maximum riser height is 7 in. (180 mm), while the minimum \r\n tread depth is 11 in. (280 mm). The riser must also be greater than \r\n 4 in. (100 mm) in height. Due to normal walking and gait, optimum \r\n riser-tread dimensions do exist. One formula for determining this \r\n relationship has been recommended for use [1]. It provides a general \r\n guideline for riser and tread dimensions. \r\n \r\n \r\n \r\n T x R = 77.5 (T x R = 500, for SI units) \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n T = tread width, in. (cm) \r\n R = riser height, in. (cm) \r\n \r\n \r\n \r\n In this equation, the riser is restricted between 4 in. (10 cm) and \r\n 7 in. (18 cm). Since brick is a small element, there are a variety \r\n of bonding patterns for the tread and riser. Figure 5 shows several \r\n examples of bonding arrangements with modular brick. \r\n \r\n \r\n \r\n Step Configurations \r\n FIG. 5 \r\n \r\n Landings may be included in steps, especially when the cumulative \r\n height of steps is great. Building codes set the maximum height between \r\n landings at 12 ft (3.7 m); however, it is usually more desirable to \r\n limit the maximum height to 5 ft (1.5 m) between landings. The length \r\n of the landing should be long enough to allow easy cadence, which \r\n is about 5 ft (1.5 m) or a multiple of 5 ft (1.5 m). \r\n Edge Details . For safety reasons, several issues relating \r\n to the edge of the steps should be considered. In most pedestrian \r\n applications, it may be beneficial to highlight the edge of the step \r\n by varying the color of the tread and riser brick, changing the bond \r\n pattern of the tread or by extending the tread slightly over the riser. \r\n These distinctions of the edge allow easy visual indication that a \r\n change is coming, which helps to avoid tripping. Extending the tread \r\n over the riser creates a shadow line highlighting the stairs and also \r\n allows the treads to be slightly deeper than if they were squared \r\n off. However, the maximum projection should be 1 1/2 in. (40 mm) to \r\n avoid catching the foot while stepping up. If a rounded tread is used, \r\n the leading edge should be a maximum 1/2 in. (13 mm) radius. \r\n Ramps . The model building codes and other accessibility codes \r\n [2] usually limit the slope of ramps to no steeper than 1:12 in most \r\n applications. Greater slopes are allowed only if the total rise is \r\n less than 6 in. (150 mm). Slopes greater than those allowed by codes \r\n make it difficult for persons in wheelchairs to negotiate the ramp. \r\n The width of a ramp should be at least 3 ft (0.9 m) wide for one-way \r\n traffic and 5 ft (1.5 m) wide for two way traffic. In addition, landings \r\n should be provided every 30 ft (9 m) horizontally. \r\n Support and Bonding . Brick steps and ramps are usually supported \r\n by a concrete base, but any material capable of supporting the brick \r\n properly could be used, if designed properly. Deflections or settlement \r\n of the support must be minimized to avoid cracking in the brickwork. \r\n Figure 6 shows a concrete support system for a step and ramp. Brick \r\n should be adequately bonded to the support or restrained around its \r\n perimeter to avoid loosening of units. Mortar is usually used to bond \r\n the brick to the concrete. This paving system is very effective when \r\n proper materials and installation are used. Dowels or ties into the \r\n mortar joints are not necessary since the mortar provides adequate \r\n bond. Newer types of adhesives are now being used to bond the brick \r\n directly to the concrete. These adhesives must be durable to withstand \r\n the severity of its environment. Adhesives can only be used when the \r\n concrete surface is fairly even and free of contaminants. Caulks and \r\n sealants are not appropriate for this purpose. \r\n \r\n \r\n \r\n Stair and Ramp Sections \r\n FIG. 6 \r\n \r\n \r\n \r\n Adequate footings should be designed for the step or ramp support. \r\n The depth of the footings should extend below the frost line. Since \r\n the paving assembly is supported on its own footing, an isolation \r\n joint should be used between the pavement and building and between \r\n the pavement and ramps or steps. \r\n Safety . In addition to the required physical dimensions of \r\n the element, the slip resistance of the surface should also be considered. \r\n The static coefficient of friction is usually used to determine if \r\n a surface is considered slippery. There is no consensus minimum value \r\n for coefficient of friction; however, some codes are promoting minimum \r\n static coefficient of friction values of 0.6 for pavements and 0.8 \r\n for ramps [2]. Limiting the static coefficient of friction to these \r\n values is believed to make the surfaces safe and passable by both \r\n able-bodied pedestrians and the physically impaired. It is usually \r\n excessive water- ponding or the contamination of the pavement by other \r\n substances which cause most slips and falls. Brick usually has an \r\n adequate slip resistance, with higher coefficient of friction values \r\n achieved when a rough textured brick is used. \r\n \r\n SELECTION OF MATERIALS \r\n \r\n Pavements can be subjected to severe weather and abrasion; therefore, \r\n the materials used to construct them must be of superior quality. \r\n Most of the materials in a pavement must conform to ASTM standards. \r\n Following are recommendations for the selection of paving materials. \r\n Additional information on material selection can be found in Technical \r\n Notes 14 Series \r\n \r\n Brick Pavers \r\n \r\n Pavers must be able to withstand the weather and the abrasion of \r\n pedestrian traffic. Pavers should conform to the requirements of ASTM \r\n C 902 Specification for Pedestrian and Light Traffic Paving Brick. \r\n Units conforming to ASTM C 1272 Specification for Heavy Vehicular \r\n Paving Brick may be used, but are usually not necessary for most landscape \r\n applications, unless heavy vehicular traffic is expected. Heavy vehicular \r\n traffic is composed of high volumes of heavy vehicles on a pavement. \r\n Two of the more critical requirements of ASTM C 902, durability and \r\n abrasion, are discussed below. Other requirements, such as dimensional \r\n tolerances, chippage and warpage should also be considered. \r\n Durability . The resistance of pavers to weathering is determined \r\n by the Class of the paver. The Class of the paver is based on the \r\n durability of the unit and is determined by compressive strength, \r\n cold water absorption and saturation coefficient of the unit. Class \r\n SX pavers are intended for use where the paver may be frozen while \r\n saturated with water. In exterior applications where freezing is not \r\n present, pavers should conform to Class MX or SX. Class NX pavers \r\n are acceptable for interior use where they are protected from freezing \r\n when wet. Alternate means of assessing durability of brick pavers \r\n are addressed in ASTM C 902 and Technical Notes 14A \r\n Revised. \r\n Abrasion Resistance . Pavers must be able to resist the abrasive \r\n action of traffic. ASTM C 902 includes three abrasion classifications \r\n of pavers; Types I, II and III. Type I pavers are appropriate for \r\n areas receiving extensive abrasion, such as commercial driveways and \r\n entrances. Type II pavers are intended for exterior walkways and floors \r\n in restaurants and stores. Type III pavers are used for residential \r\n floors and patios. The paver Type is determined by its abrasion index, \r\n which is calculated by dividing the cold water absorption by the compressive \r\n strength and multiplying by 100. The resistance to abrasion can also \r\n be determined by a laboratory test, as outlined in ASTM C 902. \r\n \r\n Setting Bed Materials \r\n \r\n The setting bed, placed between the base and the brick pavers, functions \r\n as a leveling course for slight irregularities in the base and units. \r\n Setting bed materials include sand, mortar, asphalt and building felt. \r\n \r\n Sand . Sand used as a setting bed should be a washed, well-graded \r\n angular sand with a maximum particle sized of 3/16 in. (4.8 mm). Sand \r\n should conform to ASTM C 33 Specification for Concrete Aggregates, \r\n usually referred to as concrete sand. Masons sand can also be used \r\n as the setting bed material when the thickness of the setting bed \r\n is less than 1 in. (25 mm). Masons sand should conform to ASTM C \r\n 144 Specification for Aggregates for Masonry Mortar. The thickness \r\n of the sand setting bed should be between 1/2 in. and 2 in. (13 mm \r\n and 50 mm). \r\n Mortar . Mortar setting beds are used in mortared brick paving \r\n applications. Mortar should conform to ASTM C 270 Specification for \r\n Mortar for Unit Masonry or ANSI A118.4 Specification for Latex-Portland \r\n Cement Mortar, when a latex additive is used. For exterior mortared \r\n brick pavements, Type M mortar is preferred. Type M portland cement-lime \r\n mortar consists of 1 part portland cement, 1/4 part hydrated lime \r\n and 3 3/4 parts sand. Type S mortar can be used alternately. In severe \r\n freeze/thaw environments, mortars with better freeze/thaw resistance \r\n should be used. Two mortar properties that greatly influence freeze/thaw \r\n resistance are air content and water/cement ratio. An air content \r\n for paving mortars between approximately 10 percent and 15 percent \r\n is optimal. Increasing air content too much will reduce bond between \r\n the brick paver and mortar. To address the water/cement ratio, the \r\n mortar should be mixed with just enough water to make it workable. \r\n The thickness of the mortar setting bed should be between 3/8 in. \r\n and 1 in. (10 mm to 25 mm). \r\n Asphalt . Asphalt setting beds typically consist of approximately \r\n 7 percent asphalt and 93 percent sand. The asphalt setting bed is \r\n used over a concrete or asphalt base. The thickness of the asphalt \r\n should be approximately 3/4 in. (20 mm). \r\n Building Felt . Brick may be placed directly on a new or existing \r\n asphalt or concrete base. In these applications, building felt may \r\n serve as a cushion between the pavers and the base, which can accommodate \r\n small dimensional variations of the base and pavers. Two layers of \r\n No. 15 building felt or one layer of No. 30 building felt is appropriate. \r\n \r\n Base Materials \r\n \r\n Base materials consist of crushed aggregate, gravel, sand, asphalt \r\n and concrete. Asphalt and concrete bases often require an aggregate \r\n subbase. Steps and ramps usually are built on concrete bases, whereas \r\n patios and terraces may be supported on any of the base materials \r\n listed. \r\n \r\n Aggregate Bases . Aggregate bases include \r\n crushed stone, gravel and sand. Heavier loading or areas subjected \r\n to frost heave may require crushed stone. Open-graded aggregate (gravel) \r\n is often used in areas of poor drainage, areas subjected to frost \r\n heave or when porous pavements are designed. The proper aggregate \r\n size depends on the depth of the layer and the size of the compaction \r\n equipment. Maximum aggregate size is usually 3/4 in. (20 mm) diameter. \r\n \r\n \r\n In residential pedestrian applications, sand bases can be used when \r\n the subgrade compaction is ensured, when bearing on undisturbed earth \r\n and in areas where frost heave is not a consideration. Sand used as \r\n a base material should be a concrete sand conforming to ASTM C 33 \r\n and be clean and free of deleterious materials. \r\n Concrete Bases . New or existing concrete bases may be used \r\n to support brick paving. New concrete should be installed following \r\n recommended concrete practices. Where mortar is used to bond brick \r\n pavers to the concrete, the concrete should have a rough textured \r\n finish. Caution should be used if brick is placed over an existing \r\n concrete slab. The existing concrete slab must be sound and any major \r\n cracks filled adequately with concrete or mortar. \r\n Asphalt Bases . New or existing asphalt bases may used to support \r\n mortarless brick paving. Proper asphalt materials are generally determined \r\n by paving contractors or the asphalt plant and are beyond the scope \r\n of this Technical Notes . Asphalt bases should not be used to \r\n support mortared brick paving. \r\n \r\n CONSTRUCTION \r\n \r\n One of the most important factors in long-term pavement performance \r\n is proper installation. Critical elements include proper base compaction, \r\n proper edge restraints and full mortar joints, if used. There are \r\n numerous ways to install brick paving, and techniques tend to vary \r\n by region. The recommendations in this Technical Notes are \r\n based on experience and provide a minimum level of workmanship necessary \r\n for satisfactory performance. More information on construction of \r\n brick pavements may be found in Technical Notes 14 Series. \r\n \r\n Base Preparation \r\n \r\n Proper compaction of the subgrade (soil) and base is one of the most \r\n critical factors in pavement installation. Pavements rely on the strength \r\n of the base to adequately resist loads. Poorly compacted aggregate \r\n bases usually lead to undulations (rutting) or cracking of the pavement. \r\n Most patios, steps and ramps are built adjacent to a building or residence. \r\n These are often areas over backfill rather than undisturbed earth, \r\n making proper compaction even more critical. Compaction of the subgrade \r\n should be done with the largest equipment possible so that proper \r\n compaction is achieved. Once the subgrade is compacted, the base may \r\n be built on top. The base material should be spread and compacted \r\n in layers or lifts. The thickness of each layer must be consistent \r\n with the size of compaction equipment, but never exceed 4 in. (100 \r\n mm). Vibratory rollers may be necessary, although for most residential \r\n applications plate compactors provide enough force. Typical compaction \r\n criteria is 95 percent maximum density. \r\n \r\n Mortar Installation \r\n \r\n When brick are installed with mortar, standard bricklaying or tile \r\n setting procedures should be followed. The preferred method of mortar \r\n placement is with a trowel. The concrete base should be clean and \r\n slightly dampened, but surface dry prior to placing the mortar. Brick \r\n pavers should be buttered on the ends and shoved into the mortar setting \r\n bed. All joints intended to receive mortar should be solidly filled. \r\n The joints should be tooled with a metal jointer. A shallow concave \r\n joint profile is preferred for proper compaction of the joint and \r\n to keep water from ponding on the mortar joints. \r\n \r\n CONCLUSION \r\n \r\n This Technical Notes describes elements considered in landscape \r\n design including master planning and environmental aspects of landscape \r\n architecture. Design of pavements, steps and ramps is discussed. Materials \r\n and construction of these elements and the most critical requirements \r\n for each are outlined. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering \r\n staff of the Brick Institute of America. The information contained \r\n herein must be used in conjunction with good technical judgment and \r\n a basic understanding of the properties of brick masonry. Final decisions \r\n on the use of the information contained in this Technical Notes \r\n are not within the purview of the Brick Institute of America and must \r\n rest with the project architect, engineer and owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Abdou, \r\n O. and Burdette, J., \"Masonry Stairs: Design and Material Performance,\" \r\n Proceedings Sixth North American Masonry Conference, Philadelphia, \r\n PA, June 1993, pp. 739-754. \r\n 2. \"Americans \r\n with Disabilities Act: Accessibility Guidelines for Buildings and \r\n Facilities,\" U.S. Architectural and Transportation Barriers Compliance \r\n Board, Washington, D.C., August 1992. \r\n 3. \"AIA \r\n Environmental Resources Guide,\" American Institute of Architects, \r\n Washington, D.C., 1993. \r\n 4. Arnold \r\n Associates, \"Urban Trees and Paving,\" Princeton, NJ, August 1982. \r\n 5. \"Brick \r\n Floors and Pavements, Design and Detailing,\" Technical Notes \r\n on Brick Construction 14 Revised, \r\n Brick Institute of America, Reston, VA, September 1992. \r\n 6. \"Brick \r\n Floors and Pavements, Materials and Installation,\" Technical \r\n Notes on Brick Construction 14A \r\n Revised, Brick Institute of America, Reston, VA, January 1993. \r\n 7. \"Flexible \r\n Pavement Guide for Roads and Streets,\" National Stone Association, \r\n Washington, D.C., January 1985. \r\n 8. Harris, \r\n C.W. and Dines, N.T., Time-Saver Standards for Landscape Architects , \r\n McGraw-Hill Book Co., New York, NY, 1988. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60100,"ResultID":176332,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 29A - Brick in Landscape \r\n Architecture - Garden Walls \r\n Nov. 1968 (Reissued Jan. 1999) \r\n \r\n INTRODUCTION \r\n The plan of a garden usually involves \"leading\" \r\n the sojourner through a series of spatial relationships. This can be done \r\n formally, informally or subtly, depending upon the purpose and skill of \r\n the designer. Among the tools used for this purpose are garden walls of \r\n brick. They may invite, enhance, lead, restrict, compel, separate, combine, \r\n protect, screen or prohibit; all to the purpose of the artist and his \r\n skill. \r\n The variations and possibilities with brick \r\n garden walls approach infinity. Still among the most popular of garden \r\n wall structures is the serpentine wall. The serpentine wall is believed \r\n by some to predate recorded history. Early examples of its use in America \r\n may be found in Colonial Williamsburg, and at the University of Virginia \r\n in Charlottesville (Fig. 1) where over 160 years ago Thomas Jefferson \r\n designed and built serpentine walls. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Brick Serpentine Wall - University of Virginia \r\n FIG. 1 \r\n \r\n \r\n MATERIALS AND WORKMANSHIP \r\n Obviously, most garden walls will be subjected \r\n to the extremes of exposure to the elements. Rain, snow, freezing weather, \r\n heat, direct sun and combinations of these will severely test the quality \r\n of the materials, the workmanship and the design of garden walls. Consequently, \r\n the selection of materials and the workmanship are of paramount importance \r\n in constructing successful and enduring garden walls of brick. \r\n Brick . Brick for garden walls should \r\n meet the requirements for grade SW of the ASTM Standard Specifications \r\n for Facing Brick C 216 (where exposed to view) or ASTM Standard Specifications \r\n for Building Brick C 62 (where not exposed, such as below grade), unless \r\n the brick are known to have performed satisfactorily under similar conditions \r\n of exposure. \r\n Used or salvaged brick should not be used for \r\n garden walls unless they meet the SW requirements. Used brick generally \r\n will not meet these requirements, since they often are non-uniform in \r\n degree of burning (see Technical Notes 15 , \r\n \"Salvaged Brick\"). \r\n Mortar . The recommended mortar for reinforced \r\n and non-reinforced brick garden wall construction is composed of: 1 part \r\n portland cement, 1/2 part hydrated lime and 4 - 1/2 parts sand by volume. \r\n This mortar conforms to ASTM Standard Specifications for Mortar for Unit \r\n Masonry, C 270, Type S. It is very durable and develops good bond with \r\n clay masonry units (see Technical Notes 8 \r\n Revised, \"Portland Cement-Lime Mortars for Brick Masonry\"). \r\n Workmanship . Workmanship on brick masonry \r\n garden walls should be that characterized by the complete filling of all \r\n head, bed and collar joints. It is sometimes erroneously supposed that \r\n workmanship of lesser quality may be tolerated in garden structures, since \r\n they are not weather barriers or enclosure walls, as in a building. Less \r\n than excellent workmanship should not be permitted. Because of the extreme \r\n exposure of garden walls, any defect may result in deterioration and perhaps \r\n ultimately in failure of the wall (see Technical Notes 7B \r\n Revised, \"Water Resistance of Brick Masonry-Design and Detailing\"). \r\n \r\n DESIGN \r\n The most meticulous design and details may be \r\n thwarted by the selection of inappropriate materials, or by poor workmanship. \r\n The converse is also true. The use of the best possible materials and \r\n craftsmanship will not in themselves insure a successful and permanent \r\n garden wall. Much depends on the design and attention to certain critical \r\n details, such as foundations, copings and flashing. \r\n Foundations . Since garden walls generally \r\n do not carry any vertical loads other than their own weight, the footings \r\n and foundations sometimes do not receive proper attention. Foundations \r\n for garden walls should be placed in undisturbed earth at a depth below \r\n the frost line. They may be of brick or of concrete and reinforced if \r\n necessary, particularly in areas with active soils. \r\n Copings . The appearance and character \r\n of a garden wall may be altered materially, depending on the type of cap \r\n or coping used on the top of the wall. Many materials are suitable for \r\n coping, including: natural stone, cast stone, slate, terra cotta, metals \r\n and brick. Figure 2 indicates a few suggestions for capping garden walls \r\n with various materials. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Copings \r\n FIG. 2a \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Copings \r\n FIG. 2b \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Copings \r\n FIG. 2c \r\n \r\n \r\n Whichever is used, there are certain general \r\n recommendations that should be followed. The coping should project beyond \r\n the face of the brick a minimum of 1/2 in. on both sides. This projection \r\n should contain a positive drip to keep water from flowing down the face \r\n of the wall. In most cases copings should be anchored to the brick wall \r\n with metal anchors or bolts. If the coping is of material other than brick, \r\n its thermal and moisture expansion characteristics should be compared \r\n to those of the brick masonry, and provisions made for the resulting differential \r\n movements (see Technical Notes 18 , \r\n \"Differential Movement\"). \r\n Flashing . In general, through-wall flashing \r\n is recommended immediately under the coping of garden walls. However, \r\n this may be tempered with good judgment, depending on several factors, \r\n such as: the type of coping used, many joints or relatively few; the climatic \r\n conditions of the area, high or low precipitation; and number of freezing \r\n and thawing cycles (see Technical Notes 7A \r\n Revised, \"Water Resistance of Brick Masonry - Materials\"). \r\n \r\n WALL TYPES \r\n There are many types of brick garden walls with \r\n new variations constantly appearing. Perforated walls of brick are often \r\n used to complement contemporary architecture. Perforated walls can be \r\n designed in conjunction with any of the typical types which are discussed \r\n below. If perforated walls are designed, the indicated dimensional proportions \r\n and reinforcing steel requirements indicated under the specific wall types \r\n should be followed. \r\n Straight Walls . This form of garden wall \r\n relies upon texture and color of the brick masonry for character. The \r\n straight garden wall must be designed with sufficient thickness to provide \r\n lateral stability. Assuming the finished grade on both sides of the wall \r\n is the same, so that no stresses result from earth pressure, it must be \r\n designed to resist wind and impact loads. For 10 - psf wind pressure, \r\n it is recommended that the height above grade (h) not exceed three-fourths \r\n of the wall thickness (t) squared where h and t are in \r\n inches. This recommendation is based on the assumption that the overturning \r\n moment from the wind does not exceed three-fourths of the righting moment \r\n from the wall dead load, and does not depend upon bond between the foundation \r\n and the wall. If bond is assured or steel dowels are used to tie the wall \r\n to the foundation, or if greater lateral loads exist, straight walls can \r\n be designed in accordance with the Recommended Building Code Requirements \r\n for Engineered Brick Masonry, BIA, August 1969; or \"Building Code \r\n Requirements for Reinforced Masonry\", ANSI A41.2-1960 (R1970). \r\n \r\n Pier and Panel Walls . The pier and panel \r\n wall is composed of a series of relatively thin panels, 4 in. in thickness, \r\n which are braced intermittently by masonry piers (Fig. 3). This wall is \r\n relatively easy to build and is economical due to the reduced thickness \r\n of the panels. It is also easily adapted to varying conditions of terrain. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Pier and Panel Garden Wall - Montgomery Village, \r\n Maryland \r\n FIG. 3 \r\n \r\n \r\n Details for construction of pier and panel walls \r\n are shown in Fig. 4. Three typical design possibilities are indicated. \r\n Table 1 provides the horizontal reinforcing steel requirements for panel \r\n walls and Table 2 gives the vertical reinforcing steel for the piers. \r\n The required foundation diameter and depth of embedment are given in Table \r\n 3. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Pier and Panel Garden Wall \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Note: \r\n A = 2 - No. 2 bars \r\n B = 2 - 3/16 - in. diam. wires \r\n C = 2 - 9 gage wires \r\n \r\n \r\n \r\n \r\n \r\n 1 Within heavy lines 12 by 16-in. \r\n pier required. All other values obtained with 12 by 12-in. pier (see Fig. \r\n 4). \r\n \r\n \r\n \r\n \r\n 1 Within heavy lines 23-in. diam. foundation \r\n required. All other values obtained with 18-in. diam. foundation (see \r\n Fig. 4). \r\n \r\n The reinforced brick masonry piers and panels \r\n are designed with an allowable flexural compressive stress for brick masonry \r\n of 725 psi and an allowable tensile stress for reinforcing steel of 20,000 \r\n psi for No. 2 and larger bars (min. yield strength 40,000 psi) and 24,000 \r\n psi for 3/16 -in. diam. and 9 gage wire (min. yield strength 60,000 psi). \r\n The ratio of modulus of elasticity of the steel to that of the masonry \r\n (n) is assumed to be 13. The design is in compliance with the Recommended \r\n Building Code Requirements for Engineered Brick Masonry, BIA, August \r\n 1969, and \"Building Code Requirements for Reinforced Masonry\", ANSI A41.2-1960 \r\n (R1970). One of these standards should be used to determine the required \r\n brick compressive strength. The pier foundation diameter and required \r\n embedment below grade are based upon an average allowable soil pressure \r\n of 3000 psf. If poorer soil exists at the site, a further investigation \r\n of the foundation is necessary. \r\n The reinforcing steel requirements vary with \r\n the wind load, the wall height and the wall span. The two vertical pier \r\n bars are placed 2 in. apart in the 12 by 12 - in. piers and 6 in. apart \r\n in the 12 by 16 - in. piers, one bar toward each face. These bars are \r\n to be continuous from the bottom of the foundation to the top of the brick \r\n masonry pier. If spliced, for ease of construction, they must be lapped \r\n at least 30 bar diameters. The panel wall reinforcement consists of two \r\n bars or wires spaced not less than 2 in. apart in the mortar joint at \r\n a vertical spacing not to exceed the dimensions given in Table 1. Individual \r\n bars or wires, or prefabricated joint reinforcement may be used. It is \r\n also required that the panel wall reinforcement be continuous throughout \r\n the length of the wall. Where spliced, it should be lapped 16 in. \r\n Construction of these panel walls is simple, \r\n since foundations are required only under the piers. These may be constructed \r\n by drilling or digging holes with the diameter given in Table 3. \r\n The foundations should be placed in undisturbed \r\n earth and extend below the frost line, but not less than the required \r\n embedment given in Table 3. The masons build the brick panel walls between \r\n the piers with a temporary 2 by 4 - in. wood form under the first course \r\n of brickwork. The 2 by 4 - in. forms are removed after the wall has cured \r\n at least seven days. The same mortar used to lay the brick may be used \r\n to grout the vertical reinforcing steel in the pier, if sufficient water \r\n is added so that it flows readily and completely surrounds the steel. \r\n Serpentine Walls . This ingenious technique \r\n of garden wall construction has been used for several hundred years. The \r\n serpentine shape provides lateral strength to the wall so that it normally \r\n can be built only 4 in. in thickness without additional lateral support. \r\n Since the serpentine wall depends on its shape for lateral strength, it \r\n is important that the degree of curvature be sufficient. The following \r\n general rule is based upon the performance of many successful serpentine \r\n walls. The radius of curvature of a 4 - in. wall should be no more than \r\n twice the height of the wall above finished grade, and the depth of curvature \r\n should be no less than 1/2 of the height. Figure 5 provides details of \r\n a typical serpentine garden wall. \r\n The general rule stated below is limited in \r\n application to minor garden walls. \r\n \r\n \r\n \r\n \r\n \r\n \r\n A Typical Serpentine Garden Wall \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60101,"ResultID":176333,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 29B - Brick in Landscape Architecture - Misc. Applications \r\n Apr. 1967 (Reissued May 1988) \r\n \r\n INTRODUCTION \r\n \r\n In this issue of Technical Notes are suggestions for the use \r\n of brick in landscape architecture that take advantage of the unique \r\n practicality and permanent beauty of the material. The color and texture \r\n of brick will complement the masses and lines of contemporary architecture. \r\n And for traditional architecture, brick lends the same charm that \r\n has endured for more than a century and a half on the grounds surrounding \r\n the splendid mansions of Colonial America. \r\n The success of landscape architecture depends upon the intelligent \r\n spacing and inter-relationship of the various elements, understanding \r\n the limits and possibilities of structural and plant materials, discreetly \r\n evaluating the weakness and strength of various colors and textures, \r\n and choosing materials which are sympathetic with the site, with each \r\n other and with the people who are to see and use them. \r\n Brick is an ideal material for use in landscape architecture for \r\n it is made of natural earth material, clay or shale, burned to permanent \r\n hardness. In the manufacturing process, brick take on colors which \r\n we know as earth colors - reds, browns, buffs and yellows - which \r\n are entirely harmonious with nature. \r\n \r\n MATERIALS AND WORKMANSHIP \r\n \r\n Most garden and landscape structures will be subjected to the extremes \r\n of exposure to the elements. Therefore, proper selection of materials \r\n and high quality workmanship cannot be emphasized too strongly. \r\n Brick . Brick for garden structures should meet the requirements \r\n for grade SW of ASTM Standards for Facing Brick, C 216 (where exposed \r\n to view) or ASTM Standard Specifications for Building Brick, C 62 \r\n (where not exposed such as below grade). Used or salvaged brick should \r\n not be used for garden structures unless they are tested and meet \r\n the grade SW requirements. Most used brick do not meet these requirements \r\n (see Technical Notes 15 , \"Salvaged \r\n Brick\"). \r\n Mortar . Types M and S. conforming to ASTM Specifications for \r\n Mortar for Unit Masonry, C 270, are recommended for reinforced and \r\n non-reinforced brick garden structures. \r\n Workmanship . All head, bed and collar joints should be completely \r\n filled with mortar. Less than excellent workmanship should not be \r\n permitted, since a defect may result in deterioration due to the extreme \r\n exposure of garden structures. \r\n \r\n DESIGN \r\n \r\n The best possible materials and workmanship will not in themselves \r\n assure successful and permanent garden structures. Careful consideration \r\n must also be given to construction details. The following Technical \r\n Notes outline details which may be helpful: 29 \r\n Rev \"Brick in Landscape Architecture, Terraces and Walks\", and 29A \r\n Rev Brick in Landscape Architecture, \"Garden Walls\", and 7A \r\n Rev, \"Water Resistance of Brick Masonry - Materials, Part II\", and \r\n 7B Rev., \"Water Resistance of Brick \r\n Masonry, \"Construction and Workmanship\", Part III. \r\n Steps . Brick steps, such as those shown in Fig. 1, offer a \r\n practical solution to problems which develop in landscaping a slope. \r\n The relatively small sizes of brick permit flexibility of design, \r\n such as adjustments of tread and riser dimensions, and construction \r\n of curves. All treads should pitch outward slightly (1/4 in.) for \r\n drainage. \r\n \r\n \r\n \r\n FIG. 1a \r\n \r\n \r\n \r\n \r\n \r\n FIG. 1b \r\n \r\n \r\n \r\n Brick Screens . \r\n Pierced brick screens offer beauty as well as privacy, without loss \r\n of light or air (see Fig. 2). A brick screen can provide a handsome \r\n separation between the childrens play area and the adults terrace, \r\n and cooling breezes are not thwarted by any of the numerous patterns \r\n available to the designer. Unlike hedges that require trimming or \r\n wood fences with their need for repainting, brick walls are maintenance-free. \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n Outdoor Fireplaces . An outdoor fireplace can be a garden structure of beauty when brick are \r\n used to execute an imaginative but highly practical design, such as \r\n shown in Fig. 3. Fireplaces should be planned to face the prevailing \r\n breezes. This orientation not only allows the smoke to blow away, \r\n but also provides the best draft. Fire brick should be selected for \r\n the firebox of outdoor fireplaces. \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n Planting boxes . \r\n Planters may be constructed indoors and outdoors, in a wide variety \r\n of designs. They protect decorative plants from animals and facilitate \r\n waist-high gardening as shown in Fig. 4. \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n \r\n \r\n In constructing brick planting boxes, adequate drainage must be provided. \r\n This may be accomplished by weep holes, as indicated in Fig. 5. When \r\n the planting box is designed with a closed bottom, as indicated in \r\n Fig. 6, a drain should be provided. Also, careful attention should \r\n be given to the waterproofing of the inside to prevent efflorescence \r\n and staining on the outside face of the brick. In addition, walls \r\n must be checked to insure their resistance to lateral earth pressures. \r\n \r\n \r\n \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n FIG. 6 \r\n \r\n \r\n \r\n Edging . \r\n Brick edging, as indicated in Fig. 7, may be used to define the lawn \r\n area and keep it trim and neat for all seasons. In addition, the brick \r\n strip provides a surface for the lawnmower and thereby eliminates \r\n hand trimming. \r\n \r\n \r\n \r\n FIG. 7 \r\n \r\n \r\n \r\n Concealment Structures . Figure 8 shows the condenser of a central air-conditioning system that \r\n has been concealed by a low perforated brick screen. The screen must \r\n have adequate openings to allow free circulation of air required for \r\n efficient operation. Also, access for servicing should be provided. \r\n \r\n \r\n \r\n FIG. 8 \r\n \r\n \r\n \r\n Trash cans are unsightly, but a low brick enclosure, as indicated \r\n in Fig. 9, will banish from sight such undesirable items in landscape \r\n architecture. In addition to being handsome, the structure is maintenance-free. \r\n \r\n \r\n \r\n FIG. 9 \r\n \r\n \r\n \r\n Tree Protection . Tree roots require air, water and minerals to survive. When a grade level \r\n is changed and the soil depth over the roots is either increased or \r\n decreased, the roots have difficulty obtaining a normal amount of \r\n air, water and minerals. Therefore, to insure the life of a tree, \r\n it is necessary to protect it from a grade change. \r\n \r\n The properly designed brick retaining wall, reinforced or non-reinforced, \r\n is very effective in withstanding lateral pressure from earth when \r\n changes in grade are necessary. \r\n Visual evidence of respect for nature is shown in the photographs \r\n in Fig. 10. Mature trees were preserved, utilizing a brick retaining \r\n wall and a handsome brick tree well. \r\n \r\n \r\n \r\n \r\n FIG. 10 \r\n \r\n \r\n \r\n Raising the Grade. Minor fills, 6 in. or less in depth, will not harm most species of trees, \r\n if the fill is good top soil that is high in organic matter and loamy \r\n in texture. For major grade changes, air and adequate water must be \r\n supplied to the roots of the tree. This may be accomplished by constructing \r\n a brick retaining wall around the trunk of the tree and placing a \r\n layer of gravel and a system of drain tile on original grade over \r\n the roots of the tree. Figure 11 indicates two plans for placing the \r\n drain tile. The tile should slope in the direction indicated. It is \r\n important that the tile extend through the brick retaining wall so \r\n that water will not collect around the trunk of the tree. In addition \r\n to the tile placed on original grade, it may be necessary to place \r\n a series of bell tile vertically over the roots, and connected to \r\n the tile system for additional air and water circulation. This detail \r\n is shown in Fig. 12. The system must be designed to fit the contour \r\n of the land so that water drains away from the tree trunk. \r\n \r\n \r\n \r\n FIG. 11 \r\n \r\n \r\n \r\n \r\n \r\n \r\n FIG. 12 \r\n \r\n \r\n \r\n If economy is essential, or the questionable value of a tree will \r\n not permit the expense involved in the construction of a complete \r\n areation system, a variation may be adopted. For example, if a tree \r\n was originally on a well drained slope, sufficient drainage may be \r\n obtained through the fill by using coarse gravel around a series of \r\n bell tile placed vertically over the roots, in which case the horizontal \r\n tile drains may be omitted. \r\n Lowering the Grade. Protecting a tree from a lowered grade \r\n is usually less complicated than protecting it from a raised grade. \r\n Lowering the grade can be equally harmful to a tree unless proper \r\n attention is given to cutting the roots, pruning branches, stimulating \r\n root growth and watering. Generally, protection is achieved by terracing \r\n the grade. If space is available, the tree may be unharmed if it remains \r\n on a gently sloping mound. Another way to protect a tree from a lowered \r\n grade is to build a brick retaining wall between it and the lower \r\n grade, as shown in Fig. 13. \r\n \r\n \r\n \r\n FIG. 13 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60102,"ResultID":176334,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes \r\n 30 - Bonds and Patterns in Brickwork \r\n July 1967 (Reissued Sept. 1988) \r\n \r\n BOND \r\n \r\n The word bond, \r\n when used in reference to masonry, may have three meanings: \r\n \r\n Structural Bond : The method by which individual masonry units \r\n are interlocked or tied together to cause the entire assembly to act \r\n as a single structural unit. \r\n Pattern Bond : The pattern formed by the masonry units and \r\n the mortar joints on the face of a wall. The pattern may result from \r\n the type of structural bond used or may be purely a decorative one \r\n unrelated to the structural bonding. \r\n Mortar Bond : The adhesion of mortar to the masonry units or \r\n to reinforcing steel. \r\n \r\n STRUCTURAL BONDS \r\n \r\n Structural bonding of masonry walls may be accomplished in three \r\n ways: (1) by the overlapping (interlocking) of the masonry units, \r\n (2) by the use of metal ties embedded in connecting joints, and (3) \r\n by the adhesion of grout to adjacent wythes of masonry. \r\n The overlapped bond is based on variations of two traditional methods \r\n of bonding. The first is known as English bond and consists of alternating \r\n courses of headers and stretchers (Fig. 1). The second is Flemish \r\n bond and consists of alternating headers and stretchers in every course, \r\n so arranged that the headers and stretchers in every other course \r\n appear in vertical lines (Fig. 1). \r\n \r\n \r\n \r\n English and Flemish Bonds \r\n FIG. 1a \r\n \r\n \r\n \r\n \r\n \r\n English and Flemish Bonds \r\n FIG. 1b \r\n \r\n \r\n \r\n The stretchers, laid with the length of the wall, develop longitudinal \r\n bonding strength; while the headers, laid across the width of the \r\n wall, bond the wall transversely. \r\n Modern building codes require that masonry-bonded brick walls be \r\n bonded so that not less than 4 per cent of the wall surface is composed \r\n of headers, with the distance between adjacent headers not exceeding \r\n 24 inches, vertically or horizontally. \r\n Structural bonding of masonry walls with metal ties is used in both \r\n solid wall and cavity wall construction (Fig. 2). \r\n \r\n \r\n \r\n \r\n \r\n Metal-Tied Masonry Walls \r\n FIG. 2 \r\n \r\n Most building codes permit the use of rigid steel bonding ties in \r\n solid walls. \r\n At least one metal tie should be used for each 4 1/2 sq ft of wall \r\n surface. Ties in alternate courses should be staggered. The distance \r\n between adjacent ties should not exceed 24 in. vertically nor 36 in. \r\n horizontally. Additional bonding ties, spaced not more than 3 ft apart \r\n around the perimeter and within 12 in. of the opening, should be provided \r\n at all openings. \r\n If ties less than 3/16 in. in diameter are used, tie spacing should \r\n be reduced so that the tie area per square foot of wall is not less \r\n than specified above. \r\n Structural bonding of solid and reinforced brick masonry walls is \r\n sometimes accomplished by grout which is poured into the cavity or \r\n collar joint between wythes of masonry. \r\n The method of bonding will depend on the use requirements, wall type \r\n and other factors, However, the metal tie method is generally recommended \r\n for exterior walls. Some of the advantages of this method are greater \r\n resistance to rain penetration and ease of construction. Metal ties \r\n also allow slight differential movements of the facing and backing \r\n which may relieve stresses and prevent cracking. \r\n \r\n PATTERN BONDS \r\n \r\n Frequently, structural bonds, such as English or Flemish, or variations \r\n of these, may be used to create patterns in the face of the wall. \r\n However, in the strict sense of the term, pattern refers to the change \r\n or varied arrangement of the brick texture or color used in the face. \r\n Therefore, it may be possible to secure many patterns using the same \r\n structural bond. Patterns also may be produced by the method of handling \r\n the mortar joint or by projecting or recessing certain brick from \r\n the plane of the wall, thus creating a distinctive wall texture that \r\n is not solely dependent upon the texture of the individual brick. \r\n There are five basic structural bonds commonly used today which create \r\n typical patterns. These are: Running bond, common or American bond, \r\n Flemish bond, English bond and block or stack bond, as illustrated \r\n in Fig. 3. Through the use of these bonds and variations of the color \r\n and texture of the brick, and of the joint types and color, an almost \r\n unlimited number of patterns can be developed. \r\n \r\n \r\n \r\n \r\n \r\n Traditional Pattern Bonds \r\n FIG. 3 \r\n \r\n Running bond . \r\n The simplest of the basic pattern bonds, the running bond, consists \r\n of all stretchers. Since there are no headers in this bond, metal \r\n ties are usually used. Running bond is used largely in cavity wall \r\n construction and veneered walls of brick, and often in facing tile \r\n walls where the bonding may be accomplished by extra width stretcher \r\n tile. \r\n \r\n Common or American Bond . Common or American bond is a variation \r\n of running bond with a course of full length headers at regular intervals. \r\n These headers provide structural bonding, as well as pattern. Header \r\n courses usually appear at every fifth, sixth or seventh course. \r\n In laying out any bond pattern, it is important that the corners \r\n be started correctly. For common bond, a three-quarter brick should \r\n start each way from the corner at the header course. \r\n Common bond may be varied by using a Flemish header course. \r\n Flemish Bond . Each course of brick consists of alternate stretchers \r\n and headers, with the headers in alternate courses centered over the \r\n stretchers in the intervening courses. Where the headers are not used \r\n for the structural bonding, they may be obtained by using half brick \r\n called \"clipped\" or \"snap\" headers. \r\n Flemish bond may be varied by increasing the number of stretchers \r\n between headers in each course. If there are three stretchers alternating \r\n with a header, it is known as \"garden wall\" bond. If there are two \r\n stretchers between headers, it is designated as \"double stretcher \r\n garden wall\" bond. Garden wall bond may also be laid with four or \r\n even five stretchers between the headers. \r\n English Bond . English bond is composed of alternate courses \r\n of headers and stretchers. The headers are centered on the stretchers \r\n and joints between stretchers in all courses are aligned vertically. \r\n Snap headers are used in courses which are not structural bonding \r\n courses. \r\n English Cross or Dutch Bond . English cross or Dutch bond is \r\n a variation of English bond which differs only in that vertical joints \r\n between the stretchers in alternate courses do not align vertically. \r\n These joints center on the stretchers themselves in the courses above \r\n and below. \r\n There are two methods used in starting the corners in Flemish and \r\n English bonds. Figure 3 shows the so-called \"Dutch corner\" in which \r\n a three-quarter brick closure is used, and the English corner in which \r\n a 2-in. or quarter brick closure, called a \"queen closure\", is used. \r\n The 2-in. closure should always be placed 4 in. in from the corner, \r\n never at the corner. \r\n Block or Stack Bond . Block or stack bond is purely a pattern \r\n bond. There is no overlapping of units since all vertical joints are \r\n aligned. Usually this pattern is bonded to the backing with rigid \r\n steel ties, but when 8 - in. bonder units are available, they may \r\n be used. In large wall areas and in load bearing construction, it \r\n is advisable to reinforce the wall with steel reinforcement placed \r\n in the horizontal mortar joints. In stack bond it is imperative that \r\n prematched or dimensionally accurate masonry units be used if the \r\n vertical alignment of the head joints is to be maintained. \r\n Figures 4 and 5 illustrate patterns that may be obtained by varying \r\n brick color. Figure 4 is a double stretcher garden wall bond with \r\n the pattern units in diagonal lines. Figure 5 shows a garden wall \r\n bond with the pattern units set in dovetail fashion. \r\n \r\n \r\n \r\n Double Stretcher Garden Wall Bond with Units in Diagonal \r\n Lines \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Garden Wall Bond with Units in Dovetail Fashion \r\n FIG. 5 \r\n \r\n Wall Texture . \r\n Recently many contemporary modifications of the traditional bonds \r\n have been used by projecting and recessing units, also by omitting \r\n units to form perforated walls or screens. Figure 6 illustrates contemporary \r\n uses of masonry which imaginatively extend the traditional patterns. \r\n \r\n \r\n \r\n Contemporary Bonds \r\n FIG. 6 \r\n \r\n MORTAR JOINTS \r\n \r\n As previously indicated, the treatment of mortar joints in the face \r\n of the wall affects the pattern and wall texture. \r\n The mortar serves four functions: \r\n 1. It bonds the units together and seals the spaces between. \r\n 2. It compensates for dimensional variations in the units. \r\n 3. It bonds to and, therefore, causes reinforcing steel to act as \r\n an integral part of the wall. \r\n 4. It provides a decorative effect on the wall surface by creating \r\n shadow or color lines. \r\n \r\n Mortar joint finishes fall into two classes: troweled and tooled \r\n joints. In the troweled joint, the excess mortar is simply cut off \r\n (struck) with a trowel and finished with the trowel. For the tooled \r\n joint, a special tool, other than the trowel, is used to compress \r\n and shape the mortar in the joint. \r\n Figure 7 shows a cross section of typical mortar joints used in good \r\n brickwork. \r\n \r\n \r\n \r\n \r\n \r\n Mortar Joints \r\n FIG. 7 \r\n \r\n Concave Joint ( 1 ) and V-Shaped Joint \r\n ( 2 ) . These joints are normally \r\n kept quite small and are formed by the use of a steel jointing tool. \r\n These joints are very effective in resisting rain penetration and \r\n are recommended for use in areas subjected to heavy rains and high \r\n winds. \r\n \r\n Weathered Joint (3) . This joint requires care as it must be \r\n worked from below. However, it is the best of the troweled joints \r\n as it is compacted and sheds water readily. \r\n Struck Joint (4) . This is a common joint in ordinary brickwork. \r\n As American mechanics often work from the inside of the wall, this \r\n is an easy joint to strike with a trowel. Some compaction occurs, \r\n but the small ledge does not shed water readily, resulting in a less \r\n watertight joint than joints (1), (2) or (3). \r\n Rough Cut or Flush Joint (5) . This is the simplest joint for \r\n the mason, since it is made by holding the edge of the trowel flat \r\n against the brick and cutting in any direction. This produces an uncompacted \r\n joint with a small hairline crack where the mortar is pulled away \r\n from the brick by the cutting action. This joint is not always watertight. \r\n Raked Joint (6) . Made by removing the surface of the mortar, \r\n while it is still soft. While the joint may be compacted, it is difficult \r\n to make weather-tight and is not recommended where heavy rain, high \r\n wind or freezing is likely to occur. This joint produces marked shadows \r\n and tends to darken the overall appearance of the wall. \r\n Colored mortars may be successfully used to enhance the patterns \r\n in masonry. Two methods are commonly used: (1) the entire mortar joint \r\n may be colored or (2) where a tooled joint is used, tuck pointing \r\n is the best method. In this technique, the entire wall is completed \r\n with a 1-in. deep raked joint and the colored mortar is carefully \r\n filled in later. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60103,"ResultID":176335,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 31 - Brick Masonry Arches \r\n January 1995 \r\n \r\n Abstract: The masonry arch is one \r\n of the oldest structural elements. Brick masonry arches have been used \r\n for hundreds of years. This Technical Notes is an introduction to brick \r\n masonry arches. Many of the different types of brick masonry arches \r\n are discussed and a glossary of arch terms is provided. Material selection, \r\n proper construction methods, detailing and arch construction recommendations \r\n are discussed to ensure proper structural support, durability and weather \r\n resistance of the brick masonry arch. \r\n \r\n Key Words : \r\n arch , brick, reinforced, unreinforced. \r\n \r\n INTRODUCTION \r\n \r\n In the latter part of the 19th century, an arch was discovered in the \r\n ruins of Babylonia. Archeologists estimate that the arch was constructed \r\n about the year 1400 B.C. Built of well-baked, cigar-shaped brick and \r\n laid with clay mortar, this arch is probably the oldest known to man. \r\n The Chinese, Egyptians and others also made use of the arch before the \r\n Christian era. Later, more elaborate arches, vaults and domes with complicated \r\n forms and intersections were constructed by Roman builders during the \r\n Middle Ages. \r\n The brick arch is the consummate example of form following function. \r\n Its aesthetic appeal lies in the variety of forms which can be used \r\n to express unity, balance, proportion, scale and character. Its structural \r\n advantage results from the fact that under uniform load, the invoiced \r\n stresses are principally compressive. Because brick masonry has greater \r\n resistance to compression than tension, the masonry arch is frequently \r\n the most efficient structural element to span openings. \r\n This Technical Notes addresses the detailing and construction \r\n of brick masonry arches. The common types of brick masonry arches are \r\n presented, along with proper arch terminology. Methods of selecting \r\n the type and configuration of brick masonry arches most appropriate \r\n for the application are discussed. Proper material selection and construction \r\n methods are recommended. Other Technical Notes in this series \r\n discuss the structural design of brick masonry arches and lintels. \r\n \r\n ARCH TYPES AND TERMINOLOGY \r\n \r\n Many arch forms have been developed during the centuries of use, ranging \r\n from the jack arch through the circular, elliptical and parabolic to \r\n the Gothic arch. Figure 1 depicts examples of structural masonry arches \r\n used in contemporary construction. An arch is normally classified by \r\n the curve of its intrados and by its function, shape or architectural \r\n style. Figure 2 illustrates some of the many different brick masonry \r\n arch types. Jack, segmental, semicircular and multicentered arches are \r\n the most common types used for building arches. For very long spans \r\n and for bridges, semicircular arches are often used because of their \r\n structural efficiency. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Structural Brick Arches \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Jack \r\n FIG. 2a \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Segmental \r\n FIG. 2b \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Semicircular \r\n FIG. 2c \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Bullseye \r\n FIG. 2d \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Horseshoe \r\n FIG. 2e \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Multicentered \r\n FIG. 2f \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Venetian \r\n FIG. 2g \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Tudor \r\n FIG. 2h \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Triangular \r\n FIG. 2i \r\n \r\n \r\n \r\n \r\n \r\n Arch Types: Gothic \r\n FIG. 2j \r\n \r\n Mainly due to their variety of components and elements, arches have \r\n developed their own set of terminology. Following is a glossary of arch \r\n terminology. Figure 3 illustrates many of the terms defined in this \r\n glossary. Technical Notes in this series will use this terminology. \r\n Abutment: The masonry or combination of masonry and other structural \r\n members which support one end of the arch at the skewback. \r\n Arch: A form of construction in which masonry units span an \r\n opening by transferring vertical loads laterally to adjacent voussoirs \r\n and, thus, to the abutments. Some common arch types are as follows: \r\n \r\n Blind - An arch whose opening is filled with masonry. \r\n Bullseye - An arch whose intrados is a full circle. Also known \r\n as a Circular arch. \r\n Elliptical - An arch with two centers and continually changing \r\n radii. \r\n Fixed - An arch whose skewback is fixed in position and inclination. \r\n Masonry arches are fixed arches by nature of their construction. \r\n Gauged - An arch formed with tapered voussoirs and thin mortar \r\n joints. \r\n Gothic - An arch with relatively large rise-to-span ratio, \r\n whose sides consist of arcs of circles, the centers of which are at \r\n the level of the spring line. Also referred to as a Drop, Equilateral \r\n or Lancet arch, depending upon whether the spacings of \r\n the centers are respectively less than, equal to or more than the \r\n clear span. \r\n Horseshoe - An arch whose intrados is greater than a semicircle \r\n and less than a full circle. Also known as an Arabic or Moorish \r\n arch. \r\n Jack - A flat arch with zero or little rise. \r\n Multicentered - An arch whose curve consists of several arcs \r\n of circles which are normally tangent at their intersections. \r\n Relieving - An arch built over a lintel, jack arch or smaller \r\n arch to divert loads, thus relieving the lower arch or lintel from \r\n excessive loading. Also known as a Discharging or Safety \r\n arch. \r\n Segmental - An arch whose intrados is circular but less than \r\n a semicircle. \r\n Semicircular - An arch whose intrados is a semicircle (half \r\n circle). \r\n Slanted - A flat arch which is constructed with a keystone \r\n whose sides are sloped at the same angle as the skewback and uniform \r\n width brick and mortar joints. \r\n Triangular - An arch formed by two straight, inclined sides. \r\n Tudor - A pointed, four-centered arch of medium rise-to-span \r\n ratio whose four centers are all beneath the extrados of the arch. \r\n Venetian - An arch formed by a combination of jack arch at \r\n the ends and semicircular arch at the middle. Also known as a Queen \r\n Anne arch. \r\n \r\n Camber: The relatively small rise of a jack arch. \r\n Centering: Temporary shoring used to support an arch until the \r\n arch becomes self-supporting. \r\n Crown: The apex of the archs extrados. In symmetrical arches, \r\n the crown is at the midspan. \r\n Depth: The dimension of the arch at the skewback which is perpendicular \r\n to the arch axis, except that the depth of a jack arch is taken to be \r\n the vertical dimension of the arch at the springing. \r\n Extrados: The curve which bounds the upper edge of the arch. \r\n Intrados: The curve which bounds the lower edge of the arch. \r\n The distinction between soffit and intrados is that the intrados is \r\n a line, while the soffit is a surface. \r\n Keystone: The voussoir located at the crown of the arch. Also \r\n called the key. \r\n Label Course: A ring of projecting brickwork that forms the \r\n extrados of the arch. \r\n Rise: The maximum height of the arch soffit above the level \r\n of its spring line. \r\n Skewback: The surface on which the arch joins the supporting \r\n abutment. \r\n Skewback Angle: The angle made by the skewback from horizontal. \r\n Soffit: The surface of an arch or vault at the intrados. \r\n Span : The horizontal clear dimension between abutments. \r\n Spandrel: The masonry contained between a horizontal line drawn \r\n through the crown and a vertical line drawn through the upper most point \r\n of the skewback. \r\n Springing: The point where the skewback intersects the intrados. \r\n Springer: The first voussoir from a skewback. \r\n Spring Line: A horizontal line which intersects the springing. \r\n Voussoir: One masonry unit of an arch. \r\n \r\n \r\n \r\n Arch Terms \r\n FIG. 3 \r\n \r\n STRUCTURAL FUNCTION OF ARCHES \r\n \r\n The brick masonry arch has been used to span openings of considerable \r\n length in many different applications. Structural efficiency is attributed \r\n to the curvature of the arch, which transfers vertical loads laterally \r\n along the arch to the abutments at each end. The transfer of vertical \r\n forces gives rise to both horizontal and vertical reactions at the abutments. \r\n The curvature of the arch and the restraint of the arch by the abutments \r\n cause a combination of flexural stress and axial compression. The arch \r\n depth, rise and configuration can be manipulated to keep stresses primarily \r\n compressive. Brick masonry is very strong in compression, so brick masonry \r\n arches can support considerable load. \r\n Historically, arches have been constructed with unreinforced masonry. \r\n Most brick masonry arches continue to be built with unreinforced masonry. \r\n The structural design of unreinforced brick masonry arches is discussed \r\n in Technical Notes 31A . Very long \r\n span arches and arches with a small rise may require steel reinforcement \r\n to resist tensile stresses. Also, reduction in abutment size and arch \r\n thickness for economy may require incorporation of reinforcement for \r\n adequate load resistance. Refer to the Technical Notes 17 Series \r\n for more information on reinforced brick masonry. Elaborate and \r\n intricate arches are sometimes prefabricated to avoid the complexity \r\n of on-site shoring. Most prefabricated brick masonry arches are reinforced. \r\n Prefabricated arches are built off site and transported to the job or \r\n built at the site. Cranes are often used to lift the arch into place \r\n in the wall. Such fabrication, handling and transportation should be \r\n considered in the structural design of the arch. Refer to Technical \r\n Notes 40 for a discussion of \r\n prefabricated brick masonry. \r\n If an unreinforced or reinforced brick masonry arch is not structurally \r\n adequate, the arch will require support. Typically, this support is \r\n provided by a steel angle. This is the most common means of supporting \r\n brick masonry arches in modern construction. The steel angle is bent \r\n to the curvature of the intrados of the arch. Curved sections of steel \r\n angle are welded to horizontal steel angles to form a continuous support. \r\n The angle either bears on the brickwork abutments or is attached to \r\n a structural member behind the wall. One example is shown in Fig. 4. \r\n When an arch is supported by a steel angle, the angle is designed to \r\n support the entire weight of brick masonry loading the arch, and the \r\n structural resistance of the arch is neglected. Consult Technical \r\n Notes 31B Revised for a discussion \r\n of the structural design of steel angle lintels. \r\n \r\n \r\n \r\n Arch Supported by Curved Steel Angle \r\n FIG. 4 \r\n \r\n WEATHER RESISTANCE \r\n \r\n Water penetration resistance is a primary concern in most applications \r\n of the building arch. In the past, the mass of a multi-wythe brick masonry \r\n arch was sufficient to resist water penetration. Today, thinner wall \r\n sections are used to minimize material use for economy and efficiency. \r\n Still, the arch must provide an effective weather resistant facade. \r\n Some arch applications do not require provisions for water penetration \r\n and insulation. For example, arch arcades and arches supported by porch \r\n columns typically do not conceal a direct path for water migration to \r\n the interior of the building they serve and may not require insulation. \r\n If this is the case, provisions for weather resistance need not be included \r\n in the arch design and detailing. \r\n Preventing water entry at an arch in an exterior building wall is just \r\n as important as at any other wall opening. Water penetration resistance \r\n can be provided by using a barrier wall system or a drainage wall system. \r\n Refer to Technical Notes 7 Revised \r\n for definitions and discussion of barrier and drainage wall systems. \r\n A drainage wall system, such as a brick veneer or cavity wall, is the \r\n most common brick masonry wall system used today. For either wall system, \r\n the arch should be flashed, with weep holes provided above all flashing \r\n locations. \r\n \r\n Flashing and Weep Holes \r\n \r\n Installation of flashing and weep holes around an arch can be difficult. \r\n Installation of flashing is easiest with jack arches because they are \r\n flat or nearly flat. Flashing should be installed below the arch and \r\n above the window framing or steel angle lintel. Flashing should extend \r\n a minimum of 4 in. (100 mm) past the wall opening at either end and \r\n should be turned up to form end dams. This is often termed tray flashing. \r\n Weep holes should be provided at both ends of the flashing and should \r\n be placed at a maximum spacing of 24 in. (600 mm) on centers along the \r\n arch span, or 16 in. (400 mm) if rope wicks are used. An example of \r\n flashing a jack arch in this manner is shown in Fig. 5a. Attachment \r\n of the flashing to the backing and formation of end dams should follow \r\n standard procedures. If the arch is constructed with reinforced brick \r\n masonry, flashing and weep holes can be placed in the first masonry \r\n course above the arch. \r\n \r\n \r\n \r\n Flashing Arches \r\n FIG. 5a \r\n \r\n \r\n \r\n Flashing Arches \r\n FIG. 5b \r\n \r\n \r\n \r\n Flashing Arches \r\n FIG. 5c \r\n \r\n Installation of flashing with other arch types, such as segmental and \r\n semicircular arches, can be more difficult. This is because most rigid \r\n flashing materials are hard to bend around an arch with tight curvature. \r\n If the arch span is less than about 3 ft (0.9 m), one section of tray \r\n flashing can be placed in the first horizontal mortar joint above the \r\n keystone, as illustrated in Fig. 5b. For arch spans greater than 3 ft \r\n (0.9 m), flashing can be bent along the curve of the arch with overlapping \r\n sections, as illustrated in Fig. 4. Alternately, a combination of stepped \r\n and tray flashing can be used, as shown in Fig. 5c. To form a step, \r\n the end nearest the arch should be turned up to form an end dam, while \r\n the opposite end is laid flat. A minimum of No. 15 building paper or \r\n equivalent moisture resistant protection should be installed on the \r\n exterior face of the backing over the full height of the arch and abutments. \r\n The building paper or equivalent should overlap the arch flashing. \r\n The design of a structural masonry arch should include consideration \r\n of the effect of flashing on the strength of the arch. Flashing acts \r\n as a bond break. If flashing is installed above the arch, the loading \r\n on the arch will likely be increased, and the structural resistance \r\n of the arch will be reduced. Installation of flashing at the abutments \r\n will affect their structural resistance and should also be considered. \r\n Consult Technical Notes 31A \r\n for a more extensive discussion of arch loads and structural resistance \r\n of brick masonry arches. \r\n \r\n DETAILING CONSIDERATIONS \r\n \r\n The brick masonry arch should serve its structural purpose and also \r\n provide an attractive architectural element to complement its surrounding \r\n structure. Careful consideration should be given to the options available \r\n for the arch, soffit and skewback. Proper configuration of the abutments \r\n and location of expansion joints should be considered for any arch design. \r\n \r\n Arch \r\n \r\n Arches can be configured in a variety of arch depths, brick sizes and \r\n shapes and bonding patterns. The arch is normally composed of an odd \r\n number of units for aesthetic purposes. Some of the more common arch \r\n configurations are illustrated in Fig. 6. Arch voussoirs are typically \r\n laid in radial orientation and are most often of similar size and color \r\n to the surrounding brickwork. However, the arch can be formed with brick \r\n which are thinner or wider than the surrounding brickwork and of a different \r\n color for variation. Another variation is to project or recess rings \r\n of multiple-ring arches to provide shadow lines or a label course. \r\n \r\n \r\n \r\n Typical Arch Configurations \r\n FIG. 6 \r\n \r\n Brick masonry arches are constructed with two different types of units. \r\n The first is tapered or wedge-shaped brick. These brick are tapered \r\n in the appropriate manner to obtain mortar joints of uniform thickness \r\n along the arch depth. The second is uncut, rectangular brick. When rectangular \r\n brick are used, the mortar joints are tapered to obtain the desired \r\n arch curvature. In some cases, a combination of these is used. For example, \r\n a slanted arch is formed with a tapered keystone and rectangular brick. \r\n This arch is similar to a jack arch, but can be more economical because \r\n it requires only one special-shaped brick. \r\n Selection of tapered or rectangular brick can be determined by the \r\n arch type, arch dimensions and by the appearance desired. Some arch \r\n types require more unique shapes and sizes of brick if uniform mortar \r\n joint thickness is desired. For example, the brick in a traditional \r\n jack arch or elliptical arch are all different sizes and shapes from \r\n the abutment to the keystone. Conversely, the voussoirs of a semicircular \r\n arch are all the same size and shape. Arch types with many different \r\n brick shapes and sizes should be special ordered from the brick manufacturer \r\n rather than cut in the field. \r\n The arch span should also be considered when selecting the arch brick. \r\n For short arch spans, use of tapered brick is recommended to avoid excessively \r\n wide mortar joints at the extrados. Larger span arches require less \r\n taper of the voussoirs and, consequently, can be formed with rectangular \r\n brick and tapered mortar joints. The thickness of mortar joints between \r\n arch brick should be a maximum of 3/4 in. (19 mm) and a minimum of 1/8 \r\n in. (3 mm). When using mortar joints thinner than 1/4 in. (6 mm), consideration \r\n should be given to the use of very uniform brick that meet the dimensional \r\n tolerance limits of ASTM C 216, Type FBX, or the use of gauged brickwork. \r\n Refer to Table 1 for determination of the minimum segmental and semicircular \r\n arch radii permitted for rectangular brick and tapered mortar joints. \r\n Typically, the use of tapered brick and uniform thickness mortar joints \r\n will be more aesthetically appealing. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Based on 1/4 in. (6 mm) mortar joint width at \r\n the intrados and 1/2 in. (13 mm) mortar joint width at the \r\n extrados. If the mortar joint thickness at the extrados is \r\n 3/4 in. (19 mm), divide minimum radius value by 2. \r\n 2 1 in.=25.4 mm; 1 ft=0.3m \r\n \r\n \r\n \r\n \r\n \r\n \r\n Depth. \r\n The arch depth will depend upon the size and orientation of the brick \r\n used to form the arch. Typically, the arch depth is a multiple of the \r\n bricks width. For structural arches, a minimum arch depth is determined \r\n from the structural requirements. If the arch is supported by a lintel, \r\n any arch depth may be used. \r\n \r\n The depth of the arch should also be detailed based on the scale of \r\n the arch in relation to the scale of the building and surrounding brickwork. \r\n To provide proper visual balance and scale, the arch depth should increase \r\n with increasing arch span. Because aesthetics of an arch are subjective, \r\n there are no hard rules for this. However, the following rules-of-thumb \r\n will help provide an arch with proper scale. For segmental and semicircular \r\n arches, the arch depth should equal or exceed 1 in. (25 mm) for every \r\n foot (300 mm) of arch span or 4 in. (100 mm), whichever is greater. \r\n For jack arches, the arch depth should equal or exceed 4 in. (100 mm) \r\n plus 1 in. (25 mm) for every foot (300 mm) of arch span or 8 in. (200 \r\n mm), whichever is greater. For example, the minimum arch depth for an \r\n 8 ft (2.4 m) span should be 8 in. (200 mm) for segmental arches and \r\n 12 in. (300 mm) for jack arches. \r\n The depth of jack arches will also be a function of the coursing of \r\n the surrounding brick masonry. The springing and the extrados of the \r\n jack arch should coincide with horizontal mortar joints in the surrounding \r\n brick masonry. Typically, the depth of a jack arch will equal the height \r\n of 3, 4 or 5 courses of the surrounding brickwork, depending upon the \r\n course height. \r\n Keystone. The keystone may be a single brick, multiple brick, \r\n stone, precast concrete or terra cotta. Avoid using a keystone which \r\n is much taller than the adjacent voussoirs. A rule-of-thumb is that \r\n the keystone should not extend above adjacent arch brick by more than \r\n one third the arch depth. When a keystone is used that is larger than \r\n adjacent arch brick or formed with different material, one option is \r\n to use springers that match the keystone. \r\n The use of a large keystone has its basis in both purpose and visual \r\n effect. With most arch types, the likely location of the first crack \r\n when the arch fails is at the mortar joint nearest to the midspan of \r\n the arch. Use of a large keystone at this point moves the first mortar \r\n joint further from the midspan and increases the resistance to cracking \r\n at this point. Aesthetically, a large keystone adds variation of scale \r\n and can introduce other masonry materials in the facade for additional \r\n color and texture. \r\n If the keystone is formed with more than one masonry unit, avoid placing \r\n the smaller unit at the bottom. Such units are more likely to slip when \r\n the arch settles under load. Also, it is preferred to have the arch \r\n crown (the top of the keystone) coincident with a horizontal mortar \r\n joint in the surrounding brickwork to give the arch a neater appearance. \r\n \r\n Soffit \r\n \r\n A brick masonry soffit is one attractive feature of a structural brick \r\n masonry arch. Many bonding patterns and arrangements can be used to \r\n form the arch soffit. Deep soffits are common on building arcades or \r\n arched entranceways. In this case, it is common to form a U-shaped wall \r\n section, as illustrated in Fig. 7. The arches on either wall face should \r\n be bonded to the brick masonry forming the soffit. Bonding pattern or \r\n metal ties should be used to tie the brick masonry forming the soffit \r\n together structurally and to tie the arches on either wall face to the \r\n soffit. If metal ties are used to bond the masonry, corrosion resistant \r\n box or Z metal wire ties should be placed along the arch span at a maximum \r\n spacing of 24 in. (600 mm) on center. \r\n Structural resistance of the arch should be evaluated at sections through \r\n the soffit, the exterior wall face and the interior wall face. Deeper \r\n soffits may require an increase in arch depth. If the arch is structural, \r\n connection of the brick masonry forming the soffit to interior framing \r\n members with wall ties or connectors may not be required. \r\n \r\n \r\n \r\n Structural Arch Soffit Option \r\n FIG. 7 \r\n \r\n Skewback \r\n \r\n For flat arches and arch types that have horizontal skewbacks, such \r\n as jack and semicircular arches, respectively, the most desirable spring \r\n line location is coincident with a bed joint in the abutment. For other \r\n arch types, it is preferred to have the spring line pass about midway \r\n through a brick course in the abutment, as illustrated in Fig. 8, to \r\n avoid a thick mortar joint at the springing. The brick in the abutment \r\n at the springing should be cut or be a special cant-shaped brick. This \r\n allows vertical alignment with the brick beneath, producing more accurate \r\n alignment of the arch. \r\n When two arches are adjacent, such as with a two-bay garage or building \r\n arcades, intersection of the arches may occur at the skewback. Attention \r\n should be given to proper bonding of the arches for both visual appeal \r\n and structural bonding. Creation of a vertical line between arches should \r\n be avoided. Rather, special shape brick should be used to mesh the two \r\n arches properly. One example is illustrated in Fig. 9. \r\n \r\n \r\n \r\n Skewback Options \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n Option For Intersecting Arches \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n Abutments \r\n \r\n An arch abutment can be a column, wall or combination of wall and shelf \r\n angle. Failure of an abutment occurs from excessive lateral movement \r\n of the abutment or exceeding the flexural, compressive or shear strength \r\n of the abutment. Lateral movement of the abutment is due to the horizontal \r\n thrust of the arch. Thrust develops in all arches and the thrust force \r\n is greater for flatter arches. The thrust should be resisted so that \r\n lateral movement of the abutment does not cause failure in the arch. \r\n If the abutment is formed by a combination of brickwork and a non-masonry \r\n structural member, rigidity of the non-masonry structural member and \r\n rigidity of the ties are very important. Adjustable ties or single or \r\n double wire ties are recommended. Corrugated ties should not be used \r\n in this application because they do not provide adequate axial stiffness. \r\n Consult Technical Notes 31A \r\n for further discussion of abutment and tie stiffness requirements. \r\n \r\n Lateral Bracing \r\n \r\n In addition to gravity loads, out-of-plane loads should be considered \r\n when designing a masonry arch. The arch should have adequate resistance \r\n to out-of-plane loads or lateral bracing should be provided. In veneer \r\n construction, lateral bracing is provided by the backing through the \r\n use of wall ties. Arches which are not laterally braced may require \r\n increased masonry thickness or reinforcement to carry loads perpendicular \r\n to the arch plane in addition to vertical loads. \r\n \r\n Expansion Joints \r\n \r\n Thermal and moisture movements of brick masonry are controlled by the \r\n use of expansion joints. Expansion joints avoid cracking of the brickwork \r\n and also reduce the size of wall sections. Reduction of wall size has \r\n a very important effect upon the performance of structural brick masonry \r\n arches. The state of stress in a structural brick arch and the surrounding \r\n masonry is very sensitive to the relative movements of the abutments. \r\n If an inadequate number of expansion joints are provided, the differential \r\n movement of abutments can cause cracking and downward displacement of \r\n brick in the masonry arch and surrounding masonry. Proper size and spacing \r\n of expansion joints is discussed in Technical Notes 18A \r\n Revised. \r\n If the arch is structural, care should be taken not to affect the integrity \r\n of the arch by detailing expansion joints too close to the arch and \r\n its abutments. Vertical expansion joints should not be placed in the \r\n masonry directly above a structural arch. This region of masonry is \r\n in compression, so an expansion joint will cause displacement when centering \r\n is removed and possible collapse of the arch and surrounding brickwork. \r\n In addition, vertical expansion joints should not be placed in close \r\n proximity to the springing. The expansion joint will reduce the effective \r\n width of the abutment and its ability to resist horizontal thrust from \r\n the arch. If the arch is non-structural, placement of expansion joints \r\n may be at the arch crown and also at a sufficient distance away from \r\n the springing to avoid sliding. While permitted, placement of an expansion \r\n joint at the arch crown is not preferred because it disrupts ones traditional \r\n view of the arch as a structural element. Refer to Fig. 10 for suggested \r\n expansion joint locations for structural and non-structural arches. \r\n \r\n \r\n \r\n Expansion Joints Near Arches \r\n FIG. 10a \r\n \r\n \r\n \r\n \r\n \r\n Expansion Joints Near Arches \r\n FIG. 10b \r\n \r\n Detailing of expansion joints can be difficult with very long span \r\n arches or runs of multiple arches along an arcade. Structural analysis \r\n of the arch should consider the location of expansion joints. For the \r\n particular case of multiple arches closely spaced, vertical expansion \r\n joints should be detailed at a sufficient distance away from the end \r\n arches so that horizontal arch thrusts are adequately resisted by the \r\n abutments to avoid overturning of the abutments. For long arcades, expansion \r\n joints should also be placed along the centerline of abutments between \r\n arches when necessary. In this case, horizontal thrusts from adjacent \r\n arches will not be counteracting, so the effective abutment length should \r\n be halved and overturning of each half of the abutment should be checked. \r\n Refer to Technical Notes 31A \r\n for further discussion of abutment design for adequate stiffness. \r\n \r\n MATERIAL SELECTION \r\n \r\n To provide a weather resistant barrier and maintain its structural \r\n resistance, the arch must be constructed with durable materials. The \r\n strength of an arch depends upon the compressive strength and the flexural \r\n tensile strength of the masonry. Selection of brick and mortar should \r\n consider these properties. \r\n \r\n Brick \r\n \r\n Solid or hollow clay brick may be used to form the arch and the surrounding \r\n brickwork. Solid brick should comply with the requirements of ASTM C \r\n 216 Specification for Facing Brick. Hollow brick should comply with \r\n the requirements of ASTM C 652 Specification for Hollow Brick. Refer \r\n to Technical Notes 9 Series for a discussion of brick \r\n selection and classification. The compressive strength of masonry is \r\n related to the compressive strength of the brick, the mortar type and \r\n the grout strength. For structural arches, brick should be selected \r\n with consideration of the required compressive strength of masonry. \r\n Typically, compressive strength of the brick masonry will not limit \r\n the design of the arch. \r\n Tapered voussoirs can be cut from rectangular units at the job site \r\n or special ordered from the brick manufacturer. Before specifying manufactured \r\n special arch shapes, the designer should determine the availability \r\n of special shapes for the arch type and brick color and texture desired. \r\n Many brick manufacturers produce tapered arch brick for the more common \r\n arch types as part of their regular stock of special shapes. Be sure \r\n to contact the manufacturer as early as possible if special shapes are \r\n needed. In many instances, production of the special shapes may require \r\n a color matching process and adequate lead time for the manufacturer. \r\n \r\n Mortar \r\n \r\n Mortar used to construct brick masonry arches should meet the requirements \r\n of ASTM C 270 Standard Specification for Masonry Mortar. Consult Technical \r\n Notes 8 Series for a discussion of mortar types and kinds \r\n for brick masonry. For structural arches, the flexural tensile strength \r\n of the masonry should be considered when selecting the mortar. The flexural \r\n tensile strength of the masonry will affect the load resistance of the \r\n arch and the abutments. \r\n \r\n CONSTRUCTION AND WORKMANSHIP \r\n \r\n The proper performance of a brick masonry arch depends upon proper \r\n methods of construction and attention to workmanship. Layout of the \r\n arch prior to construction will help avoid poor spacing of voussoirs, \r\n which results in thicker mortar joints and unsymmetrical arches. Some \r\n arch applications, such as barrel vaults and domes, can be entirely \r\n self-supporting, even during construction. However, most applications \r\n of the masonry arch used today require proper shoring and bracing. \r\n \r\n Centering \r\n \r\n Both structural and non-structural arches should be properly supported \r\n throughout construction. Brick masonry arches are constructed with the \r\n aid of temporary shoring, termed centering, or permanent supports, such \r\n as a structural steel angle. \r\n Centering is used to carry the weight of a brick masonry arch and the \r\n loads being supported by the arch until the arch itself has gained sufficient \r\n strength. The term \"centering\" is used because the shoring is marked \r\n for proper positioning of the brick forming the arch. Centering is typically \r\n provided by wood construction. An example of centering for an arch is \r\n shown in Fig. 11. Careful construction of the centering will ensure \r\n a more pleasing arch appearance and avoid layout problems, such as an \r\n uneven number of brick to either side of the keystone. \r\n \r\n \r\n \r\n Centering \r\n FIG. 11 \r\n \r\n Immediately after placement of the keystone, very slight downward displacement \r\n of the centering, termed easing, can be performed to cause the arch \r\n voussoirs to press against one another and compress the mortar joints \r\n between them. Easing helps to avoid separation cracks in the arch. In \r\n no case should centering be removed until it is certain that the masonry \r\n is capable of carrying all imposed loads. Premature removal of the centering \r\n may result in collapse of the arch. \r\n Centering should remain in place for at least seven days after construction \r\n of the arch. Longer curing periods may be required when the arch is \r\n constructed in cold weather conditions and when required for structural \r\n reasons. The arch loading and the structural resistance of the arch \r\n will depend upon the amount of brickwork surrounding the arch, particularly \r\n the brick masonry within spandrel areas. Appropriate time of removal \r\n of centering for a structural arch should be determined with consideration \r\n of the assumptions made in the structural analysis of the arch. It may \r\n be necessary to wait until the brickwork above the arch has also cured \r\n before removing the centering. \r\n \r\n Workmanship \r\n \r\n All mortar joints should be completely filled, especially in a structural \r\n member such as an arch. If hollow brick are used to form the arch, it \r\n is very important that all face shells and end webs are completely filled \r\n with mortar. Brick masonry arches are sometimes constructed with the \r\n units laid in a soldier orientation. It may be difficult to lay units \r\n in a soldier position and also obtain completely filled mortar joints. \r\n This is especially true for an arch with tapered mortar joints. In such \r\n cases, the use of two or more rings of arch brick laid in rowlock orientation \r\n can help ensure full mortar joints. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes is an introduction to brick masonry \r\n arches. A glossary of arch terms has been provided. Many different types \r\n of brick masonry arches are described and illustrated. Proper detailing \r\n of brick masonry arches for appearance, structural support and weather \r\n resistance is discussed. Material selection and proper construction \r\n practices are explained. Other Technical Notes in this Series \r\n discuss the structural design of arches. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the engineering \r\n staff of the Brick Institute of America. The information contained herein \r\n must be used in conjunction with good technical judgment and a basic \r\n understanding of the properties of brick masonry. Final decisions on \r\n the use of the information contained in this Technical Notes are \r\n not within the purview of the Brick Institute of America and must rest \r\n with the project architect, engineer and owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Brickwork \r\n Arch Detailing, Ibstock Building \r\n Products, Butterworth & Co. (Publishers) Ltd., London, England, \r\n 1989, 114 pp. \r\n 2. Lynch, \r\n G., Gauged Brickwork, A Technical Handbook, Gower Publishing \r\n Company, Aldershot, Hants, England, 1990, 115 pp. \r\n 3. Trimble, \r\n B.E., and Borchelt, J.G., \"Jack Arches in Masonry Construction,\" The \r\n Construction Specifier, Construction Specifications Institute, \r\n Alexandria, VA, January 1991, pp. 62-65. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60104,"ResultID":176336,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 31A - Structural Design of \r\n Brick Masonry Arches \r\n Oct. 1967 (Reissued July 1986) \r\n \r\n INTRODUCTION \r\n The railway bridge at Maidenhead, England, constructed \r\n in 1838, is a brick arch with a span of 128 ft and a rise of 24.3 ft. \r\n This arch was designed by engineer Marc Brunel, who is also credited with \r\n being the first to use reinforced brick masonry. A similar brick arch \r\n railway bridge was constructed on North Avenue, Baltimore, Maryland, in \r\n 1895. It has a span of 130 ft and a rise of 26 ft. These outstanding examples \r\n are cited only to illustrate the structural capabilities of the brick \r\n arch - capabilities on which designers may rely when architectural or \r\n structural considerations suggest their use in modern design. \r\n This issue of Technical Notes covers \r\n the structural design of major and minor brick masonry arches. \r\n Minor arches are those whose spans do not exceed \r\n 6 ft and with maximum rise-to-span ratios of 0.15. Coefficients are given \r\n from which the horizontal thrust of such arches may be determined. Equations \r\n are presented for obtaining compressive stresses developed in the masonry \r\n and for determining stability against sliding. \r\n Derivation of thrust coefficients and equations \r\n are based on the hypothesis of least crown thrust, as described in Technical \r\n Notes 31 , and the following assumptions \r\n have been made: \r\n 1. The thrust at the crown is horizontal and \r\n passes through the upper 1/3 point of the arch. \r\n 2. The reaction passes through the lower 1/3 \r\n point of the arch at the skewback. \r\n 3. The equilibrium polygon lies completely within \r\n the middle 1/3 of the arch. \r\n Figure 1 illustrates jack and segmental arches. \r\n \r\n \r\n \r\n \r\n FIG. 1a \r\n \r\n \r\n FIG. 1b \r\n Major arches are those with spans in excess \r\n of 6 ft or rise-to-span ratios greater than 0.15. In this issue of Technical \r\n Notes an example is given of major arch design based on the equations \r\n for redundant moments and forces presented in the publication, \"Frames \r\n and Arches\". (\"Frames and Arches,\" by Valerian Leontovich, McGraw Hill \r\n Book Co., 1959.) The method of analysis presented in this book is substantially \r\n shorter than others in current use. \r\n \r\n MINOR ARCH LOADING \r\n The loads falling upon a minor arch may consist \r\n of live loads and dead loads from floors, roofs, walls and other structural \r\n members. These are applied as point loads or as uniform loads fully or \r\n partially distributed. A method of determining imposed loads on a member \r\n spanning small openings is described in Technical Notes 17B . A \r\n brief resume of that explanation is given here. \r\n The dead load of a wall above an arch may be \r\n assumed to be the weight of wall contained within a triangle immediately \r\n above the opening. The sides of this triangle are at 45-deg angles to \r\n the base. Therefore, its height is 1/2 of the span. Such triangular loading \r\n may be assumed to be equivalent to a uniformly distributed load of 1/3 \r\n times the triangular load. \r\n Superimposed uniform loads above this triangle \r\n may be carried by arching action of the masonry wall itself. Uniform live \r\n and dead loads occurring below the apex of the triangle are applied directly \r\n upon the arch for design purposes. Heavy concentrated loads should not \r\n be allowed to bear directly on minor arches. This is especially true of \r\n jack arches. Minor concentrated loads bearing on, or nearly directly on, \r\n the arch may safely be assumed to be equivalent to a uniformly distributed \r\n load equal to twice the concentrated load. \r\n Figure 2 shows the use of minor arches in contemporary \r\n architecture. \r\n \r\n \r\n \r\n \r\n \r\n High School in Columbus, Indiana \r\n Harry Weese & Associates, Architects \r\n FIG. 2 \r\n \r\n \r\n MINOR ARCH DESIGN \r\n There are three methods of failure of unreinforced \r\n masonry arches: (a) by rotation of one section of the arch about the edge \r\n of a joint; (b) by the sliding of one section of the arch on another or \r\n on the skewback; (c) by crushing of the masonry \r\n (a) Rotation . The assumption for the \r\n design of minor arches, that the equilibrium polygon lies entirely within \r\n the middle third of the arch section, precludes the rotation of one section \r\n of the arch about the edge of a joint or the development of tensile stresses \r\n in either the intrados or extrados. \r\n (b) Sliding . The coefficient of friction \r\n between the units composing a brick or tile masonry arch is at least 0.60, \r\n without considering the additional resistance to sliding resulting from \r\n bond between mortar and the masonry units. This corresponds to an angle \r\n of friction of approximately 31 deg. If that angle, which the line of \r\n resistance of the arch makes with the normal to the joint between arch \r\n sections, is less than the angle of friction, the arch is stable against \r\n sliding. This angle can be determined graphically, as illustrated in Technical \r\n Notes 31 , or may be determined mathematically \r\n bar the following formula: \r\n \r\n \r\n \r\n \r\n \r\n where: b = angle between line of resistance \r\n and normal to joint, \r\n \r\n \r\n W = total equivalent uniform load on arch, \r\n H = crown thrust and \r\n g = angle of \r\n joint with vertical. \r\n \r\n \r\n \r\n For minor segmental arches, the angle between \r\n the line of resistance and the normal to the joint is greatest at the \r\n skewback. This will also be true for jack arches if the joints are radial \r\n about a center at the intersection of the planes of the skewbacks. However, \r\n if the joints are not radial about this center, each joint should be investigated \r\n for resistance to sliding. This can be done most easily by constructing \r\n an equilibrium polygon, assuming that the crown thrust is applied at the \r\n top of the middle third and the reaction at the skewback is applied at \r\n the bottom of the middle third of the section. \r\n For segmental arches with radial joints, the \r\n angle ( g ) between \r\n the skewback and the vertical is \r\n \r\n \r\n \r\n \r\n \r\n \r\n or in terms of the radius of curvature \r\n \r\n \r\n \r\n \r\n \r\n For jack arches in which the skewback equals \r\n 1/2 in. per ft of span for each 4 in. of arch depth, the angle ( g ) that the skewback makes \r\n with the vertical is \r\n \r\n \r\n \r\n \r\n \r\n In equations 2, 3 and 4: \r\n \r\n S = span, \r\n r = rise, \r\n R = radius of curvature. \r\n \r\n \r\n (c) Crushing. \r\n (1) Segmental Arch. Figure 3 is a graphic \r\n representation of thrust coefficients (H/W) for segmental arches subjected \r\n to uniform load over the entire span. Once the thrust coefficient is determined \r\n for a particular arch, the horizontal thrust (H) may be determined as \r\n the product of the thrust coefficient and the total load (W). To determine \r\n the proper thrust coefficient, one must first determine the characteristics \r\n of the arch, S/r and S/d: \r\n where: \r\n \r\n S = the clear span, \r\n r = the rise of the soffit and \r\n d = the depth of the arch. \r\n \r\n \r\n In these ratios and in the ratios and equations \r\n that follow, all terms of length must be expressed in the same units; \r\n for example, in computing S/r and S/d, if S is in feet, r and d must be \r\n in feet also. \r\n \r\n \r\n \r\n \r\n \r\n Thrust Coefficients for Segmental Arches \r\n FIG. 3 \r\n \r\n \r\n If the applied load is triangular or concentrated, \r\n the above method may still be used, but the horizontal thrust coefficient \r\n must be increased by 1/3 for triangular loading and doubled for concentrated \r\n loads. \r\n Once the horizontal thrust has been determined, \r\n the maximum compressive stress in the masonry is determined by the following \r\n formula: \r\n \r\n \r\n \r\n \r\n \r\n In this equation: \r\n \r\n f m = maximum compressive stress in the arch in pounds per \r\n square inch, \r\n H = horizontal thrust in pounds, \r\n b = breadth of the arch in inches and \r\n d = depth of the arch in inches. \r\n \r\n \r\n \r\n This value is twice an axial compressive stress \r\n on the arch, due to a load H. because the horizontal thrust is located \r\n at the third point of the arch depth. \r\n (2) Jack Arch. The common rule for jack \r\n arches is to provide a skewback (K, measured horizontally) of 1/2 in. \r\n per ft of span for each 4 in. of arch depth. Jack arches are commonly \r\n constructed in depths of 8 and 12 in. with a camber of 1/8 in. per ft \r\n of span. \r\n For jack arches, applying the same assumptions \r\n as previously outlined, the horizontal thrust at the spring line may be \r\n determined by the following formulae: \r\n For uniform loading over full span, \r\n \r\n \r\n \r\n \r\n \r\n For triangular loading over full span, \r\n \r\n \r\n \r\n \r\n \r\n Maximum compressive stress (f m ) in the jack arch may be determined \r\n from the following formulae: \r\n \r\n \r\n \r\n \r\n \r\n The maximum compressive stress in a jack arch \r\n may be computed directly from the following formulae: \r\n For uniform loading over full span, \r\n \r\n \r\n \r\n \r\n For triangular loading, \r\n \r\n \r\n \r\n \r\n \r\n Formulae 8, 9 and 10 include a factor which \r\n allows for non-axial loading. In formulae 6 through 10, inclusive: \r\n \r\n \r\n H = horizontal thrust in pounds, \r\n W = total load in pounds, \r\n S = clear span in inches, \r\n d = depth of arch in inches and \r\n b = breadth of arch in inches. \r\n \r\n \r\n THRUST RESISTANCE \r\n Resistance to horizontal thrust, developed by \r\n the arch, is provided by the adjacent mass of masonry. In areas where \r\n limited masonry is available, i.e. corners, openings, etc., it may be \r\n necessary to check the resistance of the wall to the horizontal thrusts. \r\n Figure 4 illustrates how such resistance may be calculated. \r\n \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n It is assumed that the thrust of the arch attempts \r\n to move a volume of masonry enclosed by the boundary lines ABCD. For calculating \r\n purposes the area CDEF is equivalent in resistance. It can be seen that \r\n the thrust is acting against two planes of resistance, CF and DE. The \r\n resistance to arch thrust is determined by the following formula: \r\n \r\n \r\n \r\n \r\n By using the principle given in formula (11), \r\n the minimum distance from a corner or opening at which an arch may be \r\n located is easily determined. This can be done by writing formula (11) \r\n to solve for x, substituting actual arch thrust for resisting thrust: \r\n \r\n \r\n \r\n \r\n In these formulae: \r\n \r\n H 1 \r\n = resisting thrust in pounds, \r\n v m = allowable shearing stress in the masonry wall in pounds \r\n per square inch, \r\n n = the number of resisting shear planes, \r\n x = the distance from the center of the \r\n skew-back to the end of the wall in inches and \r\n t = wall thickness in inches. \r\n \r\n The tendency for arch thrust to overturn a section \r\n of masonry, rather than slide it or rack it, must also be investigated. \r\n In general, such overturning forces are found to govern only at arches \r\n near the top of a wall, since that portion of masonry which tends to overturn \r\n must first become separated from the body of the wall. \r\n \r\n ALLOWABLE STRESSES \r\n Recommended allowable compressive stresses for \r\n use in the design of brick arches are given in Table 1. Recommended allowable \r\n shearing stresses in unreinforced walls for use in the design of abutments \r\n are given in Table 2. These are based on the requirements of Recommended \r\n Building Code Requirements for Engineered Brick Masonry, SCPI, May \r\n 1966 \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1Based on Recommended Building Code \r\n Requirements for Engineered Brick Masonry, SCPI, MA 1966 \r\n 2Linear interpolation is permissible \r\n \r\n \r\n \r\n \r\n \r\n MAJOR ARCH LOADING \r\n The principal forces acting upon arches in buildings \r\n are the result of vertical dead and live loads and wind loads. Many masonry \r\n arches are integral with surrounding masonry. In such instances, loads \r\n transmitted to the arch through the masonry are indeterminate, due to \r\n arching action of adjacent masonry. \r\n It often assumed that the entire weight of masonry, \r\n above the soffit, presses vertically upon the arch. This certainly is \r\n not accurate, since even with dry masonry a part of the wall will be self-supporting. \r\n However, this assumption is certainly on the safe side. The passive resistance \r\n of the adjacent masonry materially affects the stability of an arch. \r\n The designer must rely on empirical formulae, \r\n based on the performance of existing structures, to determine the loads \r\n on an arch. The dead load of masonry wall supported by an integral arch \r\n depends upon the arch rise and span and the wall height above the arch. \r\n It may be considered to be either uniform (rectangular) or variable (complementary \r\n parabolic) in distribution, or a combination thereof. \r\n \"Frames and Arches\" gives solutions for arches \r\n with rise-to-span ratios (f/L) ranging from 0.0 to 0.6. The following \r\n recommended assumptions for loading of such arches are believed to be \r\n safe: \r\n For low rise arches, f/L = 0.2 or less, a uniform \r\n load may be assumed. This load will be the weight of wall above the crown \r\n of the arch up to a maximum height of L/4. \r\n For higher rise arches a dead load consisting \r\n of uniform plus complementary parabolic loading may be assumed. The maximum \r\n ordinate of the parabolic loading will be equal to a weight of wall whose \r\n height is the rise of the arch. The minimum ordinate of the parabolic \r\n loading will be zero. The uniform loading will be the weight of the wall \r\n above the crown of the arch up to a maximum height of L 2 /100. \r\n Uniform floor and roof loads are applied as \r\n a uniform load on the arch. Small concentrated loads may be treated as \r\n uniform loads of twice the magnitude. Large concentrated loads may be \r\n treated as point loads on the arch. \r\n Several major arches are shown in Fig. 5. \r\n \r\n \r\n \r\n \r\n Grundtvig Church, Copenhagen, Denmark \r\n Designed in 1913 by P.V. Jensen \r\n Klint - It was completed in 1940 \r\n FIG. 5 \r\n \r\n MAJOR ARCH DESIGN \r\n General . \"Frames and Arches\" provides \r\n straightforward equations by which redundant moments and forces in arched \r\n members may be determined. The reader is referred to a discussion of this \r\n book which appears in Technical Notes 31 . \r\n Without repeating the aforementioned discussion \r\n here, let it suffice to say that, for relatively high-rise (f/L = 0.2) \r\n constant-section arches, Method A of Section 22 yields the proper solutions. \r\n The recommendations for use of this section are: \r\n 1. Establish principal dimensions of the arch. \r\n 2. On this basis and depending upon the established \r\n shape and f/L ratio of the arch, obtain the corresponding k value of the \r\n arch (see Table 3). \r\n 3. Obtain the elastic parameters ( a , b , g and d ), load constants and general constants. \r\n 4. Perform the algebraic operations with the \r\n given equations. \r\n Equations . The equations are based upon \r\n a horizontal and vertical grid coordinate system with origin at the intersection \r\n of the arch axis and left skewback. Distances x and y are coordinates \r\n of the arch axis. The general equation for the parabolic arch axis is: \r\n \r\n \r\n Each set of equations depends upon the loading \r\n conditions. Among the solutions included with those in Section 22, Method \r\n A are the following: \r\n For vertical complementary parabolic loading: \r\n \r\n \r\n \r\n \r\n \r\n When x ┬ú L / 2: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n For vertical uniform load over the entire arch: \r\n \r\n \r\n M and Q are zero at any section of the arch. \r\n \r\n \r\n \r\n When x ┬ú L / 2: \r\n \r\n \r\n \r\n \r\n \"Frames and Arches\" also contains equations \r\n for other loading conditions; e.g. concentrated loads. \r\n \r\n \r\n \r\n \r\n \r\n Note: Adapted from Table 12, \" Frames \r\n and Arches .\" \r\n \r\n Notation . In these equations, the subscripts \r\n 1 and 2 denote the left and right supports respectively. The subscript \r\n x denotes values at any horizontal distance, x, from the origin. f is the angle, at any point, whose tangent \r\n is the slope of the arch axis at that point. (See Table 4.) \r\n \r\n \r\n M = moment \r\n N = axial force \r\n Q = shearing force \r\n f = rise of the arch \r\n W = total load under consideration \r\n H = horizontal thrust \r\n V = vertical reaction \r\n L = span of the arch \r\n S and T are load constants (see Table 5). \r\n J, F and K are constants, determined by: \r\n J = 1 + ( d \r\n / g ) \r\n F = q - g J 2 \r\n K = S q / g ) \r\n a , b , g and d are parameters (see Table 6). \r\n q = 2 ( a + b ) \r\n \r\n \r\n \r\n \r\n \r\n Note: From Table 10, \" Frames and Arches. \" \r\n \r\n \r\n Note: From Table 18, \" Frames and Arches .\" \r\n Intermediate values may be obtained by interpolation. \r\n \r\n \r\n \r\n . \r\n Note: From Table 13, \" Frames and Arches. \" Intermediate values may \r\n be obtained by interpolation. \r\n \r\n \r\n ILLUSTRATIVE EXAMPLE \r\n Problem . Using the equations given in \r\n the book, \"Frames and Arches,\" design a parabolic brick masonry arch to \r\n meet the following requirements. The arch is integral with a loadbearing, \r\n brick-and-brick cavity wall. Wall weight is 80 psf. The arch dimensions \r\n are: span, 20 ft; rise, 12 ft; depth, 16 in.; thickness, 12 in.; total \r\n wall height, 8 ft. The uniform roof load, bearing on the wall above the \r\n arch, is 1200 lb per ft. The arch is of solid brick (4000 psi) and type \r\n N mortar; allowable compressive stress in the arch is 300 psi. \r\n Solution . The arch is a constant-section, \r\n high-rise, symmetrical, parabolic, hingeless arch; therefore, the equations \r\n previously given in this issue of Technical Notes are applicable. \r\n Each different loading condition must be analyzed separately. Similar \r\n loads, e.g. all uniform loads, may be added and treated as a single load. \r\n Moments, shears and thrusts resulting from each loading condition are \r\n combined to give total values. For symmetrically loaded symmetrical arches, \r\n only 1/2 of the arch need be analyzed. \r\n The loads carried by the arch are: \r\n \r\n \r\n Uniform loads \r\n Wall dead load \r\n (80) (20 2 /100) \r\n = 320 lb per ft \r\n Roof dead + live load \r\n = 1200 \r\n Arch dead load in excess \r\n of wall weight (approx.) \r\n = 260 \r\n Total uniform load = 1780 lb per It \r\n W = (1780) (20) = 35,600 lb \r\n \r\n \r\n Complementary parabolic loading \r\n Maximum ordinate \r\n p = (80) (12) = 960 \r\n lb per ft \r\n Minimum ordinate = 0 \r\n W = pL / 3 = 960 (20)/3 \r\n = 6400 lb \r\n \r\n \r\n \r\n Numbers before the following paragraphs refer to the outline of the recommended \r\n sequence. \r\n 1. The principal arch dimensions are: \r\n d = 16 in. \r\n t = 12 in. \r\n L = 20 ft \r\n f = 12 ft \r\n f / L = 0.6 \r\n \r\n \r\n \r\n 2. From Table 3, k = \r\n 2.80 \r\n 3a. For parabolic loading: \r\n From Table 5, \r\n S = 0.5943 T = 0.4286 \r\n From Table 6, \r\n \r\n \r\n a = 6.88 g = 8.046 \r\n b = 2.72 d = 2.834 \r\n From the given relationships, \r\n J = 1.3522 F = 4.4884 \r\n q = 19.20 K = 1.4182 \r\n \r\n \r\n 3b. For vertical uniform loads: \r\n From Table 5, \r\n \r\n S = 1.0061 T = 0.6800 \r\n \r\n From Table 6 (note that a , b , g and d are the same for any given arch \r\n dimensions), \r\n \r\n \r\n a = 6.88 g = 8.046 \r\n b = 2.72 d = 2.834 \r\n \r\n \r\n From the given relationships: \r\n \r\n \r\n J = 1.3522 F = 4.4884 \r\n q = 19.20 K = 2.4008 \r\n \r\n \r\n 4. The necessary substitution may now be made \r\n to evaluate the design moments and forces. In this example, moments, shears \r\n and axial thrusts are determined at increments of 0.1L (each 2 ft of span). \r\n Tabular computations are suggested for ease in evaluating these equations. \r\n The results of such tabular computations are shown in Table 7. \r\n \r\n \r\n \r\n Note: The above moments are in \r\n foot-pounds. Shears and axial thrusts are in pounds. \r\n The stresses in the arch may be determined from \r\n the following equations: \r\n \r\n \r\n \r\n \r\n In the above equations, f m denotes maximum and minimum fiber stresses \r\n and V m \r\n denotes shearing stresses. All quantities in the equations must be in \r\n units of inches and pounds. Table 8 shows stresses in the arch. \r\n Plus signs indicate compression and minus signs \r\n tension, for values of f m . These signs have only directional significance for values of V m . \r\n No tensile stresses should be permitted in unreinforced masonry arches \r\n under static loading conditions. The reader is referred to Technical \r\n Notes 31 for a discussion of mortars \r\n in arch construction. See Table 1 for allowable compressive stresses in \r\n brick masonry. \r\n \r\n \r\n \r\n \r\n \r\n Note: The above stresses are in pounds per \r\n square inch. \r\n \r\n \r\n \r\n Interpretation of Results . Table 8 indicates \r\n that the compressive stresses are, in all instances, less than the allowable \r\n 300 psi. No tensile stresses exist. The shearing stresses are insignificant. \r\n The arch is adequate. The moments and shears are caused by other than \r\n uniform loads. For this arch, and perhaps for most arches, the predominant \r\n load is uniformly distributed. As a result the moments and shears are \r\n relatively small and the arch is predominantly in compression. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60105,"ResultID":176337,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 31B - Structural Steel \r\n Lintels \r\n Nov./Dec. 1981 (Reissued May 1987) \r\n \r\n Abstract : The design of structural steel lintels for use with \r\n back masonry is too critical an element to be left to \"rule-of-thumb\" \r\n designs. Too little concern for loads, stresses and serviceability \r\n can lead to problems. Information is provided so that structural \r\n steel lintels for use in brick masonry walls may be satisfactorily \r\n designed. \r\n Key Words : beams (supports); \r\n brick ; buildings ; deflection ; \r\n design ; lintels; loads (forces); masonry ; \r\n structural steel; walls . \r\n INTRODUCTION \r\n A lintel is a structural member placed \r\n over an opening in a wall. In the case of a brick masonry wall, \r\n lintels may consist of reinforced brick masonry, brick masonry arches, \r\n precast concrete or structural steel shapes. Regardless of the material \r\n chosen for the lintel, its prime function is to support the loads \r\n above the opening, and it must be designed properly. To eliminate \r\n the possibility of structural cracks in the wall above these openings, \r\n the structural design of the lintels should not involve the use \r\n of \"rule-of-thumb\" methods, or the arbitrary selection of structural \r\n sections without careful analysis of the loads to be carried and \r\n calculation of the stresses developed. Many of the cracks which \r\n appear over openings in masonry walls are due to excessive deflection \r\n of the lintels resulting from improper or inadequate design. \r\n This Technical Notes presents the \r\n considerations to be addressed if structural steel lintels are to \r\n be used. It also provides a procedure for the structural design \r\n of these lintels. For information concerning reinforced brick masonry \r\n lintels, see Technical Notes 17H and for brick masonry arches, \r\n see Technical Notes 31 , 31A \r\n and 31C Revised. \r\n CONSIDERATIONS \r\n General \r\n When structural steel lintels are used, \r\n there are several considerations which must be addressed in order \r\n to have a successful design. These include loading, type of lintel, \r\n structural design, material selection and maintenance, moisture \r\n control around the opening, provisions to avoid movement problems \r\n and installation of the lintel in the wall \r\n Types \r\n There are several different types of structural \r\n steel lintels used in masonry. They vary from single angle lintels \r\n in cavity or veneer walls, to steel beams with plates in solid walls, \r\n to shelf angles in brick veneer panel walls. Most building codes \r\n permit steel angle lintels to be used for openings up to 8 ft 0 \r\n in. (2.4 m). Openings larger than this are usually required to have \r\n fire protected lintels. \r\n Loose Angle Lintels . Loose angle \r\n lintels are used in brick veneer and cavity wall constructions where \r\n the lintel is laid in the wall and spans the opening. This type \r\n of lintel has no lateral support. Figure 1a shows this condition. \r\n Combination Lintels . In solid masonry \r\n walls, single loose angle lintels are usually not capable of doing \r\n the job. Therefore, combination lintels are required. These combination \r\n lintels can take many forms, from a clustering of steel angles, \r\n such as shown in Figs. 1b and 1c, to a combination of steel beam \r\n and plates, as shown in Figs. 1d and 1e. \r\n Angle Lintels - In solid \r\n masonry walls, it is usually satisfactory to use multiple steel \r\n angles as a lintel. These angles are usually placed back to back, \r\n as shown in Figs. 1b and 1c. \r\n Steel Beam/Plate Lintels - In \r\n solid walls with large superimposed loads, or in walls where the \r\n openings are greater than 8 ft 0 in. (2.4 m), it may be necessary \r\n to use lintels composed of steel beams with attached or suspended \r\n plates, as shown in Figs. 1d and 1e. This permits the beam to be \r\n fully encased in masonry, and fire-protected. \r\n Shelf Angles . In panel walls systems, \r\n the exterior wythe of brickwork may be supported by shelf angles \r\n rigidly attached to the structural frame. These shelf angles, in \r\n some cases, also act as lintels over openings in the masonry. This \r\n condition is shown in Fig. 1f. \r\n \r\n \r\n \r\n \r\n Types of Structural \r\n Steel Lintels \r\n \r\n FIG. 1 \r\n \r\n Design \r\n The proper design of the structural steel \r\n lintel is very important, regardless of the type used. The design \r\n must meet the structural requirements and the serviceability requirements \r\n in order to perform successfully. Design loads, stresses and deflections \r\n will be covered in a later section of this Technical Notes . \r\n Materials \r\n The proper specification of materials \r\n for steel lintels is important for both structural and serviceability \r\n requirements. If materials are not properly selected and maintained, \r\n problems can occur. \r\n Selection . The steel for lintels, \r\n as a minimum, should comply with ASTM A 36. Steel angle lintels \r\n should be at least 1/4 in. (6 mm) thick with a horizontal leg of \r\n at least 3 1/2 in. (90 mm) for use with nominal 4 in. (100 mm) thick \r\n brick, and 3 in. (75 mm) for use with nominal 3 in. (75 mm) thick \r\n brick. \r\n Maintenance . For harsh climates \r\n and exposures, consideration should be given to the use of galvanized \r\n steel lintels. If this is not done, then the steel lintels will \r\n require periodic maintenance to avoid corrosion. \r\n Moisture Control \r\n Proper consideration must always be given \r\n to moisture control wherever there are openings in masonry walls. \r\n There must always be a mechanism to channel the flow of water, present \r\n in the wall, to the outside. \r\n Flashing and Weepholes . Even where \r\n galvanized or stainless steel angles are used for lintels in cavity \r\n and veneer walls, continuous flashing should be installed over the \r\n angle. It should be placed between the steel and the exterior masonry \r\n facing material to collect and divert moisture to the outside through \r\n weepholes. Regardless of whether flashing is used, weepholes should \r\n be provided in the facing at the level of the lintel to permit the \r\n escape of any accumulated moisture. See Technical Notes 7A \r\n for further information on flashing and weepholes. \r\n Movement Provisions \r\n Because of the diversity of movement characteristics \r\n of different materials, it is necessary to provide for differential \r\n movement of the materials. This is especially true at locations \r\n where a number of different materials come together. Technical \r\n Notes 18 Series provides additional information on differential \r\n movement. \r\n Expansion Joints . Expansion joints \r\n in brick masonry are very important in preventing unnecessary and \r\n unwanted cracking. There are two types of expansion joints which \r\n will need to be carefully detailed when lintels are involved: vertical \r\n and horizontal. \r\n Vertical - Vertical expansion joints \r\n are provided to permit the horizontal movement of the brick masonry. \r\n Where these expansion joints are interrupted by lintels, the expansion \r\n joint should go around the end of the lintel and then continue down \r\n the wall. \r\n Horizontal - In multi-story walls \r\n where the lintels are a continuation of shelf angles supporting \r\n masonry panels, horizontal expansion joints to accommodate vertical \r\n movement must be provided. Often a simple soft joint below \r\n the shelf angle is all that is needed. See Technical Notes \r\n 18A , 21 \r\n Rev, and 28B Rev for typical details. \r\n Installation \r\n The installation of steel lintels in masonry \r\n walls is a conventional construction operation, familiar to most \r\n members of the building team. The walls are built to the height \r\n of the opening, the lintel is placed over the opening, and the masonry \r\n work is continued. One item of special construction that must be \r\n noted is temporary shoring. \r\n Temporary Shoring . If the steel \r\n lintel is being designed assuming in-plane arching of the masonry \r\n above, then the lintel must be shored until the masonry has attained \r\n sufficient strength to carry its own weight. This shoring period \r\n should not be less than 24 hr. This minimum time period should be \r\n increased to three days when there are imposed loads to be supported. \r\n If the masonry is being built in cold weather construction conditions, \r\n the length of cure should be increased. If the lintel is designed \r\n for the full uniform load of the masonry and other superimposed \r\n loads ignoring any inherent arching action, then no shoring is required. \r\n STRUCTURAL DESIGN \r\n General \r\n The structural design of steel lintels \r\n is relatively simple. The computations are the same as for steel \r\n beams in a building frame, but because of the low elasticity of \r\n the masonry, and the magnitude and eccentricity of the loading, \r\n the design should not be taken lightly. A proper design must consider \r\n the loads, stresses, and serviceability of the system. If these \r\n are not properly taken into account, problems of cracking and spelling \r\n could occur. \r\n Loads \r\n The determination of imposed loads is \r\n an important factor. Fig. 2 shows an example of a lintel design \r\n situation. On the left is an elevation showing an opening in a wall \r\n with planks and a beam bearing on the wall. On the right is a graphic \r\n illustration of the distribution of the superimposed loads. \r\n \r\n Lintel Load Determination \r\n \r\n \r\n FIG. 2 \r\n \r\n Uniform Loads . The triangular wall \r\n area (ABC) in Fig. 2b above the opening has sides at 45-deg angles \r\n to the base. Arching action of a masonry wall will carry the dead \r\n weight of the wall and the superimposed loads outside this triangle, \r\n provided that the wall above Point B (the top of the triangle) is \r\n sufficient to provide resistance to arching thrusts. For most lintels \r\n of ordinary wall thickness, loads and spans, a depth of 8 to 16 \r\n in. (200 mm to 400 mm) above the apex is sufficient. If stack bonded \r\n masonry is used, horizontal joint reinforcement must be provided \r\n to ensure the arching action. \r\n Providing arching action occurs, the dead \r\n weight of the masonry wall, carried by the lintel, may be safely \r\n assumed as the weight of masonry enclosed within the triangular \r\n area (ABC). To the dead load of the wall must be added the uniform \r\n live and dead loads of the floor bearing on the wall above the opening \r\n and below the apex of the 45-deg triangle. Again, providing arching \r\n occurs, such loads above the apex may be neglected. In Fig. 2b, \r\n D is greater than L/2, so the floor load may be ignored, but, in \r\n order to use this assumed loading, temporary shoring must be provided \r\n until the masonry has cured sufficiently to assure the arching action. \r\n If arching action is not assumed and temporary \r\n shorting is not to be used, the steel lintel must be designed for \r\n the full weight of the masonry and other superimposed live and dead \r\n loads above the opening. There could be quite a substantial difference \r\n in the final lintel sizes required in each case. \r\n Concentrated Loads . Concentrated \r\n loads from beams, girders, or trusses, framing into the wall above \r\n the opening, must also be taken into consideration. Such loads may \r\n be distributed over a wall length equal to the base of the trapezoid \r\n and whose summit is at the point of load application and whose sides \r\n make an angle of 60 deg with the horizontal. In Fig. 2b, the portion \r\n of the concentrated load carried by the lintel would be distributed \r\n over the length, EC, and would be considered as a partially distributed \r\n uniform load. Arching action of the masonry is not assumed when \r\n designing for concentrated loads. Again, if stack bonded masonry \r\n is used, horizontal joint reinforcement must be provided to assure \r\n this distribution. \r\n Stresses \r\n After the loads have been determined, \r\n the next step in the design of the lintel is the design for stresses. \r\n Which stresses need to be checked will depend upon the type and \r\n detailing of the lintel. \r\n Flexure . In a simply supported \r\n member loaded through its shear center, the maximum bending moment \r\n due to the triangular wall area (ABC) above the opening can be determined \r\n by: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n M max = maximum moment \r\n (ft-lb) \r\n W = total load on lintel (lb) \r\n L = span of lintel, center to center \r\n of end bearing (ft) \r\n \r\n \r\n \r\n As an alternative, the designer may wish \r\n to calculate an equivalent uniform load by taking 2/3 of the maximum \r\n height of the triangle times the unit weight of the masonry as the \r\n uniform load across the entire lintel. If this is done, the maximum \r\n bending moment equation becomes: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where \r\n \r\n \r\n w = equivalent uniformly distributed \r\n load per unit of length (lb per ft). \r\n \r\n \r\n To this bending moment should be added \r\n the bending moment caused by the concentrated loading, if any. Where \r\n such loads are located far enough above the lintel to be distributed \r\n as shown in Fig. 2b, the bending moment formula for a partially \r\n distributed uniform load may be used. Such formulae may be found \r\n in the \" Manual of Steel Construction,\" by the American Institute \r\n of Steel Construction (AISC). Otherwise, concentrated load bending \r\n moments should be used. \r\n The next step is the selection of the \r\n required section. The angle, or other structural steel shape, should \r\n be selected by first determining the required section modulus. This \r\n becomes: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n S = section modulus (in 3 ) \r\n F b = allowable stress in \r\n bending of steel (psi) \r\n \r\n \r\n \r\n The allowable stress, F b , for ASTM A 36 structural \r\n steel is 22,000 psi (150 MPa) for members laterally supported. Solid \r\n brick masonry walls under most conditions provide sufficient lateral \r\n stiffness to permit the use of the full 22,000 psi (150 MPa). This \r\n is especially true when floors or roofs frame into the wall immediately \r\n above the lintel. The design for non-laterally supported lintels \r\n should be in accordance with the AISC Specification for the Design, \r\n Fabrication and Erection of Structural Steel for Buildings. \r\n Using the design property tables in the \r\n AISC Manual, a section having an elastic section modulus equal to, \r\n or slightly greater than, the required section modulus is selected. \r\n Whenever possible, within the limitations of minimum thickness of \r\n steel and the length of outstanding leg required the lightest section \r\n having the required section modulus should be chosen. \r\n Combined Flexure and Torsion . In \r\n some cases, the design for flexure will need to be modified to include \r\n the effects of torsion. This is the case in cavity and veneer walls \r\n where the load on the angle is not through the shear center. \r\n In some situations, such as veneers, panel \r\n or curtain walls, the lintel may be supporting only the triangular \r\n portion of masonry directly over the opening. If this is the case, \r\n then the torsional stresses will usually be negligible compared \r\n to the flexural stresses, and can be safely ignored. \r\n If, on the other hand, there are imposed \r\n uniform loads within the triangle or imposed concentrated loads \r\n above the lintel, then a detailed, combined stress analysis will \r\n be necessary. The design of a lintel subjected to combined flexure \r\n and torsion should be in accordance with the AISC Specification \r\n for the Design, Fabrication and Erection of Structural Steel for \r\n Buildings. \r\n Shear . Shear is a maximum at the \r\n end supports, and for steel lintels it is seldom critical. However, \r\n the computation of the unit shear is a simple calculation and should \r\n not be neglected. The allowable unit shear value for ASTM A 36 structural \r\n steel is 14,500 psi (100 MPa). To calculate the shear: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n V max = the actual maximum \r\n unit shear (psi) \r\n R max /FONT> = maximum reaction \r\n (lb) \r\n \r\n A s = area of steel \r\n section resisting shear (sq. in.) \r\n \r\n \r\n \r\n \r\n Bearing . In order to determine \r\n the overall length of a steel lintel, the required bearing area \r\n must be determined. The stress in the masonry supporting each end \r\n of the lintel should not exceed the allowable unit stress for the \r\n type of masonry used. For allowable bearing stresses, see \"Building \r\n Code Requirements for Engineered Brick Masonry,\" BIA; \"American \r\n Standard Building Code Requirements for Masonry,\" ANSI A41.1-1953 \r\n (R 1970); or the local building code. The reaction at each end of \r\n the lintel will be one-half the total uniform load on the lintel, \r\n plus a proportion of any concentrated load or partially distributed \r\n uniform load. The required area may be found by: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n A b = required bearing \r\n area (sq in.) \r\n f m = allowable compressive \r\n stress in masonry (psi) \r\n \r\n \r\n \r\n In addition, any stresses due to rotation \r\n from bending or torsion of the angle at its bearing must be taken \r\n into account. \r\n Since in selecting the steel section, \r\n the width of the section was determined, that width divided into \r\n the required bearing area, A b , \r\n will determine the length of bearing required, F and F 1 , in Fig. 2b. This length should not \r\n be less than 3 in. (75 mm). \r\n If the openings are close together, the \r\n piers between these openings must be investigated to determine whether \r\n the reactions from the lintels plus the dead and live loads acting \r\n on the pier exceed the allowable unit compressive stress of the \r\n masonry. This condition will not normally occur where the loads \r\n are light, such as in most one and two-story structures. \r\n Serviceability \r\n In addition to the stress analysis for \r\n the lintel, a serviceability analysis is also important. Different \r\n types of lintels have different problems of deflection and rotation, \r\n and each must be analyzed separately to assure its proper performance. \r\n Deflection Limitations . After the \r\n lintel has been designed for stresses, it should be checked for \r\n deflection. Lintels supporting masonry should be designed so that \r\n their deflection does not exceed 1/600 of the clear span nor more \r\n than 0.3 in (8 mm) under the combined superimposed live and dead \r\n loads. \r\n For uniform loading, the deflection can \r\n be found by: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n D t \r\n = total maximum deflection (in.) \r\n E = modulus of elasticity of steel \r\n (psi) \r\n I = moment of inertia of section \r\n (in. 4 ) \r\n \r\n \r\n \r\n For loadings other than uniform, such \r\n as concentrated loads and partially distributed loads, deflection \r\n formulae may be found in the AISC Manual. \r\n Torsional Limitations . In cases \r\n where torsion is present, the rotation of the lintel can be as important \r\n as its deflection. The rotation of the lintel should be limited \r\n to 1/16 in. (1.5 mm) maximum under the combined superimposed live \r\n and dead loads. As mentioned before, all additional bearing stresses \r\n due to angle rotation must be taken into account in the design for \r\n bearing. \r\n Design Aids \r\n In order to facilitate the design of steel \r\n angle lintels, several design aids are included. These design aids \r\n are not all-inclusive, but should give the designer some help in \r\n designing lintels for typical applications. Conditions beyond the \r\n scope of these tables should be thoroughly investigated. \r\n Table 1 contains tabulated load values \r\n to assist the designer in the selection of the proper size angle \r\n lintel, governed either by moment or deflection under uniform load. \r\n Shear does not govern in any of the listed cases. The deflection \r\n limitation in Table 1 is 1/600 of the span, or 0.3 in. (8 mm), whichever \r\n is less. Lateral support is assumed in all cases. \r\n \r\n \r\n \r\n 1Allowable loads to the left of the heavy \r\n line are governed by moment, and to the right by deflection \r\n 2Fb = 22,000 psi (150 MPa) \r\n 3Maximum deflection limited to L/600 \r\n 4Lateral support is assumed in all cases. \r\n 5For angles laterally unsupported, allowable \r\n load must be reduced. \r\n 6For angles subjected to torsion. make \r\n special investigation. \r\n Table 2 lists the allowable bearing stresses \r\n taken from ANSI A41.1-1953 (R 1970). In all cases, allowable bearing \r\n stresses set by local jurisdictions in their building codes will \r\n govern. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1Adapted from American Standard \r\n Building Code Requirements for Masonry,\" National Bureau \r\n of Standards, ANSI A41.1-1953 (R 1970). \r\n \r\n \r\n \r\n \r\n Table 3 lists end reactions and required \r\n length in bearing, which may control for steel angle lintels. \r\n \r\n \r\n \r\n 1End Reaction in Ibs. \r\n 2Length of Bearing in inches. \r\n \r\n \r\n \r\n \r\n \r\n 1End Reaction in Ibs. \r\n 2Length of Bearing in inches. \r\n \r\n SUMMARY \r\n This Technical Notes is concerned \r\n primarily with the design of structural steel lintels for use in \r\n brick masonry walls. It presents the considerations which must be \r\n addressed for the proper application of this type of masonry support \r\n system. Other Technical Notes address the subjects of reinforced \r\n brick masonry lintels and brick masonry arches. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the technical staff of the Brick Institute of \r\n America. The information and recommendations contained herein, if \r\n followed with the use of good technical judgment, will avoid many \r\n of the problems discussed. Final decisions on the use of details \r\n and materials as discussed are not within the purview of the Brick \r\n Institute of America, and must rest with the project designer, owner, \r\n or both. \r\n REFERENCES \r\n \r\n 1. AISC , Manual of Steel Construction, American Institute of Steel \r\n Construction, Inc., New York, New York, Eighth Edition, 1980. \r\n 2. AISC, Specification for the Design, Fabrication and Erection of Structural \r\n Steel for Buildings, American Institute of Steel Construction, \r\n Inc., New York, New York, 1978. \r\n 3. ANSI, American Standard Building Code Requirements for Masonry, ANSI \r\n A41.1-1953 (R 1970), American National Standards Institute, New \r\n York, New York. \r\n 4. BIA, Building Code Requirements for Engineered Brick Masonry, Brick \r\n Institute of America, McLean, Virginia, 1969. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60106,"ResultID":176338,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 31C - Structural Design \r\n of Semicircular Brick Masonry Arches \r\n Feb. 1971 (Reissued Aug. 1986) \r\n \r\n INTRODUCTION \r\n The semicircular arch is among the most \r\n popular arch forms used by architects today. Its smooth, continuous \r\n curve makes it easily adaptable to many architectural styles and \r\n applications. \r\n This issue of Technical Notes presents \r\n recommended procedures and tables for the structural design of non-reinforced \r\n semicircular and segmental arches. Technical Notes 31 \r\n and 31A contain further information \r\n about general arch forms and their design. \r\n DESIGN ASSUMPTIONS \r\n Since the brick masonry arch is usually \r\n an integral part of a wall and not free-standing, basic design assumptions \r\n are made which assist in making the analysis. \r\n The spring line is assumed to be located \r\n on a horizontal line one fourth the span length above the horizontal \r\n axis. The arches are assumed to be fully restrained at the spring \r\n line and the portion of semicircular arch above this line is analyzed \r\n in a manner similar to that for a parabolic arch, using the formulas \r\n in Section 10, Method A from Frames and Arches , by Valerian \r\n Leontovich, M.S., McGraw-Hill 1959. \r\n \r\n \r\n \r\n \r\n Holiday Inn, McLean, \r\n Virginia \r\n NOMENCLATURE \r\n d = arch \r\n ring depth, in inches, \r\n f = rise \r\n of arch, in feet, \r\n f m \r\n = allowable compressive stress, in psi, \r\n H = horizontal \r\n thrust, in pounds, \r\n H DL \r\n = horizontal thrust, in pounds, caused by a uniform dead load, \r\n L = span \r\n length, in feet, \r\n n = number \r\n of shear planes (see Technical Notes 31A .) \r\n P = allowable \r\n concentrated load, in pounds, \r\n P = maximum \r\n allowable concentrated load in pounds under combined loading provisions, \r\n P* = additional \r\n concentrated load capacity caused by the uniform dead load. \r\n t = wall \r\n thickness, in inches \r\n v m \r\n = allowable shear stress in brick masonry, in psi, \r\n W = allowable \r\n uniform load, in pounds per foot, \r\n x = length \r\n of wall required, in inches, to resist horizontal thrust \r\n DEVELOPMENT OF TABLES \r\n In the determination of the archs capacity \r\n for uniform loads, the limiting factor was found to be the compressive \r\n strength of the brick masonry. Additional stresses due to the circular \r\n loading of the masonry above the intrados are also taken into consideration. \r\n In determining the capacity for concentrated \r\n loads, the limiting factors were found to be bending at the center \r\n line of span, shear at the spring line (v m = 40 psi), and maximum compressive stress (f m ). Tensile stresses were not permitted \r\n to develop at mid span. \r\n Since axial forces develop in the arch \r\n ring from the concentrated and uniform loads, interaction formulas \r\n were developed for each loading condition. These formulas combine \r\n the axial stresses with the bending stresses. \r\n ALLOWABLE LOADING \r\n In all formulas used in this publication, \r\n d and t are measured in inches, and L is measured in feet. The following \r\n loading conditions were considered for analyzing a semicircular \r\n arch. \r\n Uniform Load. Tables 1, \r\n 2, 3 and 4 give the allowable uniform loads occurring over the entire \r\n span length for a 1-in. thick arch ring. Figure 1 illustrates the \r\n following requirements and limitations: \r\n \r\n FIG. 1 \r\n 1. Uniform load occurring between lines \r\n 1 and 3 (0.90 L and 0.70 L) are those provided for in the load tables. \r\n 2. Uniform loads occurring above line \r\n 1 may be ignored, at the discretion of the designer, provided arching \r\n action occurs in the brick masonry above the arch ring. (See discussion \r\n in Technical Notes 31 and 31A .) \r\n 3. There must be a minimum height \r\n of masonry (line 3) equal to 0.70 L above the horizontal \r\n axis. No superimposed loads are permitted below this line. \r\n 4. The maximum design height of masonry \r\n is 0.25 L above the crown for walls higher than line 2. \r\n 5. In all cases, the horizontal thrust \r\n (H) must be checked as shown in Technical Notes 31A , \r\n Fig. 4. For a given arch, the horizontal thrust is directly \r\n proportional to the uniform load. \r\n 6. The portion of wall that resists the \r\n horizontal thrust is assumed to be non-yielding to any lateral movement. \r\n Concentrated Load . Table \r\n 5 gives the allowable concentrated loads occurring at the center \r\n line of span for a 1-in. thick arch ring. Figure 2 illustrates the \r\n following requirements and limitations: \r\n \r\n FIG. 2 \r\n 1. Concentrated loads occurring between \r\n lines 2 and 3 (1.20 L and 0.75 L) are those provided for \r\n in the load table. \r\n 2. Concentrated loads occurring between \r\n lines 1 and 2 may be divided by the span length (L) and considered \r\n as equivalent uniform loads. \r\n 3. Concentrated loads occurring above \r\n line 1 (1.50 L) may be ignored, at the discretion of the designer, \r\n provided arching action occurs in the brick masonry above the arch \r\n ring. (See discussion in Technical Notes 31 \r\n and 31A .) \r\n 4. In all cases, condition 4 for uniform \r\n loads must be used with the resulting thrusts added to those of \r\n the concentrated loads. \r\n 5. There must be a minimum height of masonry \r\n (line 3) equal to 0.75 L above the horizontal axis. No superimposed \r\n loads are permitted below this line. \r\n 6. In all cases, the horizontal thrust \r\n H must be checked as shown in Technical Notes 31A , \r\n Fig. 4. For a given arch, the horizontal thrust is directly proportional \r\n to the concentrated load. \r\n 7. The portion of wall that resists the \r\n horizontal thrust is assumed to be non-yielding to any lateral movement. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n *Values may be linearly interpolated \r\n except where horizontal lines occur. At these lines, the allowable \r\n load is ((0.241)(L + 0.083d^3 + 0.134)(L + 0.083d)^2 * d)/(1.34(L \r\n + 0.083d) - 0.0778d) \r\n or the value above the line whichever \r\n is smaller The horizontal: thrust is 0.778P + 0.134(L + 0.083d) \r\n or value above the line whichever \r\n is smaller. \r\n \r\n \r\n Combined Loading . When \r\n the uniform loads are combined with concentrated loads, the concentrated \r\n load capacity of the arch ring increases. This additional capacity \r\n is due to the compressive stress from the uniform load equalizing \r\n the tensile bending stress at mid span due to the concentrated load \r\n (M/S = P/A). This additional capacity may be expressed by the following \r\n formula: \r\n \r\n \r\n \r\n \r\n \r\n The values of P and H in Table 6 are \r\n the allowable capacities governed by compression or shear. They \r\n should be used only as a check when combined loadings are used. \r\n In all cases, the actual load must be \r\n less than P, and less than the allowable load, P, plus the additional \r\n capacity P*. The total horizontal thrust must be checked and should \r\n be less than the maximum allowable for a uniform load. \r\n SEGMENTAL ARCHES \r\n Any segmental arch with f / L > 0.29 \r\n but < 0.50 can be considered as an equivalent semicircular arch \r\n as shown in Fig. 3. Twice the radius is the equivalent L for use \r\n with the tables. \r\n \r\n FIG. 3 \r\n ILLUSTRATIVE EXAMPLE \r\n Design an arch to meet the requirements \r\n as shown in Fig. 4. The arch is semicircular; the horizontal axis \r\n is 6 ft above the base; the span, L, is 10 ft; the arch ring depth, \r\n d, is 12 in. (11 1/2 in. actual); and the nominal wall thickness, \r\n t, is 8 in. (7 1/2 in. actual). A beam reaction of 5000 lb is located \r\n at the center line of the span and 17 ft above the base. The uniform \r\n load consists of 1000 lb per ft dead load and 500 lb per ft live \r\n load occurring 14 ft above the base. Assume f m = 400 psi and the brick masonry weighs \r\n 10 psf per 1-in. thickness. \r\n \r\n FIG. 4 \r\n Uniform Load \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n All the following calculations will be \r\n with 1 in. of wall thickness; actual t = 7.5 in., f m = 400 psi, d = 11.5 in. and L= 10 ft. \r\n Uniform Load \r\n \r\n \r\n \r\n \r\n Use Table 2, since 0.7L < 0.8L \r\n < 0.9L \r\n From Table 2, W = 724 lb per ft \r\n and \r\n H = 2993 lb \r\n \r\n \r\n \r\n \r\n \r\n Concentrated Load \r\n \r\n \r\n \r\n Use Table 5 since 0.75L < 1.1 \r\n L < 1.2L \r\n From Table 5, P = 88 lb and H = \r\n 84 lb \r\n \r\n \r\n \r\n \r\n However, since there is combined loading, \r\n advantage can be taken of the increased capacity due to the uniform \r\n load. \r\n \r\n \r\n \r\n \r\n 667 < 688 O.K. \r\n From Table 6, P= 1060 lb \r\n 667 < 1060 O.K. \r\n \r\n \r\n \r\n Horizontal Thrust \r\n \r\n \r\n H(total) =970 + 636 = 1606 < \r\n 2993 O.K. \r\n \r\n At this point the wall shear caused by \r\n the horizontal thrust at the spring line should be checked. Assume \r\n V m = 40 psi and n = 2 \r\n \r\n \r\n \r\n \r\n \r\n The overturning moment of the support \r\n due to horizontal thrust should be checked next (see Technical \r\n Notes 31A ). In this example, the horizontal \r\n thrust is 1606 (7.5) (8.5) = 102,000 ft-lb. \r\n The resistance to overturning is a function \r\n of the overall axial load, wall shape, and reinforcement, if any. \r\n This is a separate analysis that should be performed after considering \r\n the total loading conditions on the entire structure. \r\n \r\n CONCLUSION \r\n This issue of Technical Notes has \r\n presented a simplified but conservative approach to a complex structural \r\n design problem. To provide an analysis for all possible assumptions \r\n and loading conditions is beyond the scope of this publication. \r\n Most loading conditions encountered will be similar to those in \r\n Fig. 1 and Fig. 2. To load an arch unsymmetrically defeats its use \r\n as a natural load-carrying structure and induces bending stresses \r\n that may cause failure. \r\n If arches are to be loaded unsymmetrically \r\n or do not comply with the assumptions and limitations given in this \r\n Technical Notes, consideration should be given to reinforced \r\n brick masonry. (See Technical Notes 17A \r\n Revised, \"Reinforced Brick Masonry - Flexural Design\", and 17M , \r\n \"Reinforced Brick Masonry Girders - Examples\".) If conditions exist \r\n other than those covered in the tables, special analysis should \r\n be made by the designer. \r\n The Brick Institute of America can not \r\n assume responsibility for the results obtained when using this \r\n Technical Notes Issue. It is beyond the scope of the Institute \r\n to anticipate every design situation that may arise. However, so \r\n long as the design criteria agree with the assumptions and limitations, \r\n satisfactory results can be obtained which will save countless hours \r\n of calculation time. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60107,"ResultID":176339,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 36 - Brick Masonry Details, \r\n Sills, and Soffits \r\n July/Aug. 1981 (Reissued Jan. 1988) \r\n \r\n Abstract : Detailing of brick masonry is both an art and a science. Recommendations \r\n are provided for the development of successful details using brick \r\n masonry and other materials. Detailing of sills and soffits is specifically \r\n addressed. Performance, esthetic value and economics are the principal \r\n considerations in the development of successful details. \r\n \r\n Key Words : brick , connections, construction, \r\n design, detailing , economics , esthetic \r\n value , function, performance , prefabrication, \r\n sills , soffits , structural stability. \r\n \r\n INTRODUCTION \r\n \r\n Successful detailing of brick masonry is both an art and a science. \r\n Proper details should result in a structure which is pleasing to the \r\n eye, but more importantly, performs well over its lifetime. Good detailing \r\n is not accidental, it requires proper planning. This planning may \r\n involve close cooperation between the architectural, engineering and \r\n construction disciplines in the early stages of the design process. \r\n There are three items which should be considered in the development \r\n of a successful detail. These are: 1. Performance considerations; \r\n 2. Esthetic value considerations; and 3. Economic considerations. \r\n The last two of these items may be traded off against each other. \r\n But, the first is mandatory and if it is not the primary concern, \r\n the detail may, and probably will, be doomed to failure. This failure \r\n can manifest itself in several ways: cracking, structural failure, \r\n moisture penetration to the interior, or efflorescence, to mention \r\n a few. \r\n It is possible to have a successful detail while compromising either \r\n the esthetic value or the economic considerations. But, it is impossible \r\n to have a successful detail if the performance considerations are \r\n compromised. A successful detail can be developed with excellent esthetic \r\n value while completely ignoring the economic considerations or vice \r\n versa, but to ignore the performance considerations is to invite trouble. \r\n \r\n APPROACH TO DETAILING \r\n General \r\n \r\n Proper planning in the development of brick details is essential \r\n to the successful execution of that detail in the field. The designer \r\n must be familiar not only with the properties of the various materials \r\n involved, but also how they go together in the construction process \r\n and how they will perform, both individually and together in service. \r\n The most esthetically pleasing detail is of no benefit if it cant \r\n be built, or does not perform its intended function. \r\n The designer should always keep in mind that different materials \r\n react to temperature and moisture changes in different ways. While \r\n in some cases these differences may be minor, in others they may be \r\n significant. If they are not properly addressed, the result can be \r\n facade failures, such as leaking, bowing, cracking, etc. For a discussion \r\n of differential movement, see Technical Notes 18 Series. \r\n \r\n Performance Considerations \r\n \r\n Performance is all-important if the detail is to be successful. There \r\n are three items which must be considered in the development of a detail \r\n which will provide satisfactory performance. They are: 1. Functional \r\n considerations; 2. Structural stability; and 3. Construction considerations. \r\n In the development of the detail, it is imperative that all of these \r\n items be given proper consideration. \r\n Functional Considerations . One of the first steps in the development \r\n of a successful detail is to determine the function of the element. \r\n The designer must determine the purpose of the element, and how the \r\n element will affect the overall performance of the building. Typical \r\n questions which should be addressed are: 1. Is the element to serve \r\n as a weather-tight enclosure? 2. Will stresses, axial, flexural or \r\n shear, be developed in the member? 3. Should it channel and direct \r\n the flow of moisture? 4. Is it to seal the top of a vertical element? \r\n 5. Is its purpose merely for esthetic value? Only after the designer \r\n has determined the required functions of the element can he begin \r\n to consider the other factors which will dictate the final design. \r\n Structural Stability . The designer must develop a detail which \r\n ensures that all applied loads can be adequately resisted by the element \r\n or that they are transferred to other elements of the structure which \r\n can resist them. These applied loads may be axial, transverse, shear \r\n or in the case of prefabricated elements, loads due to transportation \r\n and erection. One area of concern is the manner and adequacy of the \r\n connection of the element to the structure. It is imperative that \r\n these connections be structurally sound, to ensure structural stability \r\n of the element. \r\n Construction Considerations . The designer should take great \r\n care to ensure that the details can be easily executed in the field. \r\n This requires that the designer be knowledgeable in current construction \r\n practices. While some innovation may be necessary and beneficial, \r\n the detail should not require radical deviation from conventional \r\n construction practices. Typically, the more simple and straightforward \r\n the detail is, the easier it is to construct and thus, the better \r\n its performance. In some instances, the construction can be simplified \r\n by prefabrication of the element. Care should be taken by the designer \r\n to ensure, to the greatest extent possible, that the detail does not \r\n require several crafts to be working in the same location at the same \r\n time. \r\n \r\n Esthetic Value Considerations \r\n \r\n The designer must also determine how best to fulfill the functional \r\n requirements and yet provide the desired esthetic value. This involves \r\n decisions on materials, colors and textures, and other esthetic considerations. \r\n The configuration of the element is also an important esthetic consideration. \r\n The designer may decide to project or recess parts of the element \r\n to provide shadow lines or to use a different bond pattern to call \r\n attention to the detail. The esthetic value of the detail is limited \r\n only by its function, its ease of construction, the designers imagination \r\n and possibly its economic feasibility. \r\n \r\n Economic Considerations \r\n \r\n A detail, to be successful, should have the capability of being constructed \r\n economically. Economics involves both materials and labor. A successful \r\n detail requires that both the quantity and quality of materials be \r\n closely controlled. The use of excess materials to achieve the function \r\n of the detail should be avoided. \r\n Details which require very specialized skills by the crafts involved \r\n should be avoided. If very specialized skills are required, there \r\n is usually a reduction in productivity of the craftsmen and an increase \r\n in cost. \r\n \r\n SILLS \r\n General \r\n \r\n The prime function of a sill is to channel water away from the building. \r\n The sill may consist of a single unit or multiple units; it may be \r\n built in place or prefabricated; and it may be constructed of various \r\n materials. \r\n \r\n Esthetic Value \r\n \r\n The desired esthetic effect may be achieved through the use of special \r\n shaped units, either manufactured or cut to the desired shape. A word \r\n of caution concerning manufactured special shapes-while most manufacturers \r\n are capable of making special shapes to match the color and texture \r\n of the units selected for the project, there will be an added cost \r\n for each special-shaped unit. The added cost for the special shapes \r\n is dependent upon the complexity of the configuration of the shape \r\n and the number of units of each special shape required. Some manufacturers \r\n carry certain special shapes in stock. It may be advantageous to slightly \r\n alter the detail so that these stock special shapes may be used in \r\n lieu of one with a slightly different configuration. \r\n The appearance of the sill and the overall esthetic appeal of the \r\n structure may also be achieved by the use of a contrasting color or \r\n texture or by use of materials other than brick for the sill. Esthetics \r\n may also be affected by the use of a different bond pattern than that \r\n used in the adjacent wall. See Figs. 1 and 2. \r\n \r\n \r\n \r\n General Studies/Classroom/Instructional Resources Center \r\n - \r\n State University Agricultural and Technical College \r\n - Delhi, New York \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Westgate Corporation Building - McLean, Virginia \r\n FIG. 2 \r\n \r\n Materials \r\n \r\n Sills for use in brick masonry construction are typically brick, \r\n concrete, stone or metal. The selection of material is primarily dependent \r\n upon the required esthetic effect. But it is also important to note \r\n that metal, concrete and stone sills normally require fewer joints \r\n than do brick sills, and therefore provide fewer potential avenues \r\n for water penetration. Once the decision of which material to use \r\n is made, then decisions concerning the quality of that material can \r\n be made. Whichever material is selected, it should be of high quality. \r\n A discussion of brick and mortar properties is found in Technical \r\n Notes 7B Revised. \r\n Flashings for use in sills can be of a number of materials, such \r\n as copper, lead or plastics, see Technical Notes 7A Revised \r\n for additional information. Aluminum and asphaltic-impregnated felt \r\n are not recommended for use as flashing materials. Aluminum \r\n is not recommended since alkalies in the cement of the mortar may \r\n attack it and cause corrosion. Asphaltic-impregnated felt is not recommended \r\n because it is easily punctured during construction. For the same reason, \r\n plastic films of less than 20 mil thickness should also be avoided. \r\n Once the flashing has been punctured, it ceases to fulfill its function, \r\n thus in place flashing should be inspected for punctures and tears, \r\n and appropriately repaired prior to laying brick masonry on the flashing. \r\n Also, some plastics are subject to continued degradation after having \r\n been exposed to sunlight for an extended period of time. \r\n \r\n Details \r\n \r\n General . Since the primary function of sills is to divert \r\n water away from the building, the top surface should slope downward \r\n and away from the building. In the case of brick sills, see Figures \r\n 3 and 4, the slope should be at least 15 deg from horizontal. This \r\n may vary somewhat according to the sill configuration of the window \r\n unit, particularly in the case of wood windows. The sill should extend \r\n a minimum of 1 in. (25 mm) beyond the face of the wall at its closest \r\n point to the wall, see Fig. 3. In some instances, it may be necessary \r\n that the brick units at the ends of the sills be uncored units so \r\n that no cores are exposed to view. \r\n \r\n \r\n \r\n Sill in Frame/Brick Veneer Construction \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n Sill in Cavity Wall Construction \r\n FIG. 4 \r\n \r\n \r\n \r\n When concrete or stone sills are used, they should be sloped away \r\n from the building, and also sloped from the ends toward the center, \r\n see Figs. 5 and 6. The slope away from the building should be at least \r\n 15 deg from horizontal, the slope from the ends should be 1/8 in. \r\n (3 mm) to 12 in. (300 mm) toward the center of the sill. For sills \r\n longer than 4 ft ( 1.2 m), the slope should extend for at least a \r\n distance of 2 ft (600 mm) from the ends, see Fig. 6. \r\n \r\n \r\n \r\n Concrete or Stone Sill \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n Concrete or Stone Sill \r\n FIG. 6 \r\n \r\n \r\n \r\n Flashing and Weepholes . In general, when a collar joint, cavity or air space is interrupted, \r\n such as at sills, at the base of the walls, at lintels over openings \r\n and at shelf angle supports, flashing should be provided in the wall. \r\n The function of flashing is to serve as a collector for any moisture \r\n penetrating the wall or the sill. It is important that the flashing \r\n extend through the brick to the exterior face of the wall at the lower \r\n end of the flashing and be turned down at least to in. (6 mm) to form \r\n a drip. The flashing at the sill should extend beyond the ends of \r\n the sill to the first head joint outside of the jamb of the opening, \r\n and should be turned up and outward for a distance of at least 1 in. \r\n (25 mm) at each end, see Fig. 5. If the ends are not turned up and \r\n out, the moisture collected on the flashing will have a path into \r\n the adjacent wall and there is no way to predict where it may go. \r\n The purpose of turning the flashing up and out is to assure that the \r\n moisture stays on the flashing until it drains from the wall. See \r\n Technical Notes 7A Revised for a discussion of materials to \r\n be used as flashing. \r\n \r\n Once moisture penetrating the wall or sill has been collected on \r\n the flashing, it must be removed from the wall. This is the function \r\n of weepholes. Weepholes may be installed in several ways, see Technical \r\n Notes 21C . Weepholes should be placed on top of the flashing, \r\n not one course up. If wick-type materials are employed, or \r\n if hidden flashing is used, the weepholes should have a maximum horizontal \r\n spacing of 16 in. (400 mm). If open weepholes with no wicks are used, \r\n the horizontal spacing may be increased to 24 in. (600 mm) maximum. \r\n Drips . Every sill should be provided with a drip. The function \r\n of the drip is to prevent water from returning to the exterior face \r\n of the wall. The drip of a properly sloped brick sill is the lower \r\n corner of the brickwork. A drip in a concrete or stone sill is usually \r\n formed, or cut into the bottom face of the sill, as shown in Figs. \r\n 5 and 6. The drip on a concrete or stone sill can be cut in several \r\n shapes, Vee-shape, rectangular, semi-circular, or a combination of \r\n these. The shape of the drip is not important, but its presence and \r\n location are important. The inner lip of the drip should be located \r\n a minimum of 1 in. (25 mm) from the exterior face of the wall, as \r\n shown in Fig. 5. \r\n Connections . In brick masonry sills of short length, 4 ft. \r\n (1.2 m) or less, no special anchorage is necessary. However, sills \r\n of brick, concrete, metal and stone having long runs should be anchored \r\n to the masonry below or behind the sill, see Figs. 3 and 5. This will \r\n require penetration of the flashing below or behind the sill. Care \r\n must be taken to ensure that these penetrations are adequately sealed \r\n so that the flashing functions as intended. \r\n Attachment of the sill to the window will vary with window type and \r\n manufacturer. It is most important that the joint where the sill and \r\n window make contact be sealed with a high-quality sealant, see Technical \r\n Notes 28 Revised and 28B Revised. \r\n Expansion Joints . When expansion joints are necessary, it \r\n may be desirable to install them in vertical alignment with window \r\n jamb lines. If this is done, the expansion joint should also be installed \r\n through the sill. This will enable the expansion joint to perform \r\n as intended. \r\n If the sill extends beyond the jamb of the opening and an expansion \r\n joint is required at the jamb, then the expansion joint should be \r\n continuous around the entire sill extension, as should the flashing, \r\n see Fig. 6. \r\n \r\n Construction \r\n \r\n In the past, sills for use in brick masonry construction have generally \r\n been built in place, using conventional construction practices. A \r\n trend during recent years has been to use prefabricated sills, particularly \r\n when combined with a spandrel and soffit, see Technical Notes \r\n 40 Series. This type of construction will be further discussed in \r\n the Soffits portion of this Technical Notes. \r\n When prefabricated brick, pre-cast concrete, or stone sills are used, \r\n they should have section lengths as long as is practical. The lengths \r\n will be determined by ease of handling and erection and the sills \r\n ability to resist erection stresses. The length of sill sections should \r\n be limited to a length that can easily be handled by equipment already \r\n on the jobsite. The joints between long sill sections should be constructed \r\n using a soft joint. It may also be necessary, in very long runs of \r\n sill, to provide expansion joints at the ends where the sill abuts \r\n the jamb. \r\n \r\n SOFFITS \r\n General \r\n \r\n Detailing of soffits for brick masonry requires special considerations. \r\n The primary function of a brick masonry soffit is to enclose the building \r\n while providing an esthetically pleasing appearance. There are two \r\n primary considerations in addition to esthetic value in the detailing \r\n of soffits: the structural stability of the system and whether it \r\n can be easily and economically constructed using conventional methods. \r\n Though prefabrication has not been widely used for total projects, \r\n it has been successfully used in many specialized applications and \r\n is considered a conventional construction method. Prefabrication has \r\n been widely used in the construction of soffits and may provide the \r\n most economical approach on certain projects. Construction of soffits \r\n in place often requires expensive forming and shoring. However, if \r\n there is only a small area of soffits involved on a given project, \r\n this may be the most efficient method. \r\n \r\n Materials \r\n \r\n Soffits generally are reinforced and grouted in some manner, whether \r\n built in place or prefabricated. Several projects have been constructed \r\n using reinforced and grouted hollow units, conforming to ASTM C 652. \r\n See Technical Notes 17 for information on reinforcement and \r\n grout. Properties for brick and mortar are discussed in Technical \r\n Notes 7B Revised. \r\n There are several high bond mortar additives available which may \r\n allow the designer to eliminate the reinforcement and grout. However, \r\n it should be noted that the high bond mortars do not work well with \r\n all brick units. The instructions of the additive manufacturer must \r\n be strictly followed, and a pre-design testing program should be carried \r\n out, see Technical Notes 39A . \r\n \r\n Design \r\n \r\n There are several questions which must be answered when designing \r\n soffits. Some deal with esthetic value, some with structural stability \r\n and some with construction. The primary esthetic concern is configuration. \r\n Should the soffit be horizontal, or sloped, should it be integral \r\n with the spandrel or separate? The primary design concern is structural. \r\n How should it be detailed to assure structural soundness, under all \r\n loading conditions, including any loads imparted during erection? \r\n This may require detailing and construction practices unfamiliar to \r\n the designer and contractor since this is not like a wall and demands \r\n careful consideration. One of the earliest decisions to be made about \r\n the construction of the soffit is whether it will be best to construct \r\n it in place, or to prefabricate it. The configuration, structural \r\n and economic considerations may dictate the method of construction \r\n to be used. See Figs. 7 and 8. \r\n \r\n \r\n \r\n BIA Headquarters Building - McLean, Virginia \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Evans Library, Texas A&M University - College Station, \r\n Texas \r\n FIG. 8 \r\n \r\n Details \r\n \r\n General . \r\n Each soffit entails its own unique detailing problems. These may include: \r\n configuration, support available from the surrounding structure, space \r\n restriction on built in place soffits and construction sequencing. \r\n The manner in which these problems are solved will determine how successfully \r\n the soffit will perform. \r\n \r\n Flashing and Weepholes . Normally, soffits do not require flashing \r\n or weepholes. However, in some applications, both may be required, \r\n see Fig. 9. In other applications, only weepholes may be required, \r\n since the inclusion of flashing in some cases may impair the structural \r\n stability of the soffit. It can only be stressed that the detailer \r\n should always keep in mind the primary function of flashing and weepholes \r\n in determining whether they are needed in any particular application. \r\n Their primary functions are: \r\n Flashing - collect and divert to the weepholes any moisture which \r\n might penetrate the element. \r\n Weepholes - convey all collected and diverted water to the exterior. \r\n \r\n \r\n \r\n Built-in-Place Brick Soffit \r\n FIG. 9 \r\n \r\n \r\n \r\n Connections . \r\n Whether the soffit is prefabricated or built in place, its connection \r\n to the structure is the most demanding detail for the designer to \r\n develop. Previously developed details may be totally inappropriate \r\n in the present situation. Connection details are critical in providing \r\n structural stability to the soffit. In detailing connections, it is \r\n important to keep one principal always in mind. That principle is: \r\n Keep It Simple. The simplest connection details are in most \r\n cases the most successful. \r\n \r\n Expansion Joints . The installation of expansion joints, in \r\n most cases, should be avoided in soffits; however, it may be necessary \r\n to provide expansion joints when soffits are to be installed over \r\n large areas. The installation of expansion joints may cause problems \r\n in providing structural stability of the element and require additional \r\n connections to the structure. If it is necessary that expansion joints \r\n be installed in soffits, it is important to remember that the function \r\n is expansion control. This is provided by resilient joints \r\n which can be compressed to provide for the movement of brick masonry, \r\n especially during hot weather, due to thermal expansion of the brick \r\n masonry and return to its original shape when the temperature is cooler. \r\n Reinforced and grouted brick masonry does not usually require expansion \r\n joints. \r\n \r\n Construction \r\n \r\n Structural and economic considerations normally determine the construction \r\n methods to be used. While the detailer does not normally specify the \r\n manner in which the detail is to be executed during construction, \r\n the method of support and economic aspects determined by the detail \r\n will affect the method of construction chosen. \r\n The method of supporting the soffit, both its permanent support and \r\n support during construction, has a direct bearing on the method of \r\n construction selected. The economics of constructing the element can \r\n be affected by configuration, structural support and materials selection. \r\n Economics in turn may well be the final determining factor in the \r\n selection of the construction methods employed. \r\n When a soffit is constructed in place, it sometimes requires a complicated \r\n system of centering and falsework which must be left in place for \r\n a number of days. Normal practice is to provide spacer strips on the \r\n forms which locate each unit within the form and provide a joint on \r\n the exposed face suitable for tuckpointing once the form is removed, \r\n see Fig. 10. These strips should be the width of the joint and a minimum \r\n of 1/2 in. (13 mm) in height. After the units have been placed on \r\n the form, the upper side is grouted and ties are placed in the joints \r\n for anchorage to the structure. After several days of curing, the \r\n forms are stripped and the joints can then be tuckpointed. The number \r\n of days required for curing is dependent upon conditions at the site \r\n during the curing period and the materials used. See Technical \r\n Notes 7 for tuckpointing recommendations. \r\n \r\n \r\n \r\n \r\n \r\n Built-in-Place Brick Soffit Forming \r\n FIG. 10 \r\n \r\n \r\n \r\n In some cases, the use of built in place soffits may be precluded. \r\n Then, prefabrication may be the most logical and economical approach, \r\n see Technical Notes 40 Series. This method of construction \r\n has been used very satisfactorily on many projects. On most of the \r\n projects where it has been used, the soffit is built integral with \r\n a spandrel cover and a sloped sill, see Figs 11 and 12. \r\n \r\n Prefabricated Brick Sill, Spandrel and Soffit \r\n \r\n FIG. 11 \r\n \r\n \r\n \r\n Prefabricated Brick Sill, Spandrel and Soffit \r\n \r\n FIG. 12 \r\n \r\n \r\n SUMMARY \r\n \r\n The designer, when developing details for sills and soffits, should \r\n keep in mind the function of the element being detailed, the esthetic \r\n value he wishes to achieve, the structural stability of the element, \r\n and the economics of construction. It is essential to provide details \r\n which allow the elements to perform their primary functions as well \r\n as possible. In order to do this, the designer must select the proper \r\n materials, locate them in the proper place, and provide sufficient \r\n information so that the element can be properly constructed. Several \r\n decisions and assumptions must be made by the designer because each \r\n project and each element on the project must be satisfactorily addressed. \r\n This Technical Notes addresses the major considerations necessary \r\n to successfully detail sills and soffits of brick masonry. In some \r\n cases, other considerations may be necessary due to unusual or unique \r\n conditions. It is beyond the scope of this Technical Notes to \r\n address all conditions and combinations of conditions which may occur, \r\n therefore the designer or owner, or both, must make the final decision \r\n on the details, the materials selected and the construction procedures \r\n used. The recommendations made in this Technical Notes are \r\n merely that-recommendations. The final configuration of the detail \r\n must in the long run be based on the designers application of some \r\n or all of the principles set forth here. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60108,"ResultID":176340,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 36A - Brick Masonry \r\n Details, Caps and Copings, Corbels and Racking \r\n Sept./Oct. 1981 (Reissued Jan. 1988) \r\n \r\n Abstract : Recommendations are \r\n provided for the development of successful details using brick masonry. \r\n Detailing of caps, copings, corbels and racking is specifically \r\n addressed. Performance, esthetic value and economics are the principal \r\n considerations in the develops meant of successful details. \r\n \r\n Key Words : brick , caps , connections, \r\n construction, copings , corbels , design, \r\n detailing , economics , esthetic \r\n values , function, performance , racking , \r\n structural stability. \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes is the second in a series that \r\n discusses brick masonry details. This Technical Notes will \r\n address the detailing of caps, copings, corbels and racking. Technical \r\n Notes 36 Revised addresses the \r\n detailing of sills and soffits. \r\n The recommended approach to detailing is covered in Technical \r\n Notes 36 Revised. While that Technical \r\n Notes is primarily for sills and soffits, it does provide \r\n the general approach applicable to all detailing. The following \r\n items should be considered in the development of a successful detail: \r\n 1. Functional considerations; 2. Esthetic value; 3. Construction \r\n considerations; 4. Economic considerations. \r\n \r\n DEFINITIONS \r\n Caps and Copings \r\n \r\n The definitions for cap and coping are entirely dependent upon \r\n which dictionary or glossary is used as a reference. In addition, \r\n there are other terms which are used interchangeably with them, \r\n such as water table, canting strip, and offset. For the purpose \r\n of this Technical Notes, the word \"coping\" applies to the \r\n covering at the top of a wall, and the term \"cap\" refers to a covering \r\n within the height of the wall, normally where there is a change \r\n in wall thickness. The other terms cited will not be used. \r\n \r\n Corbels and Racking \r\n \r\n A corbel is defined as a shelf or ledge formed by projecting successive \r\n courses of masonry out from the face of the wall. Racking \r\n is defined as masonry in which successive courses are stepped back \r\n from the face of the wall. \r\n \r\n CAPS AND COPINGS \r\n General \r\n \r\n The primary function of caps and copings is to channel water away \r\n from the building. The cap or coping may be a single unit or multiple \r\n units. They may be of several different materials. The tops may \r\n slope in one direction or both directions. Additionally, where caps \r\n are discontinuous, a minimum slope from the ends of 1/8 in. (3 mm) \r\n in 12 in. (300 mm) should be provided, as shown in Figures 4 and \r\n 6 in Technical Notes 36 Revised. \r\n The esthetic value the designer wishes to achieve may come from \r\n the configuration of the element, its color, or its texture. Caps \r\n and copings normally do not serve any structural function, and do \r\n not present any major problems in their construction. \r\n \r\n Materials \r\n \r\n Caps and copings can be constructed of several materials: brick, \r\n pre-cast or cast-in-place concrete, stone, terra cotta, or metal. \r\n It should be pointed out that because of their location in the structure, \r\n caps and copings are exposed to climatic extremes. This severe exposure \r\n must be of prime concern to the designer. Because caps and copings \r\n are subjected to extreme exposure, brick masonry may not be the \r\n best choice of materials. This is because caps and copings of brick \r\n require more joints than do those made of other materials. This \r\n provides more avenues for possible water penetration into the wall. \r\n If brick is the material selected, great care must be taken to provide \r\n for the movement to which the element will be subjected and also \r\n to make sure all joints are properly filled with mortar. Concrete, \r\n stone and metal caps and copings can be installed in relatively \r\n long pieces, thus requiring less joints than do those made from \r\n brick. \r\n Concrete, stone and terra cotta all have thermal expansion properties \r\n similar to those of brick masonry and normally present no extreme \r\n problems with differential movement when applied as caps and copings, \r\n if properly detailed. Metal has very different thermal expansion \r\n properties than brick masonry. Depending upon the metal used, its \r\n thermal expansion coefficient may be 3 to 4 times that of brick \r\n masonry. The designer should be aware of this and provide for this \r\n differential movement in the development of the details. Consideration \r\n must also be given to the drying shrinkage of the element if cast-in-place \r\n concrete is the material selected. \r\n If brick is the material chosen for the coping, it may be desirable \r\n in some applications to use a special shape to get a positive slope \r\n in two directions. In most applications, the slope should be only \r\n in one direction, with drainage onto the roof and not down the wall \r\n face. In such case, the coping can be built using regular shapes. \r\n \r\n Design \r\n \r\n The prime consideration in the design of caps and copings is the \r\n performance of the element in service. The designer must take into \r\n consideration the movement of the element, differential movement \r\n between the element and the wall, joint configuration and material, \r\n connection of the element to the wall, and type and location of \r\n flashings. \r\n The esthetic value of the detail should be evaluated. As with details \r\n of other elements, selection of material, color, texture and configuration \r\n will effect the esthetic value of the detail. The designer has a \r\n wide range from which to choose, but he must keep in mind that the \r\n performance should not be compromised to achieve esthetic value. \r\n The economic considerations are seldom a major consideration in \r\n the development of details for caps and copings. The material selected \r\n may have a minor effect on the economics of the detail. It affects \r\n the economics not only by its own costs, but also by the economics \r\n of installation. The economic considerations should not have a deleterious \r\n effect on the performance of the details in service. \r\n \r\n Details \r\n \r\n General . The function of caps and copings is to prevent \r\n the entry of water into the wall where the wall becomes partially \r\n or totally discontinuous vertically. Caps should have the top surface \r\n sloping downward, away from the face of the wall above. Copings \r\n may slope in one or both directions. In all cases, the slope should \r\n be a minimum of 15 deg from horizontal. \r\n The caps should overhang the wall face on the exposed side. Copings \r\n should overhang the wall on both sides. The overhang should be of \r\n sufficient dimension so that the inner lip of the drip is at least \r\n 1 in. (25 mm) from the face of the wall. Since the function of caps \r\n and copings is to prevent moisture penetration, the fewer the number \r\n of joints, the more assurance that the detail will perform its function. \r\n Flashing and Weepholes . Flashings for caps and copings generally \r\n serve a different function from flashings used elsewhere in the \r\n structure. Flashing used with caps and copings has as its prime \r\n function the prevention of the entry of moisture into the wall. \r\n The collection and diversion of the water from the wall becomes \r\n a secondary, although important function. \r\n In order to properly anchor caps and copings to the wall, it may \r\n become necessary to penetrate the flashing with the anchor, see \r\n Figs. 1, 3, and 4. To prevent moisture from entering the wall, at \r\n these points, it is absolutely necessary that the penetrations be \r\n adequately sealed, or the flashing will fail to function as intended. \r\n \r\n \r\n \r\n Precast Concrete or Stone Coping on Cavity Wall Parapet \r\n FIG. 1 \r\n \r\n \r\n \r\n Coping for Cavity Wall Parapet \r\n \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n Coping for Solid Masonry Parapet \r\n FIG. 3 \r\n \r\n \r\n \r\n \r\n \r\n Rowlock Coping on Solid Masonry Parapet \r\n FIG. 4 \r\n \r\n \r\n \r\n Flashings should be extended beyond the face of the wall and bent \r\n downward 1/4 in. (6 mm) to form a drip, as shown in Figs. 2, 5, \r\n and 6. Metal copings may also serve as flashings. It should be recognized \r\n that exterior flashings not contained within the wall serve the \r\n same functions as do interior flashing. Information on flashing \r\n materials is provided in Technical Notes 7A \r\n Revised. \r\n While the flashing for caps and copings may have a different prime \r\n function from normal usage, it is still necessary to provide weepholes \r\n immediately above the flashings to convey the water collected on \r\n the flashing out of the wall, unless exterior flashing is used. \r\n Weepholes should be spaced at a maximum of 24 in. (600 mm) o.c., \r\n unless wicks or hidden flashing are used. Then the spacing should \r\n be reduced to 16 in. (400 mm) o.c. maximum. \r\n Drips . Regardless of the material selected for caps or copings, \r\n drips should be provided. When brick caps and copings are used, \r\n the drip is the lowest point on the element, as shown in Figs. 4 \r\n and 7. When metal caps and copings are used, the drips can be formed \r\n by bending the material outward from the face of the wall, see Figs. \r\n 2, 5 and 6. With heavy gauge metals, stone concrete or terra cotta \r\n caps and copings, the drip is either cut or formed in the bottom \r\n of the projection beyond the face of the wall, as shown in Figs. \r\n 1, 3, and 7. This drip can be in several configurations, and still \r\n perform. The important thing is that a drip be provided and that \r\n the inner lip be at least 1 in. (25 mm) from the face of the wall \r\n as shown in Figs. 1, 3, and 7. \r\n \r\n \r\n \r\n \r\n Masonry Bearing Wall Coping \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Masonry Cavity Wall Coping \r\n FIG. 6 \r\n \r\n \r\n \r\n Brick and Precast Concrete or Stone Caps \r\n \r\n FIG. 7 \r\n \r\n \r\n \r\n Connections . \r\n Elements other than caps and copings require careful consideration \r\n of their connection to the structure for the structural stability \r\n of the element. In the case of caps and copings, the structural \r\n stability becomes secondary to the climatic considerations, such \r\n as moisture and temperature. Connections which are usually provided \r\n for structural purposes are generally rigid. Because of the diversity \r\n of materials used for caps and copings in conjunction with brick \r\n masonry walls, the connection in some cases should be of a flexible \r\n nature. Brick masonry, concrete, stone and terra cotta, respond \r\n to climatic conditions in much the same manner, and rigid connections \r\n can be used with little consideration of differential movement. \r\n Because of the dissimilarity of metal and brick masonry in their \r\n reaction to climatic conditions, the connections require some flexibility. \r\n \r\n Light gauge metal copings as shown in Figs. 5 and 6 should be nailed \r\n to the wall, and horizontal slots should be provided at nailing \r\n locations to prevent buckling of the coping due to thermal expansion. \r\n Metal caps and copings require an extension down the face of the \r\n wall, 4 in. (100 mm) min., and a sealant between the metal and the \r\n wall to prevent wind uplift and water penetration. Care should be \r\n taken to seal each penetration of the metal cap or coping where \r\n it is exposed to the exterior environment. \r\n Expansion Joints . It is necessary to provide expansion joints \r\n in long walls to provide for movement of the wall due to thermal \r\n and moisture expansion. This is particularly true in parapet walls \r\n and other masonry walls which are exposed to the exterior climatic \r\n conditions on both sides. Expansion joints are discussed in Technical \r\n Notes 18 Series. \r\n When expansion joints are required in the wall, the expansion joints \r\n should also be provided through any caps or copings in the same \r\n locations. It may be necessary to provide additional joints in metal \r\n copings. Metal copings should be so detailed and constructed that \r\n they function independently of the movement of the wall below. Expansion \r\n joints should be of a compressible material, but should also be \r\n extensible. One method of providing expansion joints is to leave \r\n the mortar from the head joints in a vertical line and insert a \r\n synthetic backer rod to the desired depth and fill the remainder \r\n of the joint with a high-quality sealant. \r\n Construction . Caps and copings require no special construction \r\n skills. If brick masonry is used as the cap or coping material, \r\n great care should be taken to ensure that all head and bed joints \r\n are completely filled. If cast-in-place concrete is used, some provision \r\n must be made to allow for the initial drying shrinkage of the concrete. \r\n If precast concrete or stone are used for caps or copings, non-compressible \r\n shims should be placed on the top of the wall at the exterior face \r\n of the wall. The shims are used because the weight of this type \r\n of cap or coping would compress the plastic mortar and a smaller \r\n joint would result. Then the mortar for the bed joint is spread \r\n and the cap or coping installed. The shims which should have a thickness \r\n equal to the bed joints should be left in place until the mortar \r\n has set. Once the mortar has set, the shims should be removed and \r\n the joint tuckpointed. \r\n \r\n CORBELS AND RACKING \r\n General \r\n \r\n Corbeling of brick masonry may be done to achieve the desired esthetics, \r\n or to provide structural support. There are empirical requirements \r\n provided by most codes and standards for unreinforced corbels, as \r\n shown in Fig. 8. If these requirements are to be exceeded, \r\n then the element will require a rational design as a reinforced \r\n element. \r\n \r\n Limitations on Corbeling \r\n \r\n FIG. 8 \r\n \r\n \r\n \r\n Corbels . \r\n The empirical approach requires that the total horizontal projection \r\n not exceed one-half the thickness of a solid wall, or one-half the \r\n thickness of the veneer of a veneered wall. It is also required \r\n that the projection of a single course not exceed one-half of the \r\n unit height or one-third of the unit bed depth, whichever is less. \r\n From these limitations, the minimum slope of the corbeling can be \r\n established (angle measured from the horizontal to the face of the \r\n corbeled surface is 63 deg 26 min. see Fig. 8). The required \r\n slope could be increased by the requirements that the unit projection \r\n not exceed one-third of the bed depth if they are more restrictive. \r\n It should be pointed out that the eccentricity induced into the \r\n wall by the corbeling must be considered in the wall design. If \r\n these limitations are exceeded, the wall should be reinforced to \r\n resist the stresses developed by the corbeling. \r\n \r\n Fig. 9 illustrates graphically the pattern of stresses within two \r\n corbels of different configurations under identical loading conditions. \r\n The corbel on the left is 45 deg from horizontal, which is not in \r\n accordance with building code requirements. The corbeled wall on \r\n the right has an angle of corbel 60 deg from horizontal and is very \r\n close to the building code requirement of 63 deg 26 min discussed \r\n above. The 60-deg corbel shows a stress pattern with axial and shear \r\n stresses with the only concentration of stresses directly below \r\n the applied load, P. The shear stresses are well distributed within \r\n the wall section. The 45-deg corbel, on the other hand, has bending \r\n stresses in addition to the axial and shear stresses, and the pattern \r\n of the stresses has been drastically altered. In addition to the \r\n concentration of compressive stresses immediately beneath the load, \r\n P. there is another concentration of compressive stress at the toe \r\n of the corbel. The bending stresses require that a corbel of this \r\n configuration be rationally designed and reinforced. Those corbels \r\n having an angle from horizontal of 60 deg or greater do not require \r\n reinforcement unless they exceed the other requirements given above. \r\n \r\n \r\n \r\n Corbeling Stress Distribution \r\n FIG. 9 \r\n \r\n \r\n \r\n Racking . \r\n When racking back to achieve the desired dimensions, care must be \r\n exercised to insure that, since there is no limitation on the distance \r\n each unit may be racked, the cores of the units are not exposed. \r\n Preferred construction consists of a setting bed over the racked \r\n face with the uncored brick or paving brick set to provide a weather-resistant \r\n surface. Mortar washes may also be used. They may not, however, \r\n be as durable. When using a mortar wash, it should not bridge over \r\n the rack, but should fill each step individually. \r\n \r\n SUMMARY \r\n \r\n The designer, when developing details for caps, copings, corbels \r\n and racking should keep in mind the function of the element being \r\n detailed, the esthetic value he wishes to achieve, the structural \r\n stability of the element, and the economics of construction. It \r\n is essential to provide details which allow the elements to perform \r\n their primary functions as well as possible. In order to do this, \r\n the designer must select the proper materials, locate them in the \r\n proper place and provide sufficient information so that the element \r\n can be properly constructed. Several decisions and assumptions must \r\n be made by the designer because each project and each element on \r\n the project must be satisfactorily addressed. \r\n The information and suggestions contained in this Technical \r\n Notes are based on the available data and the experience of \r\n the technical staff of the Brick Institute of America. The information \r\n and recommendations contained herein if followed with the use of \r\n good technical judgment, will avoid many of the problems discussed \r\n here. Final decisions on the use of details and materials as discussed \r\n are not within the purview of the Brick Institute of America, and \r\n must rest with the project designer, owner, or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60109,"ResultID":176341,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 39 - Testing for Engineered \r\n Brick Masonry - Brick and Mortar \r\n January 1987 \r\n \r\n Abstract : Testing of brick, mortar and grout is often required \r\n prior to and during construction of engineered brick masonry projects. \r\n The tests involve a combination of laboratory and field procedures \r\n which are described in various ASTM standards. The extent of testing \r\n is a decision made by the engineering or architectural firm responsible \r\n for the masonry design, and may consist of only a few laboratory \r\n tests to determine the properties of the brick units, or may involve \r\n extensive laboratory and field sampling and testing. This Technical \r\n Notes describes the testing of materials; other issues in this \r\n series describe testing of brick masonry assemblages. \r\n Key Words : brick , \r\n engineered brick masonry , grout, mortar, quality \r\n control , testing . \r\n INTRODUCTION \r\n The use of engineered brick masonry in \r\n the construction of loadbearing structures requires that the standard \r\n methods for determining the physical properties of both the materials \r\n and the masonry assemblages be strictly followed. The standards \r\n and specifications for engineered brick masonry are based, for the \r\n most part, on the results of American Society for Testing and Materials \r\n (ASTM) methods of testing. \r\n It is not the intent of this Technical \r\n Notes to supersede the various applicable ASTM standards, but \r\n to supplement them. The ASTM standards have been carefully developed \r\n by balanced technical committees composed of people experienced \r\n and knowledgeable in their chosen fields. Therefore, if the prescribed \r\n methods of tests are not adhered to, inaccurate and inconsistent \r\n test data and erroneous conclusions can result. This can be quite \r\n serious when the design of a masonry bearing wall structure is based \r\n on such tests, or when such tests are used as quality controls during \r\n construction. \r\n This Technical Notes covers testing \r\n of masonry materials for obtaining information needed to determine \r\n design properties for engineered brick masonry. Additional testing \r\n required for assessment of material compliance to various ASTM specifications \r\n is not included. In addition, field testing of brick, mortar and \r\n grout for quality control is discussed. \r\n This Technical Notes is the first \r\n in a series on testing. Other Technical Notes in this series \r\n discuss the construction, preparation and testing of masonry assemblages \r\n (in the laboratory); and the sampling, preparation and handling \r\n of jobsite test specimens for the purpose of quality control of \r\n the construction. \r\n ENGINEERED BRICK MASONRY STANDARDS \r\n There are several standards used in the \r\n United States for the design of brick masonry structures, all of \r\n which contain some requirements for testing of masonry materials \r\n or assemblages. Likewise, other standards and building codes require \r\n testing in order to establish various design parameters. \r\n In addition to predesign and preconstruction \r\n testing, testing for the purpose of quality control is often implemented. \r\n The BIA standard (Building Code Requirements for Engineered Brick \r\n Masonry, Brick Institute of America, McLean, Virginia, August 1969.), \r\n for example, requires that the initial rate of absorption (IRA) \r\n of brick at the time of laying not exceed .025 oz per sq in. per \r\n min (approximately 20 g/30 in. 2 /min). Since the \r\n development of the BIA Standard, ASTM C 62 and ASTM C 216 have been \r\n changed and now recommend that the limit on IRA be 30 g/30 in. 2 /min. The determination of \r\n this property may be made in the laboratory on oven-dry brick, or \r\n at the construction site as a field test. The tests outlined within \r\n this Technical Notes are those which are most commonly performed \r\n to satisfy the requirements of the BIA Standard. \r\n TESTING STANDARDS \r\n The ASTM standards which are most frequently \r\n utilized when testing brick masonry materials should be readily \r\n available to all laboratory personnel, and to individuals involved \r\n in field testing. The applicable standards are as follows: \r\n \r\n \r\n Clay Masonry Units -ASTM C 67, Standard Method of Sampling and Testing Brick and Structural \r\n Clay Tile \r\n Mortar -ASTM \r\n C 270, Standard Specification for Mortar for Unit Masonry \r\n -ASTM C 91, Standard Specification \r\n for Masonry Cement \r\n -ASTM C 109, Standard Test Method \r\n for Compressive Strength of Hydraulic Cement Mortars (Using \r\n 2-in. or 50-mm Cube Specimens) \r\n -ASTM C 780, Standard Method for \r\n Preconstruction and Construction Evaluation of Mortars for \r\n Plain and Reinforced Unit Masonry \r\n Grout -ASTM \r\n C 476, Standard Specification for Grout for Masonry \r\n -ASTM C 1019, Standard Specification \r\n for Sampling and Testing \r\n \r\n \r\n \r\n \r\n \r\n For the most part, these standards provide \r\n clear and concise explanations of the procedures for sampling and \r\n testing masonry materials; however, for the novice, some areas may \r\n present some confusion. The following sections will explain some \r\n of the procedures required by the various ASTM standards. \r\n BRICK TESTING FOR ENGINEERED BRICK \r\n MASONRY \r\n The strength of brick varies considerably, \r\n depending on raw material, method of manufacture and degree of firing. \r\n The range in compressive strength is on the order of 2000 psi to \r\n in excess of 20,000 psi. The BIA Standard does not dictate minimum \r\n compressive strength requirements for brick, but since the allowable \r\n stresses and elastic moduli of masonry are a function of compressive \r\n strength of brick, testing to determine compressive strength is \r\n required. \r\n For the determination of unit compressive \r\n strength, f b , \r\n the procedures given in ASTM C 67 should be followed. \r\n The initial rate of absorption (IRA) is \r\n another important property. If the IRA of brick exceeds an acceptable \r\n upper limit, problems with excessive shrinkage of mortar and grout, \r\n and poor bond, are apt to occur. The procedures for determining \r\n the IRA, in the laboratory and in the field, are contained in ASTM \r\n C 67. \r\n Compressive Strength \r\n Specimen Size . ASTM C 67 requires \r\n that the specimen be full height and width, and approximately one-half \r\n of a brick in length, plus or minus 1 in. (25 mm). For example, \r\n an 8-in. (200 mm) long brick may be tested using a piece of brick \r\n with a length between 3 and 5 in. (75 and 125 mm). However, if the \r\n testing machine being used is not capable of providing sufficient \r\n force to crush the approximate half-brick, a piece of brick having \r\n a length of one-quarter of the original full brick length may be \r\n used, so long as the total cross-sectional area is not less than \r\n 14 in. 2 (90 cm 2 ), see Figure 1. \r\n \r\n Compressive Strength \r\n Specimens \r\n \r\n FIG. 1 \r\n \r\n Although ASTM C 67 does not specifically \r\n state the method in which the samples are to be obtained, it has \r\n been common practice to use pieces of brick which are left over \r\n from modulus of rupture tests. If modulus of rupture tests are not \r\n being performed, then sawing the units to the desired size is acceptable. \r\n A minimum of five specimens is required. \r\n The compressive strength test specimens \r\n should be oven-dried. The amount of moisture in the brick can affect \r\n its compressive strength - the higher the moisture content, the \r\n lower the apparent strength. Therefore, by drying the specimens \r\n before testing, one variable that can affect the results is eliminated. \r\n If they are wet-cut with a masonry saw, the drying should follow \r\n the cutting. If a wet capping material, such as high-strength gypsum, \r\n is used, it is generally agreed that the small amount of moisture \r\n absorbed by the specimens will not make additional oven drying necessary. \r\n The 24-hr curing period in laboratory air will suffice. \r\n Capping Specimens . The importance \r\n of careful capping procedures cannot be over-emphasized. Brick units, \r\n by their inherent nature, are not perfectly formed and their bearing \r\n surfaces may not be parallel and free from surface irregularities. \r\n The purpose of capping the bearing surfaces is to assure reasonably \r\n parallel and smooth opposite bearing surfaces; thus reducing the \r\n likelihood of uneven bearing and stress concentrations, and the \r\n resulting premature failure of the test specimen. \r\n Laboratory technicians responsible for \r\n capping compressive test specimens should be thoroughly familiar \r\n with the capping procedures prescribed in ASTM C 67. Poor caps, \r\n resulting from careless capping techniques, can result in erratic \r\n test results and a lowering of the apparent compressive strengths \r\n of the specimens. \r\n Placing Specimens in Testing Machine . \r\n The requirement in ASTM C 67 that the specimen be centered under \r\n the spherical upper bearing block within 1/16 in. (1.6 mm) is not \r\n a capricious one. The introduction of an eccentric load, if the \r\n specimen is not carefully centered, can result in a lower apparent \r\n compressive strength for the test specimen. It should be understood, \r\n however, that this requirement assumes that the specimen is symmetrical \r\n about both horizontal axes or its center of gravity. For symmetrical \r\n specimens, the center of gravity will be the geometrical center \r\n of the unit. Such is not the case with unsymmetrical test specimens. \r\n Therefore, the centers of gravity of unsymmetrical specimens should \r\n be determined and marked, and it is those marks that should be aligned \r\n with the center of the upper bearing block. \r\n To determine the center of gravity for \r\n an unsymmetrical test specimen, a small steel rod, 1/8 in. to 1/4 \r\n in. (3 to 8 mm) in diameter, may be used. The location of the center \r\n of gravity is determined by finding the balance point of the brick \r\n specimen. To place the specimen over the rod in the exact position \r\n such that it balances perfectly is difficult, but a very good estimate \r\n of this location is not hard to achieve. \r\n Speed of Testing . The speed of \r\n testing specified in ASTM C 67 should be adhered to, primarily for \r\n the purpose of obtaining consistent results. Past experience on \r\n the effect of the rate of loading on the compressive strength of \r\n specimens has shown that, as the rate increases, there can be significant \r\n increases in the apparent compressive strengths of the specimens. \r\n The requirements of ASTM C 67, while not particularly specific, \r\n do provide a moderate rate of loading which, if followed, will produce \r\n consistent results that will represent more accurately the true \r\n compressive strengths of the specimens. \r\n ASTM C 67 specifies that the specimen \r\n should be loaded to one-half of the expected maximum load, and then \r\n the rate should be adjusted such that the test is completed in not \r\n less than one minute and not more than two minutes. For this reason, \r\n it is a good idea to do one or two preliminary tests to get an estimate \r\n of the maximum strength. Figure 2 illustrates the time vs. loading \r\n criteria of ASTM C 67. \r\n \r\n Compressive Test Loading \r\n Rate \r\n \r\n FIG. 2 \r\n \r\n Determination of Minimum Net Area (Percent \r\n Voids) . There are two reasons for determining the void area \r\n of brick: the first reason is to obtain the percentage of voids \r\n (percentage coring) in order to assess whether the brick will be \r\n classified as solid or hollow brick; the second reason is to obtain \r\n the average net cross-sectional area for determination of net area \r\n compressive strength of the units. \r\n ASTM C 216 and C 62 for solid brick, and \r\n ASTM C 652 for hollow brick require calculation of gross area \r\n compressive strength. \r\n If the net area compressive strength is \r\n required, the section \"Measurement of Void Area in Cored Units\" \r\n in ASTM C 67 should be followed. To perform these measurements, \r\n a sample of ten brick is specified by ASTM C 67. Following the procedure \r\n in this section, the cores are filled with sand. The sand is then \r\n placed in a graduated cylinder to determine the volume. Using the \r\n equation given in ASTM C 67 for percent void area, the void area \r\n can be determined. The net area can be determined by subtracting \r\n the void area from the gross area. \r\n Calculation and Report . The compressive \r\n strength is determined by dividing the maximum compressive load \r\n by the gross cross-sectional area of the specimen. If the net area \r\n compressive strength is required, the net area, as determined in \r\n the previous section, must be used to obtain the desired results. \r\n Since five specimens are used, the arithmetic average should be \r\n determined. \r\n Determination of Mean Compressive Strength, \r\n f b , of Brick Specimens . The BIA Standard requires that, when the \r\n coefficient of variation of the test results exceeds 12 percent, \r\n a reduction factor must be applied to the average compressive strength \r\n of the sample of brick. This reduction factor is not to be \r\n used when determining compliance with the various ASTM material \r\n standards, such as ASTM C 216, ASTM C 62 or ASTM C 652. \r\n The coefficient of variation is calculated \r\n as follows: \r\n \r\n \r\n \r\n where: v \r\n = the \r\n coefficient of variation, and \r\n \r\n \r\n s = \r\n the standard deviation, in psi \r\n (MPa), calculated as follows \r\n s = \r\n \r\n \r\n \r\n where: X \r\n = the compressive \r\n strength of one unit in psi (MPa) \r\n _ \r\n X = \r\n the arithmetic mean (average compressive strength of the \r\n specimens), and \r\n n = \r\n number of measurements in the sample. \r\n If the coefficient of variation, v, exceeds \r\n 12 percent, the average compressive strength, X, is multiplied by \r\n the following to obtain f b \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Initial Rate of Absorption \r\n The initial rate of absorption (IRA) is \r\n an important property of brick because it affects mortar and grout \r\n bond. If the initial rate of absorption is too high, brick will \r\n absorb moisture from the mortar or grout at a rapid rate, thus impairing \r\n the strength and extent of bond. \r\n In the laboratory, the IRA is measured \r\n using brick which are oven-dried to equilibrium. The IRA of a dry \r\n brick is apt to be higher than one which contains some moisture. \r\n The field test for initial rate of absorption is performed on brick \r\n in their field condition, i.e., no attempt is made to dry the units. \r\n The laboratory test will give an idea of the order of magnitude \r\n of the IRA and the field test can be used to determine if additional \r\n wetting is necessary. \r\n Laboratory Procedure . As previously \r\n mentioned, the laboratory procedure is performed on oven-dried specimens. \r\n Five full-size specimens are required. The technician performing \r\n the test should be aware that the larger the tray size, the less \r\n effect the absorption has on the water level. ASTM C 67 requires \r\n a tray with a cross-sectional area of at least 300 in. 2 \r\n (1950 cm 2 ). For a brick with an IRA of 40 g/min/30 in. 2 , the water level \r\n would drop less than 1/100 in., which is hardly measurable. Nevertheless, \r\n ASTM C 67 provides recommendations on maintaining the water level. \r\n Figure 3 illustrates the tray with a brick positioned for testing. \r\n The method is relatively straightforward and easy to perform. The \r\n results are reported in grams of water gained per 30 sq in. when \r\n the brick are immersed in 1/8 in. (3 mm) of water for 1 min. The \r\n calculation of IRA is as follows: \r\n \r\n \r\n IRA = \r\n 30 W / LB (Eq. \r\n 5) \r\n \r\n where: W \r\n = actual \r\n gain in weight of specimen in grams, \r\n \r\n \r\n L = \r\n length of specimen, in in. and \r\n B = \r\n width of specimen, in in. \r\n \r\n \r\n \r\n What some laboratory technicians fail \r\n to realize, however, is that the above equation is for specimens \r\n that are not cored. If the test specimens are cored brick, \r\n or are non-prismatic, the net area must be substituted for \r\n LB in Eq. 5. \r\n \r\n \r\n \r\n \r\n Determination of IRA \r\n FIG. 3 \r\n \r\n Field Procedures . Brick units on \r\n the jobsite may have a different rate of absorption than that of \r\n the same units tested for IRA in the laboratory. The IRA may be \r\n lower due to moisture which brick absorb after leaving the manufacturing \r\n plant. Two tests are available for field determination of brick \r\n absorption. One is an ASTM procedure, described in ASTM C 67, which \r\n measures quantitatively the absorption rate. The other is an approximate, \r\n but effective, test which is not covered by an ASTM standard, and \r\n yields a qualitative indication of the bricks absorption rate and \r\n necessity for wetting prior to use. \r\n ASTM Field Method for IRA - \r\n This method is described in detail in ASTM C 67, and is accomplished \r\n through volumetric means rather than by weight measurements. Using \r\n this method, the brick are placed in a pan of water for 1 min. removed \r\n and the quantity of water remaining in the pan is measured using \r\n a pycnometer (Fig. 4). The pycnometer is used to measure the initial \r\n quantity of water to be placed in the pan. The difference in the \r\n original amount of water and the quantity remaining after placement \r\n of the brick into the pan for 1 min is the amount absorbed by the \r\n brick. It is very important to use the correct size pan and to wet \r\n and drain the pan prior to testing. \r\n \r\n \r\n \r\n Pycnometer \r\n \r\n \r\n FIG. 4 \r\n \r\n Test for Wetting Brick - \r\n The following test is useful for determining the necessity of wetting \r\n brick prior to use: \r\n A circle, approximately 1 in. (25 mm) \r\n in diameter, is drawn on the bed surface of the brick, using a wax \r\n pencil and a twenty-five-cent coin as a guide. Twenty drops of water \r\n are placed into the circle using an eyedropper. If, after 90 seconds, \r\n all of the water has been absorbed, wetting the brick prior to placement \r\n is recommended. \r\n MORTAR TESTING FOR ENGINEERED BRICK \r\n MASONRY \r\n Technical Notes 8 Series discusses \r\n the various types of mortar, properties and mix designs. Also, ASTM \r\n C 270, Specification for Mortar for Unit Masonry, gives both prescriptive \r\n and performance requirements for mortar. Another recommended \r\n standard specification for mortar, BIA M1-72, provides recommendations \r\n on selection proportions and test requirements of portland cement-lime \r\n mortars. This section will outline the various mortar tests which \r\n are important when designing and building engineered brick masonry \r\n elements. \r\n Laboratory Testing of Mortar \r\n Laboratory testing of mortar is performed \r\n in accordance with ASTM C 270 and other standards referenced in \r\n ASTM C 270. The tests are performed on mortar samples which are \r\n prepared in the laboratory. ASTM C 270 is not a specification \r\n to determine mortar strength and properties through field testing. \r\n The amount of testing required by ASTM C 270 depends on the method \r\n in which the mortar is specified, i.e., proportion or property specification. \r\n If the mortar is specified by the proportion specifications, there \r\n are no testing requirements for mortar. For mortars specified \r\n by the property specifications, water retention, compressive strength \r\n and air content tests must be performed. \r\n The following sections describe the methods \r\n of tests for mortar which are specified by the property specifications. \r\n Water Retention . ASTM C 270 refers \r\n to the procedures of ASTM C 91 for water retention determination, \r\n except that the laboratory-mixed mortar shall be of the same materials \r\n and proportions to be used in the construction. Since the water \r\n content of mortar used on the jobsite varies somewhat, and is not \r\n a specified quantity, the laboratory technician should proportion \r\n the cementitious materials and sand in accordance with the job specification \r\n and add sufficient water to bring the flow up to 110 +/- 5%. \r\n To perform the water retention tests, \r\n the technician should review ASTM C 91 on Water Retention, ASTM \r\n C 305 on Mechanical Mixing, and ASTM C 109 on Performing Flow Tests. \r\n The flow test apparatus must meet the specifications of ASTM C 230. \r\n The chart in Fig. 5 indicates the ASTM standards relative to water \r\n retention testing of mortar specified by the property specifications. \r\n \r\n Related ASTM Standards \r\n for Property Specifications \r\n \r\n FIG. 5 \r\n \r\n Compressive Strength . Compressive \r\n strength testing of laboratory-prepared mortar is required under \r\n the ASTM C 270 property specifications. To determine compressive \r\n strength, samples are to have the same proportions as in the actual \r\n construction. As with the water retention test, the amount of water \r\n to be used is not clearly stated; therefore, it is recommended that \r\n sufficient water be used to bring the flow to 110 +/- 5%. As shown \r\n in Fig. 5, other associated ASTM standards which must be used are \r\n ASTM C 109, C 305 and C 230. \r\n The technician should become familiar \r\n with the procedures of ASTM C 109 for specimen molding and load \r\n application since these procedures must be followed closely in order \r\n to obtain reliable results. \r\n Air Content . Air content determination \r\n is the third and last property which must be assessed for mortars \r\n specified under the property specifications. The air content is \r\n determined using a weight-volume relationship to determine the absolute \r\n volume of solids and water. ASTM C 91 and ASTM C 185 are used to \r\n determine air content, except that the equation for percent air \r\n content is given in ASTM C 270. The equation for air-free mortar \r\n density is: \r\n \r\n \r\n \r\n \r\n and the volume of air in percent is \r\n \r\n \r\n \r\n \r\n where: W 1 = weight of portland cement, g, \r\n \r\n \r\n W 2 = weight of hydrated lime, g, \r\n W 3 = weight of masonry cement (if used), g, \r\n W 4 \r\n = weight of sand, g, \r\n V w \r\n = volume of water used, \r\n mL, \r\n P 1 \r\n = unit weight of air-free \r\n portland cement, g/cm 3 , \r\n P 2 = unit weight of air-free hydrated lime, g/cm 3 , \r\n P 3 = unit weight of air-free masonry cement (if used), g/cm 3 , \r\n P 4 \r\n = unit weight of air-free \r\n sand, g/cm 3 , \r\n W m \r\n = weight of 400 mL of mortar, \r\n g. \r\n \r\n \r\n The air-free unit weights of the various \r\n materials in Eq. 6 are equal to the specific gravity of the material \r\n times the unit weight of water (which is unity); thus, the unit \r\n weight is numerically equal to the specific gravity. The specific \r\n gravity for the various materials should be obtained from the manufacturers \r\n or determined by testing. Table 1 gives the approximate specific \r\n gravities for several mortar materials \r\n \r\n In performing the air-content tests, it \r\n is very important to weigh and measure the quantities accurately, \r\n since errors in weights and volumes would have significant impact \r\n upon the calculated air content. \r\n Field Testing of Mortar \r\n For purposes of quality control, field \r\n testing of mortar is sometimes required. Field testing should not \r\n be confused with laboratory testing, or be performed using the standards \r\n and procedures for laboratory testing of mortar. The appropriate \r\n standard for this type of testing is ASTM C 780 \"Standard Method \r\n for Preconstruction and Construction Evaluation of Mortars for Plain \r\n and Reinforced Unit Masonry\". The main purposes of field testing \r\n are to assure that mortar is proportioned properly by the mixer \r\n operator, and to obtain an indication of variability or change in \r\n constituent materials, quality and performance. \r\n There are several tests which are covered \r\n in ASTM C 780, not all of which are required. Seven tests are outlined \r\n in the Annexes of ASTM C 780 which are: A1) Consistency by Cone \r\n Penetration Test Method, A2) Consistency Retention of Mortars for \r\n Unit Masonry, A3) Mortar Aggregate Ratio Test Method, A4) Water \r\n Content Test Method, A5) Mortar Air Content Test Method, A6) Compressive \r\n Strength of Molded Masonry Mortar Cylinders and Cubes and A7) Splitting \r\n Tensile Strength of Molded Masonry Mortar Cylinders. \r\n The testing agency and the specifier should \r\n be aware that the compressive strength of mortar, as determined \r\n by field testing, does not have to meet the minimum compressive \r\n strength requirements of ASTM C 270. \r\n The specifier must decide which of the \r\n seven tests is to be performed, then preconstruction testing of \r\n the materials can be performed in order to establish requirements \r\n for construction site-sampled mortar. \r\n A complete discussion of the test procedures \r\n of ASTM C 780 is not within the scope of this Technical Notes; \r\n therefore, the technician in charge of performing the tests \r\n should become thoroughly knowledgeable with ASTM C 780 and its referenced \r\n documents. \r\n GROUT TESTING FOR ENGINEERED BRICK \r\n MASONRY \r\n The specification for grout for engineered \r\n brick masonry, ASTM C 476, does not require any laboratory testing. \r\n Experience with grout mixed in accordance with the provisions of \r\n ASTM C 476 has been extremely favorable, and grout, therefore, does \r\n not require extensive testing if mixed with the materials and in \r\n the proportions stipulated by the standard. \r\n There is a relatively new standard for \r\n both field and laboratory sampling and compressive testing of grout \r\n used in masonry construction, entitled ASTM C 1019, \"Standard Method \r\n for Sampling and Testing Grout\". \r\n Sampling and Testing Grout for Engineered \r\n Brick Masonry \r\n According to ASTM C 1019, the use of the \r\n standard may be to select grout proportions by comparing test values \r\n or as a quality control test for uniformity of grout preparation \r\n during construction. The standard specification for grout, ASTM \r\n C 476, does not contain provisions for mixing grout to property \r\n specifications; therefore, the use of ASTM C 1019, at this time, \r\n for grout mix design is not advised. For purposes of quality assurance, \r\n the grout testing standard may be useful. \r\n The specimens are prepared by using masonry \r\n units as forms (Fig. 6). The masonry units are those which are to \r\n be used in the project under construction or to be constructed. \r\n The laboratory technician may find it strange to use the brick units \r\n as forms, but the reason is to simulate the conditions of the grout \r\n after placement into the brick masonry element. Grout is placed \r\n with a high water/cement ratio, slump of 10 to 11 in. (250 mm to \r\n 275 mm), in order to facilitate consolidation and eliminate voids. \r\n Due to the absorptive nature of the masonry, the water content of \r\n the grout is reduced after placement. \r\n The methods of sampling and testing, as \r\n described in ASTM C 1019, are easily accomplished; therefore, additional \r\n description and explanation will not be given in this Technical \r\n Notes . \r\n \r\n \r\n Grout Mold Using 2 1/4 \r\n in. (152.4 mm) \r\n \r\n High Standard Size Brick \r\n FIG. 6 \r\n \r\n SUMMARY \r\n This Technical Notes has discussed \r\n testing of brick, mortar and grout used in engineered brick masonry. \r\n Most laboratory and field tests are covered by ASTM standards. Testing \r\n agencies using these tests should be fully aware of the procedures \r\n and limitations, so that improper application and erroneous results \r\n are avoided. \r\n The information contained in this Technical \r\n Notes is based on the available data and experience of the technical \r\n staff of the Brick Institute of America. The information should \r\n be recognized as recommendations which, if followed with good judgment, \r\n should prove beneficial to the performance of the masonry construction. \r\n Final decisions on the use of information, \r\n details and materials as discussed in this Technical Notes are \r\n not within the purview of the Brick Institute of America, and must \r\n rest with the project designer, owner or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60110,"ResultID":176342,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 39A - Testing for Engineered \r\n Brick Masonry - Determination of Allowable Design Stresses \r\n July/Aug. 1975 (Reissued Dec. 1987) \r\n \r\n INTRODUCTION \r\n Prior to the development of a rational \r\n design procedure for brick masonry, it was sufficient to know that \r\n brick masonry units and mortar used were in compliance with the \r\n standards outlined in Technical Notes 39 \r\n Revised, \"Testing for Engineered Brick Masonry - Brick, Mortar and \r\n Grout.\" These quality control tests provided assurance that the \r\n same quality of materials were being used throughout the building \r\n project. This did not give any assurance or knowledge as to the \r\n actual performance of the masonry in the wall. \r\n With the development of a rational design \r\n method, it became important that the architect and/or engineer have \r\n knowledge of the expected performance of the brick and mortar, not \r\n as individual parts of the wall, but as the total wall system. With \r\n this need in mind, this Technical Notes outlines several \r\n ASTM Standard Methods of Tests for Masonry Assemblages which will \r\n give the architect and/or engineer the ability to predict in-the-wall \r\n performance of masonry and determine allowable design stresses. \r\n It is essential in all of the tests described \r\n in this Technical Notes that the units, mortar and construction \r\n of the assemblage be nearly identical with the materials and methods \r\n to be used in the actual construction process. Only in this way \r\n can the actual performance of the masonry be accurately predicted. \r\n This Technical Notes will cover \r\n ASTM standards for the determination of all necessary design stresses \r\n for brick masonry as specified in the design standard, Building \r\n Code Requirements for Engineered Brick Masonry, BIA, August \r\n 1969, and the model building codes in present-day usage. It will \r\n also stipulate the revisions necessary to determine the same properties \r\n for hollow brick units. Subsequent issues of Technical Notes \r\n will discuss miscellaneous tests for masonry not to be used \r\n for design stress determinations. These tests will be used primarily \r\n for quality control, material comparability and in-the-wall performance \r\n predictions for properties other than strength. \r\n STANDARD METHODS OF TESTS \r\n The ASTM test standards with which this \r\n Technical Notes is concerned are contained in the Annual \r\n Book of ASTM Standards. The methods of tests described in the \r\n ASTM standards and listed below should be strictly adhered to; otherwise, \r\n the test performed is no longer a standard test and erroneous or \r\n misleading results may be obtained. The applicable ASTM standards \r\n for masonry are as follows: \r\n Compressive Strength and Modulus of Elasticity: \r\n \r\n Test Methods for Compressive Strength of Masonry \r\n Prisms, ASTM Designation E 447. \r\n Diagonal Tension (Shear) and Modulus of \r\n Rigidity: \r\n Test Method for Diagonal Tension (Shears \r\n in Masonry Assemblages, ASTM Designation E 519. \r\n Method for Conducting Strength Tests \r\n of Panels for Building Construction, ASTM Designation E 72. \r\n Flexural Tensile Strength: \r\n \r\n Method for Conducting Strength Tests of Panels \r\n for Building Construction, ASTM Designation E 72. \r\n In addition to the above listed standards, \r\n the brick and mortar used should conform to the standards listed \r\n in Technical Notes 39 Revised. \r\n PURPOSE AND APPLICATION OF TESTS \r\n General . If a rational design approach \r\n for masonry is employed, it is essential to establish allowable \r\n design stresses early in the design process. Present design standard \r\n requirements provide two methods to establish these values. Under \r\n these requirements, the ultimate compressive strength (f m ) may be determined by (a) prism test, or (b) an approximation based upon \r\n brick strength and mortar properties. The prism test method is the \r\n preferred method as it provides the designer with more exact information; \r\n whereas the approximation method, of necessity, provides more conservative \r\n values. \r\n Allowable design stresses may be determined \r\n under the design standard, once an ultimate compressive strength \r\n of masonry has been determined. However, in some cases, it may be \r\n desirable, or necessary, to establish tensile or shear strength \r\n to closer tolerances than is obtained by design standard values \r\n usually given as a function of ultimate compressive strength or \r\n of brick strengths and mortar types. Such conditions may occur when \r\n masonry is to be used in prefabricated panels, is to be subjected \r\n to unusual loading conditions or when high, early strengths are \r\n desirable. \r\n All masonry specimens for establishing \r\n design stresses should be built using \"inspected workmanship; \r\n that is to say, all head, bed and collar joints should be completely \r\n filled (see Technical Notes 7B \r\n Revised for proper procedures). Once strength tests have been performed \r\n and masonry properties established, it is necessary to decide if, \r\n indeed, inspected workmanship can be achieved at the jobsite. If \r\n inspected, workmanship will be achieved, the ultimate stress, f m , need not be reduced. If, however, uninspected \r\n workmanship is expected, the ultimate strength for \"uninspected \r\n workmanship\" must be used. This value is based upon inspected workmanship \r\n in which the ultimate strength is reduced by 33 1/3, percent in \r\n the design standard. \r\n Test methods for determining strengths \r\n and other properties of masonry necessary to establish allowable \r\n design stresses are outlined below. \r\n DETERMINATION OF f m AND E m \r\n The ultimate compressive strength (f m ) of masonry may be approximated \r\n if the brick to be used have been tested in accordance with ASTM \r\n C 67 (see Technical Notes 39 \r\n Revised ) and mortar type has been established. These values \r\n of f m are given in tabular format in the design standard for both \r\n types of workmanship. Values from this table for a known brick strength, \r\n mortar type and workmanship classification may be used directly \r\n in determination of f m , \r\n and thus the allowable design stresses. \r\n The ultimate compression strength of masonry \r\n is best determined by testing of compressive prisms in accordance \r\n with ASTM Standard Test Methods for Compressive Strength of Masonry \r\n Prisms, E 447. There are two methods of performing this test. Method \r\n A, which is used primarily for strength comparisons of different \r\n brick and mortars, could be used in the selection process to determine \r\n what unit or mortar to use. For determination of ultimate compressive \r\n strength of a specific brick and mortar for a specific project, \r\n Method B of E 447 should be used. This Technical Notes will \r\n concern itself only with Test Method B. \r\n The test specimens for Method B shall \r\n be built to conform as nearly as possible with the actual wall they \r\n represent. They should have the same thickness as the wall represented; \r\n that is, if the wall is to be a solid wall of two wythes with filled \r\n collar joint, the specimens should be the same. Use the same joint \r\n dimensions and bonding pattern as the wall. The length of the specimen \r\n should be equal to, or greater than, the thickness. It has been \r\n general practice to construct specimen lengths equal to 1 1/2 times \r\n the thickness. The specimen height should be at least twice the \r\n thickness of the specimen or a minimum of 15 in. (3.81 cm). The \r\n height generally should not exceed five times the thickness. See \r\n Fig. 1 for prisms with h/t from two to five. The height of specimens \r\n may be controlled by the testing facilities available. Not all laboratories \r\n have testing machines of dimensions which will permit specimens \r\n of height-to-thickness of five to be placed in the machine for test. \r\n Prior to construction of specimens, a check of facilities available \r\n should be made and the specimens constructed with the greatest height-to-thickness \r\n ratio which the available machine can accommodate. Correction factors \r\n for different height-to-thickness ratios and reasons for them are \r\n discussed elsewhere in this Technical Notes. A minimum of \r\n three specimens representing each wall type should be constructed \r\n and tested. Less than three tests will not give a representative \r\n sample. Five specimens of each type of wall are desirable and will \r\n give the designer a more accurate ultimate compressive strength \r\n value on which he can base allowable stresses. \r\n \r\n \r\n \r\n \r\n Compressive Prisms - Slenderness Ratios \r\n Two Through Five \r\n FIG. 1 \r\n \r\n All compressive strength specimens on \r\n which design stresses are to be based shall be tested at 28 days. \r\n The use of 7-day tests for quality control during construction will \r\n be discussed in a subsequent Technical Notes. Seven-day tests \r\n should not be used for determination of design stresses. However, \r\n if for some reason only 7-day test results are available, an approximation \r\n of the 28-day strength may be made. The estimated 28-day strength \r\n can be obtained by dividing the 7-day strength by 0.90. \r\n When prisms with height-to-thickness ratios \r\n of less than five are used for design determinations, a reduction \r\n factor must be used to determine the ultimate compressive strength \r\n of the masonry. Research experience indicates that the mode of failure \r\n of masonry walls under compressive loading is by vertical tensile \r\n splitting. Therefore, to accurately predict wall strength, the prism \r\n failures should be similar. Laboratory studies also show that masonry \r\n specimens having slenderness ratios (h/t) of five or greater consistently \r\n fail in compression by the mode of vertical tensile splitting and \r\n shorter prisms do not. Therefore, a slenderness ratio of five was \r\n selected as unity, and lesser slenderness ratio results must be \r\n corrected by the factors shown in Table 1. Research has shown a \r\n definite relationship between ultimate compressive strengths of \r\n prisms ranging from a slenderness ratio of two up to five. Table \r\n 1 is based upon this relationship. \r\n \r\n \r\n \r\n \r\n \r\n \r\n a Height to thickness. \r\n b \r\n Interpolate to obtain intermediate values. \r\n \r\n \r\n \r\n Solid Brick Compressive Prism - Tensile \r\n Splitting Failure \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n Hollow Brick Compressive Prism - Tensile \r\n Splitting Failure \r\n FIG. 3 \r\n \r\n The h/t of the specimens shall be determined \r\n by dividing the actual measured height of the specimen by the actual \r\n measured thickness of the specimen. These specimen dimensions shall \r\n be determined in accordance with paragraph 6.2 of ASTM E 447. \r\n The cross-sectional area shall also be \r\n determined based upon actual dimensions of the specimen in accordance \r\n with paragraph 6.2 of ASTM E 447. The cross-sectional area to be \r\n used for determination of ultimate compressive strength shall be \r\n the specimen thickness times the specimen length. For masonry units \r\n in accordance with ASTM C 62 and C 216, the gross cross-sectional \r\n area shall be used (t x l ). If units are hollow brick (ASTM \r\n C 652), the net cross-sectional area must be used for determination \r\n of ultimate compressive strength. The net cross-sectional area shall \r\n be determined as follows: the actual gross cross-sectional area \r\n (t x l ), using measured dimensions, less the area of voids \r\n in the total cross section as measured or determined as outlined \r\n in Technical Notes 39 Revised. \r\n If the coefficient of variation (v) of \r\n the test results on the specimens exceeds 10 percent, the ultimate \r\n compressive strength to be used must be modified. This should not \r\n be confused with the 12 percent coefficient of variation requirement \r\n for the test samples of individual units as covered in Technical \r\n Notes 39 Revised. If less than \r\n 10 percent, the average of the specimen tests should be used for \r\n (f m ) ultimate compressive strength. When \r\n the coefficient of variation exceeds 10 percent, modify the average \r\n compressive strength of the specimens by the following equation \r\n to obtain f m : \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n f m = ultimate design compressive strength, \r\n psi (Mpa) \r\n v = coefficient of variation of \r\n the specimen samples tested, percent \r\n _ \r\n X = average compressive strength \r\n of all specimens, psi (Mpa) \r\n \r\n \r\n \r\n The test report should include the average \r\n compressive strength, the standard deviation and the coefficient \r\n of variation. If this information is not included, they may be calculated \r\n as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n X = compressive strength of individual \r\n specimen, psi (Mpa) \r\n X t \r\n = total of all individual specimen compressive strengths, \r\n psi (Mpa) \r\n n = number of specimens \r\n s = standard deviation, psi (Mpa) \r\n v = coefficient of variation, percent \r\n \r\n \r\n In many instances, it is desirable or \r\n necessary to know the modulus of elasticity, E m , of the masonry being used. The modulus of elasticity of the \r\n masonry can be determined by instrumentation of the specimens to \r\n be tested for the determination of ultimate compressive strength. \r\n General practice for obtaining the strain of masonry in compression \r\n requires the installation of strain gages on compressive prisms. \r\n These strain gages, having equal gage lengths, are installed on \r\n each end of the prism along the neutral axis of the section (see \r\n Fig. 4). It is necessary in the case of multiple wythe wall constructions \r\n and/or multiple wythes of dissimilar materials to determine the \r\n neutral axis prior to loading as the load should also be applied \r\n at the neutral axis. The gage lengths should be as long as practicable. \r\n Dial strain gages during test should be read at predetermined load \r\n levels up to approximately 75 to 80 percent of the anticipated ultimate \r\n load and then removed to prevent damage to the gages at specimen \r\n failure. The strain in the masonry is determined by averaging the \r\n strain gage readings and dividing by the gage lengths as given by \r\n the formula: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n g = strain, \r\n average over entire section, in./in. (mm/mm) \r\n D V 1 = dial reading gage No. \r\n 1, in. (mm) \r\n D V 2 = dial reading gage No. \r\n 2, in. (mm) \r\n g = vertical gage length in. (mm) \r\n \r\n \r\n \r\n \r\n \r\n \r\n Compressive Prism Instrumentation for \r\n Modulus of Elasticity \r\n FIG. 4 \r\n \r\n Once the strains at the various load levels, \r\n determined by formula (5) are obtained and stresses are calculated, \r\n a stress-strain curve for the specimen should be plotted (see Fig. \r\n 5). There are several methods of determining the modulus of elasticity \r\n from the stress-strain curve. The most common for masonry are the \r\n initial tangent modulus and secant modulus methods. The modulus \r\n of elasticity is the slope of the tangent or the secant of the curve. \r\n The secant modulus is most commonly used for masonry and is easier \r\n to determine. The two points selected on the stress-strain curve \r\n are generally at 0 psi (Mpa) and 250 psi (1.72 Mpa) stress levels \r\n and the modulus is calculated as follows: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n E m = secant modulus of elasticity, psi (Mpa) \r\n f m0 = 0 psi (Mpa) stress \r\n f m250 = 250 psi (1.72 Mpa) stress \r\n g 0 = strain at 0 psi stress, in./in. (mm/mm) \r\n g 250 = strain at 250 psi stress, in./in. (mm/mm) \r\n \r\n \r\n In addition to the determination of the \r\n modulus of elasticity by actual tests, the modulus may be based \r\n upon f m of the compressive prism \r\n tests stated as a function of f m . (See Tables 3 and 4 of the design standard. ) \r\n \r\n \r\n \r\n \r\n Idealized Stress Strain Curve \r\n FIG. 5 \r\n \r\n \r\n \r\n DETERMINATION OF f V AND E V (V m AND G) \r\n There are two methods of test provided \r\n in ASTM standards for the determination of the shear strength of \r\n masonry. Shear or diagonal tensile strength is of considerable concern \r\n to structural designers, especially in geographical areas where \r\n seismic design is required. Until recently, ASTM standards provided \r\n only one method of test for determining shear strength. The method \r\n of test is described in ASTM E 72, Method for Conducting Strength \r\n Tests of Panels for Building Construction. This method of test, \r\n referred to as the racking load test in the standard, has been supplemented \r\n for masonry by ASTM E 519, Standard Test Method for Diagonal Tension \r\n (Shear) in Masonry Assemblages. The E 72 racking load test provides \r\n for testing materials and constructions of all types, while E 519 \r\n applies only to masonry. \r\n It has long been recognized that the method \r\n of test provided for in E 72 introduces compressive stresses into \r\n the test specimen at the tie down which cannot be measured. See \r\n Figs. 6 and 7 for the testing apparatus used for this test and method \r\n of failure. The tie down is required to prevent rotation of the \r\n specimen when load is applied. In addition to the uncertainty of \r\n the tie-down stresses, this method of test requires a specimen 8 \r\n ft by 8 ft (2.438 m x 2.438 m) in size. This method of test generally \r\n is available only in large laboratories active in masonry research. \r\n On the other hand, E 519 provides a method of test which is easier \r\n to perform and provides very reliable data. The smaller specimens, \r\n 4 ft by 4 ft (1.219 m x 1.219 m), plus more simplified equipment \r\n place this method of test within the capabilities of many private \r\n testing facilities. See Figs. 8 and 9 for test setup and loading \r\n shoes required for this test. \r\n The specimens for both E 72 and E 519 \r\n should be constructed using the brick, mortar, bonding pattern and \r\n wall thickness that will be utilized in the construction. These \r\n specimens should be constructed using \"inspected workmanship\" as \r\n previously described. Specimens for both tests should be cured for \r\n 28 days prior to testing. \r\n \r\n \r\n \r\n \r\n Racking Test Frame and Specimen \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Racking Test Frame and Specimen After \r\n Testing \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Diagonal Tension Test Instrumentation \r\n for Modulus of Rigidity \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n Diagonal Tension Loading Shoe \r\n FIG. 9 \r\n \r\n The E 72 method of test calls for three \r\n 8-ft by 8-ft (2.438 m x 2.438 m) specimens. The panel can be instrumented \r\n as shown in the standard and the horizontal deflection plotted against \r\n the load applied in graph form as described in the standard. It \r\n has been common practice within the masonry industry to slightly \r\n modify this test. In lieu of the instrumentation shown in the standard, \r\n a series of strain gages are placed to measure horizontal displacement \r\n of the panel under load. These gages are placed along the vertical \r\n face of the panel where tie downs and load devices do not occur. \r\n The horizontal displacement or strain is then taken at various load \r\n levels. The strain is the calculated average of all dial readings \r\n at a particular load. The shear stress is calculated by dividing \r\n the horizontally applied load by the panel width times the panel \r\n thickness. From these data stress-strain curves may be plotted. \r\n The instrumentation should be removed at approximately 75 to 80 \r\n percent of the calculated load and the specimen tested to failure. \r\n Data pertinent to the determination of allowable design stresses \r\n are (f v ) ultimate shear stress, a plotted stress-strain \r\n curve and the modulus of rigidity at predetermined stress levels, \r\n usually 20 percent and 50 percent of ultimate shear stress. \r\n The E 519 method of test also specifies \r\n three specimens. Instrumentation of the specimens is provided along \r\n the vertical and horizontal diagonals, as shown in Fig. 8. The vertical \r\n diagonal instrumentation measures the shortening along that diagonal. \r\n The horizontal instrumentation measures the lengthening along that \r\n diagonal. \r\n The calculations for shear stress for \r\n specimens constructed of solid units shall be based on gross area, \r\n while the shear stress for hollow unit specimens shall be based \r\n on net area. The shear stress shall be calculated as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n S s = shear stress on gross \r\n or net area, psi (Mpa) \r\n P = applied load, lb (N) \r\n A = average of the gross or net \r\n areas of the two contiguous upper sides of the specimen, sq \r\n in. (mm 2 ) \r\n \r\n \r\n Formula (8) shall be used when specimens \r\n are built of solid units and formula (8a) shall be used for specimens \r\n of hollow units. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n (t x l ) 1 . . . (t x l ) 2 = thickness and length or gross area of the two upper contiguous \r\n sides of the specimen, sq in. (mm 2 ) \r\n (t x l ) = thickness and length or gross \r\n area of upper side of specimen built of hollow units, \r\n sq in. (mm 2 ) \r\n A v = area of voids of the upper side \r\n of specimen built of hollow units, sq in. (mm 2 ) \r\n \r\n \r\n \r\n \r\n The shear strain shall be calculated as \r\n follows: \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n g \r\n = shearing strain, in./in. (mm/mm) \r\n D V = vertical \r\n shortening, in. (mm) \r\n D H = horizontal \r\n lengthening, in. (mm) \r\n g = vertical gage length, in. (mm) \r\n \r\n \r\n D H must be based \r\n on the same gage length as D V. \r\n The modulus of rigidity shall be calculated \r\n as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n E v = G = modulus of rigidity, psi (Mpa) \r\n \r\n The modulus of rigidity is calculated \r\n for predetermined stress levels, usually at approximately 20 percent \r\n and 50 percent of ultimate load. \r\n The allowable shear stress should be determined \r\n by dividing the ultimate shear strength of the specimens by a safety \r\n factor selected by the designer, when E 72 or E 519 are used to \r\n determine allowable design values. The safety factor used should \r\n be based upon the designers experience, type of workmanship expected, \r\n type of loading the masonry will be subjected to, or as recommended \r\n in the design standard or Recommended Practice for Engineered \r\n Brick Masonry. \r\n DETERMINATION OF f t \r\n At present, only one method of test is \r\n available in ASTM standards for determining the ultimate and design \r\n flexural tensile strengths for masonry. This method of test is covered \r\n in ASTM E 72. Recently ASTM adopted E 518, Standard Test Methods \r\n for Flexural Bond Strength of Masonry. This test, however, is to \r\n be used only as a compatibility test for brick and mortar or as \r\n a quality control test and should not be used for determination \r\n of flexural or transverse design stresses. ASTM E 518 will be more \r\n fully discussed in a subsequent issue of Technical Notes \r\n 39 series. \r\n ASTM E 72 provides four methods for testing \r\n the large scale panels. The specimen may be tested in either a horizontal \r\n (Fig. 10) or a vertical position (Fig. 11). In addition to these \r\n methods, the orientation of the masonry panel itself within the \r\n loading frame will have great effect on the results obtained. If \r\n the span is normal to the bed joints, simulating a wall supported \r\n by floor and roof framing in normal construction, the ultimate strengths \r\n obtained will be considerably less than those with spans parallel \r\n to the bed joints. The panel oriented with a span parallel to bed \r\n joints simulates a wall which in normal masonry construction is \r\n laterally supported by columns or pilasters. \r\n \r\n \r\n \r\n \r\n Transverse Test - Horizontal Uniform \r\n Loading (Air Bag) \r\n FIG. 10 \r\n \r\n \r\n \r\n \r\n \r\n Transverse Test - Vertical Uniform Loading \r\n (Air Bag) \r\n FIG. 11 \r\n \r\n The specimens for this method of test \r\n should be at least 4 ft by 8 ft (1.219 m x 2.438 m) and the same \r\n thickness as the proposed project walls. Three specimens are required \r\n for this method of test. The specimens should be built using the \r\n type of brick, mortar and bonding pattern proposed for the construction \r\n project. The specimens should be built using inspected workmanship \r\n as described earlier. \r\n The test procedure is as follows: The \r\n specimen once placed in the test frame, which usually has a span \r\n of 6 in. (152.5 mm) less than the specimen size, is instrumented \r\n only to measure the center of span deflection. The concentrated \r\n load method, whether the specimen is vertical or horizontal, applies \r\n two equal loads at a distance of one quarter of the span length \r\n from each support. \r\n The uniform loading is applied in either \r\n position, using an air bag. See Figs. 10 and 11. The loads should \r\n be applied in increments with deflection readings taken and recorded \r\n at each increment. Instrumentation should be removed at approximately \r\n 75 to 80 percent of anticipated ultimate load to prevent damage \r\n to the instrument at failure. \r\n The report of the test should provide \r\n a stress-deflection curve and ultimate transverse strength. The \r\n transverse stress at ultimate may be calculated as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n f t = ultimate transverse stress, psi \r\n (Mpa) \r\n M = bending moment for 1-ft (305 \r\n mm) wide strip in.-lb (N-m) \r\n S = section modulus of the specimen \r\n for 1-ft (305 mm) wide strip, in. 3 (mm 3 ) \r\n \r\n \r\n The moment for uniformly loaded specimens \r\n is calculated as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: w = uniform load, psf (Mpa) \r\n \r\n \r\n l = span length, ft (mm) \r\n \r\n The moment for the concentrated loading \r\n may be calculated as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n P = concentrated loads at the quarter \r\n points for 1-ft (305 mm) wide strip, lb (N) \r\n The section modulus for the specimen must \r\n take into account whether the masonry units are solid (up to 25 \r\n percent cored) or hollow (26 to 40 percent cored). Calculations \r\n for the section modulus of solid units would be as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n b = width of 1-ft (305 mm) wide \r\n strip, in. (mm) \r\n d = thickness of specimen, in. (mm) \r\n \r\n \r\n The calculation for the section modulus \r\n of hollow units becomes somewhat more complicated and is as follows: \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n b 1 . . . b n = width of cores, in. (mm), see Fig. 12 \r\n d 1 . . . d n = depth of cores, in. (mm), see Fig. 12 \r\n \r\n \r\n The illustration for this calculation \r\n method, Fig. 12, is based on a 3-core unit with nominal length of \r\n 12 in. (305 mm). However, the formula can be adapted to fit other \r\n sizes of units and coring patterns. All dimensions shall be actual \r\n dimensions. \r\n Once the ultimate transverse strength \r\n has been determined by the test of three specimens, the designer \r\n should select a safety factor to apply to arrive at an allowable \r\n design stress. This safety factor should be based upon the designers \r\n experience, type of workmanship expected, the in situ loadings expected \r\n or as recommended by the design standard. \r\n \r\n \r\n \r\n \r\n Typical Hollow Brick Cross Section \r\n FIG. 12 \r\n \r\n CONCLUSION \r\n The methods of tests described in this \r\n Technical Notes provide the design professional with methods \r\n to determine allowable design stresses which may be used in the \r\n rational design of brick masonry. The values derived from tests \r\n will remain valid only so long as the brick properties, mortar properties \r\n and workmanship remain relatively close to that specified. The next \r\n issue of this Technical Notes series will detail the quality \r\n control tests available to insure the designer that he is obtaining \r\n masonry properties of sufficient quality to achieve the performance \r\n desired. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60111,"ResultID":176343,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 39B - Testing for Engineered \r\n Brick Masonry - Quality Control \r\n March 1988 \r\n \r\n Abstract : Testing prior to and during the construction of engineered \r\n brick masonry may be required to provide a means of quality assurance. \r\n Testing may cover materials, to determine compliance with the project \r\n requirements, assemblies, to determine the properties of the masonry as \r\n constructed or to establish the properties of masonry in existing structures. \r\n The extent of testing required must be determined by the engineering or \r\n architectural firm responsible for the project design and will depend \r\n upon the complexity and importance of the project. This Technical Notes \r\n describes quality assurance procedures applicable to brick masonry assemblies; \r\n other issues in this series address testing of component materials and \r\n testing to establish allowable design stresses. \r\n Key Words : brick , bond \r\n strength , diagonal tension , engineered brick masonry, \r\n grout, masonry testing, mortar, prism testing , quality \r\n assurance , shear, testing . \r\n INTRODUCTION \r\n Engineered brick masonry design is a rational \r\n design procedure based on material properties and fundamental engineering \r\n analysis principles. This type of approach, as opposed to an empirical \r\n approach, permits the designer to retain the aesthetic qualities of brick \r\n masonry and make efficient use of brick masonrys structural properties. \r\n Since engineered brick masonry design is dependent \r\n on material properties, minimum material strength requirements are determined \r\n in the preliminary design phase. Materials (brick, mortar and grout) are \r\n selected and may be tested to determine allowable design stresses for \r\n the combination of materials selected (see Technical Notes 39A ). \r\n Quality assurance testing is then performed during construction to evaluate \r\n the properties of constructed masonry. The results of these tests are \r\n then used to determine if the constructed masonry is acceptable. \r\n This Technical Notes discusses standards \r\n developed by the American Society for Testing and Materials (ASTM) that \r\n may be used for quality assurance testing of engineered brick masonry. \r\n This Technical Notes is not intended to replace applicable ASTM \r\n standards, but to supplement them. \r\n The purpose of this Technical Notes is \r\n to serve as an aid in selecting, applying and interpreting tests. The \r\n engineer, architect or other responsible person must use judgment in selecting \r\n and applying these test methods, but it is hoped that this Technical \r\n Notes will aid in that process. \r\n PURPOSE OF QUALITY ASSURANCE TESTING \r\n Several standards are used in the United States \r\n for the design of brick masonry structures. These standards are referenced \r\n in most building codes and contain some type of requirement for testing \r\n of materials and assemblages to evaluate material properties, design parameters \r\n or as a means of quality assurance. Quality assurance testing is specifically \r\n performed to determine that the materials, construction and workmanship \r\n meet the project specifications. \r\n The BIA Standard ( Building Code Requirements \r\n for Engineered Brick Masonry , Brick Institute of America, McLean, \r\n Virginia, August 1969), for example, requires inspection and testing in \r\n order for the designer to make use of higher allowable design stresses. \r\n Allowable stress values under the BIA Standard are divided into two categories: \r\n \"With Inspection\" and \"Without Inspection\". If no inspection is provided, \r\n the design allowables for \"Without Inspection\" are used and represent \r\n a thirty-three percent reduction in magnitude, as compared to the values \r\n permitted for \"With Inspection\". Therefore, it is advantageous to implement \r\n quality assurance measures in some cases to permit higher allowable stress \r\n values. \r\n The type of inspection required in the BIA Standard \r\n typically consists of an inspector (the engineer, architect or other responsible \r\n party) and some type of testing. The tests outlined in this Technical \r\n Notes are those that are most commonly performed to satisfy the requirements \r\n of the BIA Standard. \r\n TESTING METHODS \r\n The ASTM standards commonly used for quality \r\n assurance testing of brick masonry materials and assemblies are contained \r\n in the Annual Book of ASTM Standards. Current copies of applicable standards \r\n should be readily available to laboratory personnel, individuals involved \r\n in field sampling and testing, and individuals involved in interpreting \r\n test results. The applicable ASTM standards are: \r\n Component Materials \r\n Clay Masonry Units \r\n ASTM C 67, Standard Method of Sampling and Testing \r\n Brick and Structural Clay Tile. \r\n Mortar \r\n ASTM C 270, Standard Specification for Mortar \r\n for Unit Masonry. \r\n ASTM C 109, Standard Test Method for Compressive \r\n Strength of Hydraulic Cement Mortars (using 2-in. or 50-mm Cube Specimens). \r\n ASTM C 780, Standard Method for Preconstruction \r\n and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry. \r\n Grout \r\n ASTM C 476, Standard Specification for Grout \r\n for Masonry. \r\n ASTM C 1019, Standard Method for Sampling and \r\n Testing Grout. \r\n Assemblies \r\n Masonry Compressive \r\n ASTM E 447, Standard Test Methods Strength for \r\n Compressive Strength of Masonry Prisms. \r\n Flexural Bond Strength \r\n ASTM E 518, Standard Test Methods for Flexural \r\n Bond Strength of Masonry. \r\n ASTM C 1072, Standard Test Method for Measurement \r\n of Flexural Bond Strength. \r\n In addition to the preceding standards, other \r\n standards, while not generally used for quality assurance testing, may \r\n be performed in conjunction with compressive and/or flexural bond strength \r\n tests to establish a relationship between test methods for quality assurance \r\n purposes. These methods listed below are discussed in detail in Technical \r\n Notes 39A . \r\n Flexural Tensile Strength \r\n ASTM E 72, Standard Methods of Conducting Strength \r\n Test of Panels for Building Construction. \r\n Shear Strength Diagonal Tension (Shear) \r\n ASTM E 519, Standard Test Method for Diagonal \r\n Tension (Shear) in Masonry Assemblages. \r\n Typically, ASTM standards provide clear and \r\n concise explanations of the procedures involved in sampling and testing; \r\n however, for the novice, some areas may be confusing. Technical Notes \r\n 39 Revised presents a complete discussion \r\n of the preceding standards for testing component materials. \r\n The standards are listed here for the sake of \r\n completeness only. The remaining standards relating to the testing of \r\n masonry assemblages are the subject of this Technical Notes . \r\n LABORATORY SELECTION \r\n A laboratory selected to perform masonry testing \r\n should be properly staffed and be experienced in masonry testing. The \r\n equipment available at a laboratory will directly affect the types of \r\n tests that can be performed, and the specimens that can be tested. As \r\n a minimum, a laboratory will require a curing room with controlled temperature \r\n and humidity, and a compression testing machine with a minimum capacity \r\n of 300,000 lb and a 15-in. stroke to perform prism tests. Other test methods \r\n described in this Technical Notes require more specialized equipment \r\n that may not be available at some laboratories. \r\n EVALUATION OF MASONRY STRENGTH \r\n Compressive Strength \r\n General . Masonry assembly compressive \r\n strength should be determined by prism tests in accordance with ASTM E \r\n 447, Method B (see Figure 1). \r\n \r\n \r\n \r\n \r\n Prism Test Schematic \r\n FIG. 1 \r\n \r\n Specimens . A minimum of three prisms \r\n should be constructed, using the same materials and workmanship as used \r\n in the project. The mortar bedding, joint thickness, joint tooling, bonding \r\n arrangement and grouting pattern should be the same as that in the project. \r\n No structural reinforcement should be included; however, metal wall ties \r\n may be included if used in the project. Prisms should not be grouted unless \r\n all hollow cells and spaces in the actual construction are to be grouted. \r\n The prism thickness should be the same as that \r\n of the actual construction. The prism length should be equal to or greater \r\n than the prism thickness. The height of the prism should be at least twice \r\n the prism thickness or a minimum of 15 in. (375 mm). \r\n Handling and Curing . Prisms should be \r\n constructed on the jobsite in an area where they will not be disturbed \r\n or damaged. Prisms should be subjected to atmospheric conditions similar \r\n to those of the masonry they represent for a period of 48 hr prior to \r\n being prepared for transportation to the testing laboratory. Prisms should \r\n be secured and transported in such a manner so as not to damage them. \r\n After prisms are delivered to the laboratory, \r\n they should be cured in laboratory air, free of drafts, at 75 deg F +/- \r\n 15 deg F (24 deg C +/- 8 deg C), with a relative humidity between 30 and \r\n 70% for a period of 26 additional days. \r\n Capping . Proper capping of prisms cannot \r\n be over-emphasized. Brick units are not perfectly formed and their bearing \r\n surfaces may not be parallel and free from surface irregularities. The \r\n purpose of capping the bearing surfaces is to assure reasonably parallel \r\n and smooth bearing planes. This reduces the likelihood of uneven bearing \r\n and stress concentrations that can result in premature prism failure. \r\n The capping material itself should have a compressive strength in excess \r\n of that expected of the prism to insure that the capping material does \r\n not fail before the prism. \r\n Laboratory personnel responsible for capping \r\n prisms should be knowledgeable of the capping procedures prescribed in \r\n ASTM C 67 and C 140. Poor capping techniques and inappropriate capping \r\n materials can result in erratic test results and lower apparent prism \r\n compressive strengths. \r\n Testing . Prisms should be centered under \r\n the spherical upper bearing block of the testing machine so that the resulting \r\n load will be applied through the center of gravity of each specimen. This \r\n is extremely important since the introduction of an eccentric load, if \r\n the specimen is not properly centered, can result in lower apparent prism \r\n compressive strength. \r\n The speed of testing specified in ASTM E 447 \r\n should be followed to obtain consistent results. Past experience on the \r\n effect of the loading rate on compressive strength has shown that, as \r\n the loading rate increases, there may be a significant increase in apparent \r\n compressive strength. The prescribed loading rate provides a moderate \r\n rate of loading that produces more consistent results and more accurately \r\n represents the true prism compressive strength. \r\n Calculation and Report . The ultimate \r\n compressive strength of a prism is calculated by dividing the maximum \r\n compressive load by the cross-sectional area of the prism. For prisms \r\n constructed with solid units (ASTM C 216 or ASTM C 62), or units grouted \r\n solid, the gross cross-sectional area is used to calculate compressive \r\n strength. For prisms constructed with ungrouted hollow units (ASTM C 652), \r\n the net cross-sectional area (determined by the procedure described in \r\n ASTM C 67) is used in the calculation. When brick masonry prisms with \r\n height-to-thickness ratios (h/t) of less than 5 are tested, the ultimate \r\n compressive strength, as calculated above, must be multiplied by the factors \r\n given in Table 1 to correct for slenderness effects. \r\n The report should contain the prism dimensions, \r\n prism age, description of materials, maximum compressive load for each \r\n prism, cross-sectional area of each prism, compressive strength of each \r\n prism, average compressive strength of the specimens, standard deviation \r\n and coefficient of variation. \r\n \r\n \r\n \r\n \r\n a These values are different \r\n from those now given in the August 1969 BIA Building Code Requirements \r\n for Engineered Brick Masonry. They are based on subsequent research \r\n and more nearly reflect the masonry behavior in prisms with h/t less \r\n than 5. \r\n b Height to thickness (h/t). \r\n c Interpolate to obtain intermediate \r\n values. \r\n \r\n \r\n Recommendations and Evaluation . When \r\n prism tests are used as a means of quality assurance for the BIA Standard, \r\n not less than 3 prisms should be constructed for each 5000 sq ft of wall \r\n area or each story height, whichever is more frequent. Additional test \r\n prisms may be constructed at the discretion of the engineer or architect. \r\n Often it is desirable to establish strength \r\n relationships for prisms cured less than 28 days to prisms cured for 28 \r\n days. This may be established by testing one set of 3 prisms (5 prisms \r\n preferred), constructed for each curing period. The prisms should be cured \r\n at the site for 24 hr and transported to the laboratory and stored with \r\n an ambient temperature and humidity as prescribed in ASTM E 447 for the \r\n remainder of the curing period. One set of prisms should be tested at \r\n 28 days and the other set tested at the desired age level, typically, \r\n 3 or 7 days. From this data, strength relationships between shorter curing \r\n periods and 28-day curing periods may be developed. \r\n It is desirable to establish the relationship \r\n between early prism strengths to 28-day strengths by testing. However, \r\n if this relationship is not or cannot be established, an approximate method \r\n may be used to predict the 28-day prism compressive strengths. \r\n The work represented by the quality assurance \r\n specimens may be deemed acceptable if the average 28-day compressive strengths \r\n or the projected average 28-day compressive strengths are not less than \r\n the specified design compressive strength. \r\n Diagonal Tension (Shear) Strength \r\n General . Under certain circumstance, \r\n it is sometimes necessary to directly establish design shear stresses \r\n more accurately than values established as a function of compressive strength \r\n (see allowable shear stresses in the BIA Standard). When this is the case, \r\n the methods outlined in ASTM E 519 or ASTM E 72 are used to establish \r\n design values (see Technical Notes 39A ). \r\n These test methods require large masonry specimens and cannot be used \r\n practically as quality assurance tests. However, these tests may be performed \r\n with companion compressive test specimens to develop a relationship between \r\n shear and compressive test results. This permits testing of smaller compressive \r\n specimens as a means of quality assurance. \r\n Companion Specimens . Compressive test \r\n prisms should be constructed and tested as outlined in Technical Notes \r\n 39A . A minimum of 3 prisms (preferably \r\n 5 prisms) should be constructed and tested. The data collected from the \r\n compressive prism tests and diagonal tension tests can be used to establish \r\n a relationship between prism compressive strength and design shear strength. \r\n When this relationship is established, tests can then be conducted by \r\n ASTM E 447, in lieu of ASTM E 72 and E 519. \r\n FLEXURAL BOND STRENGTH \r\n General . ASTM E 518 or C 1072 may be \r\n used as quality assurance tests to measure the flexural bond strength \r\n between masonry units and mortar. These tests are not intended for use \r\n in establishing design stresses. Design stresses should be established \r\n through ASTM E 72, as described in Technical Notes 39A . \r\n Companion Specimens . A relationship between \r\n the flexural bond strength obtained by ASTM E 518 or ASTM C 1072 and the \r\n transverse strength of ASTM E 72 may be developed by testing companion \r\n specimens. This requires that ASTM E 72 transverse load tests be performed \r\n and that companion specimens, as prescribed in ASTM E 518 or ASTM C 1072 \r\n be constructed and tested using the same units, mortar and workmanship \r\n as the E 72 tests. The data from these tests can then be used to establish \r\n the relationship between the transverse flexural strength and the flexural \r\n bond strength. \r\n Once this relationship has been established, \r\n ASTM E 72 tests need not be conducted. Quality assurance tests can then \r\n be made by ASTM E 518 or ASTM C 1072. \r\n ASTM E 518 Test . E 518 provides two methods \r\n for performing tests on flexural beams. Method A uses concentrated loads \r\n at 1/3 points of the span (see Fig. 2). Method B uses a uniform loading \r\n over the entire span (see Fig. 3) applied by an air bag. \r\n \r\n \r\n \r\n \r\n E518 Method A Test \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n E518 Method B Test \r\n FIG. 3 \r\n \r\n Specimens - Prisms should be built \r\n at the jobsite with the same materials and workmanship as the actual construction. \r\n Prisms constructed in the field for quality \r\n assurance testing should be protected from damage, but exposed to the \r\n same atmospheric conditions as the constructed masonry. These prisms should \r\n be stored at the jobsite until the testing date. \r\n Testing - While ASTM E 518 does \r\n not specify the orientation of the specimens, specimens for both Method \r\n A and Method B (see Figs. 4 and 5) should be placed with the tooled joints \r\n downward; that is, loads should be applied to the unfinished face. This \r\n provides a more standardized test and allows a more accurate comparison \r\n of results. \r\n \r\n \r\n \r\n \r\n E518 Method A Setup \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n \r\n E518 Method B Setup \r\n FIG. 5 \r\n \r\n If Method A is used and failure of any specimen \r\n occurs outside of the middle third of the specimen, the test results for \r\n that specimen should be discarded. \r\n Calculation and Report - After \r\n testing is completed, the gross area modulus of rupture (tensile bond \r\n strength) can be calculated using one of the following formulae: \r\n Method A test : specimen made of solid \r\n masonry units. \r\n \r\n \r\n \r\n where: \r\n \r\n R = gross area modulus of rupture, psi (Mpa) \r\n P = maximum machine-applied load, lb (N) \r\n P s = weight of specimen, lb (N) \r\n l = span, in. (mm) \r\n b = average width of specimen, in. (mm) \r\n d = average depth of specimen, in. (mm) \r\n \r\n \r\n Method B test : specimen made of solid \r\n masonry units. \r\n \r\n \r\n \r\n \r\n \r\n Method A test : specimen made of hollow \r\n masonry units. \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n S = section modulus of actual net bedded \r\n area, in. 3 (mm 3 ) \r\n \r\n Method B test : specimen made of hollow \r\n masonry units. \r\n \r\n \r\n \r\n For calculation of the section modulus based \r\n on the net bedded areas of hollow units, the following formulae may be \r\n used: \r\n Fully bedded hollow units ; (see Fig. \r\n 6). \r\n \r\n \r\n \r\n \r\n Cross Section-Full Bedded Hollow Unit \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n b 1 = width of cores, in. (mm) \r\n d 1 = depth of cores, in. (mm) \r\n \r\n \r\n Face shell bedded hollow units : (see \r\n Fig. 7) \r\n \r\n \r\n \r\n \r\n Cross Section-Face Shell Bedded Hollow Unit \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n ASTM C 1072 Test . ASTM C 1072, commonly \r\n known as the \"bond wrench test\", permits individual mortar joints to be \r\n tested for flexural bond strength by applying an eccentric load to a single \r\n joint in a prism (see Fig. 8). This method has several advantages over \r\n the ASTM E 518 test method in that: 1) More data is collected from each \r\n prism. 2) The data gathered is more representative since each joint in \r\n a specimen is tested instead of the weakest joint in the specimen. 3) \r\n It may be used to test specimens extracted from existing structures. 4) \r\n Joints remaining after testing by the ASTM E 518 method may be tested \r\n and the results of the two methods compared. \r\n Specimens - Prisms should be constructed \r\n at the jobsite with the same materials and workmanship used in the actual \r\n construction. Prisms should be constructed in a location where they will \r\n not be disturbed or damaged, but be subjected to atmospheric conditions \r\n similar to those of the actual masonry. \r\n Prisms should be a minimum of 2 units in height, \r\n with a minimum width of 4 in. (200 mm). It is recommended that the prisms \r\n be a full unit in width. Joints should be 3/8 in. ┬▒ 1/16 in. (9.4 mm ┬▒ \r\n 1.6 mm) in thickness. One face of each prism should be tooled to match \r\n the tooling of the project. Prisms should be stored at the jobsite until \r\n the testing date. As a minimum, 5 joints should be tested. \r\n Testing - Prisms should be placed \r\n in the support frame so that the tooled joints face the clamping bolts \r\n in the loading arm and are subjected to flexural tension (see Fig. 8). \r\n Prisms should be positioned vertically such that a single brick projects \r\n above the lower clamping bracket. A soft bearing material a minimum of \r\n 1/2 in. (13 mm) in thickness should be placed between the bottom of the \r\n prism and the adjustable prism support base. The loading arm clamping \r\n bolts should be tightened using a torque of not more than 20 lb-in. (2.3 \r\n N-m). Loading should be applied at a uniform rate such that the total \r\n load is applied in not less than 1 min. nor more than 3 min. \r\n \r\n \r\n \r\n \r\n Bond Wrench Test Apparatus \r\n FIG. 8 \r\n \r\n Calculation and Report - After \r\n testing is completed, the flexural bond strength can be calculated as: \r\n Specimens made of solid masonry units \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n F g = gross area flexural tensile strength, psi (MPa), \r\n P = maximum machine applied load, lb (N), \r\n P 1 = weight of loading arm, lb (N) (See Appendix X1 in ASTM \r\n C 1072) \r\n L = distance from center of prism to loading \r\n point, in. (mm), \r\n L 1 = distance from center of prism to centroid of loading \r\n arm, in. (mm) (See Appendix X1 in ASTM C 1072) \r\n b = average width of the cross-section of \r\n failure surface, in. (mm), \r\n d = average thickness of cross-section of \r\n failure surface, in. (mm) \r\n \r\n \r\n Specimens made of hollow masonry units \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n F n = net area flexural tensile \r\n strength, psi (MPa), \r\n S = section modulus of actual net bedded \r\n area, in. 3 (mm 3 ), \r\n A = net bedded area, in. 2 (mm 2 ). \r\n \r\n \r\n For calculation of section modulus, see Eqs. \r\n 5 and 6 and Figs. 6 and 7. The net bedded area may be calculated as: \r\n Fully bedded hollow units ; (see Fig. \r\n 6) \r\n \r\n \r\n \r\n \r\n \r\n Face shell bedded hollow units ; (see \r\n Fig. 7) \r\n \r\n \r\n \r\n \r\n \r\n EVALUATION OF TEST RESULTS \r\n General \r\n In most cases, strength levels are established \r\n by testing or by the selection of design values. Evaluation then becomes \r\n a simple matter of comparing the results of the quality assurance tests \r\n with the desired strength levels. \r\n Unsatisfactory Test Results \r\n Examination of Procedures . Several alternatives \r\n are available when test results fall below the required level. If backup \r\n specimens are not available for testing, then close examination should \r\n be made of the method of prism construction, the handling of the specimens \r\n during transportation and storage and of the laboratory facilities and \r\n test procedures. Actual stresses should be checked to determine if the \r\n lower strength will provide structural stability. After the above observations \r\n and calculations are completed, some judgments should then be made. They \r\n are: \r\n 1. Did mortar proportions or properties change? \r\n 2. Did brick properties change? \r\n 3. Were there unusual curing conditions? \r\n 4.Were specimens damaged during transit or storage? \r\n 5. Were specimens properly constructed? \r\n 6. Were test procedures properly followed? \r\n 7. Were calculations correctly performed? \r\n As a result of these questions, the possible \r\n cause of low test results may be determined. \r\n Alternate Test Procedure . If no immediate \r\n solution is evident and reduced strengths result in safety factors below \r\n an acceptable level, prisms may be cut from the area in question and tested \r\n as described previously. \r\n After specimens are cut from the wall, they \r\n should be transported to the lab for testing. If specimens are cut by \r\n a water-cooled saw, they should be allowed to dry prior to testing. \r\n Exercise of Judgment . If the test results \r\n are still low, then a judgment is required. If the field-cut specimen \r\n tests result in strengths that lower the factor of safety below an acceptable \r\n level, then removal of the masonry in question must be considered. Obviously, \r\n this is the last resort after all other possibilities have been closely \r\n examined. \r\n SUMMARY \r\n This Technical Notes has discussed quality \r\n assurance testing based on procedures developed by ASTM. Testing agencies \r\n using these ASTM test methods should be fully aware of their procedures \r\n and limitations, so that improper application and erroneous results are \r\n avoided. \r\n While the testing procedures outlined in this \r\n Technical Notes are primarily for engineered brick masonry under \r\n the BIA Standard, they may also be used for non-structural masonry testing \r\n and quality assurance testing under other standards. Excessive testing \r\n can add unnecessary cost to the project. It is important that care be \r\n exercised to avoid excessive testing. \r\n It should also be pointed out that, while strengths \r\n are important properties of masonry, they are not the only desirable properties. \r\n Strengths should not become so important that other desirable properties \r\n of masonry are sacrificed. It is still important that masonry be resistant \r\n to water penetration, provide sound control and be properly detailed. \r\n Quality assurance testing is just one tool to provide assurance that all \r\n of the desirable properties of brick masonry are obtained. \r\n Testing procedures described in this Technical \r\n Notes may involve the use of hazardous materials, operations and/or \r\n equipment. This Technical Notes does not purport to address all \r\n of the safety practices associated with the use of these test methods. \r\n It is the responsibility of the user of this Technical Notes to \r\n establish appropriate safety and health practices and determine the applicability \r\n or regulatory limits prior to the use of the test methods described. \r\n The information contained in this Technical \r\n Notes is based on the available data and experience of the technical \r\n staff of the Brick Institute of America. The information should be recognized \r\n as recommendations which, if followed with judgment, should prove beneficial \r\n to the performance of masonry construction. \r\n Final decisions on the use of information, details \r\n and materials as discussed in this Technical Notes are not within \r\n the purview of the Brick Institute of America and must rest with the product \r\n designer, owner or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60112,"ResultID":176344,"Text1":" \r\n \r\n \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 3A - Brick Masonry \r\n Material Properties \r\n December 1992 \r\n Abstract : Brick masonry has a long \r\n history of reliable structural performance. Standards for the structural \r\n design of masonry which are periodically updated such as the Building \r\n Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) \r\n and the Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS \r\n 602) advance the efficiency of masonry elements with rational design criteria. \r\n However, design of masonry structural members begins with a thorough understanding \r\n of material properties. This Technical Notes is an aid for the \r\n design of brick and structural clay tile masonry structural members. Clay \r\n and shale units, mortar, grout, steel reinforcement and assemblage material \r\n properties are presented to simplify the design process. \r\n Key Words : brick, grout, material \r\n properties, mortar, reinforcement, structural clay tile. \r\n INTRODUCTION \r\n The Masonry Standards Joint Committee \r\n (MSJC) has developed the Building Code Requirements for Masonry Structures \r\n (ACI 530/ASCE 5/TMS 402) and the Specifications for Masonry Structures \r\n (ACI 530.1/ASCE 6/TMS 602). In this Technical Notes , these documents \r\n will be referred to as the MSJC Code and the MSJC Specifications, respectively. \r\n Their contents are reviewed in Technical Notes 3 . \r\n The MSJC Code and Specifications are periodically revised by the MSJC \r\n and together provide design and construction requirements for masonry. \r\n The MSJC Code and Specifications apply to structural masonry assemblages \r\n of clay, concrete or stone units. \r\n This Technical Notes is a design \r\n aid for the MSJC Code and Specifications. It contains information on clay \r\n and shale units, mortar, grout, steel reinforcement and assemblage material \r\n properties. These are used in the initial stages of a structural design \r\n or analysis to determine applied stresses and allowable stresses. Material \r\n properties are explained to aid the designer in selection of materials \r\n and to provide a better understanding of the structural properties of \r\n the masonry assemblage based on the materials selected. \r\n CONSTITUENT MATERIAL PROPERTIES \r\n Because brick masonry is bonded into an \r\n integral mass by mortar and grout, it is considered to be a homogeneous \r\n construction. It is the behavior of the combination of materials that \r\n determines the performance of the masonry as a structural element. However, \r\n the performance of a structural masonry element is dependent upon the \r\n properties of the constituent materials and the interaction of the materials \r\n as an assemblage. Therefore, it is important to first consider the properties \r\n of the constituent materials: clay and shale units, mortar, grout and \r\n steel reinforcement. This will be followed by a discussion of the behavior \r\n of their combination as an assemblage. \r\n Clay and Shale Masonry Units \r\n There are many variables in the manufacturing \r\n of clay and shale masonry units. Primary raw materials include surface \r\n clays, fire clays, shales or combinations of these. Units are formed by \r\n extrusion, molding or dry-pressing and are fired in a kiln at temperatures \r\n between 1800 ° F and 2100 ° \r\n (980 ° C \r\n and 1150 ° C). \r\n These variables in manufacturing produce units with a wide range of colors, \r\n textures, sizes and physical properties. Clay and shale masonry units \r\n are most frequently selected as a construction material for their aesthetics \r\n and long-term performance. Consequently, material standards for clay and \r\n shale masonry units contain requirements to ensure that units meet a level \r\n of durability and visual and dimensional consistency. Clay and shale masonry \r\n units used in structural elements of building constructions are brick \r\n and structural clay tile. Material standards for brick and structural \r\n clay tile include: ASTM C 216 (facing brick), ASTM C 62 (building brick), \r\n ASTM C 652 (hollow brick), ASTM C 212 (structural clay facing tile) and \r\n ASTM C 34 (structural clay load-bearing tile). \r\n While brick and structural clay tile are \r\n both visually appealing and durable, they are also well-suited for many \r\n structural applications. This is primarily due to their variety of sizes \r\n and very high compressive strength. The material properties of brick and \r\n structural clay tile which have the most significant effect upon structural \r\n performance of the masonry are compressive strength and those properties \r\n affecting bond between the unit and mortar, such as rate of water absorption \r\n and surface texture. \r\n Unit Compressive Strength . The \r\n compressive strength of brick or structural clay tile is an important \r\n material property for structural applications. In general, increasing \r\n the compressive strength of the unit will increase the masonry assemblage \r\n compressive strength and elastic modulus. However, brick and structural \r\n clay tile are frequently specified by material standard rather than by \r\n a particular minimum unit compressive strength. ASTM material standards \r\n for brick and structural clay tile require minimum compressive strengths \r\n to ensure durability, which may be as little as one-fifth the actual unit \r\n compressive strength. A recent Brick Institute of America survey of United \r\n States brick manufacturers resulted in a data base of unit properties \r\n [6]. A subsequent survey of structural clay tile manufacturers was conducted. \r\n The compressive strengths of brick and structural clay tile evaluated \r\n in these surveys are presented in Table 1. As is apparent, all types of \r\n brick and structural clay tile typically exhibit compressive strengths \r\n considerably greater than the ASTM minimum requirements. Compressive strength \r\n of brick and structural clay tile is determined in accordance with ASTM \r\n C 67 Method of Sampling and Testing Brick and Structural Clay Tile. \r\n \r\n \r\n \r\n 1 Extruded only. \r\n \r\n 2 Made from other materials \r\n or a combination of materials. \r\n 3 Based on gross area. \r\n \r\n Unit Texture and Absorption . Unit texture and \r\n absorption are properties which affect the bond strength of the masonry \r\n assemblage. In general, mortar bonds better to roughened surfaces, such \r\n as wire cut surfaces, than to smooth surfaces, such as die skin surfaces. \r\n Cores or frogs provide a means of mechanical interlock. The bond strength \r\n of sanded surfaces is dependent upon the amount of sand on the surface, \r\n the sands adherence to the unit and the absorption rate of the unit at \r\n the time of laying. \r\n In practically all cases, mortar bonds \r\n best to a unit whose suction at the time of laying is less than 30 g/min/30 \r\n in 2 (1.55 kg/min/m 2 ). Generally, molded units will exhibit a higher initial \r\n rate of absorption than extruded or dry-pressed units. Unit absorption \r\n at the time of laying is an alterable property of brick and structural \r\n clay tile. In accordance with the MSJC Specifications, units with initial \r\n rate of absorption in excess of 30 g/min/30 in. 2 (1.55 kg/min/m 2 ) should be wetted to reduce the rate of water absorption \r\n of the unit prior to laying. In addition, suction of very absorptive units \r\n may be accommodated by using highly water-retentive mortars. \r\n Mortar \r\n The material properties of mortar which \r\n influence the structural performance of masonry are compressive strength, \r\n bond strength and elasticity. Because the compressive strength of masonry \r\n mortar is less important than bond strength, workability and water retentivity, \r\n the latter properties should be given principal consideration in mortar \r\n selection. Mortar materials, properties and selection of masonry mortars \r\n are discussed in Technical Notes 8 \r\n Series. Mortar should be selected based on the design requirements and \r\n with due consideration of the MSJC Code and Specifications provisions \r\n affected by the mortar selected. \r\n Laboratory testing indicates that masonry \r\n constructed with portland cement-lime mortar exhibit greater flexural \r\n bond strength than masonry constructed with masonry cement mortar or air-entrained \r\n portland cement-lime mortar of the same Type. This behavior is reflected \r\n in the MSJC Code allowable flexural tensile stresses for unreinforced \r\n masonry, which are based on the mortar Type and mortar materials selected. \r\n In addition, masonry cement mortars may not be used in Seismic Zones 3 \r\n and 4. \r\n Other MSJC Code and Specifications provisions \r\n are the same for portland cement-lime mortars, masonry cement mortars \r\n and air-entrained portland cement-lime mortars of the same Type. These \r\n include the modulus of elasticity of the masonry, allowable compressive \r\n stresses for empirical design and the unit strength method of verifying \r\n that the specified compressive strength of masonry is supplied. Following \r\n is a general description of the structural properties of each Type of \r\n mortar permitted by the MSJC Code and Specifications. \r\n Type N Mortar . Type N mortar is \r\n specifically recommended for chimneys, parapet walls and exterior walls \r\n subject to severe exposure. It is a medium bond and compressive strength \r\n mortar suitable for general use in exposed masonry above grade. Type N \r\n mortar may not be used in Seismic Zones 3 and 4. \r\n Type S Mortar . Type S mortar is \r\n recommended for use in reinforced masonry and unreinforced masonry where \r\n maximum flexural strength is required. It has a high compressive strength \r\n and has a high tensile bond strength with most brick units. \r\n Type M Mortar . Type M mortar is \r\n specifically recommended for masonry below grade and in contact with earth, \r\n such as foundation walls, retaining walls, sewers and manholes. It has \r\n high compressive strength and better durability in these environments \r\n than Type N or S mortars. \r\n For compliance with the MSJC Specifications, \r\n mortars should conform to the requirements of ASTM C 270 Specification \r\n for Mortar for Unit Masonry. Field sampling of mortar for quality control \r\n should follow the procedures given in ASTM C 780 Test Method for Preconstruction \r\n and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry. \r\n Test procedures for masonry mortars are covered in Technical Notes \r\n 39 Series. \r\n Grout \r\n Grout is used in brick masonry to fill \r\n cells of hollow units or spaces between wythes of solid unit masonry. \r\n Grout increases the compressive, shear and flexural strength of the masonry \r\n element and bonds steel reinforcement and masonry together. For compliance \r\n with the MSJC Specifications, grout which is used in brick or structural \r\n clay tile masonry should conform to the requirements of ASTM C 476 Specification \r\n for Grout for Masonry. Grout proportions of portland cement or blended \r\n cement, hydrated lime or lime putty, and coarse or fine aggregate are \r\n given in Table 2. \r\n \r\n \r\n \r\n 1 Aggregate measured by volume \r\n in a damp, loose condition. \r\n \r\n The amount of mixing water and its migration from the grout to the brick \r\n or structural clay tile will determine the compressive strength of the grout \r\n and the amount of grout shrinkage. Tests indicate that the total amount \r\n of water absorbed from grout by hollow clay units appears to be more dependent \r\n on the initial water content of the grout than the absorption properties \r\n of the unit [3]. Grouts with high initial water content exhibit more shrinkage \r\n than grouts with low initial water contents. Consequently, use of a non-shrink \r\n grout admixture is recommended to minimize the number of flaws and shrinkage \r\n cracks in the grout while still producing a grout slump of 8 to 11 in. (200 \r\n to 280 mm), unless otherwise specified. \r\n The MSJC Specifications require grout \r\n compressive strength to be at least equal to the specified compressive \r\n strength of masonry, f m , but \r\n not less than 2,000 psi (13.8 MPa) as determined by ASTM C 1019 Method \r\n of Sampling and Testing Grout. Test procedures for grout are explained \r\n in more detail in Technical Notes 39 Series. In general, the compressive \r\n strength of ASTM C 476 grout by proportions will be greater than 2,000 \r\n psi (13.8 MPa). Prediction of the compressive strength of grout which \r\n is proportioned in accordance with ASTM C 476 is difficult because of \r\n the many possible combinations of materials, types of materials and construction \r\n conditions. However, ASTM C 476 grout proportions produce a rich mix which \r\n is recommended to complement the high compressive strength of brick and \r\n structural clay tile. \r\n Steel Reinforcement \r\n Steel reinforcement for masonry construction \r\n consists of bars and wires. Reinforcing bars are used in masonry elements \r\n such as walls, columns, pilasters and beams. Wires are used in masonry \r\n bed joints to reinforce individual masonry wythes or to tie multiple wythes \r\n together. Bars and wires have approximately the same modulus of elasticity, \r\n which is stated in the MSJC Code as 29,000 ksi (200,000 MPa). In general, \r\n wires tend to achieve greater ultimate strength and behave in a more brittle \r\n manner than reinforcing bars. Common bar and wire sizes and their material \r\n properties are given in Table 3. As stated in the MSJC Specifications, \r\n steel reinforcement for masonry structural members should comply with \r\n one of the material standards given in Table 4. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 From reference [5]. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n ASSEMBLAGE MATERIAL PROPERTIES \r\n The properties of the constituent materials \r\n discussed previously combine to produce the brick or structural clay tile \r\n masonry assemblage properties. Following is a discussion of the material \r\n properties of the masonry assemblage. \r\n Compressive Strength \r\n Perhaps the single most important material \r\n property in the structural design of masonry is the compressive strength \r\n of the masonry assemblage. The specified compressive strength of the masonry \r\n assemblage, f m , is used to \r\n determine the allowable axial and flexural compressive stresses, shear \r\n stresses and anchor bolt loads given in the MSJC Code. \r\n The compressive strength of the masonry \r\n assemblage can be evaluated by the properties of each constituent material, \r\n termed in the MSJC Specifications the \"Unit Strength Method,\" or by testing \r\n the properties of the entire masonry assemblage, termed the \"Prism Testing \r\n Method.\" These methods are not to be used to establish design values; \r\n rather, they are used by the contractor to verify that the masonry achieves \r\n the specified compressive strength, f m . \r\n Unit Strength Method . A benefit \r\n of verifying compliance of the compressive strength of masonry by unit, \r\n mortar and grout properties is the elimination of prism testing. Each \r\n of the materials in the masonry assemblage must conform to ASTM material \r\n standards mentioned in previous sections of this Technical Notes . \r\n For compliance with these material standards, the compressive strength \r\n of the unit and the proportions or properties of the mortar and grout \r\n must be evaluated. Not surprisingly, there have been attempts by numerous \r\n researchers to accurately correlate the assemblage compressive strength \r\n with unit, mortar and grout compressive strengths. Testing an assemblage \r\n of three materials produces a large scatter of compressive strengths covering \r\n all possible combinations of materials. Therefore, estimates of the masonry \r\n assemblage compressive strength based on unit, mortar and grout properties \r\n are necessarily conservative. The correlations provided in the MSJC Specifications, \r\n shown in Table 5, between unit compressive strength, mortar type and the \r\n masonry assemblage compressive strength represent a lower-bound to experimental \r\n data. In addition, the MSJC Specifications unit strength method does not \r\n directly address variable grout strength, multi-wythe construction or \r\n the influence of joint reinforcement on the compressive strength of the \r\n masonry assemblage. Consequently, compliance with the specified compressive \r\n strength of masonry by prism testing will always produce a more accurate \r\n and optimum use of brick or structural clay tile masonrys compressive \r\n strength than the unit strength method. \r\n The conservative nature of Table 5 should \r\n not be overlooked by the designer. A comparison of the predicted assemblage \r\n compressive strength by the unit strength method in the MSJC Specifications \r\n and a data base of actual brick masonry prism test results [1] reveals \r\n this conservatism. The average compressive strength of prisms of solid \r\n brick units was found to be about 1.7 times the masonry compressive strength \r\n predicted by Table 5. The average compressive strength of prisms of hollow \r\n units ungrouted and grouted was found to be 1.9 and 1.4 times the compressive \r\n strengths predicted by Table 5, respectively. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Linear Interpolation \r\n is permitted. \r\n \r\n \r\n \r\n \r\n \r\n Prism Test Method . Prism testing of brick or structural clay tile \r\n masonry provides a number of advantages over constituent material testing \r\n alone. The primary benefit of prism testing is a more accurate estimation \r\n of the compressive strength of the masonry assemblage. Another benefit of \r\n prism testing is that it provides a method of measuring the quality of workmanship \r\n throughout the course of a project. Low prism strengths may indicate mortar \r\n mixing error or poor quality grout. \r\n The MSJC Specifications permit testing \r\n of masonry prisms to show conformance with the specified compressive strength \r\n of masonry, f m . In addition, \r\n the material components must meet the appropriate standards of quality. \r\n Masonry prisms are tested in accordance with ASTM E 447 Test Methods for \r\n Compressive Strength of Masonry Prisms, Method B as modified by the MSJC \r\n Specifications. At least three prisms are required by the MSJC Specifications \r\n for each combination of materials. The average of the three tests must \r\n exceed f m . Further explanation of prism testing procedures \r\n is provided in Technical Notes 39B . \r\n Shear Strength \r\n The shear strength of a masonry assemblage \r\n may be separated into four parts: 1) the shear strength of the unit, mortar \r\n and grout assemblage, 2) the effect of the shear span-to-depth ratio, \r\n M/Vd, 3) the enhancement of shear strength due to compressive stress, \r\n and 4) the contribution of shear reinforcement in the masonry assemblage. \r\n All four phenomenon are represented in the allowable shear stresses provided \r\n in the MSJC Code. However, only the first and fourth items are controlled \r\n by material properties. Items two and three vary with member size and \r\n applied loads. \r\n The shear strength of the masonry assemblage \r\n is directly related to the properties of the unit, mortar and grout. Shear \r\n failure of a unit-mortar assemblage is by splitting of units, step-cracking \r\n in mortar joints, or a combination of the two. Unit splitting strength \r\n is increased by increasing the compressive strength of the unit. In general, \r\n unit splitting is not a common shear failure mode of brick or structural \r\n clay tile masonry. Unit splitting occurs in masonry assemblages of weak \r\n units and strong mortar and may also occur in shear walls which are heavily \r\n axially loaded. Cracking in mortar joints is the more common shear failure \r\n mode for brick and structural clay tile masonry assemblages. Mortar joint \r\n failure occurs by sliding along bed joints and separation of head joints. \r\n Mortar joint shear failure is affected by bond strength and the frictional \r\n characteristics between the mortar and the unit. In general, a unit-mortar \r\n combination which provides greater bond strength will also provide greater \r\n shear strength. Grouting the masonry assemblage will also increase shear \r\n strength by providing a shear key between courses. The shear strength \r\n of a masonry assemblage may be evaluated in accordance with ASTM E 519 \r\n Test Method for Diagonal Tension (Shear) in Masonry Assemblages. The contribution \r\n of unit, mortar and grout to the allowable shear stresses stated in the \r\n MSJC Code are based on ASTM E 519 tests of masonry assemblages. \r\n Steel reinforcement may be added to the \r\n masonry assemblage to increase shear strength. Shear reinforcement should \r\n be provided parallel to the direction of applied shear force. The MSJC \r\n Code also requires a minimum amount of reinforcement perpendicular to \r\n the shear reinforcement of one-third the area of shear reinforcement. \r\n When shear reinforcement is provided in accordance with the MSJC Code, \r\n allowable shear stresses given in the MSJC Code for reinforced masonry \r\n are increased three times for flexural members and one and one-half times \r\n for shear walls. \r\n Flexural Tensile Strength \r\n Reinforced brick and structural clay tile \r\n masonry is considered cracked under service loads and the flexural tensile \r\n strength of the masonry is neglected in design. However, cracking of an \r\n unreinforced brick or structural clay tile masonry member constitutes \r\n failure and must be avoided. Thus, flexural tensile strength is an important \r\n design consideration for unreinforced masonry. Flexural tensile strength \r\n is the bond strength of masonry in flexure. It is a function of the type \r\n of unit, type of mortar, mortar materials, percentage of grouting of hollow \r\n units and the direction of loading. Workmanship is also very important \r\n for flexural tensile strength, as unfilled mortar joints or dislodged \r\n units have no mortar-to-unit bond strength. \r\n Allowable flexural tensile stresses stipulated \r\n in the MSJC Code for unreinforced masonry are given in Table 6. The allowable \r\n flexural tensile stresses for portland cement-lime mortars are based on \r\n full-size wall tests in accordance with ASTM E 72 Method of Conducting \r\n Strength Tests of Panels for Building Construction. Values for masonry \r\n cement and air-entrained portland cement-lime mortars are based on reductions \r\n obtained with comparative testing. Flexural tensile strength may be evaluated \r\n by testing small-scale prisms in accordance with ASTM E 518 Test Method \r\n for Flexural Bond Strength of Masonry or ASTM C 1072 Test Method for Measurement \r\n of Masonry Flexural Bond Strength, but these results may not directly \r\n correlate to the allowable flexural tensile stresses in the MSJC Code. \r\n \r\n \r\n \r\n \r\n \r\n 1 For partially grouted masonry allowable stresses shall be \r\n determined on the basis of linear interpolation between hollow units which \r\n are fully grouted or ungrouted and hollow units based on amount of grouting. \r\n Elastic Modulus \r\n The elastic modulus of the masonry assemblage, \r\n in combination with the moment of inertia of the section, determines the \r\n stiffness of a brick or structural clay tile masonry structural element. \r\n Elastic modulus is the ratio of applied load (stress) to corresponding \r\n deformation (strain). The elastic modulus is roughly proportional to the \r\n compressive strength of the masonry assemblage. Testing of brick masonry \r\n prisms indicates that the elastic modulus of brick masonry falls between \r\n 700 and 1200 times the masonry prism compressive strength [4]. If the \r\n Unit Strength Method is used to show compliance with the specified compressive \r\n strength of masonry, f m , an \r\n accurate estimation of the actual compressive strength of the masonry \r\n assemblage may not be known. Consequently, the elastic modulus of the \r\n masonry assemblage is determined by the mortar type and the unit compressive \r\n strength. See Table 7. The data in Table 1 can be used to estimate the \r\n modulus of elasticity of the masonry assemblage for the type of unit selected. \r\n The elastic modulus of grout is computed \r\n as 500 times the compressive strength of the grout in accordance with \r\n the MSJC Code. In general, the elastic modulus of grout and the elastic \r\n moduli of brick or structural clay tile and mortar masonry assemblages \r\n are comparable and are often considered equal for design calculations. \r\n However, the MSJC Code recommends that the method of transformation of \r\n areas based on relative elastic moduli be used for computation of stresses \r\n in grouted masonry elements. \r\n \r\n \r\n \r\n 1 MSJC Code Table 5.5.1.2. \r\n \r\n \r\n \r\n Dimensional Stability \r\n Dimensional stability is also an important \r\n property of the masonry assemblage. Expansion and contraction of the brick \r\n or structural clay tile masonry may exert restraining stresses on the \r\n masonry and surrounding elements. Material properties which affect dimensional \r\n stability of clay and shale unit masonry are moisture expansion, creep \r\n and thermal movements. Effects of these phenomenon may be evaluated by \r\n the coefficients provided in the MSJC Code, which are listed in Table \r\n 8. The coefficients in Table 8 represent average quantities for moisture \r\n expansion and thermal movements and an upper-bound value for creep. Moisture \r\n expansion and thermal expansion and contraction are independent and may \r\n be added directly. The magnitude of creep of clay or shale unit masonry \r\n will depend upon the amount of load applied to the masonry element. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Conversion based on equivalent \r\n deformation at 100 o F (38 o C). \r\n \r\n SUMMARY \r\n This Technical Notes contains information \r\n about the material properties of brick and structural clay tile masonry. \r\n This information may be used in conjunction with the MSJC Code and Specifications \r\n to design and analyze structural masonry elements. Typical material properties \r\n of clay and shale masonry units, mortar, grout, reinforcing steel and \r\n combinations of these are presented. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used in conjunction with good \r\n technical judgment and a basic understanding of the properties of brick \r\n masonry. Final decisions on the use of the information contained in this \r\n Technical Notes are not within the purview of the Brick Institute \r\n of America and must rest with the project architect, engineer and owner. \r\n REFERENCES \r\n 1. Atkinson, R.H., \"Evaluation of Strength and Modulus Tables for Grouted \r\n and Ungrouted Hollow Unit Masonry,\" Atkinson-Noland and Associates, Inc., \r\n Boulder, CO, November 1990, 47 pp. \r\n 2. Building Code Requirements for Masonry Structures and Commentary \r\n (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures \r\n and Commentary (ACI 530.1/ASCE 6/TMS 602-92), American Concrete \r\n Institute, Detroit, MI, 1992. \r\n 3. Kingsley, G.R., et al., \"The Influence of Water Content and Unit Absorption \r\n Properties on Grout Compressive Strength and Bond Strength in Hollow \r\n Clay Unit Masonry,\" Proceedings 3rd North American Masonry Conference , \r\n The Masonry Society, Boulder, CO, June 1985, pp. 7:1-12. \r\n 4. Plummer, H.C., Brick and Tile Engineering , Brick Institute of America, \r\n Reston, VA, 1977, 466 pp. \r\n 5. \"Steel Reinforcement Properties and Availability,\" Report of ACI Committee \r\n 439 , Journal of the American Concrete Institute , Vol. 74, Detroit, \r\n MI, 1977, p. 481. \r\n 6. Subasic, C.A., Borchelt, J.G., \"Clay and Shale Brick Material Properties \r\n - A Statistical Report,\" submitted for inclusion, Proceedings 6th \r\n North American Masonry Conference , The Masonry Society, Boulder, \r\n CO, June 1993, 12 pp. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n"},{"TextID":60113,"ResultID":176345,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 3B - Brick Masonry Section Properties \r\n \r\n May 1993 \r\n Abstract : This Technical Notes \r\n is a design aid for the Building Code Requirements for Masonry Structures \r\n (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures \r\n (ACI 530.1/ASCE 6/TMS 602-92). Section properties of brick masonry units, \r\n steel reinforcement and brick masonry assemblages are given to simplify \r\n the design process. Section properties are used to calculate stresses \r\n and to determine the allowable stresses given in the ACI 530/ASCE 5/TMS \r\n 402-92 Code. \r\n Key Words : brick, dimensions, section \r\n properties, steel reinforcement. \r\n INTRODUCTION \r\n An assemblages geometry determines its \r\n ability to resist loads. Section properties are properties of a masonry \r\n assemblage which are based solely on its geometry. Section properties \r\n are used in design and analysis of brick masonry structural elements. \r\n Section properties are used to determine allowable stresses which may \r\n be applied to brick masonry elements, as well as to calculate an elements \r\n stress under applied loads. Because brick is a small building unit, it \r\n may be used to construct assemblages of nearly any configuration. While \r\n this is a benefit of construction with brick masonry, it can make design \r\n tedious because each masonry assemblage will have unique section properties. \r\n To simplify the design process, this Technical Notes presents the \r\n section properties of brick units, steel reinforcement and typical brick \r\n masonry assemblages. The section properties are based on specified dimensions \r\n of the units and assemblages. \r\n This Technical Notes is a design \r\n aid for the Building Code Requirements for Masonry Structures (ACI \r\n 530/ASCE 5/TMS 402-92) and the Specifications for Masonry Structures \r\n (ACI 530.1/ASCE 6/TMS 602-92). These documents, which are promulgated \r\n by the Masonry Standards Joint Committee (MSJC), will be referred to as \r\n the MSJC Code and the MSJC Specifications, respectively. References are \r\n made to the MSJC Code and Specifications to indicate where each section \r\n property applies. Other Technical Notes in this series provide \r\n an overview of the MSJC Code and Specifications and material properties \r\n of brick masonry. \r\n NOTATION \r\n Following are notations used in the text, \r\n figure and tables in this Technical Notes . Where applicable, notations \r\n are the same as used in the MSJC Code and Specifications. \r\n A n Net cross-sectional area of masonry, in . 2 (mm 2 ) \r\n A s Area of steel, in. 2 (mm 2 ) \r\n b Width of section, in. (mm) \r\n b flange Width of flange, in. (mm) \r\n b web Width of web, in. (mm) \r\n d Distance from extreme compression \r\n fiber ot the centroid of tension reinforcement, in. (mm) \r\n E m Elastic modulus of masonry, psi (MPa) \r\n E s \r\n Elastic modulus of steel, psi (MPa) \r\n I \r\n Moment of inertia, in. 4 (m 4 ) \r\n j \r\n Ratio of distance between centroid of flexural compressive forces and \r\n centroid of tensile forces to depth \r\n k \r\n Ratio of distance between compression face and neutral axis to distance \r\n between compression face and centroid of tensile forces \r\n n \r\n Elastic moduli ratio, E s /E m \r\n Q \r\n First moment about the neutral axis of a section of that portion of the \r\n cross section lying between the neutral axis and extreme fiber, in. 3 \r\n (m 3 ) \r\n r \r\n Radius of gyration, in. (mm) \r\n S \r\n Section modulus, in. 3 (m 3 ) \r\n SECTION PROPERTIES OF CONSTITUENT MATERIALS \r\n The constituent materials of units, mortar, \r\n grout and reinforcement combine to form brick masonry assemblages. The \r\n section properties of each constituent material may be required in the \r\n design process. The section properties of clay and shale masonry units \r\n are the basis for the section properties of the total brick masonry assemblage. \r\n The section properties of steel reinforcement are used to determine the \r\n size and spacing of reinforcement within a brick masonry assemblage. \r\n \r\n \r\n \r\n \r\n Clay and Shale Masonry Units \r\n Clay and shale masonry units are manufactured \r\n in a number of sizes and shapes. Clay and shale masonry units are classified \r\n as either solid units or hollow units. Solid units may contain up to 25 \r\n percent void area as a percentage of the gross cross-sectional area of \r\n the unit. Hollow units are classified as H40V for units with a total void \r\n area greater than 25 percent and less than 40 percent of the gross cross-sectional \r\n area, or H60V for units with a total void area greater than 40 percent \r\n and less than 60 percent of the gross cross-sectional area. The number \r\n and size of voids vary with unit size and manufacturing equipment. \r\n The range of sizes of clay and shale masonry \r\n units is given in Table 1. The names given for unit sizes in Table 1 were \r\n established by consensus of United States brick manufacturers and are \r\n standard terminology for the brick industry. Further information on masonry \r\n unit sizes and coursing of brickwork can be found in the Technical \r\n Notes 10 series on estimating brickwork. \r\n \r\n \r\n One criteria for unit selection \r\n may be accommodation of reinforcement within the unit itself. Placement \r\n of steel reinforcement within the cores or cells of hollow units or solid \r\n cored units is permitted by the MSJC Code and Specifications. A core is \r\n a void area less than or equal to 1 1/2 in. 2 (970 mm 2 ). \r\n A cell is a void area which is larger than 1 1/2 in. 2 (970 \r\n mm 2 ). When placing reinforcement within a unit, adequate space \r\n for grouting must be provided. Specifically, MSJC Code Section 8.3.5 requires \r\n that the minimum distance between the steel reinforcement and the surrounding \r\n masonry unit be 1/4 in. (6 mm) when fine grout is used and 1/2 in. (13 \r\n mm) when coarse grout is used. \r\n In certain instances, the cross-sectional \r\n area of masonry units may need to be determined. For example, the compressive \r\n strength of a masonry prism is determined based on the units gross cross-sectional \r\n area when the prism is constructed of solid units or fully grouted hollow \r\n units, and on the units net cross-sectional area when the prism is constructed \r\n of hollow units. For solid units which contain cores, the gross cross-sectional \r\n area is used as the net cross-sectional area. Unit cross-sectional area \r\n may be determined in accordance with ASTM C 67 Methods of Sampling and \r\n Testing Brick and Structural Clay Tile. \r\n The shell and web thickness of hollow units \r\n may need to be determined because hollow unit brick masonry walls are \r\n typically face-shell bedded, while columns, pilasters and the first course \r\n of walls must be fully bedded. Minimum thickness requirements for shells \r\n and webs of hollow units are established by ASTM C 652 Specification for \r\n Hollow Brick (Hollow Masonry Units Made From Clay or Shale). These limits \r\n are given in Table 2. Many manufacturers exceed the minimum thickness \r\n requirements given in Table 2, so it is advisable to request actual unit \r\n dimensions for design purposes. \r\n TABLE 2 \r\n Hollow Unit Section Properties \r\n \r\n \r\n \r\n \r\n 1 Cores greater than 1 in.2 \r\n (650 mm2) in cored shells shall be not less than 1/2 in. (13 mm) from \r\n any edge. Cores not greater than 1 in.2 (650 mm2) in shells cored not \r\n more than 35% shall be not less than 3/8 in. (10 mm) from any edge. \r\n 2 The thickness of webs shall not \r\n be less than 1/2 in. (13 mm) between cells, 3/8 in. (10 mm) between cells \r\n and cores or 1/4 in. (6 mm) between cores. \r\n \r\n Steel Reinforcement \r\n Steel reinforcement for brick masonry assemblages \r\n consists of bars and wires. Reinforcing bars are placed in grouted cavities, \r\n pockets, cores, cells or bond beams of brick masonry walls, columns, pilasters \r\n and beams. Steel wire reinforcement is placed in brick masonry mortar \r\n joints to reinforce individual assemblages or to tie structural elements \r\n together, such as the wythes of a multi-wythe wall. Common bar and wire \r\n section properties are given in Table 3. The sizes of reinforcement listed \r\n in Table 3 are those permitted by the MSJC Code. The cross-sectional area \r\n of reinforcement is used in MSJC Code Eq. 7-10 to determine the spacing \r\n of shear reinforcement. The diameter of reinforcement is used to establish \r\n placement limits and minimum reinforcement development length requirements \r\n given in Chapter 8 of the MSJC Code. \r\n \r\n \r\n \r\n SECTION PROPERTIES OF BRICK MASONRY ASSEMBLAGES \r\n \r\n The section properties of the assemblage \r\n of the constituent materials, along with the strength of the materials, \r\n will determine the magnitude of loads the assemblage can resist. Consider \r\n the section properties required in the design of brick masonry assemblages \r\n following the MSJC Code. The width of the brick masonry assemblage, b, \r\n is used in MSJC Code Eqs. 6-7 and 7-3 and the effective depth of reinforcement, \r\n d, is used in MSJC Code Eqs. 7-3, 7-5, 7-8 and 7-10. Moment of inertia, \r\n I, is used in MSJC Code Eqs. 6-6 and 6-7. Radius of gyration, r, is used \r\n in MSJC Code Eqs. 6-3, 6-4, 6-6, 7-1 and 7-2 to determine allowable compressive \r\n stresses and axial load. The first moment of area, Q, is used in MSJC \r\n Code Eq. 6-7 to determine the shear stress in an unreinforced masonry \r\n element. The dimensionless quantities k and j are used to determine a \r\n cracked, reinforced masonry elements compressive stress and the allowable \r\n shear stress given in MSJC Code Eq. 7-3. The quantities k and j are functions \r\n of the area of reinforcement, As, and the moduli ratio, n. The moduli \r\n ratio, n, is the ratio of the modulus of elasticity of steel, Es, to the \r\n modulus of elasticity of masonry, Em. \r\n Following is a discussion of the section \r\n properties of typical brick masonry assemblages. Tables 4 through 7 provide \r\n section properties of these assemblages based on the dimensions indicated, \r\n which are based on the least specified brick unit dimensions given in \r\n Tables 1 and 2. The MSJC Code requires that the computation of stresses \r\n be based on the minimum net cross-sectional area of the element under \r\n consideration, An. For ungrouted, hollow brick units laid with face-shell \r\n bedding, the minimum net cross-sectional area is the mortar bedded area. \r\n The computation of stiffness of a brick masonry element may be based on \r\n the average net cross-sectional area of the element. The average cross-sectional \r\n area is permitted for stiffness computations, because the distribution \r\n of material within an element may be non-uniform. Examples of structural \r\n elements which have a non-uniform distribution of materials include partially \r\n grouted or ungrouted hollow unit masonry walls. \r\n Walls \r\n Brick masonry walls may be constructed of \r\n a single wythe (one unit in thickness) or multiple wythes and can be reinforced \r\n or unreinforced. Brick masonry walls may be loaded perpendicular to the \r\n plane of the wall or in the plane of the wall. Out-of-plane loads may \r\n be caused by wind or earth pressures or by earthquake induced ground motions. \r\n In-plane loads may be the dead weight of the structure, live loads or \r\n the result of the transfer of out-of-plane loads through wall connections. \r\n Section properties used in the MSJC Codes \r\n design equations for unreinforced masonry walls are I, r and Q. Section \r\n properties used in the MSJC Codes design equations for reinforced masonry \r\n walls are j, b and d. Additional section properties used to compute applied \r\n stresses are An, S and k. Effective areas for partially grouted, hollow \r\n unit masonry walls are illustrated in Figure 1. Shading indicates net \r\n uncracked area, net cracked area and shear area for a cracked cross section. \r\n For all illustrations in this Technical Notes , cross-hatching indicates \r\n mortar bedded areas. In Figure 1(b), the effective width, b, is taken \r\n as the least of s, 6t and 72 in. (1.8 m). In Figure 1(c), the effective \r\n width, b, is taken as the width of the grout space plus the thicknesses \r\n of the adjacent web and end web. \r\n \r\n \r\n \r\n Effective Areas for Partially Grouted, \r\n Hollow Unit Masonry Walls \r\n FIG. 1 \r\n \r\n Section properties for typical ungrouted \r\n and grouted brick masonry walls are given in Tables 4 and 5, respectively. \r\n The quantities k and j are not provided in this Technical Notes \r\n because they are dependent upon the quantity of reinforcement provided, \r\n the elastic moduli of the masonry and the steel and the loading conditions. \r\n The elastic moduli of the masonry and the steel will determine the moduli \r\n ratio, n. The moduli ratio is used to determine the state of stress in \r\n the steel and the masonry under loads. The loading conditions may be a \r\n combination of out-of-plane and in-plane loads. Walls which are subject \r\n to flexural and axial loads must be designed considering the interaction \r\n of axial load and bending moment, which may be accomplished by the use \r\n of a moment-load interaction diagram. The method of development of a moment-load \r\n interaction diagram is beyond the scope of this Technical Notes . \r\n \r\n TABLE 4 \r\n Ungrouted Wall Section Properties1 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Per foot (305 mm) of wall. \r\n 2 Section properties are based \r\n on minimum solid face shell thickness (see Table 2) and face shell bedding. \r\n \r\n \r\n \r\n \r\n \r\n TABLE 5 \r\n Grouted Wall Section Properties1 \r\n \r\n \r\n 1 Per \r\n foot (305 mm) of wall. Section properties are based on minimum solid face \r\n shell thickness (see Table2) and face shell bedding of hollow unit masonry. \r\n Columns \r\n Columns, as defined by the MSJC Code, are \r\n isolated elements whose horizontal dimension measured at a right angle \r\n from the thickness dimension does not exceed three times the thickness \r\n dimension and whose height is at least three times its thickness. Brick \r\n masonry columns are used to support large axial loads. Axial loads are \r\n typically due to the permanent weight of the structure and the transient \r\n floor or roof load which is tributary to the column. According to the \r\n MSJC Code, columns must be reinforced with a minimum of four reinforcing \r\n bars, and the area of reinforcement, As, must be at least 0.0025 but not \r\n more than 0.04 times the columns net cross-sectional area, An. The minimum \r\n nominal dimension of a column is 8 in. (200 mm) and the ratio of height \r\n to least lateral dimension must not exceed 25. These requirements will \r\n influence the brick masonry column cross section selected. Typical brick \r\n masonry column configurations and section properties are given in Table \r\n 6. Section properties are based on uncracked cross sections. Typically, \r\n a brick masonry column will be in compression and will not crack under \r\n loads. However, columns which are loaded by a eccentric axial load or \r\n a large lateral load may crack in flexure. A moment-load interaction diagram \r\n should be used to design and analyze such columns, considering the section \r\n properties of the cracked cross section. The method of development of \r\n a moment-load interaction diagram is beyond the scope of this Technical \r\n Notes . \r\n \r\n TABLE 6 \r\n \r\n \r\n \r\n Column Section Properties \r\n \r\n \r\n \r\n \r\n \r\n \r\n Pilasters \r\n A pilaster is simply an increase in the \r\n effective thickness of a wall at a specific location. To work together, \r\n the wall and the thickened section must be integrally constructed. MSJC \r\n Code Section 5.10 permits three methods of bonding a pilaster to create \r\n integral construction: 1) interlocking fifty percent of the masonry \r\n units, 2) toothing at 8 in. (200 mm) maximum offset and attachment with \r\n metal ties and 3) providing reinforced bond beams at a maximum spacing \r\n of 4 ft (1.2 m) on centers vertically. The length of the wall or flange \r\n that is considered to act integrally with the pilaster from each edge \r\n of the pilaster or web is the lesser of six times the thickness of the \r\n wall or the actual length of the wall. Typical brick masonry pilaster \r\n configurations and uncracked section properties are given in Table 7. \r\n As noted previously, cracked section properties such as k and j must \r\n be determined based on the amount of reinforcement, the moduli ratio \r\n and the loading conditions. Pilasters which are loaded both out-of-plane \r\n and in-plane must be designed considering the interaction of axial load \r\n and bending moment, which may be accomplished by the use of a moment-load \r\n interaction diagram. The method of development of a moment-load interaction \r\n diagram is beyond the scope of this Technical Notes . \r\n \r\n TABLE 7 \r\n \r\n \r\n \r\n Pilaster Section Properties \r\n \r\n \r\n \r\n \r\n 1 Section \r\n properties are based on minimum solid face shell thickness (see Table \r\n 2) face shell bedding of the flange and full bedding of the web. \r\n Beams \r\n Reinforced brick masonry beams may be \r\n used to span over wall openings such as windows and doors. Brick masonry \r\n beams provide a number of advantages over precast concrete or steel \r\n lintels. For example, brick masonry beams are a more efficient use of \r\n materials and produce a visually appealing brick masonry soffit. Some \r\n typical brick masonry beam configurations and their section properties \r\n are given in Technical Notes 17H and 17J. \r\n SUMMARY \r\n Section properties of brick masonry materials \r\n and assemblages are required whenever a rational design of brick masonry \r\n structural elements is developed following the criteria of the MSJC \r\n Code and Specifications. This Technical Notes provides a summary \r\n of section properties of brick masonry. Section properties of clay and \r\n shale masonry units, steel reinforcement and typical brick masonry assemblages \r\n are given. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used in conjunction with good \r\n technical judgment and a basic understanding of the properties of brick \r\n masonry. Final decisions on the use of the information contained in \r\n this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project architect, engineer \r\n and owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Building \r\n Code Requirements for Masonry Structures and Commentary (ACI 530/ASCE \r\n 5/TMS 402-92) and Specifications for Masonry Structures and Commentary \r\n (ACI 530.1/ASCE 6/TMS 602-92), American Concrete Institute, Detroit, MI, \r\n 1992. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60114,"ResultID":176346,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 4 - Heat Transmission \r\n Coefficients of Brick Masonry Walls \r\n Jan. 1982 (Reissued Sept. 1997) \r\n Abstract: A procedure to analyze \r\n the heat flow through the opaque walls of a building envelope is provided. \r\n The design coefficients of heat transmission are provided for commonly \r\n used construction materials. Methods of calculating heat transmission \r\n coefficients and examples of heat loss calculations under steady-state \r\n conditions are provided for opaque wall assemblies. \r\n Key Words: brick, conductance, \r\n conductivity, energy, heat loss, rate of heat flow, resistance, \r\n resistivity, steady-state conditions, series and parallel path, thermal \r\n transmission. \r\n INTRODUCTION \r\n Because of the finite supply of fossil \r\n fuels and the high cost of energy, the need to design energy-efficient \r\n buildings that are also economical becomes important. Various industry \r\n groups are continually updating and refining energy conservation standards \r\n and guidelines for use in the design of new buildings. These standards \r\n and guidelines may be used to assist the building designers. The designer \r\n is confronted with the fact that no two buildings are exactly identical, \r\n nor are the methods or modes of operation similar. Thus, the energy performance \r\n of each building, as a whole, must be evaluated relative to the real performance \r\n of its materials, systems and equipment. \r\n This Technical Notes provides information \r\n and methods of calculating transmission coefficients and heat transfer \r\n values of brick masonry walls under static conditions. These may be used \r\n in energy conservation studies and comparisons for predicting thermal \r\n performance of building components. However, ASHRAE (American Society \r\n of Heating, Refrigerating and Air-Conditioning Engineers) cautions the \r\n designer that heat flow through a building envelope is actually not static, \r\n and although steady-state calculations provide an estimate of energy consumption, \r\n they do not take into account dynamic conditions such as the thermal storage \r\n capacity of materials, direct solar radiation, wind and other variables. \r\n The term \"steady-state\" means that all ambient conditions are assumed \r\n to be constant, which in the real world is virtually never the case. \r\n BUILDING THERMAL DESIGN \r\n The ASHRAE Handbook of Fundamentals \r\n states the following concerning heat transfer calculations: \r\n \"Current methods for estimating the heat \r\n transferred through floors, walls and roofs of buildings are largely based \r\n on a steady-state or steady-periodic heat flow concept (Equivalent Temperature \r\n Difference Concept). The engineering application of these concepts is \r\n not complicated and has served well for many years in the process of design \r\n and selection of heating and cooling equipment for buildings. However, \r\n competitive practices of the building industry sometimes require more \r\n than the selection or design of a single heating or cooling system. Consultants \r\n are requested to present a detailed comparison of alternative heating \r\n and cooling systems for a given building, including initial costs as well \r\n as short- and long-term operating and maintenance costs. The degree of \r\n sophistication required for costs may make it necessary to calculate the \r\n heating and cooling load for estimating energy requirements in hourly \r\n increments for a years time for given buildings at known geographic locations. \r\n Because of the number of calculations involved, computer processing becomes \r\n necessary. The hour-by-hour heating and cooling load calculations, when \r\n based upon a steady heat flow or steady-periodic heat flow concept, do \r\n not account for the heat storage effects of the building structure, especially \r\n with regard to net heat gain to the air-conditioned spaces.\" \r\n The Handbook of Fundamentals also \r\n suggests that the designer consider the following factors when performing \r\n heating load calculations: 1) building construction-heavy, medium or light; \r\n 2) presence of insulation; 3) infiltration and ventilation loads; 4) glass \r\n area-normal or greater than normal; 5) occupancy nature and schedule; \r\n 6) presence of auxiliary heating devices; and 7) expected cost of energy. \r\n Actual heat flow through a wall under \r\n normal weather conditions will involve daily cycles of solar radiation \r\n and air temperature, changing wind speeds and directions, and radiation \r\n to the night sky. In studies (\"Effective U -Values\", New Mexico \r\n Energy Institute, 1978) of dynamic heat transmission through a building \r\n envelope, it was found that consideration of solar heat gain and material \r\n thermal storage effects provided results significantly different from \r\n steady-state heat flow calculations. These studies also showed that the \r\n optimum economic insulation level varies with wall orientations, and that \r\n changing the color of East, West and South walls was more cost-effective \r\n in some instances than insulating. For a detailed description of the thermal \r\n storage effects of brick masonry walls, see Technical Notes 43 \r\n and 43D . \r\n The actual rate of heat flow through typical \r\n masonry building walls may be up to 20% less than the calculated rate \r\n based on published U-values. This is indicated by past research (Structural \r\n Clay Products Research Foundation, Studies of Heat Transfer .), \r\n which points out that the rate of heat transfer can be 20% to 60% greater \r\n than the calculated rate for wood frame walls and metal panel walls, respectively. \r\n Masonry walls have a more favorable rate \r\n of heat transfer because of their greater heat storage capacity, which \r\n is sometimes referred to as thermal mass, or capacity insulation. The \r\n heat flows calculated by steady-state methods are 29% to 60% greater than \r\n those measured under dynamic conditions for masonry walls. ( Dynamic \r\n Thermal Performance of an Experimental Masonry Building , Building \r\n Science Series 45, National Bureau of Standards.) This means that massive \r\n masonry walls may be up to 60% better at retarding heat flow than steady-state \r\n U-values indicate. A method to modify the steady-state calculations, in \r\n order to account for the effect of mass, is provided in Technical Notes \r\n 4B . \r\n The overall coefficient of heat transmission \r\n (U-value) of various walls discussed in this Technical Notes is \r\n used in steady-state heat transfer and steady-periodic heat gain calculations. \r\n Computer programs, such as those used \r\n by the National Bureau of Standards, (National Bureau of Standards Loads \r\n Determination (NBSLD) Computer Program, T. Kasuda, \"NBSLD-National Bureau \r\n of Standards Heating and Cooling Load Determination Program\", Journal, \r\n Automated Procedures for Engineering Consultants (APEC), Winter 1973-1974.) \r\n give values much closer to the actual performance of walls than is possible \r\n under the steady-state concept of heat transfer. Government agencies and \r\n industry groups are continuing to examine simplified methods to calculate \r\n dynamic heat flow without the use of computers. \r\n TERMINOLOGY \r\n Commonly used terms relative to heat transmission \r\n are defined below in accordance with ASHRAE Standard 12-75, Refrigeration \r\n Terms and Definitions. All of these terms describe the same phenomenon, \r\n however, some are described as determined by material dimensions and boundaries. \r\n U = Overall Coefficient of Heat Transmission. \r\n The rate of heat flow through a unit \r\n area of building envelope material or assembly, including its boundary \r\n films, per unit of temperature difference between the inside and outside \r\n air. The term is commonly called the \"U-value\". The Overall Coefficient \r\n of Heat Transmission is expressed in Btu/(hr ° F \r\n ft 2 ). Note that in computing U-values, the component heat transmissions are \r\n not additive, but the overall U-value is actually less (i.e., better) \r\n than any of its component layers. Normally, the U-value is calculated \r\n by determining the resistance (R, defined below) of each component, and \r\n then taking the reciprocal of the total resistance. \r\n k = Thermal Conductivity. \r\n The rate of heat flow through a homogeneous \r\n material, 1-in. thick, per unit of temperature difference between its \r\n two surfaces. A material is considered homogeneous when the value of its \r\n thermal conductivity does not depend on its dimensions (within the range \r\n normally used in construction). Thermal Conductivity is expressed in (Btu \r\n in)/(hr ° F ft 2 ) \r\n C = Thermal Conductance. \r\n The rate of heat flow through a unit \r\n area of material per unit of temperature difference between its two surfaces \r\n for the thickness of construction given, not per in. of thickness. Note \r\n that the conductance of an air space is dependent on height, depth, position, \r\n character and temperature of the boundary surfaces. Therefore, the air \r\n space must be fully described if the values are to be meaningful. For \r\n a description of other than vertical air spaces, see the 1981 ASHRAE Handbook \r\n of Fundamentals, Chapter 23. Thermal Conductance is expressed in Btu/(hr \r\n ° F ft 2 ) \r\n h = Film or Surface Conductance. \r\n The rate of heat exchange between a \r\n unit or surface area and the air it is in contact with. Subscripts i and \r\n o are used to denote inside and outside conductances, respectively. Film \r\n or surface conductance is expressed in Btu/(hr ° F \r\n ft 2 ). \r\n R = Thermal Resistance. \r\n The reciprocal of a heat transfer coefficient, \r\n as expressed by U, C, or h. R is in (hr ° F ft 2 )/Btu. For example, a wall with a U-value of 0.25 would \r\n have a resistance value of R = I/U = 1/0.25=4.0. The value of R is also \r\n used to represent Thermal Resistivity, the reciprocal of the thermal conductivity. \r\n Thermal Resistivity is expressed in (hr ° F ft 2 )/(Btu in) \r\n Btu = British Thermal Unit. \r\n It is the approximate heat required \r\n to raise 1 lb. of water 1 deg Fahrenheit, from 59 ° F \r\n to 60 ° F. \r\n The difference of thermally homogeneous materials \r\n and thermally heterogeneous materials is shown in Figure 1. There is a directly \r\n proportional relationship between the R and C of the thermally homogeneous \r\n material, at twice the thickness the R is twice as great and the C is halved. \r\n For the thermally heterogeneous material, there is no directly proportional \r\n relationship to the R or C and the material thickness. Fig. 1 also shows \r\n the horizontal path of heat flow through a 1 ft 2 surface area of the wall component. \r\n \r\n \r\n Thermal Transmittance Through Materials a \r\n FIG. 1 \r\n \r\n a It is important to note \r\n that not all materials are isotropic with respect to heat transmission. \r\n In such thermally heterogeneous materials, the specific thermal property \r\n under consideration could vary with temperature and material orientation. \r\n For this reason, care must be taken that the direction of heat flow through \r\n a material is suitable for the materials intended use. Materials in which \r\n heat flow is identical in all directions are considered thermally homogeneous. \r\n CALCULATION OF OVERALL COEFFICIENTS \r\n General \r\n Conductance and resistance coefficients \r\n of various wall elements are listed in Table 1. These coefficients were \r\n taken from the 1981 ASHRAE Handbook of Fundamentals, Chapter 23, \r\n which states: \r\n \"The most exact method of determining \r\n heat transmission coefficients for a given combination of building materials \r\n assembled as a building section is to test a representative section in \r\n a guarded hot box. However, it is not practicable to test all the combinations \r\n of interest. Experience has indicated that U-values for many constructions, \r\n when calculated by the methods given in this chapter using accurate values \r\n for component materials, and with corrections with framing member heat \r\n loss, are in good agreement with the values determined by guarded hot \r\n box measurements, when there are no free air cavities within the construction. \r\n \"Remember, the values shown for materials in calculating overall heat \r\n transmission are representative of laboratory specimens tested under idealized \r\n conditions. In actual practice, if insulation is improperly installed \r\n (for example), shrinkage, settling, insulation compression, and similar \r\n factors may have a significant effect on the overall U-value numbers. \r\n Materials that are field fabricated and consequently especially sensitive \r\n to the skills of the mechanic, are especially prone to variations resulting \r\n in performance less than the idealized number.\" \r\n Calculation Methods \r\n Conductances and resistances of homogeneous \r\n material of any thickness can be obtained from the following formula: \r\n \r\n C x =k/x, and R x =x/k \r\n where: \r\n x=thickness of material in inches. \r\n \r\n \r\n \r\n \r\n \r\n This calculation for a homogeneous material \r\n is shown in Fig. 1. The calculation only considers the brick component of \r\n the wall assembly. Whenever an opaque wall is to be analyzed, the wall assembly \r\n should include both the outside and inside air surfaces. The inclusion of \r\n these air surfaces makes all opaque wall assemblies layered construction. \r\n In computing the heat transmission coefficients \r\n of layered construction, the paths of heat flow should first be determined. \r\n If these are in series, the resistances are additive, but if the paths \r\n of heat flow are in parallel, then the thermal transmittances are averaged. \r\n The word \"series\" implies that in cross-section, each layer of building \r\n material is one continuous material. However, that is not always the case. \r\n For instance, in a longitudinal wall section, one layer could be composed \r\n of more than one material, such as wood studs and insulation, hence having \r\n parallel paths of heat flow within that layer. In this case, a weighted \r\n average of the thermal transmittances should be taken. \r\n For layered construction, with paths of \r\n heat flow in series, the total thermal resistance of the wall is obtained \r\n by: \r\n R 1 =R 1 +R 2 +... \r\n \r\n \r\n \r\n \r\n and the overall coefficient of heat transmission \r\n is: \r\n U=1/R 1 \r\n \r\n A solid 8-in. face brick wall would be \r\n a layered construction assembly in regard to thermal analysis: \r\n R \r\n \r\n (hr * ° F * ft 2 ) \r\n -------------- \r\n BTU \r\n \r\n Outside Air Surface 0.17 \r\n 8-in. Face Brick 0.88 \r\n Inside Air Surface 0.68 \r\n Total: R 1 =1.73 \r\n \r\n U = 1/R 1 = 0.578 Btu/(hr * 0 F \r\n * ft 2 \r\n Average transmittances for parallel paths \r\n of heat flow may be obtained from the formula: \r\n \r\n u avg [A A (U A ) + A B (U B ) + ...] \r\n / A t \r\n \r\n or \r\n U avg = [1/ (R A /A A ) + 1/(R B /A B )...]/A T \r\n \r\n where: \r\n \r\n A A , A B , \r\n etc. = area of heat flow path, in Ft 2 , \r\n U A ,U B , etc.= transmission coefficients of the respective paths, \r\n R A , R B , etc.=thermal resistance of the respective paths. \r\n A t = total area beign considered (A A +A B +...), \r\n in Ft 2 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Such an analysis is important for wall construction \r\n with parallel paths of heat flow when one path has a high heat transfer \r\n and the other a low heat transfer, or the paths involve large percentages \r\n of the total wall with small variations in the transfer coefficients for \r\n the paths. \r\n Thermal bridges built into a wall may \r\n increase heat transfer substantially above the calculated amount if the \r\n bridge is ignored. Thermal bridges occur in several types of walls. Three \r\n examples of these are shown. Different methods are used in calculating \r\n the U avg for metallic and non-metallic bridges. Examples \r\n of both are shown. \r\n The brick veneer-frame wall shown in Fig. \r\n 2 has thermal bridges which occur at the wood studs. The parallel path \r\n method allows the average U-value of the wall to be calculated by first \r\n calculating the U-values in series of the two paths involved. Using the \r\n heat transmission coefficients for the various materials found in Table \r\n 1, the calculation is shown in Fig. 2. The path at the wood stud is Path \r\n A and the path at the insulation is Path B. \r\n \r\n \r\n Brick Veneer/Wood Stud \r\n FIG. 2a \r\n \r\n Brick Veneer/Wood Stud \r\n FIG. 2b \r\n \r\n This calculation reveals that, if the \r\n thermal bridge formed by the stud is considered, the U avg exceeds the U of the wall having the insulation \r\n (Path B) by approximately 6 per cent. It is common practice to calculate \r\n the U-values for the insulation path by the series method and then multiply \r\n this value by 1.08 to obtain the U avg \r\n for the wood frame walls. \r\n This method of correcting for wood framing \r\n in the walls is still used in many energy calculation guidelines procedures, \r\n although it is no longer provided in the ASHRAE Handbook of Fundamentals. \r\n It should be noted that the correction factor should be higher because \r\n this value properly predicts the U avg \r\n for the studs, but does not appropriately adjust the U-value for jambs, \r\n heads, sills, and top and toe plates. Also, if 2 in. x 6 in. wood studs \r\n are used, the correction factor may no longer be appropriate. \r\n Most masonry walls have parallel paths \r\n of heat flow which result from bonding the separate wythes together. This \r\n may be by masonry bonders or metal ties. However, for conventional constructions, \r\n the effect of the bonders is not significant, because of the relatively \r\n small area of the metal ties per sq ft of wall, and the slight differences \r\n in conductivity or conductance of masonry units. \r\n However, if masonry bonded cavity walls \r\n with insulation in the cavity of walls with a large amount of headers \r\n are being considered, the parallel path method of calculation should be \r\n used. This is illustrated by the calculated U-values of the brick cavity \r\n wall, shown in Fig. 3. \r\n \r\n \r\n Brick Masonry Cavity Wall (Masonry \r\n Bonded) \r\n FIG. 3a \r\n \r\n Brick Masonry Cavity Wall (Masonry \r\n Bonded) \r\n FIG. 3b \r\n \r\n If the thermal bridge at the bonder were \r\n ignored, the U-value would be the same as U B , which is 0.088. This is approximately an 18 per cent differential between \r\n the series and parallel path calculated transmission coefficients. \r\n The metal-tied cavity wall shown in Fig. \r\n 4 requires the parallel path method of calculation. However, a slightly \r\n modified parallel path method should be used because the ASHRAE Handbook \r\n of Fundamentals requires that calculations for metallic thermal bridges \r\n be done by the Zone Method. Under this method a slightly larger \r\n area is assumed to be affected by the metallic bridge than just the area \r\n of the metal. The wall is divided into two zones, Zone A, containing the \r\n metal; and Zone B, the remaining portion of the wall. \r\n \r\n \r\n Brick Masonry Insulated Cavity Wall \r\n FIG. 4a \r\n \r\n Brick Masonry Insulated Cavity Wall \r\n FIG. 4b \r\n \r\n The Handbook of Fundamentals also \r\n prescribes a method for determining the size and shape of Zone A. The \r\n surface shape of Zone A in the case of a metal beam would be a strip of \r\n width, W, centered on the beam. In the wall shown in Fig. 4, the shape \r\n of Zone A, due to the circular tie, would be a circle of diameter W. W \r\n is calculated from the following formula: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n where: \r\n \r\n \r\n \r\n W = width or diameter of the zone, \r\n in in., \r\n m = width or diameter of the metal \r\n heat path, in in., \r\n d = distance from the panel surface \r\n to the metal, in in. The value of d should not be taken as less \r\n than 0.5 in. \r\n \r\n \r\n \r\n \r\n Calculations for W should be run for both surfaces and the larger of the \r\n two values used. \r\n For the insulated cavity wall with one \r\n metal tie provided for each 4 1/2 sq ft of wall surface, the calculations \r\n in Fig. 4 show that there is about 3.2 per cent increase in the heat loss \r\n through the wall when the ties are considered as compared to the heat \r\n loss through the wall without consideration of the ties. \r\n For a cavity wall which does not contain \r\n any insulation, the effect of the metal ties is much less. By subtracting \r\n out the effects of the insulation and the metal ties through the insulation \r\n shown in Fig. 4, the effect of the wall tie through a 1-in. air space \r\n may be determined: \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n This calculation procedure shows that the \r\n effect of a metal tie across a 1-in. air space is negligible. Fig. 5 shows \r\n the calculations for an uninsulated cavity wall and again the effect is \r\n negligible. These calculations demonstrate that the effect of a metal tie \r\n would be negligible in the 1-in. air space in brick veneer construction \r\n and also in uninsulated cavity walls. There will be minor variations, depending \r\n on the type, size and spacing of metal ties, but the effect may usually \r\n be ignored. However, as demonstrated in the calculations in Fig. 4, if the \r\n metal tie passes through insulation, the effect of the metal tie on the \r\n thermal performance of the wall may become more significant. It should be \r\n noted that as the R-value of the material the metal tie penetrates in creases, \r\n the per cent of heat loss due to the metal tie also increases. \r\n \r\n \r\n \r\n \r\n \r\n Brick Masonry Cavity Wall \r\n FIG. 5a \r\n \r\n \r\n \r\n \r\n Brick Masonry Cavity Wall \r\n FIG. 5b \r\n \r\n Another factor which affects the thermal \r\n performance of walls containing metal is the location of the metal in \r\n the wall. The farther the metal is located from the face of the wall, \r\n the larger the area of the zone affected by the metal tie. This may be \r\n demonstrated with brick veneer/steel stud systems. Consider the brick \r\n veneer/steel stud system shown in Fig. 6. The steel stud backup system \r\n consists of 6-in., 20 gage steel studs at 24 in. o.c., with 6-in. batt \r\n insulation between the steel studs. The width of Zone A is determined \r\n from the exterior flange of the steel stud to the exterior face of the \r\n brick veneer, as shown in Fig. 6. The zone, including the metal, is quite \r\n wide for this type of construction. In accordance with steady-state analysis, \r\n assuming that the 1-in. air space is a material of the system, the width \r\n of the zone becomes 10.5359 in. The 1 5/8-in. wide flange of the metal \r\n studs, being relatively thin as compared to the wall section, is not considered \r\n in the analysis because it will not significantly affect the average thermal \r\n performance of the system. \r\n \r\n \r\n Brick Veneer/Steel Stud \r\n FIG. 6a \r\n \r\n \r\n \r\n \r\n Brick Veneer/Steel Stud \r\n FIG. 6b \r\n \r\n Without consideration of sills, jambs, \r\n heads, and toe and top channels, the performance of the brick veneer/ \r\n steel stud system analyzed is almost 50 per cent less than the value calculated \r\n through the insulation. This performance is calculated using the procedures \r\n in the 1981 ASHRAE Handbook and Product Directory . However, actual \r\n tests of the heat transmission and more precise calculation procedures \r\n will probably demonstrate that the calculated heat loss is considerably \r\n higher than the actual heat loss. \r\n The intent of this example is simply to \r\n show that the thermal performance of brick veneer/metal stud systems is \r\n not the same as brick veneer over wood frame. The designer should be aware \r\n of this discrepancy and the accuracy, or inaccuracy of the approximation \r\n of thermal performance by simplified calculation procedures. The thermal \r\n performance of the brick veneer/metal stud system would require a correction \r\n factor for the framing which greatly exceeds the 8 per cent or the 1.08 \r\n U adjustment factor allowable for wood frame given in the previous brick \r\n veneer example. Even for the wood frame, because of the presence of fire \r\n stops, heads, jambs, sills and top and toe plates, it is recommended that \r\n the 1.08 factor for wood frame be increased to about 1.20, and that an \r\n even larger factor be used for metal studs. \r\n HEAT LOSS AND HEAT GAIN \r\n Building envelope heat losses and heat \r\n gains are calculated using the overall heat transmission coefficients \r\n and other known data. \r\n Even though heat losses and heat gains \r\n are calculated using U-values in the steady-state and steady-periodic \r\n formulae in lieu of the more accurate methods available, other factors \r\n greatly affect the performance of the building envelope in conserving \r\n energy. It should be remembered that the values obtained from the steady-state \r\n and steady-periodic calculations are merely an estimate of the thermal \r\n performance of the envelope. \r\n The designer should be aware that several \r\n factors, other than U-values, determine the actual performance of the \r\n envelope in conserving energy. Some of these factors are: 1) building \r\n orientation and aspect ratio (The aspect ratio is the proportion of length \r\n to width. As the ratio approaches 1, the surface area to volume \r\n ratio decreases, and generally there will be less loss of thermal energy \r\n from interior spaces through the building envelope); 2) exterior surface \r\n color of envelope materials; 3) color of inside walls and ceilings; 4) \r\n mass and specific heat of envelope materials; 5) wind velocities; \r\n 6) infiltration through the envelope; and 7) orientation, area and external \r\n shading of glazing. \r\n These factors are not considered in the \r\n steady-state calculations. However, if their effects on heat transmission \r\n are kept foremost in the designers mind, he can utilize the energy-conserving \r\n characteristics of each of these factors. The resulting structure will \r\n be more thermally efficient than is shown by the steady-state calculations. \r\n Note that some of these factors are accounted for by the CLTD values in \r\n heat gain calculations. \r\n The steady-state method of calculation \r\n for heat loss is straightforward and simple to perform. The outdoor design \r\n temperatures required can be found in the 1981 ASHRAE Handbook of Fundamentals. \r\n The inside design temperature should be 72 o F, or as prescribed \r\n by governing codes. The formula for calculating heat loss is as follows: \r\n where: \r\n \r\n \r\n \r\n H = heat loss transmitted through \r\n the walls or other elements of the building envelope, in Btu/hr, \r\n A = area of the walls or other \r\n elements, in ft 2 , \r\n U = overall coefficient of heat \r\n transmission of the walls or other elements, in Btu/(hr ° F \r\n ft 2 ), \r\n t i \r\n = indoor design temperature, in ° F, \r\n t o = \r\n outdoor design temperature, in ° F. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n a From ASHRAE Handbook \r\n of Fundamentals , except as noted. \r\n b Face brick and common brick \r\n do not always have these specific densities. When the density is different \r\n from that shown, there will be a change in the thermal conductivity. \r\n c Calculated data based upon \r\n hollow brick (25% to 40% cored) of one manufacturer. Based upon coring \r\n and density given. R figures based upon coring and density of supplier \r\n using parallel path method. Vermiculite fill in cores. \r\n d From NCMA TEK 38 \r\n e Values for metal siding \r\n applied over flat surfaces vary widely depending upon the amount of \r\n ventilation of air space beneath the siding, whether the air space is \r\n reflective or non-reflective, and on the thickness, type. and application \r\n of insulating backing-board used. Values given are averages intended \r\n for use as design guide values and were obtained from several guarded \r\n hot-box tests (ASTM C 236) on hollow-backed types and on types made \r\n using backer-board of wood-fiber, foamed plastic, and glass fiber. Departures \r\n of +/- 50%. or more, from the values given may occur. \r\n f Thicknesses can vary. R \r\n values must be stamped on batt. \r\n g Based upon values as commercially \r\n produced. For calculations use specific manufacturers specified values. \r\n h Time-aged values for board \r\n stock with gas-barrier quality (0.001 in thickness or greater) aluminum \r\n foil facers on two major surfaces. \r\n \r\n \r\n CONCLUSION \r\n Present-day technology for heat transmission \r\n (steady-state and steady-periodic) does not permit the designer to take \r\n full advantage of the thermal mass of the element. While these design \r\n methods are relatively easy to understand and calculate, they are not \r\n a true measure of the performance of massive elements. These methods \r\n do give the designer an approximate solution which is on the conservative \r\n side in relation to the actual performance of massive walls. \r\n The designer should take into account \r\n the higher performance of massive construction which in many cases, may \r\n provide savings in operational costs, efficiency of operation and energy. \r\n To provide a more accurate prediction of these savings, a detailed computer \r\n study of the thermal performance of the structure is usually warranted. \r\n Other Technical Notes in this series \r\n discuss heat gain through opaque walls, thermal transmission corrections \r\n for dynamic conditions, balance point temperatures and energy conservation \r\n including worksheets, examples and data tables. \r\n METRIC CONVERSION \r\n Because of the possible confusion inherent \r\n in showing dual unit systems in calculations, the metric (Sl) units are \r\n not given in the data, equations or examples. Table 2 provides metric \r\n (Sl) conversion for the more commonly used heat transmission units. This \r\n table is provided so that the user may use the data and procedures with \r\n Sl units. \r\n \r\n \r\n REFERENCES \r\n 1. 1997 ASHRAE Handbook and Product Directory , Fundamentals Volume. \r\n 2. 1981 ASHRAE Handbook and Product Directory , Fundamentals Volume. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60115,"ResultID":176347,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 40 - Prefabricated Brick Masonry - Introduction \r\n Oct./Nov. 1973 (Reissued Jan. 1987) \r\n \r\n INTRODUCTION \r\n \r\n The desire of the construction industry to minimize the use of \r\n on-site labor has brought about prefabrication of building components. \r\n The masonry industry is one of the later entrants into the prefabrication \r\n field. Methods of prefabrication of masonry have been developed \r\n by several segments of the brick industry: mason contractors, brick \r\n manufacturers, equipment manufacturers and others closely associated \r\n with the industry. \r\n This series of Technical Notes deals with the prefabrication \r\n of brick masonry, including techniques, methods, controls and a \r\n suggested standard specification. This, the first of the series, \r\n will cover the history, method of prefabrication, types of mortars \r\n used, advantages, disadvantages and present applications of prefabricated \r\n brick masonry. \r\n There are several recent developments which make prefabrication \r\n of brick masonry possible. The most important is the development \r\n and acceptance of a rational design method for brick masonry. Other \r\n factors, such as research with new and improved brick units and \r\n mortars, have aided the rapid progress in the prefabrication process. \r\n \r\n This Technical Notes deals only with prefabricated brick masonry \r\n using full size brick units. Prefabricated elements of thin brick \r\n facing units, in conjunction with concrete, fiberboard or other backing, \r\n are not included because they are usually proprietary items and are, \r\n therefore, beyond the scope of this Technical Notes. See Technical \r\n Notes 28C . \r\n \r\n HISTORY AND DEVELOPMENT \r\n \r\n Prefabrication of brick masonry had its early development during \r\n the 1950s in France, Switzerland and Denmark. Prefabrication in \r\n the U.S. and other foreign countries began in the early to mid 60s. \r\n The Structural Clay Products Research Foundation, now a part of \r\n the Brick Institute of America, Engineering & Research Division, \r\n as early as the mid 1950s developed a prefabricated brick masonry \r\n system. This system, known as the \"SCR building panel\" (Reg. U.S. \r\n Pat. Off., SCPI (BIA), Pat. No. 3,248,836) was used in construction \r\n of several structures in the Chicago area which are still in service \r\n today. \r\n The ability to design brick masonry using rational engineering \r\n criteria has made prefabrication feasible. This engineering design \r\n method is based upon much research done by SCPRF and others. This \r\n research is continuing today in search of improved methods for design \r\n and broader applications of brick masonry. \r\n Other factors have influenced the development of prefabrication, \r\n such as improved quality control in the manufacture of masonry units \r\n and the development of new units. The predictability of performance \r\n of portland cement-lime mortar has also been a factor. The development \r\n of several high-bond mortar additives primarily for use in prefabrication \r\n has contributed to prefabrication development and has also found \r\n a place in conventional masonry work. \r\n Most of the early methods of panelization were attempts to mechanize \r\n the bricklaying process to produce standard panels, using unskilled \r\n labor. Later trends, especially in the United States, have been \r\n toward the retention of skilled labor using conventional masonry \r\n construction practices and devising various means to increase mason \r\n productivity. \r\n There are several different methods or systems of prefabrication \r\n being used in the U.S. today. Several of these are available on \r\n a local franchise basis. Other systems employ mechanized equipment \r\n which may be purchased outright, while still others are not patented \r\n but are merely methods of prefabrication developed by individual \r\n manufacturers or mason contractors. \r\n \r\n FABRICATION METHODS \r\n \r\n There are several manufacturing methods presently being used in \r\n brick masonry prefabrication. There are five general factors which \r\n affect the manufacturing process and properties of prefabricated \r\n brick masonry. These factors are: \r\n 1. Hand-laying \r\n 2. Casting \r\n 3. Equipment \r\n 4. Masonry Units \r\n 5. Mortar and Grout \r\n Hand-laying . The hand-laying method of prefabrication is \r\n achieved in the same manner as conventional in-place masonry, except \r\n it is accomplished in an area removed from the final location of \r\n the masonry element. The laying may be done using any of the equipment, \r\n units or mortar described in the paragraphs which follow. This method \r\n is particularly adapted to a mason contractor prefabricator since \r\n his regular labor force can be employed. The fabrication operation \r\n of this method can be and has been performed either at an off-site \r\n plant or an on-site plant. \r\n Casting . The casting method of fabrication involves the \r\n combining of masonry units and grout into a prefabricated element \r\n similar to precast concrete. The casting method is performed with \r\n the element either in a vertical or a horizontal position. This \r\n method in general lends itself to automated equipment which requires \r\n a form, some method of placing units and a system for grouting. \r\n This method of prefabrication usually takes place in an off-site \r\n plant. \r\n The usual practice is to place the units, either by hand or machine, \r\n in a form or mold, either horizontal or vertical, and fill the form \r\n with a grout at atmospheric pressure or under moderate pressure. \r\n Equipment . The equipment used in prefabrication as practiced \r\n today varies widely. It ranges from simple hand tools to highly \r\n sophisticated automated machinery. The hand-laying method will usually \r\n employ the conventional masons tools: trowel, jointing tool, etc. \r\n In addition, the hand-laying method may also utilize corner poles, \r\n jigs and templates for special shapes. The casting method also will \r\n use jigs and forms which provide the spacing for joints. The hand-laying \r\n method will usually employ some type of adjustable scaffolding. \r\n This scaffolding may be manually adjustable, although there are \r\n available some motor-driven scaffolds which provide horizontal and \r\n vertical movements. Adjustable scaffolding can greatly increase \r\n mason productivity and reduce fabrication costs. \r\n In addition to the more or less conventional equipment listed above, \r\n there are specialized tools used in prefabrication work. The casting \r\n method requires that the face of the unit be protected from contamination \r\n by the grout, which is usually done by pressure. Pressure, at the \r\n contact surface of the brick face and form, is created by either \r\n an inflated form face or by applying a load to the brick. There \r\n are available for use in the hand-laying method mechanized or pneumatic \r\n mortar spreaders for distributing mortar for the bed joints. Some \r\n prefabrication has been done using the casting method and automated \r\n unit placing machinery. This equipment places the unit with proper \r\n joint width by machine in lieu of hand placement of units in jigs \r\n or forms. Pressurized grouting systems have also been widely used \r\n in the casting method of prefabrication. \r\n Masonry Units . There have been specially manufactured units \r\n made for prefabrication; however, this text will deal primarily \r\n with standard sized and shaped units. Both solid brick and hollow \r\n brick have been used in prefabrication. Solid brick masonry units \r\n are those which have coring of less than 25 per cent of the bedding \r\n area. Hollow brick units are cored in excess of 25 per cent but \r\n less than 40 per cent of the bedding area. The hollow units are \r\n suitable for and used in applications where vertical reinforcement \r\n may be required. \r\n Large face size units have been used in prefabrication work, both \r\n in solid and hollow unit coring patterns. These units, having a \r\n finished face larger than the standard modular unit, 2 1/4 by 7 \r\n 5/8 in., provide certain advantages. The main advantage of large \r\n face size units is the economy gained by increased productivity. \r\n In a single wythe application, placement of a 4 by 12-in. face unit \r\n gives an equivalent face area of 2.25 times that of the standard \r\n modular unit, and an 8 by 8-in. face unit provides three times the \r\n face area of a standard modular unit. Single and multiple wythe \r\n elements of the units outlined above have been used in prefabrication \r\n work. \r\n \r\n Mortar and Grout . Prefabrication may use either conventional \r\n mortar or mortar with one of the high-bond mortar additives. Prefabricated \r\n panels usually are subjected to higher stresses during handling than \r\n when in service in a structure. The high-bond mortars give the needed \r\n higher tensile bond strength which may permit earlier handling of \r\n the finished panels. Extreme care must be taken to determine compatibility \r\n of the brick with the high-bond mortar. Some brick may not perform \r\n as well with high-bond mortars as others. Tests should be performed \r\n with the mortar and brick to determine if the combination will indeed \r\n produce the required flexural strengths for the project. (See Technical \r\n Notes 39 . ) \r\n \r\n ADVANTAGES OF PREFABRICATION \r\n \r\n There are several advantages in prefabrication which conventionally \r\n laid masonry does not have. By using panelized construction, the \r\n need for on-site scaffolding is virtually eliminated. This can be \r\n a significant cost savings in masonry construction. If an off-site \r\n plant is used, the work area and storage area for masonry materials \r\n at the job site are kept to a minimum. If proper scheduling of delivery \r\n is maintained, the panels can be erected as they are delivered, \r\n eliminating any need for panel storage at the site. \r\n The use of panelization makes possible the fabrication of complex \r\n shapes. These shapes can be accomplished without the need for expensive \r\n falsework and shoring necessary for in-place laid masonry of the \r\n same shapes. Complicated shapes with returns, soffits, arches, etc., \r\n are accomplished by using jigs and forms. Repetitive usage of these \r\n shapes can lower costs appreciably; the more re-uses of the jigs \r\n and forms, the lower the per panel cost will be. \r\n One of the distinct advantages of prefabrication is the factory \r\n setup. This allows for year round work and multi-shift work days. \r\n It permits the labor force to work under conditions not affected \r\n by weather. The use of prefabricated masonry may eliminate the need \r\n for or provide the means of winterizing the structure. \r\n Prefabrication requires stringent quality control. However, this \r\n may be more easily attained under factory conditions. Mortar batching \r\n systems can be tightly controlled by automation or sophisticated \r\n equipment. The curing conditions provided are consistent since they \r\n are less affected by weather changes. \r\n Panelization on some projects may save construction time. It is \r\n possible that on some projects the masonry panels could be built \r\n starting as early as ground breaking for the project, thus keeping \r\n far enough ahead of the in-place construction work to permit panel \r\n erection when needed. In the case of multi-story structures, construction \r\n time could be shortened due to panels already being cured when erected. \r\n This would allow the construction crews to immediately start erection \r\n of the next floor level and could speed construction. \r\n The savings in construction time could provide economies to the \r\n building owner. Any time saving would reduce the length of time \r\n required for high interest interim financing. Earlier completion \r\n would allow earlier occupancy which, in the case of rental or commercial \r\n properties, would allow the owner to have income production start \r\n sooner. \r\n \r\n DISADVANTAGES OF PREFABRICATION \r\n \r\n As with any construction method, prefabrication has inherent disadvantages \r\n as well as advantages. Prefabrication of masonry to date has not \r\n achieved the economy of construction originally desired. In the \r\n present-day construction market (1973) prefabricated masonry costs \r\n are approximately the same or a little higher than conventionally \r\n laid-in-place masonry on a square foot cost comparison. \r\n The use of prefabricated brick masonry is limited to use with certain \r\n types of construction. The designer should be aware of the limitations \r\n of prefabricated masonry. The size of brick masonry panels is limited \r\n primarily by transportation and erection limitations. Architectural \r\n plan layout may in some cases preclude the use of prefabricated \r\n brick masonry. \r\n The use of prefabricated masonry is also limited to some degree \r\n by its basic materials, brick and mortar. The designer must be aware \r\n of the capabilities of brick masonry to withstand loadings as they \r\n occur in the structure. \r\n Another disadvantage of prefabricated brick masonry, as in other \r\n panel systems, is the absence of adjustment capabilities during \r\n the construction process. In-place masonry construction allows the \r\n craftsman to build masonry to fit the other elements of the structure \r\n by adjusting joint thicknesses over a large area so that it is not \r\n noticeable. This is not possible with prefabricated elements. The \r\n use of prefabricated elements sometimes requires other crafts or \r\n trades to construct to accuracy beyond the standard construction \r\n practices of those trades. \r\n \r\n STATE OF THE ART \r\n \r\n The use of prefabricated brick masonry in construction has become \r\n quite widespread. Prefabricated brick panels have some very dramatic \r\n and esthetically pleasing applications throughout the U.S. The panels \r\n for these projects have been built utilizing the full spectrum of \r\n methods as previously outlined. Figures 1 through 5 show several \r\n recent construction projects using prefabricated brick masonry panels. \r\n Most of the projects built in the U.S. have used non-loadbearing \r\n curtain wall panels. However, some loadbearing panels have been \r\n used and panelized brick construction is not limited to curtain \r\n wall applications. \r\n The Penn Square Apartments, Denver, Colorado, pictured in \r\n Fig. 1 (Michael W. Lombardi, Architect; Gerald Schlegel, Structural \r\n Engineer; Loup Miller Construction, General Contractor; Dach Masonry \r\n Construction, Inc., Masonry Contractor). This project used over \r\n 1100 4-in. thick prefabricated pierced balcony railings. The exterior \r\n brick curtain walls of the structure were conventionally laid. \r\n \r\n \r\n \r\n FIG.1 \r\n \r\n \r\n \r\n The Townsend Towers, Syracuse, New York, is shown in Fig. \r\n 2 (Chloethiel Woodard Smith & Associates, Architects; Severud \r\n Associates, Structural Engineers; Paul Construction Co., General \r\n Contractor; R. H. Viau Construction Co., Masonry Contractor). The \r\n 21-story high-rise used 4-in. thick standard modular unit curtain \r\n wall panels. \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n \r\n \r\n The Sheraton Inn, Youngstown, Ohio, is shown in Fig. 3 (Ronald \r\n S. Senseman, Architect; Joseph Bucheit & Son, General Contractor; \r\n Masonry Systems Inc. of Ohio, Masonry Contractor). The 24,000 sq \r\n ft of 4-in. thick curtain wall panels cover a steel frame structure. \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n \r\n \r\n The Denver Brick & Pipe Co. Plant, Denver, Colorado, \r\n is shown in Fig. 4 (Ken R. White Co., Architects and Engineers; \r\n N. G. Petry Construction, General and Masonry Contractors). These \r\n unusually shaped prefabricated panels give the structure a pleasing \r\n appearance. These panels were built, using stacked bond, soldier \r\n coursed standard modular units. \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n \r\n \r\n The Philadelphia National Bank of Philadelphia, Pa., is \r\n shown in Fig. 5 (Ewing Cole Erdman & Eubank, Architects; McCloskey \r\n and Co., General Contractor; John B. Kelly Co., Masonry Contractor; \r\n H. & L. Royer, Inc., Panel Fabricators). Approximately 1100 \r\n C-shaped panels were fabricated for column and spandrel covers for \r\n this structure. These 4-in. panels were plant fabricated off-site \r\n by a local masonry contractor, using high-bond mortar. \r\n \r\n \r\n \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n CONCLUSION \r\n \r\n The designer must evaluate each project to determine the feasibility \r\n and adaptability of prefabrication to that project. Basic questions \r\n which he must answer prior to a decision should include, but not \r\n necessarily be limited to, the following for each individual project: \r\n 1. Is the building layout suitable to prefabrication? \r\n 2. Is it desirable to use off-site prefabrication because of building \r\n site size? \r\n 3. What is the completion schedule and what time of year is construction \r\n to take place? \r\n 4. Are structural design solutions unrealistic when prefabrication \r\n is used? \r\n 5. Can a reasonable level of quality control in all trades be achieved \r\n if prefabricated brick masonry is utilized? \r\n 6. Is prefabrication, based on answers to questions 1 through 5, \r\n an economical answer? \r\n \r\n Prefabrication of brick masonry is a rapidly developing field and \r\n future innovations could greatly affect its value as a design solution. \r\n New developments or revised practices may change some of the preceding \r\n statements as this field continues to develop. \r\n The next issue of this series of Technical Notes will be \r\n a \"Suggested Specification for Prefabricated Brick Masonry \" . \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60116,"ResultID":176348,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 41 - Hollow Brick Masonry \r\n Feb. 1996 \r\n \r\n Abstract: Hollow brick were developed \r\n in response to demand for larger sized units and for reinforced \r\n brick masonry. Hollow brick have a void area between 25 and 60 percent \r\n of the gross cross-sectional area of the unit. Performance issues \r\n relating to hollow brick masonry are discussed including structural, \r\n water penetration resistance, fire resistance and sound resistance \r\n properties. Material selection and construction methods are addressed. \r\n \r\n Key Words: clay brick, compressive strength, hollow brick, \r\n reinforced masonry. \r\n \r\n INTRODUCTION \r\n \r\n Hollow brick masonry is a natural development in brick masonry \r\n construction. Several reasons led to the production of hollow brick. \r\n These include the need for units that can be more easily reinforced \r\n and grouted, and more economically constructed with large size brick. \r\n More stringent structural requirements for buildings in high wind \r\n and seismic regions have required masonry units that can be grouted \r\n and reinforced. These requirements can not be achieved as easily \r\n with solid masonry units. \r\n The development of hollow brick began with 4 by 4 by 12 in. (100 \r\n by 100 by 300 mm) oversized solid units followed by 6 by 4 by 12 \r\n in. (150 by 100 by 300 mm) and 8 by 8 by 16 in. (200 by 200 by 400 \r\n mm) hollow brick. These large hollow brick are often called through-the-wall \r\n (TTW) units because the wall is a single wythe of brick masonry. \r\n They offer a considerable advantage in both speed and economy of \r\n construction. Some brick manufacturers initially experienced production \r\n problems with large TTW units with void areas of 25 percent or less. \r\n Consequently, manufacturers changed their coring patterns to increase \r\n the void area. The coring patterns were redesigned to increase production \r\n recovery and also to reduce weight and permit reinforcing. A new \r\n classification of brick was established - the hollow brick , \r\n whose void area is greater than 25 percent of its gross area. These \r\n units are more economical to produce due to the greater percentage \r\n of recovery in production, less fuel used in production and less \r\n expensive to ship because of their lighter weight. Larger units \r\n are also more economical to place in the wall. For example, it takes \r\n over 13 modular size brick to equal the volume of three 8 by 4 by \r\n 12 in. (200 by 100 by 300 mm) units. \r\n Hollow brick have void areas which are not less than 25 percent, \r\n but not more than 60 percent of the gross area. This compares to \r\n solid brick whose maximum void area is 25 percent. Hollow brick \r\n have different requirements from solid brick and clay tile with \r\n respect to sizes of hollow spaces, web thicknesses and face shell \r\n thicknesses. Hollow brick can be efficiently used in bearing walls, \r\n reinforced or prestressed masonry and walls requiring exposed brick. \r\n Typical applications of hollow brick include commercial, retail \r\n and residential buildings, hotels, schools, noise barrier walls \r\n and retaining walls. Figure 1 is an example of a hollow brick load-bearing \r\n structure. \r\n \r\n \r\n \r\n \r\n \r\n Hollow Brick Casino in Jackson MS \r\n FIG. 1 \r\n \r\n \r\n \r\n This Technical Notes describes the classifications, properties \r\n and uses of hollow brick. Properties of hollow brick masonry related \r\n to structural design, water penetration resistance, fire resistance \r\n and sound resistance are provided. Proper material selection and \r\n construction procedures are discussed. \r\n \r\n HOLLOW BRICK \r\n \r\n \r\n The materials used in hollow brick construction do not differ dramatically \r\n from that of other masonry construction. ASTM standards dictate many \r\n of the physical properties of hollow brick units. More information \r\n on material properties and classification can be found in Technical \r\n Notes 3A and Technical Notes \r\n 9A , respectively. \r\n \r\n ASTM Standards \r\n \r\n Hollow brick should be specified to comply with ASTM C 652 Specification \r\n for Hollow Brick (Hollow Masonry Units Made From Clay or Shale). \r\n When it was first issued in 1970, ASTM C 652 covered units with \r\n void areas up to 40 percent. The standard has since been modified \r\n to allow void areas up to 60 percent of the units gross area. \r\n Grade. Two Grades exist in ASTM C 652: Grades SW and MW. \r\n The Grade establishes requirements to ensure adequate freeze/thaw \r\n resistance. Grade SW units provide high and uniform resistance to \r\n frost action while saturated with water. Grade MW units are intended \r\n for applications that are unlikely to be saturated with water when \r\n exposed to freezing temperatures. The physical property requirements \r\n are shown in Table 1. Two alternates exist in the standard to provide \r\n compliance with the durability requirements. These alternates include: \r\n a cold water absorption less than 8 percent and passing a 50 cycle \r\n freezing and thawing test. The freeze/thaw test only applies if \r\n the units do not meet the saturation coefficient and absorption \r\n requirements in Table 1. \r\n \r\n \r\n TABLE 1 \r\n ASTM C 652 Physical Property Requirements for Hollow \r\n Brick \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Unit in stretcher position with load applied \r\n perpendicular to bed surface. \r\n \r\n \r\n Class. \r\n The extent of void area of hollow brick is separated into two Classes: \r\n H40V and H60V. Brick with void areas greater than 25 percent but \r\n less than 40 percent of the units gross cross-sectional area are \r\n classified as Class H40V. Brick with void areas greater than 40 \r\n percent but less than 60 percent of the gross cross-sectional area \r\n are classified as Class H60V. Void areas may be cores, cells, deep \r\n frogs or combinations of these. A core is defined as a void having \r\n an area equal to or less than 1.5 in. 2 (9.7 cm 2 ), while cells are \r\n voids larger than a core. A deep frog is an indentation in the bed \r\n surface of the brick which is deeper than 3/8 in. (10 mm). \r\n \r\n Hollow Spaces - The thickness of face shells and \r\n webs are limited by ASTM C 652. Table 2 defines the nomenclature \r\n associated with hollow brick units and the minimum required thickness \r\n of face shells and cross webs. The dimensions of the unit and the \r\n configuration of its voids are critical for reinforced brick masonry. \r\n The cells intended to receive reinforcement must align so that reinforcing \r\n bars can be properly placed. Most Class H60V hollow brick contain \r\n two cells that are aligned when laid in running bond. Other bond \r\n patterns, such as one-third bond and bonds at corners may require \r\n different unit configurations to permit placement of reinforcement. \r\n It is advisable to check with the brick manufacturer to determine \r\n the coring patterns available. \r\n \r\n TABLE 2 \r\n ASTM C 652 Hollow Brick Section Properties \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Cores greater than 1.in 2 (650 mm 2 \r\n in cored shells shall be not less than 1/2 in. (13mm) for \r\n any edge. \r\n Coresnotgreater than 1 in. 2 (650mm 2 ) \r\n in shells cored not more than 35% shall be not less than \r\n 3/8 in. \r\n (10mm) from any edge. \r\n 2 The thickness of webs shall not be less than \r\n 1/2 in. (13mm) between cells, 3/8 in. (10mm) between cells \r\n and cores or 1/4 in. (6mm) between cores. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Type. \r\n Four Types of hollow brick are covered by ASTM C 652: Types HBS, HBX, \r\n HBA and HBB. Each of these Types relate to the appearance of the unit. \r\n Dimensional variation, chippage, warpage and other imperfections are \r\n qualifying conditions of Type. The most common type, Type HBS, is \r\n considered to be standard and is specified for most applications. \r\n Type HBX brick is specified where a higher degree of precision is \r\n required. Type HBA brick are unique units which are specified for \r\n non-uniformity in size or texture. Where a particular color, texture \r\n or uniformity is not required, Type HBB brick is specified. These \r\n applications are usually unexposed locations. \r\n \r\n Sizes and Shapes \r\n \r\n Hollow brick are generally larger than solid brick and are produced \r\n in a variety of sizes. Typical sizes and configurations are illustrated \r\n in Table 3. Units with larger face dimensions allow the mason to lay \r\n more exposed wall area per day. Such units, when compared to standard \r\n or modular size units, may increase the wall area completed per day \r\n by over 50 percent. However, there is a point of diminishing return \r\n as units get larger and heavier. \r\n Hollow brick are also made in a variety of special shapes. These \r\n may be for aesthetic reasons or for practical reasons. Special shapes \r\n include radial, bullnose, interior and exterior angled corner units \r\n and others. Bond beam units are often used to accept horizontal reinforcing \r\n bars. They may be specially made at the plant or cut on site. Fig. \r\n 2 is an example of a bond beam that was cut on site. It is best to \r\n check with the brick manufacturer for the availability of these special \r\n units. \r\n \r\n \r\n \r\n \r\n \r\n Hollow Brick Bond Beam \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n TABLE 3 \r\n Typical Nominal Brick Sizes \r\n \r\n \r\n \r\n \r\n \r\n \r\n Compressive Strength \r\n \r\n Compressive strength of hollow brick can be reported on a basis \r\n of either the gross cross-sectional area or the net cross-sectional \r\n area, depending on how the value is to be used. The gross area compressive \r\n strength is used to determine compliance with ASTM C 652 for purposes \r\n of durability. The net area compressive strength is needed for structural \r\n computations. \r\n A survey conducted in 1994 showed the range of compressive strength \r\n of hollow brick based on gross cross-sectional area is between 2,190 \r\n psi (15.1 MPa) and 12,795 psi (88.2 MPa), with an average compressive \r\n strength equal to 6,740 psi (46.5 MPa). \r\n \r\n PROPERTIES OF HOLLOW BRICK MASONRY \r\n \r\n Many designers are familiar with the design, construction and performance \r\n of masonry built with solid units. Hollow brick masonry is similar \r\n in many instances. Some of the more important performance requirements \r\n for hollow brick masonry are discussed. \r\n \r\n Structural Properties \r\n \r\n The structural design of hollow brick masonry is governed by the \r\n three model building codes and the ACI 530/ASCE 5/TMS 402 Building \r\n Code Requirements for Masonry Structures , also known as the \r\n Masonry Standards Joint Committee (MSJC) Code [1]. Hollow brick \r\n masonry can be designed by empirical requirements or by rational \r\n design procedures. Where appropriate, allowable stresses are different \r\n for hollow brick masonry and solid brick masonry. The following \r\n sections highlight some of the specific requirements for hollow \r\n brick units. \r\n Compressive Strength. The compressive strength of hollow \r\n brick walls depends on unit strength, mortar type, mortar bedding \r\n area, grouting and thicknesses of face shells and webs. The compressive \r\n strength of the masonry can be verified by testing prisms (prism \r\n test method) or from tabulated values based on brick strength and \r\n mortar type (unit strength method). Prism tests give more accurate \r\n values for compressive strength. Ungrouted prisms exhibit failure \r\n in compression by a splitting of the unit through the cross webs, \r\n as shown in Fig. 3. The splitting effect is due to the lateral expansion \r\n of the mortar. Filling the cells of hollow brick with grout will \r\n generally increase the masonrys capacity; however, the result is \r\n a decrease in the net area compressive strength. The strength of \r\n grouted hollow prisms is affected more by the tensile strength of \r\n the unit and a change in mortar strength [8]. \r\n \r\n \r\n \r\n \r\n \r\n Compression Failure of Ungrouted Hollow Brick Prism \r\n FIG. 3 \r\n \r\n \r\n \r\n The compressive strength of hollow brick masonry is based on the \r\n minimum net cross-sectional area. This is normally the net mortar \r\n bedded area (face shell bedding) and is used in structural calculations. \r\n When determining compliance of the specified compressive strength, \r\n the MSJC Code requires the units to be fully bedded in mortar. Fig. \r\n 4 shows various cross-sectional areas for hollow brick masonry. \r\n \r\n \r\n \r\n Hollow Brick Bond Beam \r\n FIG. 4 \r\n \r\n \r\n \r\n Values obtained from prism tests must be corrected based on the \r\n height-to-thickness (h/t) ratio of the prism. The h/t ratio provides \r\n a uniform basis for the determination of compressive strength. Hollow \r\n units are less sensitive to the h/t effects of slenderness than \r\n solid units. Codes stipulate the correction factors to use for hollow \r\n brick prisms. Past research has used an h/t of 5 as a basis, as \r\n do most current codes. However, an h/t of 2 is becoming more recognized, \r\n especially for larger hollow units. \r\n Research shows typical values of ungrouted hollow brick masonry \r\n compressive strength based on net area ranging from 3,470 psi (23.9 \r\n MPa) to 6,620 psi (45. 6 MPa). Figure 5 shows typical values of \r\n the net area compressive strength of grouted and ungrouted hollow \r\n brick masonry prisms from the research [3,8]. \r\n \r\n \r\n \r\n Net Area Compressive Strengths of Hollow Brick Prisms \r\n FIG. 5a \r\n \r\n \r\n \r\n \r\n \r\n Net Area Compressive Strengths of Hollow Brick Prisms \r\n FIG. 5b \r\n \r\n \r\n \r\n Flexural Strength. The flexural tensile strength of hollow brick masonry is influenced by \r\n mortar and unit configurations and the use of reinforcing steel. \r\n It has been found that hollow brick exhibits a lower flexural tensile \r\n strength than solid brick masonry laid with the same mortar. This \r\n is due to the relative thickness of the face shell bedded mortar \r\n joints and the rapid drying of the mortar before the hollow unit \r\n is laid. \r\n \r\n Reinforcement is grouted into hollow brick walls to increase the \r\n flexural strength, provide ductility and carry tension forces. The \r\n flexural strength of a hollow brick wall depends primarily on the \r\n amount of vertical reinforcement because the compressive strength \r\n is rarely the limiting factor. The reinforcement resists the flexural \r\n tension and the brickwork resists the flexural compression. Building \r\n codes may dictate a minimum amount of reinforcement for improved \r\n ductility in seismic regions. In reinforced masonry, the steel takes \r\n all of the tension forces and any tension in the masonry is neglected. \r\n \r\n Water Penetration \r\n \r\n The water penetration resistance of hollow brick masonry depends \r\n upon the materials and construction used. Most hollow brick walls \r\n are single-wythe walls and many are designed to act as barrier walls. \r\n Hollow brick walls are not impervious to water, so a secondary barrier \r\n to water must be used. Although the cells of the units may act as \r\n drainage spaces, they will not provide the excellent type of protection \r\n that a continuous drainage cavity provides. Hollow brick are usually \r\n face shell bedded; that is, only the face shells of the unit are \r\n mortared. This may not provide adequate resistance to wind-driven \r\n rain. \r\n Increased water penetration resistance may be obtained by requiring \r\n full head joints. In many cases the walls are grouted solid which \r\n helps the wall resist water penetration. Other methods used to increase \r\n the resistance to water include the incorporation of an internal \r\n drainage space in the wall or the application of a colorless coating. \r\n In cases where water penetration resistance is critical, a drainage \r\n space may be provided on the interior of the wall assembly, as shown \r\n in Fig. 6. The interior may be furred out with insulation and gypsum \r\n board attached. Flashing and weep holes are used to drain the space. \r\n Another precaution may be the use of a water-resistant membrane \r\n placed on the inside face of the wall. Waterproof membranes or polyethylene \r\n sheet have been used to resist water that has penetrated the hollow \r\n brick wall. Any puncture in the membrane must be properly sealed. \r\n \r\n \r\n \r\n \r\n Hollow Brick Wall Flashing \r\n FIG. 6a \r\n \r\n \r\n \r\n \r\n \r\n \r\n Hollow Brick Wall Flashing \r\n FIG. 6b \r\n \r\n \r\n \r\n \r\n \r\n \r\n Hollow Brick Wall Flashing \r\n FIG. 6c \r\n \r\n \r\n \r\n Flashing should be provided at the wall base, below and above all \r\n wall openings and at the tops of walls. Flashing and weep holes \r\n will collect water that enters the wall and direct it back to the \r\n exterior. Flashing is a bond break so the tensile strength of the \r\n wall at that location is zero. Also the shear stress will be reduced. \r\n The structural design of the buildings should address this issue \r\n appropriately. Flashing is necessary in all areas except where there \r\n is negligible rainfall. \r\n \r\n Another alternative to increase the water penetration resistance \r\n of a wall is the application of a clear water repellent on the exterior \r\n face of the wall. Water repellents will help deter moisture absorption. \r\n However, water repellents must be used with caution since they may \r\n cause problems in climates where freezing occurs. Other considerations \r\n include limited lifetime, trapping of efflorescence or stains behind \r\n the coating, reapplication and ineffectiveness on cracks in the wall. \r\n See Technical Notes 6A for more \r\n information on the appropriate use of clear water repellent coatings. \r\n \r\n Fire Resistance \r\n \r\n The excellent fire-resistant qualities of brick masonry are well \r\n known. However, there have been relatively few full-scale fire tests \r\n of hollow brick masonry walls. This is due in part to the acknowledgment \r\n that brick masonry is inherently fire resistant. Results from actual \r\n wall tests in accordance with ASTM E 119 are listed in Table 4 [5]. \r\n When a 5/8 in. (16 mm) thick layer of plaster is added to these \r\n walls, the fire rating may be increased by 1 hour. \r\n \r\n \r\n TABLE 4 \r\n Fire Ratings of Hollow Brick Walls 1 \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Adapted from Ref. 5 \r\n 2 Nominal wall thickness \r\n \r\n \r\n \r\n An alternative way of determining the fire resistance of a wall assembly \r\n is by the equivalent thickness method. This approach has been approved \r\n by the model building codes to determine fire ratings of walls not \r\n physically tested by ASTM E 119. The fire rating of hollow brick masonry \r\n is determined by its equivalent solid thickness. The equivalent thickness \r\n is calculated by subtracting the volume of core or cell spaces from \r\n the total gross volume of a brick unit and dividing by the exposed \r\n face area of the unit. Technical Notes 16B \r\n explains the procedures for determining a hollow bricks equivalent \r\n thickness and the calculated fire resistance of various hollow brick \r\n masonry walls. \r\n \r\n Sound Resistance \r\n \r\n Because sound resistance improves with increasing wall weight, \r\n hollow brick masonry provides very good sound penetration resistance. \r\n The Sound Transmission Class (STC) rating is used to determine the \r\n sound insulation of walls. Tests on units similar to hollow clay \r\n brick (structural clay tile) ranged from an STC of 39 for a 4 in. \r\n (100 mm) structural clay tile wall, to an STC of 45 for an 8 in. \r\n (200 mm) structural clay tile wall. Assumed values of STC ratings \r\n can be determined from an equation based on existing test data. \r\n The following equation could be used to estimate an STC rating when \r\n existing tests are not available [6]. \r\n STC = 0.17W + 40 \r\n The STC rating is a function of the weight of the wall, w, which \r\n is expressed in pcf. This equation is a best fit to a curve based \r\n on the average of the data. \r\n \r\n CONSTRUCTION REQUIREMENTS \r\n Mortar Bedding \r\n \r\n Since hollow brick have large voids, units are laid with face shell \r\n bedding. Face shell bedding consists of mortar coverage on the inner \r\n and outer face shells of the unit. Cross webs or end webs of the \r\n unit may require mortar bedding when grout must be confined within \r\n certain cells of partially grouted masonry or on the first course \r\n of brickwork. \r\n \r\n Grouting \r\n \r\n Grout is a highly fluid mixture used to fill the cells of units. \r\n Grout should conform to ASTM C 476 Specification for Grout for Masonry. \r\n The proportion specification is recommended for grout in hollow \r\n brick. The use of fine grout and coarse grout is limited by the \r\n size of the space to be grouted. See Table 5. Spaces smaller than \r\n these listed in Table 5 will not be fully filled due to congestion \r\n in the space. \r\n Walls can be ungrouted, fully grouted or partially grouted. This \r\n depends on the design of the wall. In some cases, only those cells \r\n containing reinforcement are grouted. However, as the spacing of \r\n the reinforcement becomes less than about 30 in. (760 mm), it becomes \r\n more economical to grout the entire wall. \r\n Brick masonry absorbs water from the grout, resulting in considerable \r\n shrinkage of the grout. Although consolidation of the grout is required, \r\n it may not compensate for all of the shrinkage. Therefore, a non-shrink \r\n grout admixture is recommended [7]. \r\n Prior to grouting, the cells of the hollow units should be cleared \r\n of mortar protrusions and blockage to allow uninterrupted flow of \r\n the grout. This may be done during construction with a sponge or \r\n after construction with a rod to knock down hardened mortar protrusions. \r\n A clear grout space allows the required clearances and intimate \r\n contact between grout, masonry units and steel reinforcement. The \r\n height to which grout is placed in one operation is limited by the \r\n size of the cells to be grouted, as shown in Table 5. Grouting after \r\n the wall has been constructed, often referred to as high-lift grouting, \r\n is more difficult the smaller the cells are in size. After grout \r\n is placed, and before it loses its plasticity, the grout should \r\n be consolidated to completely fill all spaces designed to receive \r\n grout. Grout pour heights greater than 12 in. (300 mm) are typically \r\n reconsolidated by mechanical vibration after initial water loss \r\n and settlement has occurred. \r\n \r\n \r\n TABLE 5 \r\n Grout Space Requirements \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1Grout space dimension is the clear dimension between any \r\n masonry protrusion and shall be increased by the diameters \r\n of the horizontal bars within the cross section of the grout \r\n space. Area of reinforcement shall not exceed 6 percent \r\n of the area of the grout space. \r\n \r\n \r\n Cleanouts \r\n \r\n Cleanouts are required when grout pours exceed 5 ft (1.5 m) in \r\n height. Cleanouts are typically made by removing face shells of \r\n units in the bottom course of spaces to be grouted. These cleanouts \r\n allow removal of mortar droppings that have collected at the bottom \r\n of a cell. Once the cleanouts have been cleared of debris, the face \r\n shell of the unit can be replaced. The face shell can be cut to \r\n form a wedge so that the grout pressure will hold it in place. The \r\n replaced face shell may require additional bracing against the hydrostatic \r\n pressure of the grout to avoid blowing out the face shell. \r\n \r\n Reinforcement \r\n \r\n Although reinforcement is not always used in hollow brick masonry, \r\n the large cells allow the units to be easily reinforced and grouted. \r\n The reinforcing must be embedded in grout, not mortar. The maximum \r\n bar size permitted by code for masonry is a No. 11 bar. The size \r\n of the reinforcement is often limited by the size of the space to \r\n be grouted and the need for adequate cover. A recommended rule-of-thumb \r\n is that the maximum bar size should equal the nominal unit thickness. \r\n For example, the maximum bar size for nominal 6 in. (150 mm) hollow \r\n brick is a No. 6 bar. \r\n Reinforcement is placed prior to grouting. The reinforcement must \r\n be accurately positioned in the wall as designed. Reinforcing is \r\n most often positioned in the center of the wall, but may be placed \r\n to one side to maximize the distance from the compression face. \r\n The reinforcement should be spaced to coincide with the spacing \r\n of the cells of the hollow brick. Spacing is typically in increments \r\n of 4 in. (100 mm) or 6 in. (150 mm). Reinforcement is sometimes \r\n held in place by the use of positioners or chairs. Positioners are \r\n typically placed horizontally, no more than 200 bar diameters apart. \r\n Splices in reinforcement must be in accordance with building code \r\n requirements. Splices are most often achieved by lapping the discontinuous \r\n ends of the bars by a certain minimum number of bar diameters. Mechanical \r\n devices and butt welding of reinforcing is also permitted to provide \r\n continuity. \r\n \r\n CONCLUSION \r\n \r\n This Technical Notes provides a discussion of the classification \r\n and use of hollow brick. Various properties of hollow brick masonry \r\n are described. Design, material and construction requirements are \r\n provided as a basis for good masonry performance. \r\n The information and suggestions contained in this Technical \r\n Notes are based on the available data and the experience of \r\n the engineering staff of the Brick Institute of America. The information \r\n contained herein must be used in conjunction with good technical \r\n judgment and a basic understanding of the properties of brick masonry. \r\n Final decisions on the use of the information contained in this \r\n Technical Notes are not within the purview of the \r\n Brick Institute of America and must rest with the project architect, \r\n engineer and owner. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. ACI \r\n 530/ASCE 5/TMS 402-95, Building Code Requirements for Masonry \r\n Structures , ACI 530.1/ASCE 6/TMS 602-95, Specifications \r\n for Masonry Structures , American Concrete Institute, Detroit, \r\n MI, 1995. \r\n 2. Amrhein, \r\n J.E., Reinforcing Steel in Masonry , Masonry Institute of \r\n America, Los Angeles, CA, 1991. \r\n 3. Brown, \r\n R.H. and Borchelt, J.G., \"Compression Tests of Hollow Brick Units \r\n and Prisms\", Masonry: Components to Assemblages , ASTM STP \r\n 1063, J.H. Matthys, Ed., ASTM, Philadelphia, PA, 1990. \r\n 4. Commentary \r\n to Chapter 21, Masonry, of the 1994 Uniform Building Code , The Masonry Society, Boulder, CO, 1995. \r\n \r\n 5. \"Fire \r\n Resistance\", Technical Notes 16 \r\n Revised, Brick Institute of America, May 1987. \r\n \r\n 6. Grimm, \r\n C.T., Acoustical Properties of Masonry Walls , Construction \r\n Specifier, March 1993, pp. 78-82. \r\n 7. Kingsley, \r\n G. R., Tulin, L. G., and Noland, J. L ., \"Parameters Influencing \r\n the Quality of Grout in Hollow Clay Masonry\" , 7th International \r\n Brick Masonry Conference, Melbourne, Australia, 1985, pp. 1085-1092. \r\n 8. Whitlock, \r\n A.R. and Brown, R.H., \"Compressive Strength of Grouted Hollow \r\n Brick Prisms\" , Masonry: Materials, Properties, and Performance , \r\n ASTM STP 778, J.G. Borchelt, Ed., ASTM, Philadelphia, PA, 1982, \r\n pp. 99-117. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60117,"ResultID":176349,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 42 - Empirical Design \r\n of Brick Masonry \r\n November 1991 \r\n \r\n Abstract : This Technical Notes provides requirements for \r\n the empirical design of masonry structures. These requirements are \r\n based on past proven performance. The provisions are taken from ACI \r\n 530-92/ASCE 5-92, \"Building Code Requirements for Masonry Structures\", \r\n Chapter 9. Subjects discussed pertaining to ACI 530/ASCE 5 are: lateral \r\n stability; allowable stresses; lateral support; thickness of masonry; \r\n bonding; anchorage and miscellaneous requirements. Seismic considerations \r\n and material requirements are also included. \r\n Key Words : brick, building codes, \r\n design standards, empirical design, masonry, stresses. \r\n INTRODUCTION \r\n Empirical design is a procedure for sizing \r\n and proportioning masonry elements to form an entire structure or \r\n parts of a structure. Empirical design does not require a rational \r\n analysis. It is based on rules of thumb and formulas developed over \r\n many years of experience. This design method has been used successfully \r\n for many decades. \r\n Empirical design is generally used for buildings \r\n of a small scale nature. The basic premise is that masonry walls are \r\n incorporated into two directions of the building along with floor \r\n and roof systems for lateral support. \r\n Chapter 9 of ACI 530-92/ASCE 5-92 is devoted \r\n solely to empirical design procedures. The provisions of earlier empirical \r\n standards have been modified to reflect contemporary construction \r\n materials and methods. Many requirements remain the same as earlier \r\n standards but new restrictions have been added to reflect recent developments. \r\n The current model building codes contain \r\n requirements for empirical design of masonry. Until the development \r\n of ACI 530/ASCE 5, most of the model building code empirical design \r\n procedures were based on the ANSI A41.1 (R1970) document which has \r\n been discontinued. \r\n It is the purpose of this Technical Notes \r\n to review many of the pertinent design and construction requirements \r\n included in Chapter 9 of ACI 530/ASCE 5. In this Technical Notes, \r\n sections of ACI 530/ASCE 5 referenced are given in parenthesis. \r\n SCOPE (9.1) \r\n Chapter 9 of ACI 530/ASCE 5 covers empirical \r\n design criteria which can be used for masonry components and masonry \r\n buildings in lieu of the design requirements in Chapters 5, 6, 7 and \r\n 8. Chapters 5 through 8 contain a rational design for masonry based \r\n on the working stress method. The scope of Chapter 9 has three basic \r\n restrictions that have not been incorporated in other previous empirical \r\n procedures: 1) buildings cannot be located in Seismic Zones 3 and \r\n 4 as defined in ASCE 7-88, \"Minimum Design Loads for Buildings and \r\n Other Structures\" (formerly referred to as ANSI A58.1); 2) lateral \r\n load forces, i.e. wind loads, are restricted to a maximum of 25 psf \r\n (1.2 kPa) as referenced in ASCE 7; 3) buildings relying on masonry \r\n walls for lateral load resistance cannot exceed 35 ft (10.7 mm) in \r\n height. \r\n Chapter 9 permits empirical design of masonry \r\n elements not acting as a portion of the lateral force resisting system \r\n even though the main lateral force resisting system is rationally \r\n designed by other chapters contained in ACI 530/ASCE 5. Further, Chapter \r\n 9 can be used to design masonry elements in frame structures. \r\n DESIGN \r\n Consideration of lateral stability and lateral \r\n support are of prime importance in empirical design. Compressive stresses, \r\n thickness of masonry, bonding and anchorage requirements are incorporated \r\n in this design methodology. \r\n Lateral Stability (9.3) \r\n Shear walls are necessary when lateral support \r\n is provided by masonry construction. Shear walls must be provided \r\n in two directions, parallel and perpendicular to the assumed direction \r\n of the lateral load resisted. The minimum cumulative length of shear \r\n walls in any one direction must be at least 40 percent of the long \r\n dimension of the building. Portions of walls with openings cannot \r\n be included when determining the cumulative length of shear walls. \r\n BIA recommends that the cumulative length of shear walls include only \r\n wall lengths greater than or equal to one-half the story height of \r\n the building. Bearing walls are permitted to serve as shear walls. \r\n Shear walls must be a minimum nominal thickness of 8 in. (200 mm). \r\n Figure 1 provides an example calculation to determine the cumulative \r\n shear wall length. \r\n \r\n \r\n \r\n \r\n \r\n MINIMUM CUMULATIVE LENGTH OF SHEAR WALLS \r\n = 0.4 X LONG DIMENSION \r\n MINIMUM CUMULATIVE LENGTH = 0.4 X 36 \r\n FT = 14.4 FT \r\n X-DIRECTION = 2 ( 6 + 6 + 6 + 6 ) = \r\n 48 FT > 14.4 FT OK \r\n Y-DIRECTION = 2 ( 24 + 10 +10 ) = 88 \r\n FT > 14.4 FT OK \r\n \r\n \r\n \r\n Cumulative Length of Shear Walls \r\n FIG. 1 \r\n \r\n Shear wall spacing requirements are based \r\n on the type of floor or roof construction used in the building under \r\n consideration. When using stiffer elements such as cast-in-place concrete \r\n floors, the shear wall spacings are greater. Table 1 provides the \r\n maximum ratio of shear wall spacing to shear wall length based on \r\n the type of floor or roof construction. \r\n \r\n \r\n \r\n \r\n \r\n Allowable Stresses (9.4) \r\n Allowable compressive stresses permitted \r\n in Chapter 9 are given in Table 2. Compressive stress calculations \r\n are based on gross area, not minimum net area as is the case in the \r\n rational analysis chapters of ACI 530/ASCE 5. Gross area is based \r\n on the actual dimensions of the masonry unit under consideration. \r\n When multi-wythe walls are used in construction, the allowable stress \r\n taken from Table 2 should be based on the weakest combination of the \r\n unit and mortar used for each wythe. \r\n The allowable stresses in Table 2 are considered \r\n as allowable average stresses, not maximum fiber stresses. These allowable \r\n stresses only pertain to vertically applied loads reasonably centered \r\n on the wall. Any influence of an eccentrically applied load is limited \r\n by the minimum wall thickness and maximum lateral support requirements. \r\n \r\n \r\n \r\n \r\n 1 Linear interpolation for determining \r\n allowable stresses for masonry units having compressive strengths \r\n which are intermediate between those given in the table is permitted \r\n 2 1 psi = 6.9 kPa \r\n 3 Where floor and roof loads \r\n are carried upon one wythe, the gross cross-sectional area is that \r\n of the wythe under load; if both wythes are loaded, the gross cross-sectional \r\n area is that of the wall minus the area of the cavity between the \r\n wythes. Walls bonded with metal ties shall be considered as non-composite \r\n walls unless collar joints are filled with mortar or grout. \r\n Lateral Support (9.5) \r\n Chapter 9 contains arbitrary limits on the \r\n ratios of wall thickness to distance between lateral supports. These \r\n limits provide controls on the flexural tension stresses within the \r\n wall and limit possible buckling under compressive stresses. Maximum \r\n h/t or l/t ratios and minimum thickness used for determining distance \r\n between lateral supports are consistent with past masonry standards. \r\n Definitions for height (h), length (l) and thickness (t) for use in \r\n the allowable lateral support ratios are as follows: h = the vertical \r\n distance or height between lateral supports; I = the horizontal distance \r\n or length between lateral supports: and t = the nominal thickness \r\n of the masonry wall under consideration. ACI 530/ASCE 5 does not provide \r\n guidance for computing the thickness of masonry bonded hollow walls \r\n or cavity walls bonded with metal ties. BIA suggests that the value \r\n for thickness be the sum of the nominal thicknesses of the inner and \r\n outer wythes. \r\n Masonry walls should be laterally supported \r\n in either the horizontal or vertical direction at intervals not exceeding \r\n those given in Table 3. Lateral support should be provided by cross \r\n walls, pilasters, buttresses or structural frame members when the \r\n limiting distance is taken horizontally. Floors, roofs or structural \r\n frame members should be used when the limiting distance is taken vertically \r\n (see Fig. 2). \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Lateral Support Requirements \r\n FIG. 2 \r\n \r\n Cantilever type walls also have a minimum \r\n lateral support criteria. The h/t ratio for cantilever walls should \r\n not exceed 6 for solid masonry walls nor 4 for hollow masonry walls. \r\n Thickness of Masonry (9.6) \r\n Empirical design requirements pertaining \r\n to the thickness of bearing walls and foundation walls are found in \r\n Section 9.6. Masonry walls must conform to thickness requirements \r\n as well as lateral support and allowable stress requirements. Thicknesses \r\n given are nominal dimensions. These requirements are more conservative \r\n than empirical design criteria in previous masonry standards. \r\n Bearing Walls . The minimum thickness \r\n of masonry bearing walls more than one story in height must be 8 in. \r\n (200 mm). Bearing walls of one story buildings may be reduced to 6 \r\n in. (150 mm). The height to thickness limitation in Table 3 requires \r\n a wall of 6 in. (150 mm) in thickness to have a maximum height of \r\n 10 ft (3.1 m) \r\n Specific provisions are incorporated due \r\n to a change in wall thickness between floor levels or floor and roof \r\n levels. If a change in wall thickness between floors or between floor \r\n and roof levels is desired, the greater wall thickness must extend \r\n to the lower support level. Wall thicknesses may be changed to meet \r\n fire, sound or thermal requirements. Where walls of hollow masonry \r\n units or masonry bonded hollow walls are decreased in thickness, a \r\n course or courses of solid masonry should be constructed between the \r\n thicker wall below and the thinner wall above. Special units or construction \r\n are permitted to be used as long as the loads from face shells or \r\n wythes of masonry above are transmitted to the wall system below. \r\n Foundation Walls . Foundation walls \r\n have empirical thickness requirements which are shown in Table 4. \r\n Foundation walls must be constructed of either Type M or S mortar. \r\n The height of unbalanced fill (height of finished ground above the \r\n basement floor or inside ground level) and the height of the wall \r\n between lateral supports must not exceed 8 ft (2.4 m), and the equivalent \r\n fluid weight of unbalanced fill must not exceed 30 pcf (480.5 kg/m 3 ). \r\n Most well-drained sand and gravel backfills have an equivalent fluid \r\n weight of less than 30 pcf (480.5 kg/m 3 ). When these conditions are not met, foundation walls must be designed \r\n in accordance with Chapters 5 and 6 or 5 and 7 of ACI 530/ASCE 5. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 1 in = 25.4 mm \r\n 2 1 ft = 0.3048 \r\n \r\n \r\n \r\n \r\n Parapets . Parapets are required to \r\n have a minimum thickness of at least 8 in. (200 mm). Their height \r\n cannot exceed three timed their thickness. \r\n Bonding (9.7) \r\n Multi-wythe masonry walls may be bonded \r\n together by either masonry headers or metal wall ties. Limitations \r\n on the area and spacing of masonry headers or metal ties for both \r\n solid and hollow units are contained in Chapter 9 of the code. \r\n Masonry headers are typically used when \r\n bonding barrier type walls (walls of solid units built without air \r\n spaces) or hollow walls composed of solid masonry units. Metal ties \r\n can be used for barrier type walls (with grouted collar joints) and \r\n drainage type walls (a clear air space between wythes of masonry). \r\n The necessary requirements for bonding multi-wythe \r\n walls with masonry headers is shown in Fig. 3. Masonry headers of \r\n solid units must comprise not less than 4 percent of wall surface \r\n area and extend at least 3 in. (75 mm) into each wythe. The distance \r\n between adjacent full-length headers should not exceed 24 in. (610 \r\n mm) horizontally or vertically along the wall surface. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Multi-Wythe Bond With Masonry Headers \r\n FIG. 3 \r\n \r\n Two options exist when bonding multi-wythe \r\n walls with metal ties, the use of unit metal ties and the use of prefabricated \r\n horizontal joint reinforcement. When using unit metal ties, such as \r\n Z-ties or rectangular ties (box ties), one tie must be provided for \r\n each 4 1/2 ft 2 \r\n (0.42 m 2 ) of wall area. Ties should be at least 3/16 in. (4.76 mm) in diameter \r\n and be corrosion resistant. The maximum vertical distance between \r\n ties should not exceed 24 in. (610 mm), and the maximum horizontal \r\n distance should not exceed 36 in. (914 mm). Z-ties may not be used \r\n with hollow masonry units. Additional metal ties should be provided \r\n at all openings, spaced not more than 3 ft (0.91 m) apart around the \r\n perimeter and within 12 in. (300 mm) of the opening. These provisions \r\n are similar to those for cavity wall construction. \r\n When bonding multi-wythe walls with horizontal \r\n joint reinforcement, there should be one crosswire metal tie for each \r\n 2 2/3 ft 2 \r\n (0.25 m 2 ) of wall area. The vertical spacing should not exceed 16 in. (400 mm). \r\n Crosswires should not be smaller than No. 9 gage wire (W 1.7) and \r\n be corrosion resistant. \r\n Pattern Bond . Masonry walls can be \r\n laid in either running or stack bond. Running bond is defined by each \r\n wythe of masonry head joints in successive courses being offset by \r\n at least one-quarter the unit length (see Fig. 4). It is considered \r\n stack bond if the longitudinal bond is offset less than one-quarter \r\n the unit length, and horizontal joint reinforcement or bond beams \r\n with a maximum spacing of 4 ft (1.2 m) vertically with a minimum area \r\n of steel equal to 0.0003 times the vertical cross-sectional area of \r\n the wall must be provided. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Typical Foundation Details \r\n FIG. 4 \r\n \r\n Anchorage (9.8) \r\n Masonry elements must be anchored to various \r\n components of the building which provide lateral support when using \r\n empirical design. Anchorage must occur at intersecting walls, at floors \r\n and roofs which adjoin masonry walls and where masonry walls abut \r\n structural framing. Anchorage requirements for masonry walls contained \r\n in ACI 530/ASCE 5 are as follows: \r\n \"9.8.2 Intersecting walls - \r\n Masonry walls depending upon one another for lateral support shall \r\n be anchored or bonded at locations where they meet or intersect by \r\n one of the following methods: \r\n 9.8.2.1 Fifty percent of the units \r\n at the intersection shall be laid in an overlapping masonry bonding \r\n pattern, with alternate units having a bearing of not less than \r\n 3 in. (75 mm) on the unit below. \r\n 9.8.2.2 Walls should be anchored by \r\n steel connectors having a minimum section of 1/4 in. (6.4 mm) by \r\n 1 1/2 in. (38.1 mm) with ends bent up at least 2 in. (50 mm) or \r\n with cross pins to form anchorage. Such anchors shall be at least \r\n 24 in. (600 mm) long and the maximum spacing shall be 4 ft (1.22 \r\n m). \r\n 9.8.2.3 Walls shall be anchored by \r\n joint reinforcement spaced at a maximum distance of 8 in. (200 mm). \r\n Longitudinal rods of such reinforcement shall be at least 9 gage \r\n (W 1. 7) and shall extend at least 30 in. (762 mm) in each direction \r\n at the intersection. \r\n 9.8.2.4 Interior non-loadbearing walls \r\n shall be anchored at their intersection, at vertical intervals of \r\n not more than 16 in. (400 mm) with joint reinforcement or 1/4 in. \r\n (6.4 mm) mesh galvanized hardware cloth. \r\n 9.8.2.5 Other metal ties, joint reinforcement \r\n or anchors, if used, shall be spaced to provide equivalent area \r\n of anchorage to that required by this section. \r\n 9.8.3 Floor and roof anchorage - Floor \r\n and roof diaphragms providing lateral support to masonry shall be \r\n connected to the masonry by one of the following methods: \r\n 9.8.3.1 Wood floor joists bearing on \r\n masonry walls shall be anchored to the wall at intervals not to \r\n exceed 6 ft (1.8 m) by metal strap anchors. Joists parallel to the \r\n wall shall be anchored with metal straps spaced not more than 6 \r\n ft (1.8 m) on centers extending over or under and secured to at \r\n least 3 joists. Blocking shall be provided between joists at each \r\n strap anchor. \r\n 9.8.3.2 Steel floor joists shall be \r\n anchored to masonry walls with 3/8 in. (9.5 mm) round bars, \r\n or their equivalent, spaced not more than 6 ft (1.8 m) on center. \r\n Where joists are parallel to the wall, anchors shall be located \r\n at joists cross bridging. \r\n 9.8.3.3 Roof structures shall be anchored \r\n to masonry walls with 1/2 in. (12.7 mm) bolts 6 ft (1.8 m) on center \r\n or their equivalent. Bolts shall extend and be embedded at least \r\n 15 in. (381 mm) into the masonry, or be hooked or welded to not \r\n less than 0.20 in 2 (129 mm 2 ) \r\n of bond beam reinforcement placed not less than 6 in. (150 mm) from \r\n the top of the wall. \r\n \r\n 9.8.4 Walls adjoining structural framing \r\n - Where walls are dependent upon the structural frame for lateral \r\n support they shall be anchored to the structural members with metal \r\n anchors or otherwise keyed to the structural members. Metal anchors \r\n shall consist of 1/2 in. (12. 7 mm) bolts spaced at 4 ft (1.2 m) \r\n on center embedded 4 in. (100 mm) into the masonry, or their equivalent \r\n area. \" \r\n \r\n Miscellaneous Requirements (9.9) \r\n General limitations for masonry structures \r\n such as masonry over chases and recesses, lintels over openings, noncombustible \r\n supports for masonry walls and corbeling have empirical requirements \r\n for proper design and construction. \r\n Chases and recesses in masonry walls are \r\n sometimes used for visual effects or to receive pipes, conduits or \r\n ducts. When chases or recesses are wider than 12 in. (300 mm), the \r\n masonry above the chase must be supported by noncombustible lintels, \r\n which could be steel angle lintels or reinforced brick masonry lintels. \r\n The design of lintels must be in accordance \r\n with Section 5.6 which stipulates that the deflection of lintels due \r\n to vertical loads should not exceed the span divided by 600 nor 0.3 \r\n in. (7.6 mm) when supporting unreinforced masonry. Minimum bearing \r\n for lintels is 4 in. (100 mm) on each end of the masonry opening. \r\n Masonry is not permitted to be supported \r\n by combustible construction, i.e. wood. Even though wood construction \r\n may meet the deflection requirements for lintels, this restriction \r\n is a fire safety requirement. \r\n Corbeling limitations are the same as those \r\n required by the model building codes used throughout the country. \r\n The maximum corbeled projection beyond the plane of the wall should \r\n not be more than one-half of the wall thickness or one-half the wythe \r\n thickness for hollow walls. The maximum projection of any single course \r\n of masonry should not exceed one-half the unit height or one-third \r\n the unit thickness. Solid units are required for corbeled courses \r\n of Masonry. Figure 5 illustrates these criteria for corbeling masonry. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Corbeling Limitations \r\n FIG. 5 \r\n \r\n Seismic Considerations for Empirically \r\n Designed Masonry \r\n Appendix A of ACI 530/ASCE 5 contains special \r\n requirements for masonry in seismic zones as specified in ASCE 7 (formerly \r\n ANSI A58.1). The provisions of Chapter 9 on empirical design of masonry \r\n may be used in Seismic Zones 0, 1 and 2, and are modified by Appendix \r\n A. Empirical design cannot be used in buildings located in Seismic \r\n Zones 3 and 4. \r\n For Seismic Zones 0 and 1, all provisions \r\n of Chapter 9 apply without modification. There are no restrictions \r\n on materials or design methods since these areas of the country represent \r\n low seismic risk. \r\n Masonry elements in Seismic Zone 2 must \r\n meet more stringent requirements. Connections are strengthened and \r\n minimum vertical and horizontal reinforcement is required in order \r\n to provide more ductility in the structure. All materials also are \r\n permitted to be used in the structure. \r\n Seismic requirements for buildings or structures \r\n in Seismic Zone 2 as contained in Appendix A are as follows: \r\n \r\n \"A.3.5 Veneer and units not specifically \r\n intended for structural use shall not be designed to resist loads \r\n other than their own weight or their own shear loads. \r\n A.3.6 Masonry walls shall be anchored \r\n to all floors and roofs which provide lateral support for the walls. \r\n Such anchorage shall provide direct connection capable of resisting \r\n horizontal forces required in Section 5.2 or a minimum of 200 lb \r\n (90.9 kg) per lineal foot (meter) of wall, whichever is greater. \r\n Walls shall be designed to resist bending between anchors where \r\n anchor spacing exceeds 4 ft (1.2 m). Anchors in masonry walls shall \r\n be embedded in reinforced bond beams or reinforced vertical cells. \r\n A.3.7 Structural members framing into \r\n or supported by masonry columns shall be anchored thereto. Anchor \r\n bolts located in the tops of columns shall be set entirely within \r\n the reinforcing cage composed of column bars and lateral ties. A \r\n minimum of two #4 lateral ties shall be provided in the top 5 in. \r\n (127 mm) of the column. Welded or mechanical connections for reinforcing \r\n bars in tension shall develop 125 percent of the yield strength \r\n of the bars in tension. \r\n A.3.8 Vertical reinforcement of at \r\n least 0.20 in. 2 (129 mm 2 ) in cross-sectional area shall be provided continuously \r\n from support to support at each corner, at each side of each opening \r\n and at the ends of walls. Horizontal reinforcement not less than \r\n 0.20 in. 2 (129 mm 2 ) \r\n in cross section area shall be provided: (1) at the bottom and \r\n top of wall openings and shall extend not less than 24 in. (610 \r\n mm) nor less than 40 bar diameters past the opening, (2) continuously \r\n at structurally connected roof and floor levels and at the top of \r\n walls, (3) at the bottom of the wall or in the top of the foundations \r\n when doweled to the wall, (4) at maximum spacing of 10 ft (3.1 m) \r\n unless uniformly distributed joint reinforcement is provided. Reinforcement \r\n at the top and bottom openings when used in determining the maximum \r\n spacing specified in Item No. (4) above shall be continuous in the \r\n wall. \" \r\n \r\n Minimum reinforcement requirements are shown \r\n in Fig. 6. \r\n \r\n \r\n \r\n \r\n \r\n Minimum Reinforcement Requirements for Seismic Zone 2 \r\n FIG. 6 \r\n \r\n \r\n \"A.3.9 Where head joints in successive \r\n courses are horizontally offset less than one-quarter of the unit \r\n length, the minimum horizontal reinforcement shall be 0.0007 times \r\n the gross cross-sectional area of the wall. This reinforcement shall \r\n be satisfied with uniformly distributed joint reinforcement or with \r\n horizontal reinforcement spaced not over 4 ft (1.2 m) and fully \r\n embedded in grout or mortar \" \r\n \r\n MATERIALS AND CONSTRUCTION \r\n General \r\n The provisions of ACI 530.1-92/ASCE 6-92, \r\n \"Specifications for Masonry Structures\" have minimum material and \r\n construction requirements for masonry structures designed in accordance \r\n with Chapter 9 empirical provisions. Masonry units, mortar, grout, \r\n reinforcement and accessories are included. This document should be \r\n referenced in the project specifications and can be modified as required \r\n for the particular project. \r\n Masonry Units \r\n The products section permits the use of \r\n clay brick, concrete masonry units and stone masonry in empirically \r\n designed masonry structures. ASTM standards for clay or shale masonry \r\n covered by ACI 530.1/ASCE 6 are ASTM C 34, C 56, C 126, C 212, C 216 \r\n and C 652. Grade or class of the units to be used in construction \r\n are determined by exposure conditions and required durability. For \r\n further information on the manufacture, designation and selection \r\n of clay masonry units, see Technical Notes 9 Series. \r\n Mortar and Grout \r\n Mortar is required to conform to ASTM C \r\n 270 Mortar for Unit Masonry. When job site pigments are used to color \r\n mortar there are maximum percentages of color pigment by weight of \r\n the cement content which can be added. For portland cement-lime mortars, \r\n the maximum content of the coloring pigment is limited to 10 percent \r\n for mineral oxide pigments and 2 percent for carbon black. If masonry \r\n cements are used, the percentage by weight for color pigments are \r\n halved. \r\n Grout is required to conform to ASTM C 476 \r\n Grout for Unit Masonry. This is a proportion specification for either \r\n fine or coarse grout used in construction. \r\n Reinforcement and Accessories \r\n ACI 530.1/ASCE 6 contains provisions for \r\n reinforcement and metal accessories. All reinforcement and metal accessories \r\n are required to be corrosion resistant. Procedures described represent \r\n current construction practices and are consistent with model building \r\n codes now in existence. Topics that are covered are ASTM standards \r\n for the materials, inspection, and detailing and placement of reinforcement \r\n and accessories which include tolerances. \r\n Corrosion Resistance . Conventional \r\n corrosion protection methods attempt to protect metals embedded in \r\n masonry by isolating them with impervious coatings, by using metals \r\n that are corrosion resistant or by providing cathodic protection. \r\n ACI 530.1/ASCE 6 provides requirements for corrosion protection for \r\n carbon steel by galvanized coatings. The amount of galvanizing required \r\n increases with the severity in exposure of the masonry wall. Anchors, \r\n ties and joint reinforcement must meet minimum corrosion protection \r\n requirements. Table 5 shows the minimum corrosion protection requirements \r\n needed for metal accessories used in masonry walls. \r\n \r\n \r\n \r\n Construction \r\n Construction requirements within ACI 530.1/ASCE \r\n 6 cover the conventional construction practices used in projects that \r\n involve empirically designed masonry. The provisions are similar to \r\n those found in the model building codes. The basic premise under the \r\n construction requirements is to ensure proper placement of materials. \r\n Mortar joint filling depends on the type of unit used in construction. \r\n Solid units have full head and bed joints. Hollow units are laid with \r\n face shell bedding. Requirements include tolerances for erection, \r\n collar joints and placement of embedded items such as wall ties and \r\n reinforcement. Grout placement is also covered. \r\n SUMMARY \r\n This Technical Notes reviews empirical \r\n design procedures contained in ACI 530/ASCE 5. The discussion centers \r\n on the requirements which are needed by engineers and architects to \r\n fully understand the empirical design of masonry structures within \r\n the limits of Chapter 9. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the engineering staff of the Brick Institute of \r\n America. The information contained in this publication must be used \r\n with good technical judgment. Final decisions on the use of materials \r\n and suggestions contained herein are not within the purview of the \r\n Brick Institute of America and must rest with the project architect, \r\n engineer and owner. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60118,"ResultID":176350,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 43 - Passive Solar Heating \r\n with Brick Masonry - Part 1 Introduction \r\n June 1981 \r\n \r\n Abstract : Brick masonry passive solar energy systems can be used to \r\n significantly reduce the use of fossil fuels for heating and cooling buildings. \r\n The basic concepts and necessary considerations for the design of passive \r\n solar heating systems are discussed. The basic concepts involve the incorporation \r\n of the passive solar heating system into the architectural design of the \r\n intended use and operation of the building. Consideration of environmental \r\n factors is also discussed. \r\n Key Words : attached sunspaces, bricks , \r\n buildings, cavity wall systems, climatology, conservation, direct gain \r\n systems, energy, masonry, passive solar heating systems , \r\n solar radiation, system operation, thermal storage walls. \r\n INTRODUCTION \r\n Energy conservation and fuel consumption have \r\n become a major concern in recent years. Much of the nations fuel is used \r\n in the heating of buildings. The use of solar heating systems will help \r\n to reduce this consumption of non-renewable energy resources. Solar energy \r\n is an immediately available renewable energy source. Most buildings can \r\n easily be designed to benefit from solar heating. \r\n Two types of solar energy systems may be used \r\n to heat buildings, active and passive. Active solar heating systems are \r\n those which require mechanical equipment for operation. Pumps and other \r\n mechanical devices are required to circulate liquids or gases through \r\n solar collectors, to storage media, and then to transfer the collected \r\n heat to the occupied spaces of the building. \r\n Passive solar heating systems do not require \r\n the use of mechanical equipment. The heat flow in passive solar heating \r\n systems is by natural means: radiation, convection, and conductance. The \r\n thermal storage is in the structure itself. Although passive solar heating \r\n systems do not require mechanical equipment for operation, this does not \r\n mean that fans or blowers may not, or should not, be used to assist the \r\n natural flow of thermal energy. The passive systems assisted by mechanical \r\n devices are referred to as hybrid\" heating systems. \r\n Passive solar systems utilize basic concepts \r\n incorporated into the architectural design of the building. They usually \r\n consist of: buildings with rectangular floor plans, elongated on an East-West \r\n axis; a glazed South-facing wall; a thermal storage media exposed to the \r\n solar radiation which penetrates the South-facing glazing; overhangs or \r\n other shading devices which sufficiently shade the South-facing glazing \r\n from the summer sun; and windows on the East and West walls, and preferably \r\n none on the North walls. Passive solar systems do not have a high initial \r\n cost or long-term payback period, both of which are common with many active \r\n solar heating systems. \r\n This Technical Notes introduces the general \r\n features and requirements for the development and application of passive \r\n solar heating systems. Passive solar cooling systems are discussed in \r\n Technical Notes 43C . Due to the \r\n variations in building type and environment which must be considered, \r\n it is not normally feasible for passive solar systems to be the sole source \r\n of heat in most climatological areas. Construction details are provided \r\n in Technical Notes 43G . \r\n \r\n \r\n \r\n \r\n Passive Solar Building with Thermal Storage \r\n Wall Under Construction \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n \r\n Combined Thermal Storage Wall System and Attached Sunspace \r\n FIG. 2 \r\n \r\n ENVIRONMENTAL DATA AND REQUIREMENTS \r\n Many environmental factors must be considered \r\n to fully utilize the concepts of passive solar heating systems. Environmental \r\n data is given in Tables 1 and 2 of this Technical Notes. \r\n Temperature \r\n Exterior design temperatures are important considerations \r\n in developing passive solar heating systems. The size of the system will \r\n depend upon daily, monthly and annual temperature fluctuations. In mild, \r\n sunny climates, the required glazing and thermal storage areas may be \r\n relatively small. In temperate, cloudy climates, the required glazing \r\n area may be small, but the thermal storage requirements may be greater. \r\n In colder climates, the amount of glazing and thermal storage is usually \r\n large. \r\n The average monthly heating degree days are \r\n related to exterior temperature conditions. These values are necessary \r\n to determine the total monthly thermal load of the building. Average monthly \r\n heating degree days and exterior temperatures are given in Table 2 at \r\n the end of this Technical Notes . \r\n Latitude \r\n Latitude is important to determine the amount \r\n of solar radiation and the appropriate summertime shading provided by \r\n overhangs and other devices. The further North the building is to be located, \r\n the less winter solar radiation it will receive. This is because the sun \r\n is above the horizon for a shorter period of time and the solar radiation \r\n must penetrate more of the atmosphere. Values of solar radiation at various \r\n latitudes are given in Table 1. \r\n At higher latitudes, the sun appears lower in \r\n the sky. At these latitudes, where the position (altitude) of the sun \r\n in the sky is low, larger overhangs are required to shade the South-facing \r\n wall from the summer sunlight. Figure 3 shows how the altitude of the \r\n sun changes from winter to summer, demonstrating how the South-facing \r\n wall may be shaded from summer solar radiation and still be exposed to \r\n winter solar radiation by using an overhang. The length of projection \r\n required to shade a South-facing wall from the summer sun is given in \r\n Table 3. \r\n \r\n \r\n \r\n \r\n Sun Altitude-Winter and Summer \r\n \r\n a Reprinted with permission from the 1972 ASHRAE \r\n Handbook of Fundamentals Volume. ASHRAE HANDBOOK & Product Directory. \r\n b \r\n Projection greater than 20 ft required. \r\n Solar Radiation Data \r\n Solar radiation data is required to determine \r\n the amount of radiation transmitted through the South-facing glazing. \r\n Actual average solar radiation data for various geographical locations \r\n is given in Table 2. The amount of solar radiation is dependent on \r\n climate, elevation and latitude. Clear day solar radiation for various \r\n latitudes is given in Table 1. \r\n Orientation \r\n Orientation is extremely important in the \r\n design of passive solar buildings. The best performance will usually \r\n result when the passive solar system faces true South. True South \r\n may be obtained from isogonic (magnetic variation) charts developed \r\n by the United States Department of Commerce, Coast and Geodetic Survey, \r\n or by consulting a local land surveyor. \r\n When the passive solar system faces true \r\n South, the system will be exposed to the maximum amount of winter \r\n solar radiation. Deviations of more than 30 o East or West \r\n of true South are not recommended, especially where maximum \r\n performance is desired. \r\n Site Topography \r\n The topography of the site is of major concern. \r\n If the South-facing wall of the building is shaded by natural or man-made \r\n elements, it will probably not be feasible to consider passive solar \r\n systems. An ideal siting for a passive solar building is to be bermed \r\n into a South-facing slope. This provides a South wall exposed to the \r\n sun, and a North wall protected from environmental changes by the \r\n earth berm. Berming the North wall of the building should be done \r\n cautiously to avoid problems caused by ground water and earth pressure. \r\n BUILDING TYPE AND USE \r\n In addition to environmental considerations \r\n building type and use are very important in developing and applying \r\n passive solar heating systems. Building type and use are flexible \r\n requirements which allow the designer to make appropriate adaptations \r\n to the structure to provide the desired energy performance. \r\n Thermal Load Requirements \r\n Thermal load requirements are important \r\n in the selection and sizing of passive solar heating systems. The \r\n effects of building type and use on the thermal load are determined \r\n by the interior design temperature and the allowable temperature fluctuation. \r\n A warehouse may not require the same interior design temperature as \r\n a residential structure. Many commercial buildings are only occupied \r\n during daylight hours and do not have to maintain the higher interior \r\n working hour temperatures overnight. In many applications, the passive \r\n solar heating systems may provide similar performance as conventional \r\n heating systems with night-time setbacks. \r\n Another aspect which affects the requirements \r\n of the buildings use is human comfort. Passive solar systems provide \r\n conditions which contribute to human comfort. The brick storage areas \r\n of the system are warm. When surrounded by warm surfaces, the human \r\n body receives radiation from the warm surfaces. This permits the occupants \r\n to feel comfortable at lower interior air temperatures because heat \r\n is radiated to the body rather than from the body. \r\n Glazing and Lighting Quality \r\n The amount of natural lighting required \r\n will affect the selection of the type of passive solar heating system. \r\n Fabrics and even the glazing material itself may suffer from ultraviolet \r\n degradation when exposed to direct sunlight. In applications such \r\n as studios, admitting large quantities of diffuse solar radiation \r\n provides appropriate lighting. \r\n The amount of glazing for most conventional \r\n structures is typically determined by the need or desire to provide \r\n contact with the exterior or to meet building code egress requirements. \r\n This is not usually a primary design consideration for the passive \r\n solar heating system \r\n Material Properties \r\n Massive brick masonry is recommended for \r\n thermal storage because of its inherent ability to store heat. Typically, \r\n brick exposed to direct sunlight should be of a dark color wherever \r\n it is to perform as a thermal storage media. The American Society \r\n of Heating, Refrigerating and air-conditioning Engineers (ASHRAE) \r\n defines dark colors as dark blue, red, brown and green. The properties \r\n of brick as related to passive solar applications are discussed in \r\n Technical Notes 43D . \r\n System Operation \r\n Passive solar heating systems may be shaded \r\n from the summer sun by fixed, adjustable or removable shading devices. \r\n Adjustable or removable overhangs or shading devices require operation, \r\n but permit the optimum use of the winter sun and can completely eliminate \r\n any solar exposure on the South-facing glass in the summer. \r\n The performance of passive solar systems \r\n may be greatly enhanced by the use of night insulation. The insulation \r\n may be applied on the interior in the form of drapes or panels. Insulation \r\n may also serve as reflector panels or shading devices. Reflector-insulating \r\n panels may be hinged at the base of the South-facing glazing so that, \r\n when opened during the day, they reflect additional solar radiation \r\n through the glazing and when closed, provide night insulation. Night \r\n insulation may be operated manually or automatically. \r\n Building Design and Appearance \r\n There is no reason for passive solar heating \r\n systems to have an extremely unconventional design or appearance. \r\n The only required variations are: additional South-facing wall glazing, \r\n reduced glazing on the East and West walls, and preferably no glazing \r\n on the North wall; sufficient overhang or some other shading device \r\n to prevent the South-facing glazing from being exposed to the summer \r\n sun; and interior brick masonry. The interior brick masonry exposed \r\n to direct sunlight is used as the thermal storage component of the \r\n passive solar energy system. Additional interior brick masonry unexposed \r\n to direct sunlight is used to provide a thermal flywheel which reduces \r\n interior temperature fluctuations. \r\n Spatial Requirements \r\n The spatial requirements may dictate the \r\n type of system used. The depth of penetration of solar radiation into \r\n the structure may affect the system type selected. Buildings should \r\n be arranged with a longitudinal East-West orientation to maximize \r\n the solar exposure of the South-facing glazing. This minimizes the \r\n distance from the South wall to the North wall, across which the thermal \r\n energy from the passive solar energy system has to be distributed. \r\n Building energy performance may be increased by heating the North \r\n wall with solar radiation entering through the South-facing glazing. \r\n DIRECT GAIN SYSTEMS \r\n The direct gain system is simple and often \r\n used. The system consists of South-facing glazing which allows winter \r\n sunlight to enter the habitable spaces of the building. This \r\n thermal energy is stored in brick floors and walls. A schematic of \r\n a direct gain system is shown in Fig. 4. The South-facing glazing \r\n may be windows (operable or fixed), or glass doors. The brick masonry \r\n exposed to the solar radiation should generally be a dark color and \r\n 4 to 8 in. thick. All walls or other components not exposed to solar \r\n radiation should have light-colored surfaces. \r\n In the direct gain system, the South-facing \r\n glazing permits sunlight to strike the brick masonry construction. \r\n The brick masonry, because of its color, mass and thermal properties, \r\n provides the thermal storage for the system. The brick masonry absorbs \r\n the thermal energy from the sunlight striking its surface. The heat, \r\n which is stored during the daylight hours, is released gradually. \r\n The heat that is reflected from the brick masonry provides heat to \r\n the habitable space during the daylight hours. The light-colored surfaces \r\n reflect the heat radiated or reflected from the brick masonry to the \r\n air and surroundings in the habitable space. If large amounts of heat \r\n are required during the daytime hours and less during night-time hours, \r\n this may be accomplished by using lighter colors of brick masonry. \r\n Direct gain systems provide rapid temperature \r\n increases in the habitable space and may have large temperature fluctuations. \r\n This is because such systems often must be designed to prevent overheating. \r\n The systems may have limited amounts of brick masonry exposed to the \r\n winter sunlight. This is especially true in the lower latitudes where \r\n the winter sun has a higher altitude. This may be overcome by providing \r\n clerestories to obtain solar radiation on the North wall, as shown \r\n in Fig. 4. \r\n \r\n \r\n \r\n \r\n \r\n Increased Building Depth Using Direct Gain System with Clerestory \r\n FIG. 4 \r\n \r\n Ultraviolet degradation is of the greatest \r\n concern when direct gain systems are utilized. Materials subject to \r\n ultraviolet degradation should not be exposed to direct sunlight. \r\n This may become an inconvenience in the living areas heated by direct \r\n gain. The walls and floors exposed to the sunlight and used for thermal \r\n storage should not be covered. Wall hangings and carpet greatly decrease \r\n the performance of the system. \r\n THERMAL STORAGE WALL SYSTEMS \r\n The thermal storage wall system, often referred \r\n to as a Trombe Wall System, is schematically represented in Fig. 5. \r\n The thermal storage wall may be vented, as shown in Fig. 5, and provide \r\n heat by radiation and convection, or it may be unvented and supply \r\n heat by radiation alone. A thermal storage wall system is shown on \r\n the left of Fig. 2. It consists of glazing, usually spaced 2 to 4 \r\n in. on the exterior of a South-facing wall, constructed of brick masonry. \r\n The massive brick wall, usually 10 to 18 in. thick, may be loadbearing, \r\n or non-loadbearing. \r\n \r\n \r\n \r\n \r\n \r\n Vented Thermal Storage Wall System \r\n FIG. 5 \r\n \r\n The winter sunlight penetrating the South \r\n glazing heats the brick, the heat slowly penetrates the brick wall \r\n and warms the interior. Thermal storage walls may have sufficient \r\n heat storage to maintain comfortable temperatures in buildings for \r\n periods up to three completely overcast days. The thermal storage \r\n wall systems have considerably less temperature fluctuation than do \r\n direct gain systems, but usually do not achieve the same high initial \r\n interior temperatures. \r\n The massive brick thermal storage wall prevents \r\n ultraviolet degradation of materials contained in the living space \r\n because solar radiation does not directly enter the habitable space. \r\n The performance may be substantially increased by providing vents \r\n at the top and bottom of the brick wall to provide convection in addition \r\n to the heat radiated from the interior face of the wall. Vented walls \r\n may be used to decrease the temperature fluctuations and increase \r\n the maximum temperature achieved in the living space. Fig. 1 shows \r\n a vented thermal storage wall under construction. When venting the \r\n storage wall system, vents with automatic or manual closures should \r\n be used so that the system does not reverse at night, creating a heat \r\n loss. \r\n If controlled vents are not installed on \r\n the vented thermal storage wall systems, night insulation is essential \r\n to prevent heat losses at night. Night insulation may be required \r\n on unvented thermal storage walls and those with controlled vents \r\n to increase the efficiency of the system. \r\n COMBINED SYSTEMS \r\n The best thermal performance and living \r\n conditions result by combining the thermal storage wall system and \r\n the direct gain system. This combination permits some direct sunlight \r\n into the living spaces, achieves higher interior temperatures than \r\n the thermal wall system alone, provides less temperature fluctuation \r\n than the direct gain system alone and provides natural lighting. The \r\n combination essentially utilizes the best of the two systems. \r\n ATTACHED SUNSPACES \r\n Attached sunspaces are a combination of \r\n the components of the direct gain system and the thermal storage wall \r\n system, as shown in Fig. 2 on the right, and in Fig. 6. The sunspace \r\n is a room, or space, which typically has both a glass roof and a glass \r\n South-facing wall. The East and West walls may also be glass. The \r\n floor is similar to that of the direct gain system. It consists of \r\n 4 to 8-in. thick brick masonry. The North wall is a 10 to 18-in. thick \r\n brick thermal storage wall. The room is vented or ducted to other \r\n areas of the structure. With the assistance of fans and blowers, the \r\n structure is heated by the extreme temperatures achieved in the sunspace. \r\n The sunspace usually has severe temperature fluctuations and is often \r\n unbearably hot during daylight hours. They do require removable shading \r\n devices to prevent solar gains in the summer. They will also require \r\n night insulation if they are to become useable living space in the \r\n evening hours. \r\n \r\n \r\n \r\n \r\n \r\n Attached Sunspace \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n CAVITY WALL SYSTEM \r\n The cavity wall system, shown in Fig. 7, \r\n is a modification of the double envelope system. The concept of the \r\n cavity wall system is that the South-facing thermal storage wall heats \r\n up and creates a convective loop around the entire building envelope. \r\n The warmed air space minimizes the temperature differential from the \r\n interior of the building through the inner wythe of the cavity wall. \r\n There are no generally accepted design procedures for this type of \r\n system presently available. Some experts in the passive solar design \r\n field feel that the increased thermal performance may be accounted \r\n for by the insulation in the interior and exterior shells of the double \r\n envelope system. Others feel that there is no convective loop occurring, \r\n i.e., the air between the double envelope shells is stagnant. \r\n \r\n \r\n \r\n \r\n \r\n Cavity Wall System \r\n FIG.7 \r\n \r\n The use of a properly constructed, insulated \r\n brick cavity wall on the North side of the building could be used \r\n to provide a moderate heat loss to drive the convective loop through \r\n the air space in the building envelope. This would reduce the temperature \r\n of the air being circulated through the cavity, but the air should \r\n still reach high enough temperatures as it passes through the air \r\n space of the thermal storage wall system to provide a net heat gain. \r\n Since there is still considerable controversy \r\n regarding this type of system, and since accurate performance analysis \r\n is not easily accomplished, these systems should only be designed \r\n and constructed with the appropriate awareness of the expected and \r\n achievable performance level of the system. \r\n METRIC CONVERSION \r\n Because of the possible confusion inherent \r\n in showing dual unit systems in the calculations, the metric (SI) \r\n units are not given in this Technical Notes. Table 13 in Technical \r\n Notes 4 provides metric (SI) conversion factors for the more commonly \r\n used units. \r\n SUMMARY \r\n This Technical Notes has provided \r\n general information concerning passive solar heating systems. It has \r\n described several passive solar heating systems, the basic principles \r\n of their operation and general design consideration. This introduction \r\n to passive solar heating systems hopefully provides sufficient familiarization \r\n with concepts so that the design of such systems will be understood. \r\n Passive solar cooling is discussed in Technical Notes 43C . \r\n The material properties of brick masonry, as related to passive solar \r\n energy systems, is provided in Technical Notes 43D . \r\n Details and construction information are provided in Technical \r\n Notes 43G . \r\n This Technical Notes does not \r\n and is not intended to provide information for specific \r\n designs and applications, but rather offers general information to \r\n assist in the consideration and use of brick masonry in passive solar \r\n heating systems. The decision to use these concepts in the design \r\n specific applications is not within the purview of the Brick \r\n Institute of America, and must rest with the owner or designer of \r\n any specific project. \r\n \r\n \r\n Environmental Data for Passive Solar \r\n Systems \r\n \r\n \r\n \r\n TABLE 2 a,b \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n a Reprinted from the U.S. Department \r\n of Commerce, National Oceanic and Atmospheric Administration, Environmental \r\n Data and Information Service, National Climate Center, Asheville, \r\n North Carolina - \"Input Data for Solar Systems,\" by V. V. Cinquemani. \r\n J. R. Owenby, Ir., and R. G. Baldwin. \r\n b Based on 1941 - 1970 Period. \r\n Zeros appearing for all values appearing in these columns signify \r\n that 1941 - 1970 period normals were not available. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n a Reprinted with permission from the 1972 ASHRAE Handbook of Fundamentals \r\n Volume, ASHRAE HANDBOOK & Product Directory \r\n Projection greater then 20 ft required. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60119,"ResultID":176351,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 43C - Passive Solar Cooling \r\n with Brick Masonry - Part 1 - Introduction \r\n March 1980 \r\n \r\n Abstract: Brick masonry passive \r\n solar energy systems can be used to significantly reduce the use of \r\n fossil fuels for heating and cooling buildings. The concepts of passive \r\n solar cooling systems discussed here are simple modifications to passive \r\n solar heating systems. For locations where humidity is high, or there \r\n is little exterior temperature fluctuation, or applications where \r\n low interior design temperatures are required, passive solar cooling \r\n may not be viable. Several methods of pre-cooling and the concept \r\n of dehumidifying air with these systems are introduced. \r\n \r\n Key Words : attached sunspace, bricks , buildings, \r\n cavity wall systems, climatology, conservation, direct gain systems, \r\n effective temperature , energy, masonry, passive \r\n solar cooling systems , passive solar heating systems, solar \r\n radiation, system operation, temperature, thermal storage wall systems. \r\n \r\n INTRODUCTION \r\n \r\n The application of passive solar energy systems using brick masonry \r\n can help to significantly reduce the amounts of fossil fuels and electric \r\n energy currently being used for heating and cooling buildings. Other \r\n Technical Notes in this Series address passive solar heating \r\n systems with brick masonry. They discuss the general concepts, the \r\n procedures for sizing the systems, and the performance calculations. \r\n This Technical Notes introduces the concept of passive solar \r\n cooling systems using brick masonry. \r\n \r\n PASSIVE SOLAR COOLING \r\n \r\n The terminology \"passive solar cooling\" does not necessarily refer \r\n to the actual reduction of the interior air temperature of the building. \r\n \"Passive solar cooling\" is a means of providing comfortable interior \r\n conditions by properly using the natural flow of thermal energy to \r\n create air movement. These \"cooling\" systems provide comfort by controlling \r\n the effective temperature of the interior of a building. \r\n The effective temperature is a measure of the comfortable \r\n air conditions in a building dependent upon the actual temperature \r\n of the air, the level of relative humidity, and the amount of air \r\n movement. By properly varying any one, or any combination of these \r\n factors, more comfortable interior conditions can be achieved. The \r\n American Society of Heating, Refrigerating and Air-Conditioning Engineers \r\n (ASHRAE) provides methods which may be used to determine the amount \r\n of change or fluctuation necessary to achieve comfortable interior \r\n conditions. These methods are described in ASHRAE 1977 Handbook \r\n of Fundamentals, and ASHRAE Standard 55-74, Thermal and Environmental \r\n Conditions for Human Occupancy. \r\n The actual determination of the effectiveness of passive solar cooling \r\n is complex and its performance is not yet satisfactorily predicted \r\n with calculation procedures alone. The type of passive solar cooling \r\n system selected, and its performance can be greatly affected by the \r\n site and the climatological conditions. \r\n \r\n SYSTEMS AND OPERATION \r\n \r\n The basic passive solar heating systems, utilizing brick masonry, \r\n are discussed in Technical Notes 43 , \r\n These systems are: thermal storage wall systems, direct gain systems, \r\n attached sunspaces and combinations of these. These passive solar \r\n heating systems can be easily modified to provide interior comfort \r\n during the cooling season. Obtaining all the necessary cooling \r\n with passive solar cooling systems usually is neither economically \r\n nor thermally feasible for the entire cooling season. These simple \r\n modifications to passive solar heating systems can be used \r\n to create more comfortable interior conditions for at least part of \r\n the cooling season in most climates. \r\n The necessary modifications to passive solar heating systems to provide \r\n passive solar cooling are provisions for 1) exhausting air from the \r\n interior, and 2) intaking exterior air. Schematics are shown in Figs. \r\n 1, 2, and 3 for the direct gain system, attached sunspace, and thermal \r\n storage wall system, respectively. The principal modification is to \r\n provide controlled openings for exhausting the internal heat gained \r\n by the passive solar heating system. The controlled openings should \r\n be at the highest points of the structure, preferably in the roof/ceiling, \r\n or gable. Control of the openings may be provided with operable vents, \r\n or registers. Similar openings can be placed at the low points of \r\n the structure for intaking exterior air. The openings for intaking \r\n exterior air may be the windows or doors of the structure. \r\n The operation of each of these systems is very similar in the cooling \r\n mode: (1) sunlight strikes the south-facing glazing, (2) solar energy \r\n is transmitted through the south-facing glazing to the brick masonry \r\n thermal storage media, (3) the brick masonry absorbs and stores the \r\n heat, (4) radiant heat from the surface of the brick masonry rises, \r\n (5) the heated air is exhausted through the controlled openings at \r\n the top of the structure, (6) as the heat is exhausted, exterior air \r\n is drawn into the structure, and (7) the air movement created by exhausting \r\n and intaking air through the structure creates the effect of cooling \r\n and provides more comfortable interior conditions. \r\n \r\n \r\n \r\n Cooling With the Direct Gain System \r\n FIG.1 \r\n \r\n \r\n \r\n Direct Gain System \r\n \r\n The direct gain system, when applied as passive solar cooling, is \r\n the most economical, but probably the least effective. The minimum \r\n 4-in. ( 100 mm) thick brick masonry floors and walls on the interior \r\n are exposed to direct sunlight to absorb and store heat. \r\n The interior brick masonry should be dark to absorb most of the heat \r\n and radiate and reflect only a small portion during the day. The gradual \r\n release of radiant heat through the night draws the cool night air \r\n into the structure and cools the structure. \r\n The system is only advantageous when the nighttime temperatures consistently \r\n fall below the interior design temperature and when internal solar \r\n heat gain can be adequately controlled to prevent overheating in the \r\n daytime. \r\n A major problem with using a direct gain system is that the interior \r\n space used to store heat is also an integral part of the habitable \r\n space of the building. \r\n \r\n Attached Sunspace \r\n \r\n Using the attached sunspace for passive solar cooling is probably \r\n more effective but less economical than direct gain cooling. In the \r\n attached sunspace, the heat storage element is not usually part of \r\n the space that is to be cooled. The system schematic is shown in Fig. \r\n 2. \r\n Although the intent in many applications is to use the attached sunspace \r\n as a greenhouse, this is not advantageous in most applications because \r\n the greenhouse will be vented to the interior and the humidity from \r\n watering plants may result in uncomfortable interior conditions and \r\n condensation problems. The major disadvantage of this system is the \r\n cost of the additional floor area which has limited use. \r\n \r\n \r\n \r\n \r\n \r\n Cooling With the Attached Sunspace \r\n FIG. 2 \r\n \r\n The system consists of minimum 4-in. ( 100 mm) thick brick masonry \r\n floors, south-facing glazing and preferably a 10 to 18-in. (250 to \r\n 450 mm) thick vented brick masonry thermal storage wall between the \r\n sunspace and the habitable portion of the building. \r\n In the cooling mode, the top vents of the brick masonry storage wall \r\n are closed and the bottom vents are open. The air in the sunspace \r\n is heated by radiant heat from the brick masonry. The heated air rises \r\n through operable openings in the roof of the sunspace, drawing air \r\n from the habitable spaces through the bottom vents of the brick masonry \r\n thermal storage wall. The air drawn from the habitable space is replaced \r\n by exterior air drawn in through operable windows or doors. \r\n \r\n Thermal Storage Wall System \r\n \r\n One of the most economical and effective passive solar cooling systems \r\n is the vented thermal storage wall, shown schematically in Fig. 3. \r\n The greatest advantage of the thermal storage wall is that the heat \r\n used for the passive solar cooling does not directly enter the interior \r\n spaces of the habitable portion of the building. \r\n The system consists of exterior glazing 2 to 4 in. (50 to 100 mm) \r\n in front of a 10 to 18-in. (250 to 450 mm) thick vented brick masonry \r\n wall used for storing heat. Operation is similar to that of the attached \r\n sunspace. The operable openings for exhausting the heated air may \r\n be located at the top of the exterior glazing. The exhaust system \r\n may also be operable vents at the top of the airspace from which the \r\n air may be exhausted through additional vents in the roof. When using \r\n the latter exhaust system, additional vents from the habitable space \r\n through the roof/ceiling component may be used to increase the heat \r\n flow from the interior, thereby drawing additional air into the building. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Cooling With the Vented Thermal Storage Wall System \r\n FIG. 3 \r\n \r\n CONTROLS \r\n \r\n These three basic passive solar heating systems, as modified for \r\n passive solar cooling, require controls to regulate internal heat \r\n gain and the level of comfort, \"cooling\", achieved. These controls \r\n may be automatically or manually operated vents, or registers. The \r\n controls should be such that the system can be totally \"shut down\" \r\n when it is not being effective, i.e., when exterior conditions are \r\n such that a comfortable effective temperature cannot be maintained \r\n inside the building. Shading devices are required as a means of controlling \r\n the amount of sunlight permitted to enter the structure for operation \r\n of the passive solar cooling system. These may also be automatic or \r\n manual devices, but are necessary to prevent overheating that can \r\n occur during the cooling season when the interior temperature, i.e., \r\n effective temperature, will no longer be within the comfort range. \r\n The entire system must be completely shut down before mechanical/refrigeration \r\n cooling systems are put into operation. Shading the south-facing glazing \r\n and closing openings are required for efficient use of any conventional \r\n cooling system. \r\n Anticipation of when overheating or a comfortable effective temperature \r\n will no longer be maintained is necessary so that the passive solar \r\n systems can be deactivated prior to creating additional cooling loads \r\n for the conventional cooling system. Obviously, operation is a critical \r\n factor in the performance of \"passive solar cooling systems\". \r\n \r\n CAVITY WALL SYSTEM \r\n \r\n A system which may be effectively used for cooling, with less consideration \r\n of the climatic conditions, is the cavity wall system, schematically \r\n represented in Fig. 4. The north and south walls of the structure \r\n are uninsulated cavity walls (see Technical Notes 21 Series). \r\n The south-facing wall, above grade, is an unvented thermal storage \r\n wall. The airspace in the thermal storage wall system is open at the \r\n bottom to the cavity of the basement or foundation wall, and at the \r\n top to the roof/ceiling. The cavity of the wall is open to ductwork \r\n extended in the north-south direction through the basement floor, \r\n or crawl space. As shown in Fig. 4, this provides an air passageway \r\n within the building envelope components. A ductwork system is provided \r\n from the base of the cavity to vents on the exterior. Exhaust vents \r\n are provided in the roof or gable ends. \r\n \r\n \r\n \r\n Cavity Wall System Cooling Mode \r\n FIG. 4 \r\n \r\n \r\n \r\n With the cavity wall system, the south-facing glazing exposes the \r\n brick thermal storage wall to sunlight, which heats up and causes \r\n air to rise through the cavity. As the air rises, it is vented to \r\n the exterior from the top of the cavity, and exterior air is drawn \r\n into the cavity via the ductwork system and exterior vents. This provides \r\n a means of keeping the entire building envelope cooled. Since the \r\n surfaces warmed during the daytime hours retain heat, this continues \r\n through the evening hours, further cooling the building envelope. \r\n The cooled building envelope and interior require a longer time period \r\n to be heated up to uncomfortable temperatures during the daytime hours \r\n of the next day. The advantages of passive solar cooling with the \r\n cavity wall system are: (1) shutdown is not essential for conventional \r\n cooling to work effectively (the cooling systems are isolated from \r\n each other), and (2) since the exterior air for cooling is not brought \r\n into the habitable space, the effects of humidity (a major drawback \r\n in most passive solar cooling systems, depending on climate), may \r\n be reduced. \r\n The east and west walls do not have to be uninsulated cavity walls. \r\n By keeping all walls cavity walls, the east and west walls may perform \r\n as a buffer zone between the north and south walls. This may increase \r\n the overall performance of the system. \r\n A schematic of the system in the heating mode is shown in Fig. 5. \r\n The vents are closed, which creates a convective loop around the entire \r\n shell of the building; through the floor, wall and roof/ceiling components. \r\n This thermal convective loop warms both the interior and exterior \r\n wythes of the building envelope. Since this operation warms the interior \r\n wythe, there is little or no heat loss through those portions of the \r\n building envelope. This system, properly designed and operated, may \r\n provide the most effective passive solar heating and cooling. \r\n \r\n \r\n \r\n Cavity Wall System Heating Mode \r\n FIG. 5 \r\n \r\n \r\n FACTORS \r\n AFFECTING PERFORMANCE \r\n \r\n The effects of the environmental conditions and building use on passive \r\n solar heating systems are discussed in Technical Notes 43 . \r\n These must also be considered for passive solar cooling systems, however, \r\n the necessary considerations of these factors vary for passive solar \r\n cooling systems. The major variations and additional effects which \r\n must be addressed specifically are: temperature, humidity and shading. \r\n \r\n Exterior Design Temperature \r\n \r\n The exterior design temperature may be such that the effective temperature \r\n range cannot be achieved or maintained within the structure. Since \r\n the effects of cooling are principally achieved by air movement, this \r\n may make the cooling system ineffective. One option is to take maximum \r\n advantage of the daily temperature swing. When the nighttime temperatures \r\n drop below the interior design temperature, the structure may be cooled \r\n during the night, delaying the time to heat up the next day. Caution \r\n must be used when considering the daily temperature swing to guard \r\n against overcooling in moderate climates. \r\n \r\n Humidity \r\n \r\n Humidity is an additional environmental factor not generally addressed \r\n in passive solar heating systems. In areas where the effects of high \r\n humidity cannot be eliminated by air movement, these simple versions \r\n of passive solar cooling systems may not be effective. Additional \r\n complex modifications to the basic passive solar cooling systems may \r\n be necessary to dehumidify the air. \r\n \r\n Shading Devices \r\n \r\n Operable shading devices are usually required in passive solar cooling \r\n systems. The shading devices are used to control the amount of solar \r\n radiation permitted to strike the system. This is necessary to prevent \r\n overheating, especially when the system is marginal because the effective \r\n temperature cannot be attained by natural air flow. In this case, \r\n the system should be completely shaded from the summer sunlight. \r\n In instances where the system is providing cooling by night air intake, \r\n it may be advantageous to have the system shaded from the morning \r\n and possibly early afternoon sunlight. Exposure to only the late afternoon \r\n sunlight may result in sufficient performance to draw cool night air \r\n through the structure. \r\n \r\n SPECIAL CONSIDERATIONS \r\n \r\n The performance of the passive solar cooling system may be greatly \r\n increased by pre-cooling, or dehumidifying the air before introducing \r\n it into the structure. Pre-cooling and dehumidifying the air are both \r\n fairly straightforward concepts. Adapting the system for pre-cooling \r\n air is usually simple, but dehumidifying the air is much more complicated. \r\n \r\n Pre-Cooling Air \r\n \r\n Air may be cooled before it is introduced into the structure by providing \r\n underground ductwork or piping, and venting it to the surface as shown \r\n schematically in Figs. 6, 7 and 8. This is easily adaptable for direct \r\n gain, attached sunspace and thermal storage wall cooling systems. \r\n The ductwork should be corrosion-resistant and installed for a sufficient \r\n length and at the appropriate depth to pre-cool the air. The number \r\n of ducts and their length and depth requirements are beyond the scope \r\n of this Technical Notes because they are a function of climate, \r\n soil type, elevation of ground water and other related factors, all \r\n of which affect the amount of pre-cooling, both required and attainable. \r\n General design information and calculation procedures may be obtained \r\n from the References 1, 2, 6 and 7 of this Technical Notes. \r\n \r\n \r\n \r\n Pre-Cooling and Dehumidification of Exterior Air \r\n for Cooling With the Direct Gain System \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n Pre-Cooling and Dehumidification \r\n of Exterior Air With Attached Sunspace \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n \r\n Pre-Cooling and Dehumidification \r\n of Exterior Air With Vented Thermal Storage Wall System \r\n FIG. 8 \r\n \r\n \r\n DEHUMIDIFICATION \r\n Air may be dehumidified by using the concept shown in Figs. 6 through \r\n 8, for pre-cooling. Dehumidifying the air with the passive solar system \r\n alone can be very difficult. Again, it is a function of climate, soil \r\n type, level of ground water and other related factors. The procedure \r\n for determining the amount of dehumidification involves fairly complex \r\n calculations. These calculation procedures are similar to those in \r\n the ASHRAE 1977 Handbook of Fundamentals and ASHRAE Standard \r\n 55-74. The temperature fluctuations necessary to saturate air and \r\n condensate water by the natural flow of air further complicates the \r\n use of passive solar cooling systems for providing dehumidification. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes provides general information concerning \r\n passive solar cooling systems. In addition to describing modifications \r\n of the passive solar heating systems which may be used to supply successful \r\n passive solar cooling, it introduces an innovative system - the cavity \r\n wall system - which may be quite effectively used for heating and \r\n cooling buildings. The basic concepts of the passive solar cooling \r\n systems and the principles of their operation are also discussed. \r\n The purpose of this Technical Notes is to provide general \r\n information on passive solar cooling systems with brick masonry. It \r\n discusses type, operation, advantages and disadvantages of these systems. \r\n This Technical Notes does not and is not intended \r\n to provide information for specific designs or applications, but rather \r\n offers general information to assist in the consideration of the use \r\n of passive solar cooling systems of brick masonry. The decision to \r\n use the concepts and the design of specific applications is not \r\n within the purview of the Brick Institute of America, and must \r\n rest with the designer, or owner, of any specific project. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. Proceedings \r\n of the Fourth Passive Solar Conference, October \r\n 3-5, 1979, Kansas City, Missouri, published by the publishing office \r\n of the American Section of the International Solar Energy Society, \r\n Incorporated, McDowell Hall, University of Delaware, Newark, Delaware, \r\n 1979. \r\n 2. Proceedings \r\n of the International Solar Energy Society, Silver Jubilee Congress, Atlanta, Georgia, May 1979, Pergamon Press, Inc., \r\n Maxwell House, Fairview Park, Elmsford, New York 10523, 1979. \r\n 3. Technical \r\n Notes 43 , \r\n \"Passive Solar Heating with Brick Masonry, Part I - Introduction\", \r\n Brick Institute of America, McLean, Virginia, Mar/Apr. 1979. \r\n 4. ASHRAE \r\n 1977 Handbook of Fundamentals, American Society of Heating, \r\n Refrigerating and Air-Conditioning Engineers, Inc., 345 East 47th \r\n Street, New York, New York 10017, 1977. \r\n 5. ASHRAE \r\n Standard 55-74, Thermal Environmental Conditions for Human Comfort, \r\n American Society of Heating, Refrigerating and Air-Conditioning \r\n Engineers, Inc., 345 East 47th Street, New York, New York 10017, \r\n 1977. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60120,"ResultID":176352,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 43D - Brick Passive Solar \r\n Heating Systems - Part 4 - Material Properties \r\n Sept./Oct. 1980 (Reissued Sept. 1988) \r\n \r\n Abstract : The inherent properties of brick masonry make it one \r\n of the most advantageous storage media materials for passive solar \r\n energy systems. Brick masonry may be used to provide an aesthetic \r\n effect, structural capacity and other design considerations in addition \r\n to thermal storage. Most of these inherent properties of brick masonry \r\n are already well understood for conventional applications. However, \r\n in order to properly use brick masonry as a thermal storage media \r\n for passive solar energy systems additional information may be needed \r\n by the designer. This additional information has to do with the effective \r\n thermal storage of brick masonry. \r\n Keywords : absorptivity, brick , \r\n density, emissivity, energy heat transfer, masonry, material \r\n properties , passive solar energy systems , reflectance, \r\n solar radiation, specific heat, temperature, effective thermal \r\n storage , thermal conductivity, thermal diffusivity . \r\n INTRODUCTION \r\n Brick masonry can be used most advantageously \r\n as the thermal storage media in direct gain systems, thermal storage \r\n wall systems and attached sunspaces. The general concepts, empirical \r\n procedures for sizing systems and performance calculations are discussed \r\n in Parts I through III of this Technical Notes Series. This \r\n Technical Notes provides information and references regarding \r\n the material properties of the basic components of passive solar energy \r\n systems. This information includes the properties of brick masonry \r\n when used for thermal storage, with major emphasis on the effective \r\n thermal storage of brick masonry and a general discussion of the properties \r\n of glazing materials when used as collectors. \r\n BRICK MASONRY \r\n General \r\n Most of the design requirements and performance \r\n of brick masonry as a general building material are discussed in other \r\n Technical Notes. The inherent properties of brick masonry offer \r\n many design advantages in addition to those required for use as a \r\n thermal storage material. \r\n Structural \r\n Brick masonry has many applications as a \r\n structural element in buildings. Brick masonry is commonly used as \r\n loadbearing elements in commercial and residential structures. Brick \r\n masonry when considered as a thermal storage media for passive solar \r\n energy systems may also be considered as a structural element. Information \r\n on loadbearing brick masonry is provided in Technical Notes \r\n 24 Series. \r\n One of the reasons brick masonry is less \r\n frequently considered as a structural element in one and two-family \r\n construction is because of the difficulties in insulating solid masonry \r\n walls to meet prescriptive energy code requirements for the reduction \r\n of heat loss. This can be overcome by using loadbearing insulated \r\n cavity walls which provide a durable facade, sufficient space for \r\n insulation and interior brick masonry which may be used as thermal \r\n storage in direct gain systems. Cavity wall construction is addressed \r\n in Technical Notes 21 Series. \r\n The structural design may require reinforced \r\n brick masonry. Reinforcement in brick masonry usually has little if \r\n any effect on the thermal performance of the wall. This is because \r\n the reinforcement is usually horizontal and/or vertical in the plane \r\n of the wall, and occurs at or near the center of the wall section \r\n resulting in very little increase of thermal transmission through \r\n the wall. Information regarding reinforced brick masonry is provided \r\n in Technical Notes 17 Series. \r\n Durability \r\n Brick masonry is an extremely durable building \r\n material requiring little or no maintenance. It does not require \r\n coatings or coverings which could reduce its thermal performance as \r\n a storage media. Coatings and coverings may decrease the emissivity \r\n and thermal conductivity of the brick masonry. This is not desired \r\n when trying to optimize on the available thermal storage and thermal \r\n energy retrieval. Since coatings and coverings are not required, brick \r\n masonry may be exposed to enhance the aesthetics of the building. \r\n The use of coating applied to exterior brick masonry is discussed \r\n in Technical Notes 6A . \r\n Aesthetics \r\n Brick masonry is normally used as an exterior \r\n facade, not only because of its durability but also because it provides \r\n architectural freedom. Brick masonry offers many bond patterns, colors \r\n and textures. As elements of the building, brick masonry provides \r\n options for architectural freedom that no other building material \r\n can offer. For instance, not only the texture of the brick itself \r\n is available in many varieties, but brick allows variation in wall \r\n texture, also. The texture of the wall may be varied by using projected \r\n or recessed brick or even sculptured brickwork. The typical modular \r\n sizes of brick masonry are given in Technical Notes 10B \r\n and common bond patterns are given in Technical Notes 30 . \r\n Brick masonry used as paving is discussed in Technical Notes \r\n 14 Series. Information on the use of brick masonry sills and soffits \r\n is provided in Technical Notes 36 Series. The use of brick \r\n masonry arches and reinforced brick masonry lintels are discussed \r\n in Technical Notes 31 Series and 17H, respectively. \r\n Fire Resistance \r\n Depending upon the specific application \r\n of brick masonry in passive solar energy systems, brick masonry may \r\n be designed and placed to offer fire protection. The fire resistance \r\n of brick masonry is discussed in Technical Notes 16 Series. \r\n Sound Transmission Resistance \r\n Brick masonry, because of its inherent properties \r\n offers considerable reduction in sound transmission. Thus, depending \r\n on specific design applications, strategically placed thermal storage \r\n elements may be used to reduce sound transmission from one area of \r\n the building to another or from the exterior to the interior of the \r\n building. Information on the sound transmission classification of \r\n brick masonry is provided in Technical Notes 5A . \r\n Effective Thermal Storage \r\n The overall performance of the brick masonry \r\n as a passive solar energy system thermal storage component is dependent \r\n on its absorptivity, emissivity, and ability to store heat. The ability \r\n of a material to store heat is usually referred to as heat capacity \r\n which is a function of the specific heat and density of a material. \r\n In addition to the heat capacity, the way the wave of thermal energy \r\n penetrates the material being used to store heat should also be considered. \r\n The performance as a thermal storage media may be estimated using \r\n the value of the thermal diffusivity of the material. Thermal diffusivity \r\n is not only a good value for assisting in the selection of materials \r\n but is also useful in simplified heat flow calculations to determine \r\n the amount of heat penetrating a material and the number of hours \r\n it takes for the heat transmission to occur. This information is useful \r\n for selecting the thickness of thermal storage. The thermal diffusivity \r\n is a function of the specific heat, density and thermal conductance \r\n of a material. \r\n Specific Heat . The specific heat, \r\n c, of material is the amount of heat required to increase the temperature \r\n of a unit weight of material one degree. The specific heat, c, in \r\n Btu per pound per degree Fahrenheit, for brick may vary from 0.20 \r\n to 0.26. Typically this variation is due to the impurities in the \r\n clay used to manufacture the brick. The greater the percentage of \r\n metallic oxides in the clay, usually the greater the specific heat. \r\n Building brick which usually have a low percentage of metallic oxides \r\n by weight have low specific heats usually between 0.20 to 0.22 Btu/lb/ o F, \r\n whereas face brick which contain larger amounts of metallic oxides, \r\n typically up to 35%, have specific heats ranging between 0.22 to 0.26 \r\n Btu/lb/ o F. A value of specific heat of face brick which \r\n may be used when the actual specific heat is not known is 0.24 Btu/lb/ o F. \r\n For building brick or brick containing a \r\n low percentage of metallic oxides, a value of 0.22 Btu/lb/ o F \r\n may be used. Generally red, brown and blue brick contain high amounts \r\n of metallic compounds. \r\n The value of the specific heat for brick \r\n may be assumed for brick masonry. The specific heat of grouted hollow \r\n brick may be approximated by determining the percent of the brick \r\n masonry which is to be grouted, and averaging the specific heat, accordingly. \r\n This may be done by adding the product of the specific heat of face \r\n brick times the fraction of the brick which is solid, at least 0.60, \r\n and the specific heat of grout times the fraction of the brick which \r\n is cored, less than or equal to 0.40. For grouted hollow walls, the \r\n specific heat for the masonry wall may be modified for the grout by \r\n using Equation 1: \r\n \r\n \r\n c w = [(t b1 X c b1 ) + (t b2 X c b2 )+ (t g X c g )] / (t b1 + t b2 + t g ) (1) \r\n \r\n \r\n \r\n where: c w = Average specific heat of a grouted brick masonry wall, in Btu/lb/ o F. \r\n \r\n \r\n t b1 = Nominal thickness \r\n of the exterior wythe of brick masonry, in inches. \r\n c b1 = Specific heat of the \r\n brick in the exterior brick masonry wythe, in Btu/lb/ o F. \r\n t b2 = Nominal \r\n thickness of the interior wythe of brick masonry, in inches. \r\n c b2 = Specific \r\n heat of the brick in the interior brick masonry wythe, in Btu/lb/ o F. \r\n t g = Nominal thickness of \r\n the grout, in inches. \r\n c g \r\n = Specific heat of the grout, \r\n in Btu/lb/ o F. \r\n \r\n \r\n \r\n \r\n Consider a 14-in. thick brick thermal storage \r\n wall constructed of 4-in. face brick, a 4-in. grouted space and a \r\n 6-in. grouted hollow brick wythe. Although this example is not \r\n representative of typical brick masonry thermal storage components, \r\n it is offered to include the available combinations of brick masonry \r\n construction. The specific heat of the wall assembly components may \r\n be determined by using Table 1 where: \r\n \r\n \r\n t b1 = 4 in., c b1 = 0.24 Btu/lb/ o F \r\n t b2 \r\n = 6 in., c b2 = 0.22 Btu/lb/ o F \r\n t g \r\n = 4 in., c g = 0.20 Btu/lb/ o F \r\n \r\n \r\n \r\n \r\n a These values are representative \r\n of the information available to the Brick Institute of America, and \r\n are typical for brick being manufactured today. These values may vary \r\n by plus or minus 10 % depending on the specific brick being considered. \r\n b Hollow brick are assumed to \r\n be 60 % solid and the core space fully grouted. \r\n c Source is Reference 3. \r\n d The thermal conductivity of \r\n grouted hollow brick should be determined by dual path analysis. Typically \r\n grouted hollow brick, 60 % solid, fully grouted will have a thermal \r\n conductivity of approximately 10 Btu/hr/ o F/ft 2 , per inch. \r\n \r\n The approximate average specific heat \r\n of the wall assembly is found by substituting these values into Equation \r\n 1: \r\n \r\n \r\n c w \r\n = [(4 X 0.24) + (6 X 0.22) + (4 \r\n X 0.20)] / (4 + 6 + 4) \r\n c w \r\n = 0.22 Btu/lb/ o F \r\n \r\n \r\n \r\n Density . The density, r , of brick varies with the type of \r\n clay, the additives used in manufacturing and with the extent of firing. \r\n Generally the longer the firing and the higher the temperature, the \r\n more dense the brick. Typical densities for various brick are provided \r\n in Table 1. These values are average densities. The density for grouted \r\n hollow brick assumes 130 lb per cu ft density brick and 120 lb per \r\n cu ft density grout. Hollow brick may range from 75% to 60 % solid. \r\n This may significantly change the density, however the values provided \r\n in Table 1 are for grouted hollow brick assuming 60% solid. \r\n The density, as the specific heat, of brick \r\n masonry is slightly less than that of brick, however for simplified \r\n effective thermal storage calculations these differences are usually \r\n insignificant. Typically, the maximum amount of mortar in solid brick \r\n or grouted hollow brick walls constructed with full collar joints \r\n would be about 30% of the wall volume; however, considering that mortar \r\n has a density of about 120 lb per cu ft. this results in a less than \r\n 3% reduction in the density of the wall as compared to the density \r\n of the brick. \r\n when considering the use of a grouted hollow \r\n wall, two wythes of masonry constructed with a grouted space in between, \r\n the density of the wall should be approximated by calculation using \r\n Equation 2: \r\n \r\n \r\n r w \r\n = [(t b1 X r b1 ) + (t b2 X r b2 ) + (t g X r g )] / (t b1 + t b2 \r\n + t g ) (2) \r\n \r\n \r\n where: r w = Average density of the wall, in Ib/cu ft. \r\n \r\n \r\n r b1 = Density of \r\n exterior brick, in Ib/cu ft. \r\n r b2 = Density \r\n of interior brick, in Ib/cu ft. \r\n r g = Density of grout, \r\n in Ib/cu ft. \r\n \r\n \r\n \r\n For a 14-in. thick brick thermal storage \r\n wall, constructed of a wythe of 4-in. face brick, a 4-in. grouted \r\n space and a 6-in. grouted hollow brick wythe, the densities may be \r\n selected from Table 1 where: \r\n \r\n \r\n t b1 = 4 in., r b1 = \r\n 130 Ib/cu ft \r\n t b2 \r\n = 6 in., r b2 = 26 Ib/cu ft \r\n t g \r\n = 4 in., r g = 120 Ib/cu ft \r\n \r\n \r\n \r\n By substituting these values into Equation \r\n 2, the average density of the wall, r w , is found to be: \r\n \r\n \r\n r w = [(4 X 130) + (6 X 126) \r\n + (4 X 120)] / (4 + 6 + 4) \r\n r w \r\n = 125 Ib/cu ft \r\n \r\n \r\n \r\n Thermal Conductivity . The thermal \r\n conductivity, k, of brick is discussed in Technical Notes 4 \r\n Revised. Typical values of the thermal conductivity of brick are provided \r\n in Table 1. The thermal conductivity of brick varies with density. \r\n The denser the brick, generally the greater the thermal conductivity. \r\n The thermal conductivity of grouted brick should be determined by \r\n the dual path procedure described in Technical Notes 4 \r\n Revised. \r\n For hollow brick which is grouted, there \r\n are two paths for heat flow, one path is through the webs of the hollow \r\n brick and the other path is through the face shells and grout. The \r\n average thermal resistivity of grouted hollow brick may be determined \r\n by using Equation 3: \r\n \r\n \r\n r h = [(r b X t w ) / l ] + [[(r b \r\n X 2t f ) \r\n + r g x (t - 2t f )] X [( I - t w ) / ( l X t)]] \r\n (3) \r\n \r\n \r\n where: r h = Average \r\n thermal resistivity of grouted hollow brick, in ( o F ft 2 \r\n hr)/Btu. in. \r\n \r\n \r\n r b = Thermal resistivity of brick, in ( o F ft 2 hr)/Btu. in. \r\n r g = Thermal resistivity \r\n of grout, in ( o F ft 2 hr)/Btu. in. \r\n t = Thickness of the brick, in inches. \r\n t f = Thickness of the face shell, in inches. \r\n t w = Total thickness of \r\n the webs, in inches. \r\n / = Length of the brick, in inches. \r\n \r\n \r\n \r\n Considering the thermal resistivities and \r\n thickness of a 6 X 4 X 12 grouted hollow brick: \r\n \r\n \r\n r b = 0.11 ( o F ft 2 hr)/Btu. in. \r\n t = 6 in. \r\n r g \r\n = 0.08 ( o F ft 2 hr)/Btu in. t f = 1.25 in. \r\n / = 12 in. t w = 4 in. \r\n \r\n \r\n \r\n and substituting these values into Equation \r\n 3, the average thermal resistivity of a 6 X 4 X 12 grouted hollow \r\n brick would be: \r\n \r\n \r\n r h = [(0.11 X 4) / 12] + [[(0.11 X 2.50) + 0.08 X (6 - 2.50)] \r\n \r\n X [(12 - 4) / (12 x 6)]] \r\n r h = 0.037 + [[0.275 + 0.280] X 0.11] \r\n r h = 0.098 ( o F ft 2 hr)/Btu in. or approximately \r\n 0.10 ( o F ft 2 hr)/Btu. in. \r\n \r\n \r\n \r\n The average thermal conductivity is the \r\n inverse of the average thermal resistivity. The average thermal conductivity, \r\n k h , for a 6 X 4 X 12 grouted \r\n hollow brick would be: \r\n \r\n \r\n k h = 1/r h (4) \r\n k h = 1/0.10 ( o F ft 2 hr)/Btu in. \r\n k h = 10.00 Btu/hr/ o F/ft 2 per inch of thickness \r\n \r\n \r\n \r\n The average thermal resistivity of a storage \r\n media is the summation of the thermal resistivity times the thickness \r\n of the materials divided by the total thickness. This is expressed \r\n in Equation 5: \r\n \r\n \r\n r w =[(r 1 X t 1 ) + (r 2 X t 2 ) + . . . ] / (t 1 + t 2 + . . . ) (5) \r\n \r\n \r\n where: r w = The average thermal resistivity of the storage media, in ( o F \r\n ft 2 hr)/Btu. in. \r\n \r\n \r\n r = The thermal resistivity of each \r\n component, in ( o F ft 2 hr)/Btu. in. \r\n t = The thickness of each component, \r\n in inches. \r\n \r\n \r\n \r\n Thus consider again the 14-in. grouted hollow \r\n wall constructed of a 4-in. wythe of face brick, a 4-in. grouted space, \r\n and a 6-in. wythe of grouted hollow brick. The nominal thickness and \r\n respective average thermal resistivities of each component would be: \r\n \r\n \r\n t 1 = 4 in., r 1 = 0.11 ( o F \r\n ft 2 hr)/Btu in. \r\n t 2 \r\n = 4 in., \r\n r 2 = \r\n 0.08 ( o F ft 2 hr)/Btu. in. \r\n t 3 \r\n = 6 in., \r\n r 3 = \r\n 0.10 ( o F ft 2 hr)/Btu in. \r\n \r\n \r\n \r\n Substituting these values into Equation \r\n 5, the average thermal resistivity of the wall, r w , is determined to be: \r\n \r\n \r\n r w = [(0.11 x 4) + (0.08 \r\n x 4) + (0.10 x 6)] / (4 + 4 + 6) \r\n r w \r\n = [1.36( o F ft 2 hr)/Btu in.] \r\n / 14 in. \r\n r w \r\n = 0.097 ( o F ft 2 hr)/Btu per \r\n inch of thickness \r\n \r\n \r\n \r\n Thermal Conductance . Thermal conductivity \r\n and thermal resistivity refer to the value of heat loss for one inch \r\n of thickness. The thermal conductance is the value of heat loss for \r\n a specified thickness. The average thermal conductance for a one foot \r\n thickness of the storage media is used in the simplified equations \r\n of heat transfer for determining effective thermal storage. The average \r\n thermal conductance for a one foot thickness of the brick storage \r\n media may be determined using Equation 6: \r\n \r\n \r\n C a = 1 / (r w X 12 in./ft) (6) \r\n where: C a = The average thermal conductance of the storage media for one foot \r\n of thickness. in (Btu/hr/ o F/ft 2 ) / ft. \r\n \r\n \r\n \r\n \r\n The 4-in wythe of face brick, 4-in. grouted \r\n space and 6-in. wythe of grouted hollow brick is calculated to have \r\n a thermal conductance per foot of thickness of: \r\n \r\n \r\n C a = 1 / [0.097 ( o F ft 2 hr) / Btu in. X 12 in./ft] \r\n C a = 0.859 (Btu/hr/ o F/ft 2 ) / ft \r\n \r\n \r\n \r\n Thermal Diffusivity . Typically the \r\n storage capacity of a material is represented by the amount of heat \r\n which can be stored in the material, the heat capacity of the material. \r\n The heat capacity may be determined by using Equation 7: \r\n \r\n \r\n b \r\n = c X r (7) \r\n \r\n \r\n where: b = Heat capacity, in Btu/cu ft/ o F. \r\n Typical values for the heat capacity of \r\n various brick are provided in Table 1. Thermal diffusivity is a function \r\n of the heat capacity and thermal conductance per foot of material \r\n thickness. The thermal diffusivity of a material may be determined \r\n by using Equation 8: \r\n \r\n \r\n d \r\n = C a / b or d \r\n = C a \r\n / (c X r ) (8) \r\n \r\n \r\n where: d = Thermal diffusivity, in ft 2 \r\n /hr. \r\n The values of thermal diffusivity for typical \r\n brick masonry are provided in Table 1. The value of thermal diffusivity \r\n may be used to provide the designer with a better concept of heat \r\n storage in the passive solar energy system thermal storage component. \r\n The use of the thermal diffusivity in simplified heat transfer equations \r\n may provide a more rational approach for selecting the thickness of \r\n thermal storage walls. \r\n The average value of thermal diffusivity \r\n may be determined by using Equation 9: \r\n \r\n \r\n d a \r\n = C a / \r\n (c w X r w ) (9) \r\n \r\n \r\n where: d a = Average thermal diffusivity, in ft 2 /hr. \r\n Thus for the 14-in. thick wall assembly \r\n constructed of 4-in. solid brick wythe, a 4-in. grouted space, and \r\n a 6-in. wythe of grouted hollow brick the average thermal diffusivity \r\n may be determined using Equation 9. C a \r\n for this wall was determined to be 0.859 (Btu/hr/ o F/ft 2 )/ft, r w was determined to be 125 Ib/cu ft and c w = 0.22 Btu/Ib/ o F. \r\n Thus, the average thermal diffusivity would be: \r\n \r\n \r\n d a = 0.859 (Btu/hr/ o F/ft 2 )/ft/(0.22 \r\n Btu/lb/ o F X 125 Ib/cu ft) \r\n d a = 0.031 ft 2 /hr \r\n \r\n \r\n \r\n The value of the average thermal diffusivity \r\n is useful in simplified heat transfer equations, however if precise \r\n values are desired, each component in section should be analyzed individually. \r\n Emissivity . The emissivity of a surface \r\n is its ability to radiate heat to the surroundings. This is the basis \r\n of heat retrieval in passive solar energy systems as discussed here. \r\n The radiant heat from the surface of the brick masonry is what causes \r\n the useable natural flows of thermal energy; i.e., surface to air \r\n conduction, convection between surfaces and radiation to surfaces \r\n and the air, which heat the interior spaces of the building. Typical \r\n values of emissivity for brick are provided in Table 1. \r\n Exposed brick masonry allows the use of \r\n various bond patterns, projections and even sculptured brick work \r\n to increase the aesthetic value of the thermal storage media. Although \r\n at first the idea of leaving the brick exposed seems merely aesthetic, \r\n it does serve a function important to the thermal performance of the \r\n thermal storage media. Brick masonry does not require nor should it \r\n have any coverings; i.e., gypsum wall board, paints, wall papers, \r\n or carpeting which could decrease the emissivity of the surface. The \r\n addition of coatings and coverings not only may reduce the emissivity \r\n of the thermal storage element but will usually decrease the thermal \r\n conductivity thus decreasing the surface temperatures and the amount \r\n of surface radiant heat available. \r\n If the value of emissivity, the surface \r\n temperature of the thermal storage element, and the surface temperature \r\n of the interior materials being radiated to are known, the amount \r\n of radiant thermal energy emitted may be approximated. The approximate \r\n amount of thermal radiation emitted per square foot of thermal storage \r\n surface area may be calculated using Equation 10: \r\n \r\n \r\n q r = [0.174 X e X [T r4 - T c4 ]] / 10 8 (10) \r\n \r\n \r\n where: q r = Radiation, \r\n in Btu/hr/ft 2 \r\n \r\n \r\n e \r\n = Emissivity. \r\n T r = Temperature of the radiant surface measured from absolute \r\n zero, degrees Fahrenheit plus 459.6. \r\n T c = Temperature of the receiving surface measured from absolute \r\n zero, degrees Fahrenheit plus 459.6. For most applications \r\n in passive solar energy systems, the value of T c is usually interior design temperature \r\n in o F plus 459.6, typically 72 o F + 459.6 \r\n or 531.6. \r\n \r\n \r\n \r\n \r\n Consider an average surface temperature \r\n of a radiating surface at 83 o F and an interior design temperature \r\n of 72 o F. Measuring these temperatures from absolute zero \r\n would result in T r \r\n = 83 + 459.6 or 542.6 and T c = 72 + 459.6 or 531.6. The radiation from a dark brown brick wall, with \r\n e = 0.93, \r\n may be determined using Equation 10 to be: \r\n \r\n \r\n q r = [0.174 X 0.93 X [(542.6) 4 - (531.6) 4 ]] / 10 8 \r\n q r \r\n = [0.168 X (8.668 X 10 10 )] / 10 8 \r\n q r \r\n = (1.103 X 10 9 ) / 10 8 \r\n q r \r\n = 11.03 Btu/hr/ft 2 \r\n \r\n \r\n \r\n Absorptivity . The solar absorptivity \r\n of a material is mostly dependent on color. The solar absorptivity \r\n is the ratio between how much solar radiation is absorbed by a material \r\n to that absorbed by a standard black surface. Typically, passive solar \r\n thermal storage components (or any finish applied to such components) \r\n should be as dark a color as possible to provide sufficient energy \r\n absorption. However, trade-offs do exist between color, wall thickness \r\n and the amount of surface area exposed to sunlight. Trade-offs also \r\n exist between darkness of color and how much heat is desired and when \r\n the available heat is wanted. These trade-offs can only be adequately \r\n determined by rigorous analysis and are not recommended for use with \r\n rule-of-thumb approaches. Surfaces (such as frame walls) not being \r\n used for storage should be painted light colors in order to reflect \r\n as much energy as possible to the darker storage material. Although \r\n black is the most desirable storage material color from a thermal \r\n point of view, it has been determined that the darker natural brick \r\n colors (browns, blues and reds) will perform almost as effectively, \r\n without deterioration problems which may result when using paint or \r\n other coverings. Typical values for solar absorptivity of brick are \r\n given in Table 2. Brick with glossy glazed ceramic coatings should \r\n be avoided as they will reflect too great a percentage of the solar \r\n radiation striking them. Several brick manufacturers can supply brick \r\n with dull black ceramic glazed faces, which may increase the solar \r\n radiation absorbed. \r\n \r\n Although it would seem at first glance that \r\n rough-textured brick, by providing more surface area for the collection \r\n of energy, would be more effective than smooth brick as an energy \r\n storage media, but it has been determined that this is not the case. \r\n It appears that brick texture does not have a major impact on the \r\n performance of passive solar installations and that any desired texture \r\n can be used without significant loss or gain in effectiveness. \r\n GLAZING MATERIALS \r\n General \r\n Information regarding the transmittance, \r\n reflectance, absorptance, thermal performance and durability of glazing \r\n materials for passive solar energy systems should be obtained from \r\n the glazing manufacturer. Some general suggestions to assist in the \r\n design and selection of glazing materials for passive solar energy \r\n systems applications are discussed. \r\n Transmittance \r\n The glazing material used should have a \r\n high transmittance, low absorptance and low reflectance of solar radiation. \r\n The high transmittance is important so that the maximum amount of \r\n solar energy may be transmitted to the interior of the passive solar \r\n building where it can be absorbed and stored in the interior brick \r\n masonry. Generally, the higher the transmittance the lower the absorptance \r\n and reflectance. When the glazing is desired to provide specific daylighting \r\n requirements, it may be preferred to use a glazing material which \r\n diffuses the direct solar radiation. \r\n Absorptance \r\n Depending on the glazing material and the \r\n frame assembly, absorptance should be a factor in selecting the glazing \r\n material or a proper framing assembly. The higher the absorptance, \r\n the lower the amount of energy transmitted to the interior. Typically, \r\n the absorptance of most glazing materials is low. The amount of solar \r\n absorptance may be important because of thermal stress that may occur \r\n within the glazing material itself or between the glazing material \r\n and framing assembly. The framing assembly should be such that it \r\n allows for thermal expansion of the glazing material being used to \r\n avoid structural failure of the collector component. \r\n Reflectance \r\n The reflectance of the glazing material \r\n should be kept to a minimum, so that the maximum amount of solar radiation \r\n may be transmitted to the interior. In addition to the consideration \r\n of reflectance, as related to transmittance and maximum solar performance, \r\n reflectance might also require consideration of exterior glare which \r\n may be annoying or even hazardous because of impairing vision. \r\n Thermal Conductivity \r\n Typical values for overall coefficient of \r\n heat transmission of glass are given in Table 3. Table 3 also provides \r\n solar transmittance correction factors for glass. The solar transmittance \r\n correction factors are based on double glass having a solar transmittance \r\n value of 1. Information regarding plastics or other glazing materials \r\n must be obtained from the material manufacturer. \r\n The basic material properties for single, \r\n double and triple glass given in Table 3 may be used as a means of \r\n selecting the appropriate glazing material by considering the trade-offs \r\n between the transmittance and U value. Single glass has about a 21% \r\n increase in transmittance and 124% increase in heat loss, over double \r\n glass, and thus should only be used in lieu of double glass when night \r\n insulation is used. However, triple glass has approximately an 18% \r\n reduction in transmittance and a 37% reduction in heat loss over double \r\n glass and may be used in lieu of double glass with night insulation, \r\n to increase economic feasibility at only a slight reduction in overall \r\n performance. When considering such trade-offs it is extremely important \r\n to consider the specific environmental factors at the site. Triple \r\n glass in lieu of double glass may be excellent in areas of high solar \r\n radiation and cold exterior temperatures, but not effective in areas \r\n of low solar radiation and moderate exterior temperatures. The effectiveness \r\n should be determined by steady-state heat loss calculations and passive \r\n solar performance analysis. \r\n \r\n \r\n \r\n \r\n \r\n aValues may vary with material, see manufacturers \r\n recommendations. \r\n Durability \r\n The durability of the glazing material must \r\n be such that it resists failure due to thermal stresses and that it \r\n does not degrade or discolor when exposed to solar radiation for extended \r\n periods of time. Of course these considerations will vary with economics. \r\n If a material degrades frequently but is inexpensive to replace, it \r\n may be more economical than a more expensive, more durable glazing \r\n material. Additional considerations in selection of a glazing material \r\n may be resistance to impact, and ease of replacement due to breakage. \r\n No matter what glazing material is selected, \r\n the designer should be assured it will maintain an expected condition \r\n that is not detrimental to the performance of the passive solar energy \r\n system for its intended period of use. Materials that discolor or \r\n degrade rapidly and have significant reduction of solar radiation \r\n transmittance should not be used. \r\n METRIC CONVERSION \r\n Because of the possible confusion inherent \r\n in showing dual unit systems in the calculations, the metric (Sl) \r\n units are not given in the examples. Table 13 in Technical Notes \r\n 4 provides metric (Sl) conversion factors \r\n for the more commonly used heat transmission units. \r\n SUMMARY \r\n This Technical Notes provides information \r\n on the component materials for passive solar energy system applications. \r\n This offers a designer or owner sufficient information regarding the \r\n material properties of brick to assist in the design and use of brick \r\n masonry in passive solar applications. Consideration of the properties \r\n of brick masonry could result in a thermal storage media that is an \r\n aesthetic, durable, maintenance free, fire resistant structural component \r\n of a building that provides sound transmission reduction. In addition, \r\n sufficient values of the material properties of brick masonry are \r\n provided for passive solar energy system analysis techniques, manual \r\n or computer calculations. The decision to use the information and \r\n concepts presented in this Technical Notes is not within the \r\n purview of the Brick Institute of America, and must rest with the \r\n designer or owner of any specific project. \r\n REFERENCES \r\n \r\n 1. ASHRAE Handbook and Product Directory, 1977, Fundamentals Volume, American \r\n Society of Heating, Refrigerating and Air-Conditioning Engineers, \r\n Inc., 345 East 47th Street, New York City, New York 10017. \r\n 2 . Brick Masonry for Thermal Storage by Stephen S. Szoke, \r\n a paper presented at \"Passive Solar Building Construction Program,\" \r\n 21-22 November 1980, Madison, Wisconsin. \r\n 3. Brick Walls for Passive Solar Use by G. C. Robinson, C. C. Fain, \r\n Stephen M. Jansen and Paul Harshman, February 1980, Clemson University, \r\n South Carolina. \r\n 4. Chemical Engineers Handbook prepared by a staff of Specialists, \r\n John H. Perry, Ph.D., Editor, Third Edition, 1950, McGraw-Hill Book \r\n Company, Inc., New York, Toronto, and London. \r\n 5. The Chemistry and Physics of Clays and Other Ceramic Materials, by \r\n Alfred B. Searle and Rex W. Grimshaw, Third Edition, 1959, Ernest \r\n Benn Limited, London, England. \r\n 6. Heating and Ventilatings Engineering Handbook by Clifford Strock, \r\n First Edition, 1948, The Industrial Press, New York City, New York. \r\n 7. Proceedings of the Solar Glazing 1979 Topical Conference 22-23 \r\n June 1979 Stockton State College, Pomona, New Jersey, Sponsored \r\n by the Mid-Atlantic Solar Energy Association. \r\n 8. Properties of Engineering Materials by Glenn Murphy, C.E., Ph.D., \r\n Second Edition, 1952, International Textbook Company, Scranton, \r\n Pennsylvania. \r\n 9. Smithsonian Physical Tables by William Elmer Forsythe, Ninth Edition, \r\n 1956, Smithsonian Institute, Washington, D.C. \r\n 10. Thermal Environmental Engineering by James L. Threlkeld, Second \r\n Edition, 1970, Prentice-Hall Inc.. Englewood Cliffs. New Jersey. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60121,"ResultID":176353,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 43G - Brick Passive Solar \r\n Heating Systems - Part 7 - Details and Construction \r\n Mar./Apr. 1981 (Reissued Sept. 1986) \r\n \r\n Abstract : Details and construction of brick masonry for passive \r\n solar energy system applications vary only slightly from conventional \r\n residential and commercial brick masonry construction. Typical construction \r\n details are provided for direct gain and thermal storage wall systems. \r\n These details, with slight modifications, are also applicable for \r\n attached sunspaces. Construction variations from conventional construction \r\n and considerations for compliance with the major model building codes \r\n are also discussed. \r\n Key Words : attached sunspaces, bricks , \r\n building code requirements , details , direct \r\n gain systems, energy, masonry, passive solar energy systems , \r\n thermal storage wall systems. \r\n INTRODUCTION \r\n Brick masonry construction and recommended \r\n details for passive solar energy systems are similar to conventional \r\n residential and commercial brick masonry construction and details. \r\n The general concepts of direct gain systems, attached sunspaces and \r\n thermal storage wall systems are discussed in Technical Notes \r\n 43 . Empirical sizing, rational approaches \r\n for determining the thickness of brick masonry as a storage medium, \r\n material properties and performance calculations are discussed in \r\n other Technical Notes in this series. In these passive solar \r\n applications, brick masonry may be used as a storage medium and structural \r\n component of the building. Brick masonry also offers the capability \r\n for esthetic designs, fire resistance and sound transmission reduction. \r\n These recommended details are presented \r\n in an effort to show as many applications of brick masonry in passive \r\n solar heating systems as possible and are not offered as typical combinations \r\n of details. The details may be slightly varied and different combinations \r\n of the details may be used to satisfy the requirements of any specific \r\n passive solar heated building design. \r\n DIRECT GAIN \r\n General \r\n Details for brick masonry floors and walls \r\n used for thermal storage in direct gain systems are provided in Figs. \r\n 1 through 3. Each of these figures shows a typical connection detail \r\n for the ground floor, interim floors and roof. \r\n Exterior Loadbearing Walls \r\n Exterior loadbearing brick masonry walls \r\n may be constructed as insulated cavity walls to provide an interior \r\n brick masonry wythe for thermal storage and an exterior brick masonry \r\n wythe for durability, as shown in Fig. 1. The brick masonry should \r\n be continuous through all floor intersections so that the brick masonry \r\n bears on the foundation or foundation wall, provides adequate support \r\n and complies with building code fire safety requirements. Where wood \r\n joists frame into brick masonry wall construction, the wood joists \r\n should be fire cut. \r\n \r\n \r\n Cavity Wall Construction \r\n \r\n \r\n FIG. 1 \r\n \r\n The design should consider the local code \r\n requirements for minimum bearing. A thicker interior wythe may be \r\n required for bearing or special provisions incorporated into the detail \r\n so that both the exterior and interior wythes may be used for bearing. \r\n Bearing on both wythes should only be used when other alternatives \r\n are not practical, since there may be difficulty in properly constructing \r\n and detailing such a connection without interfering with the performance \r\n of the cavity wall. Additional information on the design, detailing, \r\n construction and insulating of cavity wall construction is provided \r\n in Technical Notes 21 Series. \r\n Providing clerestories with the appropriate \r\n pitched roof in conjunction with a cathedral type ceiling and exposed \r\n beams or trusswork may allow even the North wall to be exposed to \r\n sunlight and used for thermal storage. This type of detailing may \r\n require consideration of exposed trusses in the roof/ceiling component. \r\n The trusses or other means of eliminating the thrust at the top of \r\n the cavity wall is necessary because the building codes do not allow \r\n lateral thrust on cavity wall construction. When considering the use \r\n of trusses or other members to relieve a cavity wall of this thrust, \r\n the spacing of the trusses or other members should be such that the \r\n interior of the wall is subjected to only minimal shading if it is \r\n to be used as thermal storage for direct gain. \r\n When considering the use of insulated cavity \r\n walls, the exterior wythe of brick masonry is thermally isolated from \r\n the rest of the wall system. Thus, the exterior wythe of the cavity \r\n wall is usually subjected to greater temperature fluctuations than \r\n the interior wythe used for thermal storage. For cavity wall construction, \r\n both the interior and exterior wythes may require expansion joints \r\n for thermal movement. \r\n Exterior Non-Loadbearing Walls \r\n Cavity wall construction may also be used \r\n for exterior non-loadbearing walls. East or West-facing walls may \r\n be positioned in the structure so that they are exposed to morning \r\n or afternoon sunlight for direct gain storage. Typically, passive \r\n solar buildings require a large amount of additional interior mass \r\n which may be unexposed to direct sunlight. This mass provides supplementary \r\n thermal storage, resulting in a thermal flywheel for reduced interior \r\n temperature fluctuations. The interior wythe of the cavity wall may \r\n be considered when determining the amount of additional mass. \r\n Interior Loadbearing Walls \r\n Typical details for interior loadbearing \r\n brick masonry walls are shown in Fig. 2. These details are similar \r\n to conventional loadbearing construction. Wood floor joists bearing \r\n on the brick should be fire cut. \r\n \r\n \r\n Interior Loadbearing \r\n \r\n \r\n FIG. 2 \r\n \r\n A roof construction detail is provided, \r\n offering the option to use a skylight to expose the brick masonry \r\n loadbearing wall to sunlight. The interior brick masonry wall may \r\n be exposed to direct sunlight through South-facing windows and doors, \r\n or a clerestory may be used, depending on the distance from the South-facing \r\n wall. \r\n The use of interior loadbearing brick masonry \r\n construction does not require any special consideration over and above \r\n conventional construction. The only exception is that provisions for \r\n thermal expansion may be required. \r\n Interior Non-Loadbearing Walls \r\n Interior non-loadbearing brick wall construction \r\n is quite similar to conventional brick veneer construction. The brick \r\n veneer should be constructed as shown in Fig. 3. The brick masonry \r\n should be continuous through all floor intersections so that all the \r\n brick masonry bears on the foundation or foundation wall and complies \r\n with building code fire safety requirements. Additional information \r\n on brick veneer construction is provided in Technical Notes \r\n 28 Series. \r\n \r\n \r\n Interior Non-Loadbearing \r\n \r\n \r\n FIG. 3 \r\n \r\n The requirements in Technical Notes \r\n 28 Series apply to interior brick veneer construction, except that \r\n the requirements for the effect of weathering may be disregarded. \r\n The backup material; wood frame, metal stud, etc., should be constructed \r\n as in conventional construction. \r\n If the interior brick veneer is constructed \r\n with wood frame or metal studs without sheathing between the backup \r\n and the brick veneer, the 1-in. airspace between the brick and the \r\n backup, as recommended in Technical Notes 28 Series, may be \r\n eliminated. If the brick veneer is constructed with a framing system \r\n that requires sheathing on the side to be veneered, it is recommended \r\n that a 1-in. airspace be maintained. This provides finger room\" \r\n to facilitate the laying of the brick. The use of the sheathing on \r\n the side of the backup material which is to be veneered may be required \r\n to provide the appropriate structural rigidity of the backup system. \r\n This sheathing may also be used to increase the fire resistance and \r\n sound transmission classification of the wall. \r\n Interior Flooring \r\n Typical details for brick flooring are provided \r\n in Figs. 1 through 6. The interim floor details show mortarless paving, \r\n and the ground floor details show brick masonry set in a mortar bed. \r\n These details are interchangeable. The interim floor detail shown \r\n in Fig. 3 is a typical detail for mortarless brick paving in a sand \r\n bed. The difference in thermal performance of mortarless paving as \r\n compared to paving units set in a mortar bed is insignificant. There \r\n may be a slight reduction in heat transfer from unit to unit, but \r\n this will typically have a negligible effect on overall thermal performance \r\n of the floor system being used as direct gain thermal storage. Paving \r\n units are used as the flooring in the thermal storage wall details, \r\n Figs. 4 through 6. These paving units in combination with glazing \r\n incorporated into the thermal storage wall for daylighting and visual \r\n contact with the exterior may be used to form a direct gain system. \r\n The brick flooring may also be used to achieve the additional interior \r\n mass required by many passive solar heated buildings. \r\n \r\n \r\n \r\n \r\n Solid Brick Thermal Storage \r\n Wall \r\n \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Grouted Hollow Thermal \r\n Storage Walls \r\n \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n The Use of Hollow Brick \r\n in Thermal Storage Walls \r\n \r\n FIG. 6 \r\n \r\n A soft joint should be installed around \r\n the perimeter of the brick paving, mortarless or set in a mortar bed, \r\n to provide relief of the stresses due to thermal movement, deflection \r\n and differential movement between the brick flooring and adjacent \r\n construction. Additional soft joints may be required for thermal expansion. \r\n Supporting brick masonry paving on floor \r\n systems requires sufficient stiffness of the system to adequately \r\n support the additional weight in such a manner as to satisfy the minimum \r\n deflection requirements of the brick paving. For mortarless brick \r\n paving, the maximum deflection should be less than or equal to L/360. \r\n For brick paving set in a mortar bed, the maximum deflection should \r\n be less than or equal to L/600. For wood floor systems supporting \r\n brick flooring, the sizing and spacing of the floor joists should \r\n be adequate to support the additional weight, satisfy the floor joist \r\n structural requirements and the deflection requirements of the brick \r\n flooring. \r\n The floor connection details shown in Figs. \r\n 2 and 3 should be such that the top surface of the brick flooring \r\n is level with other floor finishes. If this is not desirable, or possible, \r\n the appropriate riser distance between the surfaces of the different \r\n floor finishes should be provided to comply with the governing building \r\n code. \r\n The use of brick paving is discussed in \r\n detail in Technical Notes 14B . \r\n The brick flooring may also be constructed by laying face brick in \r\n a rowlock position. Another option is to use reinforced brick masonry \r\n floors, as discussed in Technical Notes 14B . \r\n THERMAL STORAGE WALLS \r\n General \r\n Figures 4 through 6 show the thermal storage \r\n wall being used as a structural component of the building, supporting \r\n various floor and roof systems. These combinations are not typical, \r\n but are offered to demonstrate the various alternatives available. \r\n The thickness required for thermal storage \r\n walls is usually sufficient for the wall to be used as a loadbearing \r\n component of the building without any special considerations. However, \r\n it may be necessary to check the structural adequacy of the wall. \r\n The thermal storage wall may be several \r\n wythes of solid brick, as shown in Fig. 4; solid through-the-wall \r\n units; a grouted cavity wall system, as shown in Fig. 5; or grouted \r\n hollow units or combinations of grouted hollow units and solid units, \r\n as shown in Fig. 6. \r\n Details \r\n Details for solid brick thermal storage \r\n walls are shown in Fig. 4. Corbeling the thermal storage wall to provide \r\n support for the exterior glazing is one way to eliminate the need \r\n for thick foundation walls. Brick masonry may be laid as projected \r\n headers to provide a durable support for attaching the glazing assembly \r\n to the wall. This eliminates the use of combustible materials exposed \r\n to high temperatures for extended periods of time. Projected headers \r\n may provide a durable non-combustible, horizontal separation between \r\n individual floors for multi-story vented thermal storage wall systems. \r\n This may be used to comply with the building code requirements regarding \r\n the fire-stopping of plenums. Vertical separation to provide a means \r\n of closing the sides of the thermal storage wall air space may also \r\n be achieved with projected headers. \r\n Depending upon the structural loads imposed \r\n on the projected headers and to avoid exposing cores, corbeling may \r\n be required, as shown in Fig. 4. The air space between the glazing \r\n and the thermal storage wall should be of a thickness that satisfies \r\n the building code requirements for unreinforced corbeling. If these \r\n limitations cannot be met, an alternate means of support for the glazing \r\n will be required. \r\n Additional glazing is provided in each detail \r\n to show that the thermal storage wall need not be a solid barrier \r\n eliminating any view of the exterior or daylighting. This glazing \r\n may be used as a direct gain collector with interior brick masonry \r\n floors and walls as the thermal storage. \r\n The air space between exterior glazing and \r\n the thermal storage wall may be interrupted at various intervals and \r\n the thermal storage wall made discontinuous, as shown in Fig. 7. This \r\n may be used to incorporate direct gain and thermal storage walls into \r\n a combined system. \r\n Operable or stationary shading devices may \r\n be attached to the structural framing of the glazing assemblies. The \r\n glazing assemblies should be sufficiently anchored to the brick masonry \r\n to accommodate these additional loads. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Vents \r\n If the thermal storage wall is to be vented, \r\n each opening through the thermal storage wall should be approximately \r\n 64 sq in. The length of the opening should be about 4 times the height \r\n of the opening. The vents should occur as sets, one at the top of \r\n the wall directly over one at the bottom of the wall, to facilitate \r\n air flow. The number of sets of vents may be approximated by using \r\n Equation 1. \r\n \r\n \r\n n v = F v [(l w X h w ) / (l v X h v )] (1) \r\n \r\n \r\n \r\n where: n v = approximate \r\n number of sets of vents. \r\n \r\n \r\n F v = vent area factor from \r\n Table 1. \r\n l w = length of the vented \r\n thermal storage wall, in ft. \r\n h w = height of the vented \r\n thermal storage wall, in ft. \r\n I v = length of the vent \r\n opening, in inches, approximately 4 X h v \r\n h v = height of the vent \r\n opening, in inches. \r\n \r\n \r\n \r\n The actual number of sets of vents to be \r\n installed, n v , \r\n should be a whole number. Performance tends to decrease as the percentage \r\n of vent area to wall area increases. The next lower whole number to \r\n n v should typically \r\n be used as the actual number of vents to be installed, if n v \r\n is less than n v plus 0.70. If the value of n v is greater than or equal \r\n to n v \r\n plus 0.70, the next larger whole number would typically be used as \r\n the number of sets of vents to be installed. \r\n Both the vertical and horizontal spacing \r\n of vents will also affect performance. Top vents should be located \r\n as close to the ceiling as possible and the bottom vents as close \r\n to the floor as possible. The vertical distance between top and bottom \r\n vents should be at least 6 ft for full story height vented thermal \r\n storage walls. \r\n The horizontal spacing of vents, s v , may be determined \r\n by using Equation 2. \r\n \r\n \r\n s v = l w / n v \r\n (2) \r\n \r\n \r\n \r\n Example . A 25-ft long vented thermal \r\n storage wall system 8 ft high is expected to supply about 35% of a \r\n buildings heating load, SSF = 0.35. Vent openings are formed by omitting \r\n one and one-half courses of standard modular brick vertically and \r\n two standard modular brick horizontally as shown in Fig. 7. Thus, \r\n the opening has a height of about 4 in. and a length of about 16 in. \r\n The dimensions of the vent opening satisfy the criteria of the length \r\n being approximately 4 times the height and the area being approximately \r\n 64 sq in. If other size brick are used, the courses and number of \r\n brick omitted to meet the area and height-to-length requirements of \r\n the vent opening will vary. \r\n \r\n Locating Vents \r\n \r\n \r\n FIG. 7 \r\n \r\n Using Equation 1, and F v = 1.58 from Table 1 for a \r\n solar savings fraction of 0.35, the approximate number of vents would \r\n be: \r\n \r\n \r\n n v = 1.58 (25 X 8) / (16 \r\n X 4) \r\n n v = 4.94 \r\n \r\n \r\n \r\n Thus, n v is 5 sets of vents to be \r\n installed. \r\n The horizontal spacing of vents may be approximated \r\n by using Equation 2. \r\n \r\n \r\n s v \r\n = 25/5 = 5 ft \r\n \r\n \r\n \r\n The result is that the 25 ft long vented \r\n thermal storage wall should have 5 sets of top and bottom vents, each \r\n having an opening of approximately 64 sq in., spaced horizontally \r\n at 5 ft o.c. \r\n ATTACHED SUNSPACES \r\n The typical details for direct gain thermal \r\n storage and thermal storage walls may be used for attached sunspaces \r\n with only modifications to the glazing details. Depending on the type \r\n of attached sunspace, the thermal storage components may be direct \r\n gain floors and walls or direct gain floors and vented or unvented \r\n thermal storage walls. \r\n CONSTRUCTION \r\n Solid brick masonry used as a thermal storage \r\n medium, as in all brick masonry construction, requires that all head, \r\n bed and collar joints be solidly filled with mortar. Solid brick are \r\n units which are cored less than 25 percent of the gross cross-sectional \r\n area parallel to the bedding plane. In typical running bond or stack \r\n bond construction, the brick should be shoved into full bed joints. \r\n This results in sufficiently filled cores so that there is little \r\n or no effect on the overall thermal performance of the wall. When \r\n soldier courses or projected headers are being considered, uncored \r\n units may be preferred. \r\n Hollow brick are brick units in which the \r\n coring is less than 40 percent and greater than 25 percent of the \r\n gross cross-sectional area in the bedding plane. Hollow brick masonry \r\n used for thermal storage requires all head and collar joints and bedding \r\n surfaces to be solidly filled with mortar and all cores fully grouted. \r\n Projected headers and corbels may best be achieved by combining solid \r\n brick masonry with hollow brick masonry construction. \r\n Grouted hollow walls are discussed in Technical \r\n Notes 17 and 17A . When considering the use of \r\n grouted hollow walls, constructed of two wythes of brick separated \r\n by a fully grouted space, the only control over thickness will be \r\n requirements for adequate thermal storage. Thus, grouted hollow brick \r\n masonry walls may be advantageous when the thickness desired is not \r\n easily achieved by using modular sizes of brick. As in all brick masonry \r\n construction, the brick wythes should have all head and bed joints \r\n solidly filled with mortar. \r\n MISCELLANEOUS CONSIDERATIONS \r\n Thermal Expansion \r\n For most applications of brick masonry as \r\n interior direct gain thermal storage, the temperatures within the \r\n brick masonry will probably range from 72 to 96 o F. Thus, \r\n thermal expansion will not normally be a problem except where long \r\n interior walls or floors are used. Interior brick masonry used for \r\n direct gain thermal storage occurring in lengths longer than 100 ft \r\n or exposed to a higher maximum temperature should be analyzed for \r\n thermal expansion. The thermal expansion of brick masonry is discussed \r\n in Technical Notes 18A . \r\n Thermal storage walls may be subjected to \r\n larger temperature fluctuations than direct gain thermal storage components. \r\n Usually, the difference between the maximum temperature and minimum \r\n temperature at the center of the thermal storage wall is small and \r\n no provision for thermal expansion is necessary. Generally, thermal \r\n expansion need only be considered for long or high thermal storage \r\n walls or for walls exposed to extreme temperature fluctuations. \r\n The maximum mean temperature of brick thermal \r\n storage walls may be determined by using the temperature fluctuation \r\n equation in Technical Notes 43 . \r\n The minimum mean temperature may be determined by using the steady-state \r\n temperature gradient through the wall as discussed in Technical \r\n Notes 7C . \r\n Flashing \r\n Flashing brick masonry thermal storage components \r\n is usually not required because the brick masonry is on the interior \r\n of the building. Cavity walls will require flashing as discussed and \r\n shown in Technical Notes 21B . \r\n Flashing may be required for thermal storage wall systems, depending \r\n on the type of glazing assembly and how it is mounted in front of \r\n the thermal storage wall. \r\n Reinforced Brick Masonry \r\n Reinforced brick masonry, as discussed in \r\n Technical Notes 17 Series, may be required depending on the \r\n structural design loads. For thermal storage walls, this is easily \r\n accomplished by using reinforced grouted hollow brick or reinforced \r\n hollow wall construction. Reinforced brick masonry may be designed \r\n so that the wall will be able to sustain lateral thrust. \r\n Typically in reinforced brick masonry construction, \r\n the reinforcement is both horizontal and vertical, placed as near \r\n to the center of the wall as practical. This, in combination with \r\n the minimum required spacing to sufficiently reinforce a brick masonry \r\n wall does not result in any significant decrease in the walls thermal \r\n performance due to thermal bridges. \r\n Lintels and Sills \r\n The thermal storage wall details provide \r\n several options for constructing lintels and sills. Additional information \r\n on lintels is provided in Technical Notes 17B and 31B . \r\n Information regarding the construction of brick masonry arches is \r\n provided in Technical Notes 31 Series. Brick masonry sill details \r\n are provided in Technical Notes 36 Series, however, most sills \r\n for thermal storage walls do not require a sloped top surface or a \r\n drip since they are not exposed to exterior weather. \r\n Fireplaces \r\n Interior fireplaces may be used to obtain \r\n additional mass to decrease the interior temperature fluctuations. \r\n Brick masonry fireplaces may be incorporated in the thermal storage \r\n component in any of these passive solar heating systems. A fireplace \r\n may be used for direct gain storage or may be constructed in a thermal \r\n storage wall. The design and construction of fireplaces is discussed \r\n in Technical Notes 19 Series. \r\n Glazing \r\n It is desirable that the glazing component \r\n of these passive solar energy systems be operable to facilitate cleaning, \r\n exhausting excess heat, providing a means of egress or a combination \r\n of these. The glazing may be sliding glass doors, awning type windows, \r\n hinged glass doors or other options. Hinged doors installed vertically \r\n or horizontally may greatly facilitate the cleaning of vented or unvented \r\n thermal storage wall collectors. \r\n Depending upon building classification, \r\n building codes may require a 3-ft vertical separation between openings \r\n located vertically one above the other. This is not typically a requirement \r\n for residential buildings, or any building under 3 stories in height. \r\n METRIC CONVERSION \r\n Because of the possible confusion inherent \r\n in showing dual unit systems in the calculations, the metric (SI) \r\n units are not given in this Technical Notes. Table 13 in Technical \r\n Notes 4 provides metric (SI) conversion \r\n factors friar the more commonly used units. \r\n SUMMARY \r\n This Technical Notes provides information \r\n on the construction and detailing of brick masonry thermal storage \r\n components for passive solar energy systems. The information, recommendations \r\n and details contained in this Technical Notes are based on \r\n the available data and experience of the Institutes technical staff. \r\n They should be recognized as suggestions and recommendations for the \r\n consideration of the designers and owners of buildings when using \r\n brick in passive solar energy applications. \r\n All of the possible variations cannot be \r\n covered in a single Technical Notes. However, it is believed \r\n that the information is presented in a form such that specific details \r\n are interchangeable. The final decision for details to be used is \r\n not within the purview of the Brick Institute of America, and must \r\n rest with the project designer, owner or both. \r\n REFERENCES \r\n 1. Passive \r\n Solar Design Handbook , Volume Two of Two Volumes: Passive Solar \r\n Design Analysis, January 1980, prepared by Los Alamos Scientific Laboratory, \r\n University of California, J. Douglas Balcomb, Dennis Barley, Robert \r\n McFarland, Joseph Perry, Jr., William Wray and Scott Noll, prepared \r\n for the U.S. Department of Energy, Office of Solar Applications, Passive \r\n and Hybrid Solar Buildings Program, Washington, D.C. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60122,"ResultID":176354,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 44 - Anchor Bolts for Brick \r\n Masonry \r\n April 1986 \r\n \r\n Abstract: Anchor bolts are used extensively in brick masonry to make \r\n structural attachments and connections. To date, a limited amount of information \r\n has been available to aid designers in the selection and design of anchor \r\n bolts in brick masonry. This Technical Notes addresses the types \r\n of anchor bolts available, detailing of anchor bolt placement and suggested \r\n design procedures. A discussion of current and proposed codes and standards \r\n is also presented. \r\n Key Words: anchors , bolts , \r\n conventional anchors (bent bar, plate, sleeve, wedge), edge \r\n distance , headed bolts, loads, proprietary anchors \r\n (adhesive, expansion), shear , tension , through bolts. \r\n INTRODUCTION \r\n Anchor bolts are used in masonry construction \r\n with few or no guidelines for the practicing designer to follow. This \r\n Technical Notes offers basic information covering 1) the types \r\n of anchor bolts available for structural applications in brick masonry, \r\n 2) typical details of proper anchor bolt installation, 3) suggested allowable \r\n anchor bolt design loads and 4) the current and proposed codes and standards \r\n governing anchor bolts in brick masonry construction. \r\n In new masonry construction, anchor bolts are \r\n commonly embedded in walls and columns to support beams, plates and ledgers. \r\n In prefabricated panel construction, anchor bolts are used to facilitate \r\n connections to the structural frame. Renovation and rehabilitation of \r\n existing masonry structures usually require that anchor bolts be used \r\n to attach stair risers, elevator tracks and various frame assemblages \r\n for equipment installation. This is only a fraction of the possible uses \r\n of anchor bolts in masonry construction and with the increase of new, \r\n innovative architectural masonry designs, the uses of anchor bolts in \r\n masonry construction are likely to increase. \r\n This Technical Notes is the first \r\n in a series on masonry anchors, fasteners and ties, and addresses anchor \r\n bolts for brick masonry. Other Technical Notes in this series will \r\n address brick masonry fasteners and ties. \r\n ANCHOR BOLT TYPES \r\n Anchor bolts can be divided into two major groups: \r\n conventional (unpatented) anchors and proprietary (patented) anchors. \r\n Conventional anchor bolts are usually embedded in the masonry during construction \r\n and require careful attention to bolt location and grip length requirements \r\n to avoid problems with connection alignment and erection. Proprietary \r\n anchors, however, are typically installed after completion of construction \r\n and therefore, permit a larger degree of freedom in anchor placement. \r\n For this reason, proprietary anchors are becoming popular in masonry construction \r\n and add new concerns in the area of anchor bolt design. \r\n Conventional Anchor Bolts \r\n Conventional bolts are usually made to the specific \r\n project requirements by steel fabricators or they may be purchased in \r\n standard sizes (diameters and lengths) from steel suppliers. The availability \r\n and cost of conventional bolts are generally based on demand and fabrication \r\n requirements. The types of conventional anchor bolts most often used are \r\n discussed below. \r\n Headed Bolts. Square or hex-headed ASTM \r\n A 307 bolts are frequently used as anchor bolts due to their wide availability \r\n and relatively low cost (see Figure 1). Higher strength bolts, such as \r\n ASTM A 325 bolts, are available and can be used, but are more expensive. \r\n A washer placed against the bolt head is often used with the intention \r\n of increasing the bearing area and thus increasing the anchor strength. \r\n However, the actual strength increase obtained by adding a washer is small, \r\n if any, and under certain conditions (small edge distances), may actually \r\n decrease the tensile strength. \r\n \r\n \r\n \r\n \r\n Headed Bolts \r\n \r\n FIG. 1 \r\n \r\n Bent Bar Anchors. Bent bar anchors, frequently \r\n used in masonry construction, are usually made in \"J\" or \"L\" shapes (see \r\n Fig. 2). Even though the \"J\" and \"L\" shapes are the more popular, a variety \r\n of shapes (see Fig. 3) is available since there currently is no standard \r\n governing the geometric properties of bent bar anchors. These anchors \r\n are usually made from ASTM A 36 bar stock and are shop-threaded. \r\n \r\n \"L\" and \"J\" Bent Bar Anchors \r\n \r\n \r\n FIG. 2 \r\n \r\n \r\n Other Bent Bar Anchors \r\n \r\n \r\n FIG. 3 \r\n \r\n Plate Anchors. Plate anchors are usually \r\n made by welding a square of circular steel plate perpendicular to the \r\n axis of a steel bar that is threaded on the opposite end (see Fig. 4). \r\n There are no standards governing the dimensions (length, width or diameter) \r\n of the plate. The American Institute of Steel Construction does limit \r\n the fillet weld size based on the plate thickness (see Table 1). Both \r\n the plate and bar are usually made from ASTM A 36 steel. \r\n \r\n Plate Anchors \r\n \r\n FIG. 4 \r\n \r\n \r\n Through Bolts. As the name implies, through \r\n bolts extend completely through the thickness of the masonry and are composed \r\n of a threaded rod or bar with a bearing plate located on the surface opposite \r\n the attachment (see Fig. 5). In the early 1900s, through bolts were used \r\n in loadbearing masonry structures to tie floor and wall systems together. \r\n Often decorative cast bearing plates were used since through bolts were \r\n visible on the exterior masonry surfaces (see Fig. 6). Today, through \r\n bolts are primarily used in industrial construction where aesthetics are \r\n not a principal concern, or in retrofitting existing structures. Through \r\n bolt rods are usually made from ASTM A 307 threaded rod or threaded ASTM \r\n A 36 bar stock. Bearing plates are typically made from ASTM A 36 steel \r\n plate. \r\n \r\n \r\n \r\n \r\n Through Bolt \r\n \r\n FIG. 5 \r\n \r\n \r\n Decorative Through Bolt Bearing \r\n Plate \r\n \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n * American Institute of Steel Construction \r\n \r\n \r\n Proprietary Anchor Bolts \r\n Proprietary anchors are available through a \r\n number of manufacturers under numerous brand names. Although the style \r\n and physical appearance of the anchors differ between manufacturers, the \r\n basic theories behind the anchors are very similar. For this reason, proprietary \r\n anchors can be divided into two generic categories: expansion-type anchors \r\n and adhesive or chemical-type anchors. \r\n Expansion Anchors. Two different types \r\n of expansion anchors are generally recommended by their manufacturers \r\n for use in brick masonry: the wedge anchor and the sleeve anchor (see \r\n Fig. 7). These anchors develop their strength by means of expansion into \r\n the base material. Wedge anchors develop their hold by means of a wedge \r\n or wedges that are forced into the base material when the bolt is tightened. \r\n The wedges create large point bearing stresses within the hole; therefore, \r\n this anchor requires a solid base material to develop its full capacity. \r\n For this reason, voids formed by brick cores and partially filled mortar \r\n joints in some brick masonry may make the construction unsuitable for \r\n wedge anchor installation. \r\n \r\n \r\n \r\n \r\n Proprietary Expansion Anchors \r\n \r\n \r\n FIG. 7 \r\n \r\n Sleeve anchors develop their strength by the \r\n expansion of a cylindrical metal sleeve or shield into the base material \r\n as the bolt is tightened. The expansion of the sleeve along the length \r\n of the anchor provides a larger bearing surface than the wedge anchor, \r\n and is less affected by irregularities and voids in the base material \r\n than is the wedge anchor. For this reason, sleeve anchors are recommended \r\n by their manufacturers for use in brick masonry more often than wedge \r\n anchors. \r\n Drop-in and self-drilling anchors (see Fig. \r\n 8) are two other types of expansion anchors available, but are typically \r\n not recommended by their manufacturers for use in masonry. The reason \r\n for this is due to the embedment and setting characteristics of the two \r\n anchors. Both anchors are produced to allow shallow embedment depths and \r\n are expanded or set by an impact setting tool. The combination of shallow \r\n embedment and high stresses imparted by the expansion tend to cause cracking \r\n or splitting in masonry. Depending on the extent of cracking or splitting, \r\n the anchor could experience a reduction in load-carrying capacity or undergo \r\n complete failure during installation. \r\n \r\n Other Proprietary Expansion \r\n Anchors \r\n \r\n FIG. 8 \r\n \r\n There are several considerations that should \r\n be examined when contemplating the use of expansion-type anchors in brick \r\n masonry. These are: 1) Expansion anchors should not be used to \r\n resist vibratory loads. Vibratory loads tend to loosen expansion anchors. \r\n 2) Specific torques are required to set expansion anchors. Excessive torque \r\n can reduce anchor strength or may lead to failure as excessive torque \r\n is applied. 3) Expansion anchors require solid, hard embedment material \r\n to develop their maximum capacities. Some brick construction may not provide \r\n a good embedment material due to voids formed by brick cores and partially \r\n filled mortar joints. \r\n Adhesive Anchors. Two basic types of \r\n adhesive anchors are currently available. The major difference between \r\n the two is that one anchor is manufactured as a pre-mixed, self-contained \r\n system, whereas the second type requires measurement and mixing of the \r\n epoxy materials at the time of installation. The more popular self-contained \r\n types use a double glass vial system (see Fig. 9) to contain the epoxy. \r\n The outer vial contains a resin and the inner vial contains a hardener \r\n and aggregate. The glass vial is placed in a pre-drilled hole and a threaded \r\n rod or bar is driven into the hole with a rotary hammer drill, breaking \r\n the vials and mixing the adhesive components. The other type of adhesive \r\n anchor requires that the epoxy components be hand-measured and mixed before \r\n the epoxy is placed into a pre-drilled hole. A threaded rod or bar is \r\n then set into the epoxy mixture, as shown in Fig. 10. Adhesive epoxies \r\n usually vary slightly between manufacturers, but the steel rods or bars \r\n are typically ASTM A 307 or ASTM A 325 threaded rod, or ASTM A 36 shop-threaded \r\n bar. \r\n \r\n Self-Contained Adhesive Anchor \r\n \r\n \r\n FIG. 9 \r\n \r\n \r\n \r\n \r\n Site-Mixed Adhesive Anchor \r\n \r\n \r\n FIG. 10 \r\n \r\n There are special requirements and limitations. \r\n that should be considered when contemplating the use of adhesive anchors \r\n in brick masonry. They are: 1) Specially designed mixing and/or setting \r\n equipment may be required. 2) Dust and debris must be removed from \r\n the pre-drilled holes to insure proper bond between the adhesive and base \r\n material. 3) The adhesive mixture tends to fill small voids and irregularities \r\n in the base material. 4) Large voids (due to brick cores, intentional \r\n air spaces and partially filled joints) may cause reductions in anchor \r\n capacities. This is especially true with the self-contained adhesive anchors \r\n since a limited volume of epoxy is available to fill the voids and provide \r\n a bond to the anchor. 5) The adhesive bond strength is reduced at elevated \r\n temperatures and may also be adversely affected by some chemicals (see \r\n Table 2 and Fig. 11). \r\n \r\n \r\n \r\n \r\n aThe manufacturer should always be consulted \r\n when adhesive anchors are to be used in areas where contact with chemicals \r\n is likely. \r\n \r\n \r\n \r\n \r\n Effect of Temperature on Ultimate \r\n Tensile Capacity \r\n \r\n FIG. 11 \r\n \r\n INSTALLATION DETAILS \r\n Conventional Anchor Bolts \r\n Typical embedment details for each type of conventional \r\n anchor used in grouted collar joint construction are shown in Fig. 12. \r\n The conventional embedded anchors (headed bolts, bent bar and plate anchors) \r\n are usually placed at the intersection of a head joint and bed joint. \r\n By using this location, the brick units adjacent to the anchor can be \r\n chipped or cut to accept the anchor without altering the joint thickness. \r\n \r\n Conventional Anchors in Grouted \r\n Collar Joints \r\n \r\n FIG. 12 \r\n \r\n Typical embedment details of conventional anchors \r\n in multi-wythe brick construction are shown in Fig. 13. A brick, or portion \r\n of a brick, is left out of the inner wythe to form a cell for the embedded \r\n anchor (Fig. 14). After the anchor is placed, the cell is filled with \r\n mortar or grout prior to placement of the next course. \r\n \r\n Conventional Anchors in Multi-Wythe \r\n Brick Masonry \r\n \r\n FIG. 13 \r\n \r\n \r\n Plan View of Grout Cell in \r\n Multi-Wythe Brick Masonry \r\n \r\n FIG. 14 \r\n \r\n In hollow brick construction, the units are \r\n laid so that the cells are aligned and provide continuous channels for \r\n reinforcing steel placement and for grouting. Depending on the design, \r\n every cell or intermittent cells may be reinforced and grouted (see Technical \r\n Notes 41 Revised). The anchor embedment \r\n detail will depend on the reinforcing pattern used in the construction. \r\n Figure 15 shows typical embedment details for conventional anchors embedded \r\n between reinforcing cells. The anchor should be solidly surrounded vertically \r\n and horizontally by grout for a minimum distance of twice the embedment \r\n depth (1 b ) (Figs. 14 and 15) for full tension cone development. The tension cone \r\n theory is discussed in following sections. This may require that some \r\n cells be partially grouted. A wire mesh screen can be placed in the bed \r\n joint across cells that are to be partially grouted to restrict the grout \r\n flow beyond a certain point. Figure 16 shows typical embedment details \r\n for conventional anchors embedded in reinforced cells. In this detail, \r\n the anchor may be tied with wire to the reinforcing to secure the anchor \r\n during the grouting process. Again, the anchor should be solidly surrounded \r\n by grout to a minimum distance of twice the actual anchor embedment depth, \r\n both vertically and horizontally. \r\n \r\n Conventional Anchors in Reinforced \r\n Hollow Brick \r\n \r\n FIG. 15 \r\n \r\n \r\n \r\n \r\n \r\n Conventional Anchors in Partially Grouted \r\n Hollow Brick \r\n \r\n FIG. 16 \r\n \r\n Two typical embedment details for conventionally \r\n embedded anchor bolts installed in composite brick and concrete block \r\n construction are shown in Fig. 17. As shown, anchor bolts may be placed \r\n in the collar joint between the brick and block wythes or placed into \r\n cells in the concrete block wythe and grouted into place. In details similar \r\n to Fig. 17(a), the anchor bolt type and diameter may be controlled by \r\n the width of the collar joint. Collar joints should be a minimum of 1 \r\n in. (25 mm) wide when fine grout is used, or a minimum of 2 in. (50 mm) \r\n wide when coarse grout is used (see Technical Notes 7A \r\n Revised). When the collar joint dimension is in the 1 in. (25 mm) range, \r\n it may become difficult to position anchor bolts in the collar joint and \r\n maintain the recommended clear distance between the masonry and the anchor \r\n (Fig. 17). The practice of using soaps to accommodate anchors larger than \r\n the collar joint is not recommended because the reduction in the brick \r\n masonry thickness around the anchor could lead to strength reductions. \r\n If the anchor dimensions required are larger than the collar joint, a \r\n detail similar to that shown in Fig. 17(b) should be considered. \r\n \r\n \r\n Conventional Anchors in Composite \r\n Brick/Block Masonry \r\n \r\n FIG. 17 \r\n \r\n Through bolts are typically installed after \r\n construction and grouting by drilling through the completed masonry work. \r\n When through bolts are to be installed after construction in reinforced \r\n brick masonry, care should be taken during installation to avoid cutting \r\n or damaging reinforcement while drilling the through bolt holes. Reinforcing \r\n bar locations can be identified by specially tooled joints or other marks \r\n made during construction. \r\n Proprietary Anchors \r\n Proprietary expansion and adhesive anchors typically \r\n require special installation procedures and equipment. The manufacturer \r\n should be contacted to determine the appropriate anchor for a particular \r\n application, the correct installation procedure and if any special installation \r\n equipment is required. Improper application and installation of proprietary \r\n anchors may lead to less than satisfactory structural performance. \r\n Typical proprietary anchor details are shown \r\n in Fig. 18. It is suggested that proprietary anchors be embedded in head \r\n joints when facing or building brick are used. This reduces the possibility \r\n of placing anchors in brick cores that occur within the thickness of the \r\n brick and adjacent to the bed joint surfaces. Anchors set in grouted hollow \r\n brick should be placed in holes drilled in the bed joints so that they \r\n intersect grouted cells, or should be placed in holes drilled through \r\n the faces of the units into the grouted cells. As with conventional anchors, \r\n proprietary anchors should be solidly surrounded vertically and horizontally \r\n by grout for a minimum distance of twice their embedment depth. \r\n \r\n Typical Proprietary Anchor \r\n Details \r\n \r\n FIG. 18 \r\n \r\n ANCHOR BOLT DESIGN \r\n Anchor bolts are used as a means of tying structural \r\n elements together in construction and therefore, provide continuity in \r\n the overall structure. In virtually all applications, anchor bolts are \r\n required to resist a combination of tension and shear loads acting simultaneously \r\n due to combinations of imposed dead loads, live loads, wind loads, seismic \r\n loads, thermal loads and impact loads. For this reason, and also to insure \r\n safety, anchor bolt details should receive the same design considerations \r\n as would any other structural connection. However, due to a lack of available \r\n research and design guides, anchor bolt designs are based largely on past \r\n experience with very little engineering backup. This situation may lead \r\n to conservative, uneconomical designs at one extreme, or nonconservative \r\n designs at the other. \r\n Recently, however, research investigating the \r\n strength of conventional and proprietary anchors in masonry has been completed. \r\n Reports have been issued that evaluate anchor performance and suggest \r\n equations to predict ultimate anchor strengths. By combining the research \r\n findings with design practices currently used in concrete design, equations \r\n for allowable tension, shear and combined tension/shear loads for plate \r\n anchors, headed bolts and bent bar anchors are under consideration for \r\n adoption in the proposed \"Building Code Requirements for Masonry Structures\" \r\n (ACI/ASCE 530). These equations are outlined below. \r\n Tension \r\n \r\n The tensile capacity of an anchor \r\n is governed either by the strength of the masonry or by the strength of \r\n the anchor material. For example, if the embedded depth of an anchor is \r\n small relative to its diameter, a tension cone failure of the masonry \r\n is likely to occur. However, if the embedded depth of the anchor is large \r\n relative to its diameter, failure of the anchor material is likely. For \r\n these reasons, the allowable tensile load is based on the smaller of the \r\n two loads calculated for the masonry and anchor material. Thus, the allowable \r\n load in tension is the lesser of: \r\n \r\n \r\n \r\n \r\n \r\n or \r\n \r\n where: T A = Allowable tensile load, lb, \r\n A p = Projected area of the masonry \r\n tension cone, in. 2 , f m = \r\n Masonry prism compression strength (In composite construction, when the \r\n masonry cone intersects different materials, f m should be based on the weaker material), \r\n psi, \r\n A B = Anchor gross cross-sectional \r\n area, in. 2 , \r\n f y = Anchor steel yield strength, \r\n psi. \r\n \r\n \r\n The value of A p in Eq. 1 is the area of a circle formed \r\n by a failure surface (masonry cone) assumed to radiate at an angle of \r\n 45 o (see Fig. 19) from the anchor base. When an anchor is embedded \r\n close to a free edge, as shown in Fig. 20, a full masonry cone cannot \r\n be developed and the area A p must be reduced so as not to over-estimate the masonry capacity. Thus, \r\n the area A p , \r\n in Eq. 1 will be the lesser of: \r\n \r\n \r\n or \r\n \r\n \r\n where: A p = Projected \r\n area of the masonry tension cone, in. 2, \r\n \r\n 1 b = Effective embedded anchor length, in., \r\n 1 be = Distance to a free edge, in. \r\n \r\n \r\n \r\n \r\n \r\n \r\n Full Masonry Tension Cone \r\n \r\n \r\n FIG. 19 \r\n \r\n \r\n Reduced Masonry Tension \r\n Cone \r\n \r\n FIG. 20a \r\n \r\n \r\n \r\n Reduced Masonry Tension Cone \r\n FIG. 20b \r\n \r\n The effective anchor embedded length (1 b ) is the length of embedment \r\n measured perpendicular from the surface of the masonry to the plate \r\n or head for plate anchors or headed bolts. The effective embedded length \r\n of bent bar bolts (1 b ) \r\n is the length of embedment measured perpendicular from the surface of \r\n the masonry to the bearing surface of the bent end minus one bolt diameter. \r\n Where the projected areas of adjacent anchors overlap, A p of each bolt is reduced by one-half \r\n of the overlap area. Also, any portion of the projected cone falling \r\n across an opening in the masonry (i.e., holes for pipes or conduits) \r\n should be deducted from the value of A p calculated in Eqs. 3 or 4. \r\n Shear \r\n The allowable shear load is based on the same \r\n logic as the allowable tension load. That is, the anchor capacity is \r\n governed by either the masonry strength or the anchor material strength. \r\n The distance between an anchor and a free masonry edge has an effect \r\n on the masonry shear capacity. Calculations have shown that for edge \r\n distances less than twelve times the anchor diameter, the masonry shear \r\n strength controls the anchor capacity. (Calculations based on masonry \r\n with f m = 1000 psi and anchor steel yield strength \r\n with f y \r\n = 60 ksi. Therefore, where the edge distance equals or exceeds 12 anchor \r\n diameters. the allowable shear load is the lesser of: \r\n \r\n \r\n \r\n or \r\n \r\n \r\n \r\n where: V A = Allowable shear load, lb. \r\n When anchors are located less than 12 anchor \r\n diameters from a free edge, the allowable shear load is determined by \r\n linear interpolation from a value of V A obtained in Eq. 5 at an edge distance of 12 anchor diameters \r\n to an assumed value of zero at an edge distance of 1 in. (25 mm). This \r\n takes into consideration the reduction in the masonry shear capacity \r\n due to the edge distance. \r\n Combined Tension and Shear \r\n Allowable combinations of tensile and shear \r\n loads are based on a linear interaction equation between the allowable \r\n pure tension and pure shear loads calculated in Eqs. 1, 2, 5 and 6. \r\n Anchors subjected to combinations of tension and shear are designed \r\n to satisfy the following equation: \r\n \r\n \r\n T / T A + V / V A ┬ú 1.0 (Eq. \r\n 7) \r\n where: T = Applied tensile load, lb., \r\n \r\n V = Applied shear load, lb. \r\n \r\n \r\n Proprietary Anchor Bolts \r\n The allowable load equations previously presented \r\n are intended for use with plate anchors, headed bolts and bent bar anchors \r\n and have been proposed to the ACI/ASCE 530 Committee on Masonry Structures. \r\n However, when the allowables from these equations are compared to test \r\n results for proprietary anchors, they appear to produce acceptable safety \r\n factors. \r\n Allowable Loads. Average factors of \r\n safety are 4.0 for tensile tests and 5.0 for shear tests on proprietary \r\n anchors. The combined tension/shear interaction equation produced an \r\n average safety factor of 7.0 when compared to test results on proprietary \r\n anchors. Therefore, based on comparison to test results, the allowable \r\n load equations proposed in this Technical Notes are suggested \r\n for use in the design of proprietary anchors in brick masonry. The embedment \r\n depth used to calculate the allowable load values should be equal to \r\n the embedded depth of the proprietary anchor. \r\n Edge Distance. Edge distance is of \r\n particular concern when expansion anchors are used in brick masonry, \r\n due to lateral expansion forces produced when the anchors are tightened. \r\n These forces are often large enough to cause cracking or spelling of \r\n the brick when edge distances become small. To date, no research has \r\n been conducted in this area. Therefore, due to the lack of information, \r\n it is suggested that a minimum edge distance of 12 in. (300 mm) be maintained \r\n when expansion anchors are installed in brick masonry. \r\n Through Bolts \r\n There are no known published reports available \r\n addressing the strength characteristics of through bolts in brick masonry. \r\n However, based on the conservatism in the allowables for bent bar anchors \r\n and proprietary anchors, the allowable load equations should provide \r\n acceptable allowable load values for through bolts used in brick masonry. \r\n The embedment depth used to calculate the allowable load values should \r\n be taken as equal to the actual thickness of the masonry. \r\n Current Codes and Standards \r\n At the present time, one model code and one \r\n design standard contain provisions for anchor bolt design in brick masonry. \r\n The BIA Standard, Building Code Requirements for Engineered Brick \r\n Masonry, and the Uniform Building Code cover design allowables \r\n and embedment depths for anchors loaded in shear. There are no provisions \r\n for axial tensile loads or combined tension/shear loads in these documents. \r\n Tables 3 and 4 show the allowable shear loads and minimum embedment \r\n depths from the two documents. The values in Table 4(a) are based on \r\n rational analysis and in Table 4(b) on empirical analysis. As can be \r\n seen, the tables are very similar and are generally more conservative \r\n than the allowable shear loads obtained from Eqs. 5 and 6 for the same \r\n embedment depths (Table 5). \r\n \r\n \r\n \r\n \r\n \r\n \r\n * From Building Code Requirements \r\n for Engineered Brick Masonry, Brick Institute of America, \r\n August 1969. \r\n 1 In determining the stresses \r\n on brick masonry, the eccentricity due to loaded bolts and anchors \r\n shall be considered. \r\n 2 Bolts and anchors shall \r\n be solidly embedded in mortar or grout. \r\n 3 No engineering or architectural \r\n inspection of construction and workmanship. \r\n 4 Construction and workmanship \r\n inspected by engineer, architect or competent representative. \r\n \r\n \r\n \r\n \r\n * Reproduced from the Uniform Building \r\n Code, 1985 Edition, Copyright 1985 with permission of the publisher, \r\n The International Conference of Building Officials.\" \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n *American Concrete Institute/American \r\n Society Of Civil Engineers Committee 530 on Masonry Structures. \r\n \r\n 1 Assuming: fm = 2,000 psi \r\n \r\n \r\n ASTM A36 steel fy = 36 ksi \r\n Edge Distance = 12 Bolt Diameters \r\n \r\n \r\n \r\n \r\n \r\n SUMMARY \r\n This Technical Notes is the \r\n first in a series on brick masonry anchors, fasteners and ties. It covers \r\n anchor bolt types, detailing and allowable loads for anchor bolts in \r\n brick masonry. Other Technical Notes in this series will address \r\n brick masonry fasteners and ties. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the technical staff of the Brick Institute of America. \r\n The information and recommendations contained herein should be used \r\n along with good technical judgment and an understanding of the properties \r\n of brick masonry. Final decisions on the use of the information discussed \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project designer, owner \r\n or both. \r\n REFERENCES \r\n \r\n 1. Manual of Steel Construction, 8th Edition, American Institute of \r\n Steel Construction, Inc., Chicago, Illinois, 1980. \r\n 2. Whitlock, A.R. and Brown, R.H., Strength of Anchor Bolts in Masonry, \r\n NSF Award No. PRF-7806095, \"Cyclic Response of Masonry Anchor Bolts\", \r\n August 1983. \r\n 3. Brown, R.H. and Dalrymple, G.A., Performance of Retrofit Embedments \r\n in Brick Masonry, NSF Award No. CEE-8217638, \"Static and Cyclic \r\n Behavior of Masonry Retrofit Embedments (Earthquake Engineering)\", Report \r\n No. 1, April 1985. \r\n 4. Hatzinikolas, M.; Lee, R.; Longworth, J. and Warwaruk, J., \"Drilled-In \r\n Inserts in Masonry Construction\", Alberta Masonry Institute, Edmonton, \r\n Alberta, Canada, October 1983. \r\n 5. Building Code Requirements for Engineered Brick Masonry, Brick \r\n Institute of America, McLean, Virginia, August 1969. \r\n 6. Uniform Building Code, International Conference of Building Officials, \r\n Whittier, California, 1985. \r\n 7. Technical Notes on Brick Construction 17 \r\n Revised, \"Reinforced Brick Masonry, Part I of IV\", Brick Institute of \r\n America, McLean, Virginia, October 1981. \r\n 8. Technical Notes on Brick Construction 41 \r\n Revised, \"Hollow Brick Masonry-Introduction\", Brick Institute of America, \r\n McLean, Virginia, 1983. \r\n 9. Specification for the Design and Construction of Load-Bearing Concrete \r\n Masonry, National Concrete Masonry Association, McLean, Virginia, \r\n April 1971. \r\n 10. The BOCA Basic/National Building Code, 9th Edition, Building Officials \r\n and Code Administrators, International, Country Club Hills, Illinois, \r\n 1984. \r\n 11. Standard Building Code, Southern Building Code Congress, International, \r\n Inc.. Birmingham, Alabama, 1985. \r\n 12. Technical Notes on Brick Construction 7A \r\n Revised, \"Water Resistance of Brick Masonry-Materials, Part II of III\", \r\n Brick Institute of America, Reston, Virginia, 1985. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60123,"ResultID":176355,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 44A - Fasteners for \r\n Brick Masonry \r\n May 1986 (Reissued Aug. 1997) \r\n \r\n Abstract: Fasteners are used extensively in brick masonry construction \r\n to attach fixtures, equipment and other objects. This Technical \r\n Notes discusses the different types of fasteners used in brick \r\n masonry construction, their applications, appropriate fastener selection \r\n based on brick type, fixture weight, environmental exposure and \r\n aesthetics. \r\n \r\n Key Words: adhesives, bolts , brick , fasteners , \r\n fixtures, hardware , masonry , screws. \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes is the second in a series that addresses \r\n brick masonry anchor bolts, fasteners and ties. The term \"fastener\", \r\n as used in this text, refers to devices for securing equipment, \r\n fixtures or other objects to brick masonry. This Technical Notes \r\n discusses the different fastener types used to attach these \r\n items to brick masonry. \r\n When other materials, fixtures, etc., are to be attached to brick \r\n masonry, the procedure is relatively simple and can be executed \r\n either during or after construction. The designer or builder has \r\n a wide variety of fastening methods from which to choose. The final \r\n selection will depend largely upon what is to be attached, when \r\n it will be attached and the type of brick used in the construction. \r\n \r\n TYPES OF FASTENERS \r\n \r\n Fasteners can be divided into two general categories: those installed \r\n during the construction of the masonry, and those that are installed \r\n after the completion of the masonry work. \r\n \r\n Fasteners Installed During Construction \r\n \r\n Nailing Blocks and Wall Plugs. Wooden nailing blocks and \r\n metal wall plugs are placed in mortar joints as the brick are laid \r\n (see Figure 1). Wooden nailing blocks are not used today as frequently \r\n as they were in the past, but do provide an acceptable means of \r\n attachment to brick masonry walls. If wooden blocks are used, they \r\n should be of seasoned soft wood to prevent shrinkage and treated \r\n to inhibit deterioration. Wooden blocks should be placed only in \r\n head joints. \r\n \r\n \r\n \r\n Fasteners Installed During Construction \r\n FIG. 1 \r\n \r\n Metal wall plugs are made of galvanized metal, and may contain \r\n wooden or fiber inserts. Metal plugs are preferred over wooden blocks \r\n since problems with shrinkage and decay are not associated with \r\n metal plugs. Metal plugs may be placed in either head joints or \r\n bed joints of masonry. \r\n The primary consideration when using fasteners installed during \r\n construction is location. Their exact location is not a serious \r\n problem when used to attach moldings, such as baseboards, chair \r\n rails, etc., but it may be difficult to predetermine fastener locations \r\n for fixtures, cabinets, shelving, etc. For this reason, post-construction \r\n fasteners have virtually replaced wooden blocks and metal nailing \r\n plugs for fastening to masonry. \r\n \r\n Post-Construction Fasteners \r\n \r\n Screw Shields and Plugs. Screw shields and plugs are produced \r\n in plastic, fiber, rubber, nylon and lead (see Fig. 2). Some are \r\n advertised by their manufacturers as vibration-resistant, chemical-resistant \r\n or water-resistant. These fasteners are generally used for lightweight \r\n attachments and are typically installed in mortar joints or may \r\n be placed directly into solid masonry units (see Fig. 3). \r\n \r\n \r\n \r\n Shields and Plugs \r\n FIG. 2 \r\n \r\n \r\n \r\n \r\n \r\n Shields and Plugs Installed \r\n FIG. 3 \r\n \r\n \r\n \r\n Bolts and Screws. Several types of bolts and screws are available for use in both solid and \r\n hollow masonry. These fasteners are generally used to attach medium \r\n to heavy-weight fixtures. Toggle bolts (made of steel or plastic), \r\n hollow wall screws, small diameter sleeve anchors and screws are \r\n used to attach fixtures to walls constructed of hollow units (see \r\n Fig. 4). These fasteners may be placed in holes drilled through \r\n bed joints or through the unit faces into hollow cells (see Fig. \r\n 5). Small diameter sleeve anchors, wedge anchors, screws and lag \r\n bolt shields (see Fig. 6) are used to attach fixtures to solid masonry \r\n and are usually installed in mortar joints (see Fig. 7). \r\n \r\n \r\n \r\n Fasteners for Hollow Masonry Units \r\n FIG. 4 \r\n \r\n \r\n \r\n \r\n \r\n Fasteners Installed in Hollow Units \r\n FIG. 5 \r\n \r\n \r\n \r\n \r\n \r\n Fasteners for Solid Masonry Units \r\n FIG. 6 \r\n \r\n \r\n \r\n \r\n \r\n Fasteners Installed in Solid Masonry Units \r\n FIG. 7 \r\n \r\n \r\n \r\n \r\n Nails . \r\n Case-hardened cut and spiral nails (masonry nails) are often used \r\n to attach furring strips to masonry walls (see Fig. 8). If used, the \r\n nails should be hammered directly into the mortar joints and not into \r\n the brick units. Caution should be exercised when nails are used in \r\n single-wythe walls with exposed exterior faces. The nails could open \r\n small cracks in the mortar joints, allowing water to penetrate the \r\n wall (see Technical Notes 7F \r\n for problems associated with water penetration). \r\n \r\n \r\n \r\n \r\n Masonry Nails \r\n FIG. 8 \r\n \r\n \r\n \r\n Powder-Driven Fasteners. Powder-driven fasteners are hardened steel pins that are driven \r\n into masonry by means of a powder-actuated tool (Fig. 9). The power \r\n for the tool is provided by a powder charge typically ranging from \r\n .22 to .38 caliber with varying charges, depending on the material \r\n and required pin penetration. Powder-driven fasteners are generally \r\n used on commercial or industrial projects where large volumes of \r\n fasteners are required. Several pin styles and lengths are produced \r\n for different fastening requirements (see Fig. 10). \r\n \r\n \r\n \r\n \r\n Powder-Driven Fastening Tool \r\n FIG.9 \r\n \r\n \r\n \r\n \r\n \r\n Powder-Driven Pins \r\n FIG. 10 \r\n \r\n \r\n \r\n Powder-driven fasteners require special installation equipment, \r\n safety equipment and inspection procedures. For this reason, the \r\n manufacturer should be contacted to determine proper equipment and \r\n installation specifications. \r\n Adhesives. A multitude of adhesives, such as epoxies, mastics \r\n and contact cements, is produced for various bonding applications. \r\n Many of these produce high bond strengths, have short setting times \r\n and offer versatility in bonding different materials. Adhesives \r\n may be used to attach furring, electrical boxes, wall paneling, \r\n etc. (see Fig. 11). The manufacturers literature should be referred \r\n to when determining the suitability of an adhesive for a particular \r\n application. Some adhesives may not bond properly to masonry, may \r\n not have the elasticity required to accommodate movements of dissimilar \r\n materials and may be affected by exposure to weather, chemicals \r\n or temperature extremes. \r\n \r\n \r\n \r\n \r\n \r\n Adhesive Fastening \r\n FIG. 11 \r\n \r\n \r\n \r\n FASTENER SELECTION \r\n \r\n The selection of an appropriate fastener can usually be based on \r\n four considerations: 1) the type of brick used in the construction, \r\n 2) the weight of the attachment, 3) the environmental exposure (i.e., \r\n interior or exterior) and 4) aesthetics. \r\n \r\n Construction and Attachment \r\n \r\n The type of brick used in construction will determine the choice \r\n of a fastener as either a solid or hollow wall type fastener; the \r\n weight of the fixture will determine the size of the fastener required. \r\n The fastener selection chart shown in Table 1 can be used as a general \r\n guide in selecting a fastener type based on the brick type, installation \r\n location and fixture weight. \r\n \r\n \r\n \r\n Environment \r\n \r\n Environmental factors may have a definite impact on the long-term \r\n service life of fasteners and should be considered in their selection. \r\n Environmental factors do not, in general, influence the type of \r\n fastener selected, but should influence the choice of fastener based \r\n on the material from which the fastener is made. Corrosion is a \r\n major concern, especially when fasteners are exposed to the elements \r\n or when fasteners are used in areas where contact with corrosive \r\n agents is likely. \r\n Steel fasteners used for applications under normal exposure conditions \r\n should be galvanized (zinc-coated) to resist corrosion. Lead, copper-coated \r\n or brass fasteners also provide adequate corrosion resistance for \r\n normal exposures. In applications where fasteners are subject to \r\n severe exposure conditions or exposed to chemicals, stainless steel \r\n fasteners should be used. \r\n \r\n Aesthetics \r\n \r\n In most applications, the fastener or fasteners installed will \r\n be hidden by the attachment (i.e., cabinets, baseboards, electrical \r\n boxes or furring), and the physical appearance of the fastener (usually \r\n the head of a screw or bolt) will not be of importance. However, \r\n when fasteners are used to attach privacy partitions, lighting fixtures \r\n or rails, the head of the fastener is usually visible and required \r\n to match or accent the finish of the fixture. In these cases, finished \r\n screws or bolts (i.e., chrome or brass-plated, solid brass or painted) \r\n can be purchased to match the fixtures. The manufacturers should \r\n be contacted to determine the availability and range of finishes \r\n available in their products. \r\n \r\n SUMMARY \r\n \r\n This Technical Notes is the second in a series on brick \r\n masonry anchors, fasteners and ties. It addresses the types of fasteners \r\n available for use in brick masonry construction. Other Technical \r\n Notes in this series address brick masonry anchor bolts and \r\n wall ties. \r\n The products described in this Technical Notes may involve \r\n the use of hazardous materials, operations and/or equipment. This \r\n Technical Notes does not purport to address all of the safety \r\n practices associated with the use of these products. It is the responsibility \r\n of the user of this Technical Notes to establish appropriate \r\n safety and health practices and determine the applicability of regulatory \r\n limitations prior to the use of the products described. \r\n The information and suggestions contained in this Technical \r\n Notes are based on available data and experience of the technical \r\n staff of the Brick Institute of America. This information should \r\n be recognized as recommendations and should be used with judgment. \r\n Final decisions on the use of the information discussed herein are \r\n not within the purview of the Brick Institute of America, and must \r\n rest with the project owner, designer or both. \r\n \r\n REFERENCES \r\n \r\n \r\n \r\n 1. Technical \r\n Notes on Brick Construction 7F , \r\n \"Moisture Resistance of Brick Masonry - Maintenance\", Brick Institute \r\n of America, Reston, Virginia, February 1986. \r\n 2. Construction \r\n Sealants and Adhesives, 2nd \r\n Edition, J. R. Panek and J. P. Cook, John Wiley and Sons, New \r\n York, 1984. \r\n 3. Architectural \r\n Graphic Standards. 7th Edition, \r\n C. G. Ramsey and H. R. Sleeper, John Wiley and Sons, New York, \r\n 1981. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60124,"ResultID":176356,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 44B - Wall Ties for Brick \r\n Masonry \r\n Reissued Sept. 1988 \r\n \r\n Abstract: The use of metal ties in brick masonry dates back to the 1850s. Heretofore, \r\n the size, spacing and type of ties have been entirely empirical. An \r\n attempt to replace masonry bonders, the use of thinner masonry walls, \r\n the use of backup systems other than masonry and a need for adjustability \r\n have resulted in ties of various sizes, configurations and adjustability \r\n being used without a rational basis for their selection and use. This \r\n Technical Notes addresses the selection, specification and \r\n installation of wall tie systems for use in brick masonry construction. \r\n Information and recommendations are included which address tie configuration, \r\n detailing, specifications, structural performance and corrosion resistance. \r\n \r\n Key Words: anchors , brick , cavity \r\n walls, corrosion , design, differential movement, fasteners , \r\n grout, masonry , structural masonry, ties , \r\n veneer, walls . \r\n \r\n INTRODUCTION \r\n \r\n This Technical Notes is the third in a series that \r\n addresses anchor bolts, fasteners and wall ties for brick masonry. \r\n This Technical Notes discusses wall ties commonly used in brick \r\n construction, their function, selection, specification and installation. \r\n The term \"wall tie\", as used in this Technical Notes, refers \r\n to wire or sheet metal devices used to connect two or more masonry \r\n wythes or used to connect masonry veneers to a structural backup system. \r\n \r\n GENERAL \r\n \r\n The first use of wall ties in brick masonry construction can be traced \r\n to England in the mid-nineteenth century, where wrought iron ties \r\n were used in brick masonry cavity walls. Use of wall ties in the United \r\n States grew after testing showed that metal-tied walls were more resistant \r\n to water penetration than were masonry-bonded walls. Bonders or \"headers\", \r\n used in masonry-bonded walls may provide direct paths for possible \r\n water penetration. Testing also indicated that the compressive strength \r\n of metal-tied cavity walls and solid walls, and the transverse strength \r\n of metal-tied solid walls were comparable to those of masonry-bonded \r\n walls. \r\n The use of wall ties has continued to increase over the years due \r\n to a trend away from massive, multi-wythe masonry walls to relatively \r\n thin masonry cavity walls, double-wythe walls and veneers. An increase \r\n in construction using backup systems other than masonry, i.e., steel, \r\n concrete and wood, has rendered bonding with masonry headers impossible, \r\n leading to the development of a number of different metal tie systems. \r\n During this period of evolution, little progress was made in the \r\n area of rational design of wall tie systems. Typically, the structural \r\n selection (sizing and spacing) of wall ties has been based largely \r\n on empirical information and the designers judgment. Recently, questions \r\n concerning strength, stiffness, corrosion and the effects of these \r\n on the long-term performance of wall ties, have been posed. Selection \r\n of a tie system to function properly under these conditions is further \r\n complicated by the vast number of tie types available and the variety \r\n of materials from which they are fabricated. Most tie systems perform \r\n well for their intended application. Some tie systems, however, are \r\n poorly designed and do not provide adequate support for brick masonry. \r\n The distinction between the two is often subtle and requires an understanding \r\n of the properties and characteristics of brick masonry. \r\n \r\n Function of Wall Ties \r\n \r\n Typically, wall ties perform three primary functions: 1) provide \r\n a connection, 2) transfer lateral loads, 3) permit in-plane movement \r\n to accommodate differential material movements and, in some cases, \r\n restrain differential movement. In addition to these primary functions, \r\n metal ties (as joint reinforcement) may also be required to serve \r\n as horizontal structural reinforcement or provide longitudinal continuity. \r\n For a tie system to fulfill these functions, it must: 1) be securely \r\n attached and embedded, 2) have sufficient stiffness to transfer lateral \r\n loads with minimal deformations, 3) have a minimum amount of mechanical \r\n play, 4) be corrosion-resistant and 5) be easily installed to reduce \r\n installation errors and damage to the tie system. This listing is \r\n far from complete; special project conditions, unusual details and \r\n special building code requirements must also be considered. Availability \r\n and cost are always factors in product specifications. However, cost \r\n should not have a major influence on the selection of a wall tie system \r\n since the cost of ties is typically a very small part of the total \r\n wall cost. \r\n \r\n TYPES OF WALL TIES \r\n \r\n General \r\n \r\n There is a number of different wall tie systems available for cavity, \r\n multi-wythe, grouted and veneer wall systems. These include unit ties, \r\n continuous horizontal joint reinforcement, adjustable ties (unit and \r\n continuous) and re-anchoring systems. \r\n \r\n Unit Ties \r\n \r\n Unit ties are rectangular ties, \"Z\" ties and corrugated ties, as \r\n shown in Figure 1. Rectangular and \"Z\" ties are usually fabricated \r\n from cold-drawn steel wire or copper-clad wire conforming to ASTM \r\n A 82 or ASTM B 227, respectively. Rectangular and \"Z\" ties made of \r\n stainless steel conforming to ASTM A 167 are also available for use \r\n in more corrosive environments. Corrugated sheet steel ties are typically \r\n manufactured from steel sheet conforming to ASTM A 570, Grade D, but \r\n are also available in copper and stainless steel. \r\n \r\n \r\n \r\n Unit Ties \r\n FIG. 1 \r\n \r\n \r\n \r\n Rectangular and \"Z\" ties are used to bond walls constructed of two \r\n or more masonry wythes. \"Z\" ties should only be used to bond walls \r\n constructed with solid units (not less than 75% solid). Rectangular \r\n ties may be used with either solid or hollow units. \r\n \r\n Corrugated ties are typically used in low-rise, \r\n residential veneer over wood frame construction and are not \r\n recommended for construction incorporating brick veneer over steel studs, \r\n masonry-backed cavity walls, multi-wythe walls or grouted masonry \r\n walls. Typical installation details are shown in Fig. 2. \r\n \r\n \r\n \r\n Unit Tie Details \r\n FIG. 2 \r\n \r\n Joint Reinforcement \r\n \r\n Continuous horizontal joint reinforcement is typically made from \r\n #8, 9, 10, or 11 ga wire, or 3/16 in. (5 mm) diameter wire, conforming \r\n to ASTM A 82, in lengths of 10 to 12 ft (3 to 4 m). The most common \r\n configurations are the ladder, truss, and tab types (see Fig. 3). \r\n \r\n \r\n \r\n Continuous Joint Reinforcement \r\n FIG. 3 \r\n \r\n Structural testing performed in the early 1960s indicated that multi-wythe \r\n walls tied with joint reinforcement performed as well as walls tied \r\n with unit ties or masonry bonders. Test results also indicated that \r\n truss-type joint reinforcement, in cavity wall systems, helped to \r\n develop a degree of composite action in the horizontal span, but did \r\n not contribute to any composite action in the vertical span. \r\n Joint reinforcement may be used in multi-wythe solid walls, masonry \r\n cavity walls and grouted masonry walls (see Fig. 4). Truss-type joint \r\n reinforcement is not recommended for use in insulated cavity \r\n walls. The configuration of the truss diagonals can restrain differential \r\n movement between wythes and possibly result in bowing of the walls. \r\n \r\n \r\n \r\n \r\n Joint Reinforcement Details \r\n FIG. 4 \r\n \r\n Adjustable Ties \r\n \r\n Adjustable tie systems were initially developed to accommodate the \r\n use of face brick that did not course out vertically with interior \r\n masonry wythes. This concept has been extended to ties used to attach \r\n brick to backup systems other than masonry (concrete, steel frames \r\n and steel studs), resulting in the use of both adjustable unit ties \r\n and adjustable joint reinforcement. \r\n The use of adjustable ties has increased rapidly for a number of \r\n reasons: 1) Adjustable ties permit the construction of interior masonry \r\n wythes prior to the construction of exterior facing wythes, permitting \r\n the structure to be enclosed faster. 2) Adjustable ties are two-piece \r\n systems. One piece is installed as the backup is constructed and the \r\n other piece is installed as the facing wythe is constructed, reducing \r\n the risk of damage to exposed ties that might occur when unit ties \r\n or standard joint reinforcement are used. 3) Adjustable ties can accommodate \r\n construction tolerances common in multi-material construction. 4) \r\n Adjustable ties can accommodate larger differential movements than \r\n standard unit ties or joint reinforcement. \r\n The advantages offered by adjustable tie systems are not without \r\n possible problems: 1) Mislocation of adjustable ties placed prior \r\n to construction of facing wythes, if extreme, can render the ties \r\n useless. 2) Adjustable ties may encourage less than perfect layout \r\n of the wall system since a built-in adjustment allowance is available. \r\n 3) Large variations in construction tolerances may not allow full \r\n engagement of ties installed before facing wythes are constructed. \r\n 4) Improperly positioned ties may result in large vertical tie eccentricity. \r\n 5) The structural performance of some adjustable ties in regard to \r\n strength and stiffness is less than that of standard unit ties or \r\n joint reinforcement. \r\n Adjustable Unit Ties. Adjustable unit ties produced for use \r\n with masonry backup, concrete backup, steel frames and steel studs \r\n are shown in Figs. 5 and 6. Slot-type ties (dovetail, channel slot, \r\n etc.) have been used for a number of years with concrete, steel frame \r\n and steel stud backup systems, and are recognized as tie systems capable \r\n of accommodating differential movement, as further discussed in Technical \r\n Notes 18 Series (see Fig. 5). Other types of adjustable \r\n unit tie systems are available for brick with masonry backup and other \r\n backup systems. These ties are typically two-piece systems, consisting \r\n of a single or double eye and pintle arrangement (see Fig. 6). Typical \r\n installation details are shown in Fig. 7. \r\n \r\n \r\n \r\n Adjustable Unit Ties for Steel, Concrete and Stud Backup \r\n FIG. 5 \r\n \r\n \r\n \r\n Adjustable Unit Ties for Masonry Backup \r\n FIG. 6 \r\n \r\n \r\n \r\n Adjustable Unit Tie Details \r\n FIG. 7 \r\n \r\n Adjustable Assemblies. Adjustable ladder and truss-type joint reinforcement assemblies are available \r\n for use in masonry-backed cavity, veneer and grouted wall construction. \r\n This joint reinforcement typically consists of rectangular tab or \r\n \"Z\" type extensions, connected to standard joint reinforcement by \r\n means of an eye and pintle arrangement (see Fig. 8). Installation \r\n details are shown in Fig. 9. \r\n \r\n \r\n \r\n Adjustable Joint Reinforcement Assemblies \r\n FIG. 8 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Adjustable Assembly Details \r\n FIG. 9 \r\n \r\n Masonry Re-anchoring Systems \r\n \r\n Masonry re-anchoring systems are the most recent development in masonry \r\n tie systems. Three general types of systems are being produced and \r\n typically consist of a mechanical expansion system, screw system or \r\n an epoxy adhesive system (see Fig. 10). These systems are primarily \r\n used to: 1) provide ties in areas where ties were not installed during \r\n original construction, 2) replace existing ties, 3) replace failed \r\n masonry bonding units, 4) upgrade older wall systems to current code \r\n levels, or 5) attach new veneers over existing facades. \r\n \r\n \r\n \r\n Masonry Re-Anchoring Systems \r\n FIG. 10 \r\n \r\n \r\n \r\n As stated, re-anchoring systems are relatively new and many designers \r\n and contractors may not be fully familiar with their installation \r\n or limitations. For this reason, consultation with the system manufacturer \r\n is essential to assure proper application, detailing, installation, \r\n inspection, and performance. \r\n \r\n TIE SELECTION \r\n Strength and Deformation \r\n \r\n The strength and deformation characteristics of tie systems are not \r\n generally analyzed nor investigated during the project design or specification \r\n phase. Building codes and standards have typically required minimum \r\n tie size (diameter or gage) and maximum tie spacing limits to control \r\n tie loading and deformation. Present tie size and spacing requirements \r\n have been derived from some testing and from the past performance \r\n of traditional tie systems (rectangular ties, \"Z ties and standard \r\n joint reinforcement). The growing use of adjustable tie systems has \r\n caused some concerns in regard to tie strength and deformation. Most \r\n adjustable ties permit vertical adjustment up to approximately one-half \r\n the height of a standard brick unit, some permit greater adjustments. \r\n Depending on the tie configuration, the deflections of adjustable \r\n ties can become quite large as vertical adjustment eccentricities \r\n are increased. This deflection is further increased if mechanical \r\n play is present in the tie system. \r\n Analytical and experimental investigations of cavity wall and veneer \r\n wall systems have shown that tie loads and deformations are a function \r\n of: 1) the relative stiffness between facing and backup materials, \r\n 2) tie spacing, 3) tie stiffness, 4) support conditions of the facing \r\n and backup systems, 5) location of openings, 6) cavity width and 7) \r\n applied loads. \r\n Estimating tie loads based on tributary area can lead to large errors, \r\n depending on the geometry and properties of the wall system. Fig. \r\n 11 shows tie loads and deflections calculated from a simplified model \r\n of a cavity wall system. As shown, adjustable tie deflections become \r\n large as the adjustment eccentricity becomes large. These values were \r\n calculated assuming that no mechanical play existed in the tie system. \r\n Mechanical play must be added to these values to determine the total \r\n deflection of the exterior wythe. Typical adjustable ties have values \r\n of mechanical play ranging from approximately 0 to 0.3 in. (0 to 8 \r\n mm). Some adjustable ties may have an extreme amount of mechanical \r\n play when not properly installed (see Fig. 12). If satisfactory performance \r\n is to be expected, total tie and backup deflections must be maintained \r\n within the working range of the masonry facade under full design loads. \r\n \r\n \r\n \r\n Calculated Tie Loads and Deflections \r\n FIG.11 \r\n \r\n \r\n \r\n \r\n \r\n Mechanical Play \r\n FIG. 12 \r\n \r\n \r\n \r\n Recommendations. At present, analysis techniques that accurately model metal-tied wall systems \r\n are still in the developmental stage and require further refinement \r\n and verification through testing. Until more accurate methods are \r\n available, the Brick Institute of America feels that acceptable strength \r\n and deformation characteristics can be achieved by one or more of \r\n the following measures: 1) Reduce or eliminate lateral mechanical \r\n play in adjustable tie systems. Limit the total mechanical play to \r\n 0.02 to 0.05 in. (0.5 to 1.2 mm), see Fig. 12. 2) Reduce or eliminate \r\n adjustment eccentricity in adjustable tie systems. This can be accomplished \r\n by installing ties as facing wythes are constructed or by using starter \r\n courses or ledges when facing wythes are constructed over masonry \r\n backup. 3) Eliminate possible disengagement of adjustable ties by \r\n providing positive vertical movement limitations. 4) Provide additional \r\n ties within 8 in. (200 mm) of openings and discontinuities, i.e., \r\n windows, shelf angles, vertical expansion joints, etc. 5) Do not specify \r\n ties with formed drips. Testing has shown that drips can reduce the \r\n ultimate buckling load by approximately 50 percent. 6) Reduce tie \r\n spacing, as shown in Table 1, based on the tie system and wall system. \r\n 7) Specify stiff ties. This can be accomplished by specifying ties \r\n with maximum deflections of less than 0.05 in. (1.2 mm) when tested \r\n at an axial load of 100 lb in tension and compression. When adjustable \r\n ties are specified, the deflection limit should be satisfied at the \r\n eccentricity expected in the field. See Table 2 for minimum tie gage \r\n and diameter recommendations. 8) Select an appropriate tie system \r\n for the wall system (see Table 3). \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Based on minimum tie diameters and gages listed in \r\n Table 2. \r\n 2 Masonry laid in running bond. Consult applicable building \r\n code for special bond patterns such as stack bond. \r\n 3 One and two-family wood frame construction not over \r\n 2 stories in height. \r\n 4 Wood frame construction over 2 stories in height. \r\n 5 For high-lift grouted walls. Masonry laid in running \r\n bond. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Thicker diameters and gages are available. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 See Table 1 for spacing; Table 2 for minimum \r\n diameters and gages; Table 5 for corrosion protection. \r\n \r\n \r\n \r\n Corrosion \r\n \r\n General. Awareness of possible corrosion problems in metal-tied masonry walls has \r\n increased due to corrosion damage found on reinforcement in concrete \r\n highway pavements, bridge decks and some masonry structures. The potential \r\n for corrosion problems in masonry has increased as construction and \r\n design philosophies have changed and as environmental conditions have \r\n changed over the last decades. These changes include use of thinner \r\n masonry walls and masonry veneers that are most susceptible to water \r\n penetration, increases in atmospheric pollutants, use of accelerators \r\n containing calcium chloride, increased use of insulated cavities (resulting \r\n in the relocation of the dew point within the wall section) and combinations \r\n of different metals in brick veneer wall systems. This list is not \r\n all-inclusive; corrosion potential can also be affected by the function \r\n of a structure, geographic location, compatibility of construction \r\n materials, detailing and workmanship. \r\n \r\n Corrosion Protection. In order to provide corrosion protection, \r\n environmental factors must be controlled or metals used in construction \r\n must be protected. Conventional corrosion protection methods attempt \r\n to protect metals embedded in masonry by isolating them with impervious \r\n coatings (barrier protection), by using metals that are corrosion-resistant, \r\n or by providing cathodic protection in which one metal becomes sacrificial \r\n to protect another. \r\n \r\n Galvanizing - Galvanizing (zinc-coating) provides \r\n resistance to corrosion by two methods. First, the zinc coating acts \r\n as a barrier shielding the underlying steel from corrosive action. \r\n Second, it acts as a sacrificial element that is consumed before the \r\n base steel is attacked. This sacrificial nature protects the base \r\n steel at scratches and holidays in the zinc coating caused by fabrication, \r\n handling or installation, until most of the adjacent zinc coating \r\n is consumed. Studies have shown that the protective value of zinc \r\n coating is proportional to its thickness. Thus, for longer periods \r\n of protection, a thicker zinc coating is required. Also, when the \r\n protective zinc coating is depleted, the corrosion of the base steel \r\n will progress as if no galvanizing were present. \r\n Two methods of galvanizing are used to protect metal masonry ties: \r\n mill galvanizing and hot-dip galvanizing. Mill galvanizing takes place \r\n after steel wire or sheets have been processed to their specified \r\n dimensions and prior to fabrication of the tie. During the mill galvanizing \r\n process, zinc can be applied in a variety of thicknesses, as shown \r\n in Table 4. Hot-dip galvanizing is performed by dipping completely \r\n fabricated assemblies into molten zinc until a specified amount of \r\n zinc is bonded to the base metal. Hot-dip galvanized coatings are \r\n typically thicker than mill galvanized coatings and therefore, provide \r\n longer periods of protection. \r\n \r\n \r\n \r\n \r\n 1 Class B - Rolled, pressed or forged articles. \r\n \r\n \r\n \r\n B-1: 3/16 in. and over in thickness and over 15 in. in length \r\n B-2: Under 3/16 in. in thickness and over 15 in. in length. \r\n B-3: Any thickness and 15 in. and under in length. \r\n \r\n \r\n \r\n \r\n Hard-Drawn Copper-Clad Steel Wire \r\n - Metal ties made from hard-drawn copper wire are available only as unit \r\n ties since copper cannot be effectively welded to fabricate continuous \r\n joint reinforcement. Due to coppers electrochemical properties, it \r\n only provides barrier protection and does not provide sacrificial \r\n protection. Therefore, if nicks penetrate the copper cladding, the \r\n base steel can experience corrosion. \r\n \r\n Stainless Steel - Stainless steel ties are often \r\n specified for use in very corrosive environments. Stainless steel \r\n ties are specified under ASTM A 167 and are generally made from one \r\n of the austenitic stainless steels. Stainless steel resists corrosion \r\n well; however, if in contact with carbon steel, a galvanic cell can \r\n result and actually increase the potential for corrosion. For this \r\n reason, combining stainless steel ties or screws with carbon steel \r\n or galvanized steel components is not recommended. \r\n \r\n Fusion-Bonded Epoxy - Epoxy coating is a relatively \r\n new process used to provide corrosion protection for metal ties. The \r\n process has been adapted from epoxy-coated reinforcement bars used \r\n successfully in concrete systems with severe environmental exposures. \r\n Epoxy coating provides protection by acting as an impervious barrier. \r\n The epoxy coating is bonded to the base steel by a heat-induced chemical \r\n reaction through which a chemical and mechanical bond is formed. The \r\n combination of the two types of adhesion helps to prevent cracking \r\n of the coating due to handling, installation or stress reversals. \r\n The epoxy coating is not sacrificial like zinc; therefore, nicks and \r\n holidays in the coating can lead to corrosion of the base steel. At \r\n present, there is no ASTM standard specification governing fusion-bonded \r\n epoxy coating of wire or steel sheet for metal ties. Some manufacturers \r\n are reportedly using a modified version of ASTM A 775 governing fusion-bonded \r\n epoxy reinforcing bars. \r\n \r\n Recommendations - The past performance of metal \r\n ties in regard to corrosion has generally been satisfactory. At present, \r\n there are no widely accepted methods for predicting corrosion rates \r\n or specific levels of required corrosion protection. Until research \r\n can produce accurate methods of assessing corrosion potential and \r\n predicting adequate levels of protection, the Brick Institute of America \r\n suggests minimum levels of corrosion protection for metal ties \r\n and hardware, as indicated in Table 5. As with all other engineering \r\n considerations minimum recommendations may not be adequate in every \r\n situation, and should not serve as substitutes for engineering investigation \r\n or judgment. Decisions must be based on individual project conditions, \r\n performance requirements and safety. \r\n \r\n \r\n \r\n \r\n \r\n SUMMARY \r\n \r\n This Technical Notes is the third in a series addressing \r\n brick masonry anchor bolts, fasteners and wall ties. It is primarily \r\n concerned with the types of wall ties commonly used in brick masonry \r\n construction, their function, selection, specification and installation. \r\n Other Technical Notes in this series individually address anchor \r\n bolts and fasteners for brick masonry. \r\n The information and suggestions contained in this Technical Notes \r\n are based on the available data and the experience of the technical \r\n staff of the Brick Institute of America. The information and recommendations \r\n contained in this publication must be used in conjunction with \r\n good engineering judgment and a basic understanding of the properties \r\n of brick masonry and related construction materials. Final decisions \r\n on the use of the materials and recommendations contained in this \r\n publication are not within the purview of the Brick Institute of America \r\n and must rest with the project architect, engineer, owner or all. \r\n \r\n REFERENCES \r\n \r\n \r\n 1. DeVekey, \r\n R.C., Corrosion of Steel Wall Ties: Recognition, Assessment and \r\n Appropriate Action\", Building Research Establishment Information \r\n Paper, IP 28/79, Building Research Establishment, Garston, Watford, \r\n England, October 1979. \r\n 2. Fishburn, \r\n C.C., Water Permeability of Walls Built of Masonry Units\", Report \r\n BMS 82, National Bureau of Standards, Department of Commerce, Washington, \r\n D.C., April 1942. \r\n 3. Allen, \r\n M. H. , Research Report No. 10, \"Compressive and Transverse Strength \r\n Tests of Eight-Inch Brick Walls\", Structural Clay Products Research \r\n Foundation, Geneva, Illinois, October 1966. \r\n 4. Allen, \r\n M.H., Research Report No. 14, \"Compressive Strength of Eight-Inch \r\n Brick Walls with Different Percentages of Steel Ties and Masonry \r\n Headers\", Structural Clay Products Research Foundation, Geneva, \r\n Illinois, May 1969. \r\n 5. Bortz, \r\n S.A., \"Investigation of Continuous Metal Ties as a Replacement for \r\n Brick Ties in Masonry Walls\", Summary Report ARF 6620, Armour Research \r\n Foundation, Chicago, Illinois, June 1960. \r\n 6. \"Investigation \r\n of Masonry Wall Ties\", ARF Project B870-2 (Revised), Armour Research \r\n Foundation, Chicago, Illinois, December 1962. \r\n 7. Flexural \r\n Strength of Cavity Walls\", ARF Project B870, Armour Research Foundation, \r\n Chicago, Illinois, March 1963. \r\n 8. Brown, \r\n R.H. and Elling, R.E., Lateral Load Distribution in Cavity Walls\", \r\n Proceedings of the Fifth International Brick Masonry Conference, \r\n Washington, D.C., October 1979. \r\n 9. Bell, \r\n G.R. and Gumpertz, W.H., Engineering Evaluation of Brick Veneer/Steel \r\n Stud Walls, Part 2 -Structural Design, Structural Behavior and Durability\", \r\n Proceedings of the Third North American Masonry Conference, Arlington, \r\n Texas, June 1985. \r\n 10. Arumala, \r\n J.O. and Brown, R.H., Performance of Brick Veneer With Steel Stud \r\n Backup\", Clemson University, Clemson, South Carolina, April 1982. \r\n 11. Development \r\n of Adjustable Wall Ties\", ARF Project No. B869, Armour Research \r\n Foundation, Chicago, Illinois, March 1963. \r\n 12. Catani, \r\n Mario J., Protection of Embedded Steel in Masonry\", The Construction \r\n Specifier , January 1985. \r\n 13. Catani, \r\n Mario J. and Whitlock, A. Rhett, Coping With Wide Cavities\", The \r\n Construction Specifier , August 1986. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60125,"ResultID":176357,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Note 45 - Brick Masonry Noise \r\n Barrier Walls - Introduction \r\n Feb. 1991 \r\n \r\n Abstract : Because our national highway system has grown significantly \r\n over the last few decades, public awareness of traffic noise on \r\n neighborhood communities has increased. Neighborhood associations \r\n and governmental bodies look for ways to reduce traffic noise without \r\n adversely affecting the surrounding environment. A solution to this \r\n problem lies in brick masonry noise barrier walls. Brick masonry \r\n noise barrier walls can easily blend into the environment and give \r\n residential communities protection from unwanted highway noise. \r\n Key Words : acoustics, brick, noise \r\n barrier walls. \r\n INTRODUCTION \r\n Continued growth of our national highway \r\n system combined with an increase in public awareness of environmental \r\n issues has focused on a need to evaluate the impact of traffic noise \r\n associated with highway systems on neighboring communities. When \r\n noise levels exceed acceptable limits, community action generally \r\n alerts governmental bodies to the problem or potential problems. \r\n Governmental bodies then investigate measures to prevent or alleviate \r\n noise problems. \r\n The severity of the noise and the stage \r\n at which the problem is identified determine the measures available \r\n to reduce the impact of highway noise. Measures to alleviate highway \r\n noise include traffic controls and regulations, modification of \r\n the highway configuration, land-use planning and zoning, and brick \r\n noise barrier walls. \r\n When new highway systems are in the planning \r\n and design stages, a comprehensive analysis of and consideration \r\n to noise abatement measures can be given. However, when existing \r\n highway systems are renovated or if restrictions are placed on the \r\n routing of new highway systems or use of adjacent land, the most \r\n practical solution to noise control may be the use of noise barrier \r\n walls to isolate the highway noise sources from the surrounding \r\n communities. \r\n Three major types of noise barriers are \r\n currently being used in the United States: earth berms, walls and \r\n berm-wall combinations. Of these three, the noise barrier wall is \r\n typically the most common means of achieving noise abatement and \r\n is the primary topic of this Technical Notes . \r\n This Technical Notes , the first \r\n in a series, addresses acoustical, visual, structural, construction, \r\n detailing and maintenance considerations of brick masonry noise \r\n barrier walls. The other Technical Notes in this series addresses \r\n the structural design of brick masonry noise barrier walls. \r\n ACOUSTICAL CONSIDERATIONS \r\n To understand the function of a noise \r\n barrier wall or how the wall reduces the noise level perceived by \r\n a receiver, it is necessary to discuss some of the fundamental principles \r\n involved in sound propagation and noise reduction. \r\n When there are no obstacles or barriers \r\n between highway noise sources and receivers, sound travels in a \r\n direct path from the source to the receiver (Figure 1). When a noise \r\n barrier wall is placed between the noise source and the receiver, \r\n the barrier disperses the sound along three paths: a diffracted \r\n or bent path over the top of the wall, a reflected path away from \r\n the receiver and a transmitted path through the wall (Fig. 2). \r\n \r\n \r\n \r\n \r\n Direct Noise Path \r\n FIG. 1 \r\n \r\n \r\n \r\n \r\n \r\n Noise Path With Barrier Wall \r\n FIG. 2 \r\n \r\n Diffraction of sound over the top of the \r\n wall produces a shadow zone behind the barrier. The boundary of \r\n this shadow zone is outlined by a straight line drawn from the noise \r\n source over the top of the barrier wall (Fig. 3). All receivers \r\n located within the shadow zone will experience some degree of sound \r\n attenuation. The amount of reduction or attenuation is directly \r\n related to the diffraction angle ├ÿ-. As this angle increases, the \r\n barrier attenuation increases. Thus, barrier attenuation is a function \r\n of the wall height and the distances between the source, barrier \r\n and receiver. Two other factors also affect the amount of attenuation: \r\n the sound transmission characteristics of the material from which \r\n the barrier is constructed and the length of the barrier. \r\n \r\n \r\n \r\n \r\n Noise Barrier Shadow Zone \r\n FIG. 3 \r\n \r\n The sound transmission characteristics \r\n of a material are related to its weight, stiffness and loss factors. \r\n The sound transmission characteristics of materials can be assessed \r\n and compared by means of transmission loss values. The sound transmission \r\n loss is related to the ratio of the incident noise energy to the \r\n noise energy transmitted through the material. Typically, transmission \r\n loss values can be expected to increase with increasing square foot \r\n surface weights of barrier materials. Table 1 lists the transmission \r\n loss values at a frequency of 550 hertz (Hz) for materials commonly \r\n used in noise barrier wall construction. 550 Hz is the accepted \r\n frequency used to determine the transmission loss of highway noise \r\n barrier wall materials. As a general rule for design, the transmission \r\n loss value should be a minimum of 10 decibels (dB) above the attenuation \r\n resulting from the diffraction over the top of the barrier. The \r\n transmission loss values for brick masonry are at the higher end \r\n of the range and sound transmission through a brick barrier will \r\n not significantly affect the attenuation. However, when less massive \r\n materials are used, the transmission loss values may not be adequate \r\n and the noise reduction provided by the barrier can be severely \r\n affected. \r\n The actual acoustical design of a barrier \r\n system to determine the length and height requirements are beyond \r\n the scope of this Technical Notes . A detailed discussion \r\n of noise barrier acoustical design procedures and considerations \r\n can be found in Reference 1. \r\n VISUAL CONSIDERATIONS \r\n General \r\n Highway noise barriers tend to dominate \r\n the visual environment adjacent to roadways (Fig. 4). They are often \r\n thousands of feet long and can be as high as 25 ft (7.6m) above \r\n the road surface. When noise barrier walls higher than 16 ft (4.9m) \r\n are acoustically required, visual consideration of surrounding features \r\n should be evaluated. Exceptionally high walls can have an unsightly \r\n impact on the aesthetic features of the territory and can give the \r\n driver a claustrophobic feeling. For safety reasons, the designer \r\n should reduce the visual impact of the noise barrier wall. The motorist \r\n must pass the barrier with as little visual disruption as possible. \r\n The primary attention of the driver should be on the road ahead \r\n and adjacent traffic conditions. This can be achieved by doing one \r\n of several things. \r\n \r\n \r\n \r\n \r\n Brick Noise Barrier Wall \r\n FIG. 4 \r\n \r\n For relatively low walls, the line of \r\n the noise barrier should reflect similar lines of the surrounding \r\n environment. For instance, in rolling terrain, a straight line will \r\n be out of place and attention will be drawn to that line. However, \r\n in a flat terrain where the horizon is visible as a straight line, \r\n a straight line in a noise barrier wall may not appear to be visually \r\n dominant. The introduction of vertical lines, such as with pilasters, \r\n placed along relatively low walls is recommended to achieve visual \r\n balance. Plantings such as columnar trees can emphasize vertical \r\n lines in a noise barrier wall. Further, shrubbery can be used to \r\n soften the transition between ground and wall intersection. Wherever \r\n possible, the wall should step back to open up the view for the \r\n motorist (Fig. 5). However, this can only be practically achieved \r\n in rolling or hilly terrain. In an urban environment where the horizon \r\n is composed of alternating heights of buildings, an appropriate \r\n wall may vary in height as a reflection of the citys profile. \r\n \r\n \r\n \r\n \r\n Effect of Wall Placement on Sight Lines \r\n FIG. 5 \r\n \r\n Another way to reduce the visual impact \r\n on the environment is through changes in height and location of \r\n the wall. A wall with offsets can break the monotony of a straight \r\n wall and create pockets which can be used for plantings (Fig. 6). \r\n These transitions may further be used as areas for change in texture, \r\n color or wall height. A serpentine wall can create the same visual \r\n interest as a wall with offsets (Fig. 7). Moreover, due to their \r\n geometry, both of these walls have the added advantage of being \r\n more resistant to seismic and wind forces than their straight counterparts. \r\n \r\n \r\n \r\n \r\n Offset Wall \r\n FIG. 6a \r\n \r\n \r\n \r\n \r\n \r\n Offset Wall \r\n FIG. 6b \r\n \r\n \r\n \r\n \r\n \r\n Serpentine Wall \r\n FIG. 7a \r\n \r\n \r\n \r\n \r\n \r\n Serpentine Wall \r\n FIG. 7b \r\n \r\n Regardless of the shape, noise barrier \r\n walls should not begin or end abruptly. The best transition of beginning \r\n and end is to tie the wall into a natural hillside or a man-made \r\n earth berm. If no natural hills or berms are available, the wall \r\n termination should taper down and angle away from the roadway. Not \r\n only is this visually pleasing, it is also functional. This transition \r\n can effectively reduce the amount of noise traveling around the \r\n end of the wall as a result of approaching traffic. \r\n Access through noise barrier walls may \r\n be needed in certain instances. Maintenance personnel may require \r\n doors for equipment or service. Firefighters may require access \r\n to hydrants or water sources on the opposite side of the barrier \r\n wall. The appropriate highway and emergency agencies should be consulted \r\n regarding access locations and requirements. Openings through noise \r\n barrier walls must not reduce the acoustic or structural performance \r\n of the noise barrier. \r\n Larger openings are best located at offsets \r\n in the wall, or with piers or pilasters at the jamb of the opening. \r\n This geometry provides an easier means of accommodating loads and \r\n reducing sound penetration. Openings in straight wall sections change \r\n the load distribution and this influence must be considered. Loose \r\n steel lintels or reinforced masonry beams should be used to span \r\n over the openings. \r\n Texture \r\n A change of texture on noise barriers \r\n helps to create a pleasant variety for motorist, adjacent residents \r\n and pedestrians. The requirements of each are different, however, \r\n and must be treated separately. Since motorists usually drive at \r\n high rates of speed, they have little opportunity to examine details. \r\n To be effective, textures along the highway need to be bold or coarse \r\n and visible at a glance because the motorists attention should \r\n not be diverted from the highway. However, textures on the opposite \r\n of the highway should be more detailed. The residents and pedestrians \r\n on this side view the barrier at much slower speeds and at closer \r\n distances. Bold textures can be overbearing and monotonous to them \r\n and, therefore, should not be used. \r\n Unlike other materials, masonry can be \r\n adapted to create the bold textures for the motorist and the subtle, \r\n more detailed textures for those on the other side. Because of its \r\n versatility, the possibilities for brick masonry are almost limitless. \r\n Bold textures can be created by offsetting brick in random patterns \r\n which can cast varying textural shadows during the day. The use \r\n of pilasters, special shape brick and copings can also create bold \r\n textural interest. Further, brick sculpture can create detailed \r\n textures for residents (Fig. 8). Brick can be carved to portray \r\n a desired logo, mural or composition. \r\n \r\n \r\n \r\n \r\n Brick Sculpture \r\n FIG. 8 \r\n \r\n Color \r\n The color of the wall plays an important \r\n role in blending the wall into the surrounding environment. Since \r\n brick barrier walls are man-made structures placed in a natural \r\n environment, their color should not attempt to match the color of \r\n trees, grass, or shrubbery because they are not related to such \r\n natural features by form. Earthen colors, such as browns, grays, \r\n and rusts of varying tones, when used on barrier walls help to blend \r\n the structures into their environment. Repetitious polychromatic \r\n patterns are not recommended on the highway side of the barrier. \r\n These types of patterns draw the motorists attention away from \r\n the road ahead. However, they can be used on the side of the wall \r\n opposite of the highway. Moreover, placing units of different color \r\n in alternating bonding patterns can also easily create visual interest. \r\n Further, color interest and variety may be achieved through the \r\n use of plants and trees. Foliage which changes color will impart \r\n a pleasing seasonal variation. \r\n STRUCTURAL CONSIDERATIONS \r\n Structurally, brick masonry noise barrier \r\n walls can be designed in various ways. The most popular designs \r\n though are the pier and panel, pilaster and panel, and the cantilever \r\n walls. \r\n Pier and Panel Wall \r\n The pier and panel wall is composed of \r\n a series of single-wythe panels, usually four inches in thickness. \r\n These panels are braced periodically by piers (Fig. 9). This type \r\n of wall is relatively easy to build and is economical due to the \r\n efficient use of materials. It is easily adapted to varying terrain \r\n and is acoustically adequate for a highway noise barrier. The pier \r\n and panel wall can also be built with returns of varying angles. \r\n However, the most easily constructed and economical return is one \r\n which is perpendicular to an adjacent panel. The panels, usually \r\n built from 8 to 20 ft long (2.4 to 6.1 m), are placed between piers \r\n of reinforced masonry, concrete, or steel. The panels can either \r\n be prefabricated or built in place and can be as high as acoustically \r\n or aesthetically necessary. However, any space left between the \r\n bottom of the wall and the ground must be adequately backfilled \r\n to prevent noise penetration underneath the wall. \r\n \r\n \r\n \r\n \r\n Pier and Panel Assembly \r\n FIG. 9 \r\n \r\n The panels, supported on piles or clip \r\n angles attached to piers, essentially act as thin, simply supported \r\n beams. The panel, which spans horizontally between the piers, will \r\n develop flexural tensile stresses parallel to the bed joints due \r\n to out-of-plane wind and seismic loads (Fig. 10). Horizontal joint \r\n reinforcement is required if the calculated flexural stresses exceed \r\n the allowable stresses found in the local building code. If horizontal \r\n reinforcement is required, it must be distributed the full height \r\n of the panel. \r\n \r\n \r\n \r\n \r\n Out-of-Plane Deflection of Panel in \r\n Pier and Panel Wall \r\n \r\n FIG. 10 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60126,"ResultID":176358,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 45A - Brick Masonry Noise \r\n Barrier Walls - Structural Design \r\n April 1992 \r\n \r\n Abstract: Rationally designed brick masonry noise barrier walls \r\n provide an attractive wall form with reliable structural function. \r\n This Technical Notes addresses the structural design of pier \r\n and panel, pilaster and panel, and cantilever brick noise harrier \r\n walls. Suggested design methodology and design examples are provided. \r\n The information presented in this Technical Notes can be applied \r\n with slight modifications to the many design schemes and loading demands \r\n of noise barrier walls. The result is an attractive noise barrier \r\n wall with the durability and versatility inherent in brick masonry \r\n structures. \r\n Key Words: brick, cantilever, noise \r\n barrier, pier, pilaster, structural design, wall system. \r\n INTRODUCTION \r\n Technical Notes 45 \r\n presented an introduction to acoustical, visual, structural, and \r\n construction considerations for brick masonry noise barrier walls. \r\n In continuation of the series, this Technical Notes addresses \r\n structural design considerations in greater detail and provides design \r\n examples. Recommended procedures are presented on the structural design \r\n of the wall system assuming acoustic and visual considerations are \r\n previously addressed. Design recommendations for noise barrier wall \r\n footings and caissons have not been addressed in this Technical \r\n Notes. \r\n A design approach is presented which follows \r\n criteria contained in the Building Code Requirements for Masonry \r\n Structures (ACI 530/ASCE 5/TMS 402-92) and, where applicable, \r\n the Load and Resistance Factor Design Manual of Steel Construction-First \r\n Edition (AISC LRFD). Refer to Technical Notes 3 series \r\n for a discussion of the ACI/ASCE/TMS document. \r\n NOTATION 1 \r\n A s Area of steel, in. 2 \r\n b Width of section, in. \r\n c Distance from extreme compression fiber to the neutral axis \r\n of the cross section, in. \r\n d Distance from extreme compression fiber to the centroid of \r\n tension reinforcement, in. \r\n E m Modulus of elasticity of masonry in compression, psi \r\n E s Modulus of elasticity of steel, psi \r\n f a Calculated compressive stress in masonry due to axial load only, psi \r\n f cr Modulus of rupture, psi \r\n f b Calculated compressive stress in masonry \r\n due to flexure only, psi \r\n F b Allowable compressive stress in masonry due to flexure only, psi \r\n f m Compressive stress in masonry, psi \r\n Specified compressive strength of masonry, psi \r\n f s \r\n Calculated tensile or compressive \r\n stress in reinforcement, psi \r\n F s Allowable tensile or compressive stress in reinforcement, psi \r\n f t Calculated tensile stress in masonry, \r\n psi \r\n F t Allowable flexural tensile stress in masonry, psi \r\n f v Calculated shear stress in masonry, \r\n psi \r\n F v Allowable shear stress in masonry, psi \r\n f y Specified yield stress for reinforcement, \r\n psi \r\n h Height of wall or panel, ft \r\n I cr Moment of inertia of cracked masonry cross section, in. 4 \r\n I e Effective moment of inertia, in. 4 \r\n I g Moment of inertia of uncracked masonry cross section, in. 4 \r\n I x Moment of inertia of steel pier about the strong axis, in. 4 \r\n j Ratio of distance between centroid of flexural compressive forces and \r\n centroid of tensile forces to depth \r\n k Ratio of distance between compression face and neutral axis to distance \r\n between compression face and centroid of tensile forces \r\n M Design moment, ft-lb \r\n M n \r\n Nominal moment \r\n strength, ft-lb \r\n M o \r\n Overturning \r\n moment, ft-lb \r\n M px \r\n Moment due to \r\n spanning between piers, ft-lb \r\n M py \r\n Moment induced \r\n by M px \r\n due to plate effects, ft-lb \r\n M r Resisting moment, ft-lb \r\n M u Ultimate moment strength, ft-lb \r\n M w Moment due to spanning between caissons, \r\n ft-lb \r\n n Elastic moduli ratio, E s /E m \r\n P Design axial load, lb \r\n p Reinforcement ratio, A s /bd \r\n r Radius of gyration, in. \r\n t Thickness of wall or panel, in. \r\n V Design shear force, lb \r\n V n Nominal shear strength, lb \r\n V px Shear due to spanning between piers, lb \r\n V u Ultimate shear strength, lb \r\n W Lateral load, lb/ft \r\n x Width of footing, ft \r\n y Depth of footing, ft \r\n D Deflection, in. \r\n f b Resistance factor \r\n \r\n 1 Metric \r\n equivalents: \r\n 1 in. = 25.4 mm \r\n 1 ft = 0.3048 m \r\n 1 lb = 4.448 N \r\n 1 psi = 0.006895 N/mm 2 \r\n \r\n SELECTION OF A WALL SYSTEM \r\n As discussed in Technical Notes 45 , \r\n there are three typical brick masonry noise barrier wall systems: \r\n cantilever walls, pier and panel walls, and pilaster and panel walls. \r\n Preliminary consideration of design parameters can help select the \r\n wall system that is most appropriate and efficient without having \r\n to develop and compare three separate designs. \r\n Cantilever Noise Barrier Walls \r\n A cantilever wall system is better suited \r\n for shorter noise barriers, i.e. walls that are 12 ft (3.7 m) or less \r\n in height. In most instances, taller cantilever walls are less desirable \r\n because strip footings become too massive. Cantilever walls are more \r\n efficient for shorter heights because they are likely the easiest \r\n and most economical to construct, and will require the least quality \r\n control and inspection. This is because construction techniques used \r\n are similar to building wall construction familiar to mason contractors. \r\n Pier and Panel Noise Barrier Walls \r\n Pier and panel wall systems are best for \r\n quick site erection. Brick panels can be prefabricated on or off site, \r\n or laid in place. Also, pier caissons are typically constructed faster \r\n and require less concrete than strip footings. Strip footings under \r\n the panel are not required, as the panel can span from pier to pier. \r\n Material costs for pier and panel wall systems will typically be the \r\n least of the three systems. Disadvantages of the pier and panel system \r\n include increased construction supervision and inspection, tight construction \r\n tolerances for pier-to-panel connections, and increased costs to install \r\n the panels. \r\n Pilaster and Panel Noise Barrier Walls \r\n Pilaster and panel walls, like pier and \r\n panel walls, typically utilize caissons for quick foundation construction. \r\n Wall construction is done on site, as the panel is built integral \r\n with the pilaster. This requires panel support between caissons during \r\n construction. Supervision and inspection are required to ensure proper \r\n construction. However, construction tolerances are more liberal than \r\n those for pier and panel systems. Generally, pilaster and panel wall \r\n systems permit longer pier spacing and taller wall height. A pilaster \r\n and panel wall assembly is structurally more efficient than a pier \r\n and panel wall assembly, as a fixed condition may be developed at \r\n the pilaster-panel connection. \r\n DESIGN ASSUMPTIONS \r\n It has been widely accepted that masonry \r\n stress-strain behavior is similar to that of concrete. Thus, design \r\n assumptions made for masonry under working stress and strength conditions \r\n are analogous to assumptions made in concrete design. Figure 1 depicts \r\n the assumed stress-strain relationship for masonry in flexure under \r\n working loads. In all cases, the principles of equilibrium and compatibility \r\n of strains of masonry materials are assumed to apply. Assumptions \r\n made following a working stress design are as follows: 1) plane sections \r\n before bending remain plane after bending, 2) moduli of elasticity \r\n of masonry and steel remain constant, 3) reinforcement is completely \r\n bonded to masonry, and 4) in cracked masonry members, the tensile \r\n capacity of masonry is neglected. \r\n \r\n Straight Line Stress Distribution \r\n \r\n \r\n FIG. 1 \r\n \r\n In this Technical Notes, a number \r\n of additional assumptions will be made to facilitate design. It is \r\n assumed that the brick masonry will be reinforced. Most noise barrier \r\n wall applications demand tall slender walls to meet acoustic requirements \r\n and minimize material costs and land use. Reinforcing is required \r\n for brick masonry to meet these criteria. Additional assumptions placed \r\n on both material properties and wall behavior are as follows. \r\n Material Properties \r\n Grout and concrete are assumed to have compressive \r\n strength equal to or greater than the masonry compressive strength, \r\n and elastic moduli of the masonry and the grout are assumed to be \r\n equal. The method of transformation of areas may be used in lieu of \r\n these assumptions. \r\n Wall Behavior \r\n Masonry walls are plate structures. Thus, \r\n a masonry wall loaded perpendicular to its plane will experience strain \r\n along its length and its height. However, the traditional masonry \r\n wall design approach is to use the strip method. In this method, a \r\n one foot wide section of wall is designed considering one span direction. \r\n Strains perpendicular to the strip span direction are ignored. For \r\n cantilever walls, this method is nearly exact, as plate effects are \r\n negligible. Pier and panel and pilaster and panel walls, however, \r\n exhibit wall behavior which can make plate effects significant. This \r\n does not mean a rigorous plate analysis is necessary for these walls. \r\n Rather, a few simple observations and assumptions can be made to simplify \r\n design. \r\n For pier and panel and pilaster and panel \r\n wall systems, the panel is subject to three different deflection conditions: \r\n a horizontal simple span between piers or pilasters subject to wind \r\n or seismic load, a horizontal simple span between caissons subject \r\n to panel weight, and a vertical cantilever span subject to deflection \r\n of the pier or pilaster. If the panel is free to deflect both in-plane \r\n and out-of-plane, the moment due to simple spanning between piers \r\n or pilasters, M px , and the moment due to simple spanning \r\n between caissons, M w , are combined by vector addition to calculate the maximum \r\n design moment for the horizontal span of the panel. However, the panel \r\n must be flush with the ground to avoid noise penetration under the \r\n wall. Thus, the panel may, in fact, be supported along its entire \r\n length by the ground. This is significant, because the design moment \r\n in this case is solely M px , the moment about the weak \r\n axis of the panel. This condition will require the most amount of \r\n horizontal reinforcement for the panel. In the panel design examples \r\n that follow it is assumed that the ground supports the entire length \r\n of the panel. \r\n Because of plate effects, M px will induce moment about the horizontal \r\n axis as well, denoted as M py . The strip solution does not and cannot \r\n calculate M py , as plate effects are ignored in this method. However, plate analysis \r\n shows that M py \r\n can be significant and that the ratio of M py to M px increases as the height to length ratio \r\n of the panel increases. As an approximation, M py is calculated as one tenth the height \r\n to length ratio times M px . M py is \r\n a maximum at the middle of the panel. However, moment due to vertical \r\n cantilever deflection of the wall is a maximum at the bottom of the \r\n panel. Thus, the design moment about the horizontal axis is the greater \r\n of: 1) the moment due to vertical cantilever deflection at the bottom \r\n of the panel, or 2) the sum of M py \r\n and the moment due to vertical cantilever deflection at the middle \r\n of the panel. \r\n Vertical cantilever deflection of the panel \r\n is a function of the rigidity of the piers or pilasters. If the piers \r\n or pilasters are very rigid, cantilever deflection of the panel will \r\n be negligible. However, optimal flexural design may result in less \r\n rigid piers or pilasters with considerable deflection, especially \r\n when steel piers are used. Induced tensile stresses in the panel must \r\n be within allowable tensile stresses for unreinforced masonry if the \r\n panel cannot be reinforced in the vertical direction. Thus, deflection \r\n criteria will often govern pier and pilaster design. \r\n Reinforced brick masonry pilaster and panel \r\n and pier and panel wall systems are typically very rigid, so deflections \r\n in many cases will be small. However, the deflection of the pilaster \r\n must be calculated considering the ratio of applied moment to cracking \r\n moment. Cracking moment is calculated using the gross moment of inertia \r\n of the pier or pilaster. \r\n In the pilaster and panel design example \r\n that follows, a two span continuous panel is assumed. Thus, the pilaster \r\n panel interface is assumed to be a fixed connection for the middle \r\n pilaster, and a simple connection for the two exterior supports. This \r\n allows for expansion joints at the simple supports to accommodate \r\n horizontal expansion of the panels. \r\n Lastly, compression steel in the pilaster \r\n is usually ignored in design. If consideration of the increased compressive \r\n strength due to the compression steel is made, the steel must be properly \r\n confined within the pilaster with lateral or spiral ties. \r\n DESIGN PROCEDURE \r\n It is important to establish a set design \r\n procedure to ensure an accurate and comprehensive noise barrier wall \r\n design. The following nine steps are presented as a guide to the structural \r\n design of a brick masonry noise barrier wall. Additional criteria \r\n may be warranted for a particular wall design scheme. \r\n 1) Determine required wall height based \r\n upon acoustical considerations. \r\n 2) Determine critical lateral and axial \r\n load combinations on wall elements. Loads should be determined according \r\n to the recommendations of the local building code or as contained \r\n in the document Minimum Design Loads for Buildings and Other Structures \r\n (ASCE 7). For the examples that follow, inertial wall force due \r\n to seismic base shear is divided by wall surface area for comparison \r\n with wind loads. \r\n 3) To determine required reinforcement, \r\n assume j = 0.9: \r\n \r\n A s reqd=M/F s jd \r\n \r\n 4) Calculate masonry compressive stresses \r\n and the steel tensile stress: \r\n \r\n f b = 2M/jkbd 2 \r\n f a = P/bkd \r\n f s = M/A s jd \r\n \r\n 5) Check the allowable compressive stress \r\n in masonry and the tensile stress in steel (Table 1). Axial compression \r\n and buckling seldom govern design of noise barrier wall elements. \r\n However, axial compression must be included to calculate the maximum \r\n flexural compression. Note that allowable stresses for wind or seismic \r\n load conditions may be increased by one-third over those given in \r\n Table 1. \r\n \r\n \r\n \r\n \r\n 1 Allowable stresses for wind and seismic \r\n loading conditions may be increased by one-third. \r\n \r\n \r\n \r\n 6) Calculate shear stress: \r\n \r\n f v = V/bjd \r\n \r\n 7) Check the allowable shear stress in masonry \r\n (Table 1). If exceeded, member must be reinforced for shear and the \r\n shear stress checked. \r\n 8) Design the pier or pilaster, if applicable. \r\n If the pier or pilaster is made of reinforced masonry, design will \r\n follow steps 3 through 7. If a steel pier is used, follow the design \r\n recommendations given in the Load and Resistance Factor Design \r\n Manual of Steel Construction. Flexural tensile stresses developed \r\n in unreinforced masonry panels due to pier or pilaster deflection \r\n may not exceed the allowable flexural tensile stresses given in Table \r\n 2. \r\n 9) Calculate overturning and resisting moments, \r\n and sliding resistance (Fig.2). These are functions of the wall, footing, \r\n and caisson dimensions, as well as the soil pressure resistance. The \r\n factor of safety is the ratio of resisting moment, M r , to the overturning moment, M o. \r\n A factor of safety of 2 or greater is recommended. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Allowable stresses for \r\n wind and seismic loading conditions may be increased by one-third. \r\n 2 For partially grouted \r\n masonry allowable stresses shall be determined on the basis \r\n of linear interpolation between hollow units which are fully \r\n grouted or ungrouted and hollow units based on amount of grouting. \r\n \r\n \r\n \r\n \r\n DESIGN EXAMPLES \r\n Design Example #1: Hollow Brick Cantilever \r\n Noise Barrier Wall \r\n \r\n Type S portland cement/lime mortar, MISSING \r\n Equation \r\n \r\n \r\n Wall dimensions shown in Fig. 3, running bond, face shell bedding \r\n \r\n Grade 60 reinforcement, \r\n \r\n Loads: wind = 20 psf, wall weight =73 psi \r\n \r\n \r\n \r\n \r\n \r\n \r\n Wall/Footing Forces \r\n FIG. 2 \r\n \r\n \r\n \r\n Noise Barrier Wail Design \r\n Example #1 \r\n Hollow Brick Cantilever Wall \r\n FIG. 3 \r\n Step 1: Based on acoustical considerations, \r\n the wall height shall be 10 ft minimum. \r\n Step 2: Critical load combinations \r\n result in the following design values (per ft of wall): \r\n \r\n M = (0.5)(W)(h) 2 = (0.5)(20 psf) (10ft) 2 \r\n = 1000 ft-ob \r\n V = (W)(h) = (20 psf)(10ft) = 200 lb \r\n P = (wall weight)(h) = (73 psf)(10 ft) = 730 lb \r\n \r\n Step 3 : \r\n Calculate required reinforcement. \r\n \r\n Try #5 bars @32 in. o.c., per foot of wall \r\n (Table 3). \r\n \r\n Step 4: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Area of steel listed \r\n is for one wire. \r\n \r\n \r\n \r\n \r\n \r\n Step 5: Check compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6: Calculate shear stress. \r\n \r\n Step 7: Check shear stress. \r\n Step 8: Does not apply. \r\n Step 9: Neglect the soil pressure \r\n resistance to overturning. Calculate overturning and resisting moments, \r\n and the safety factor on overturning (Fig. 2). Note: Sliding must \r\n also be considered. Sliding is a function of the soil conditions, \r\n and is beyond the scope of this Technical Notes. \r\n \r\n Design Example #2: Steel Pier with 4 \r\n Inch Panel Noise Barrier Wall \r\n Type S portland cement/lime mortar, MISSING \r\n Equation \r\n Wall dimensions shown in Fig. 4 \r\n Running bond, full bedding, spacing of piers \r\n shall be 15ft \r\n Ladder type joint reinforcement: \r\n Pier I-beam: Grade 50 W Section, \r\n Loads: wind = 15psf, panel weight = 40psf, \r\n seismic = 25psf \r\n \r\n \r\n \r\n \r\n Noise Barrier Wall Design \r\n Example #2 \r\n \r\n Steel Pier With 4 Inch Panel \r\n FIG. 4 \r\n \r\n Step 1: Based on acoustical considerations, \r\n the wall height shall be 16 ft minimum. \r\n Step 2: Critical load combinations \r\n result in the following design values: \r\n a) For the panel span between piers (per \r\n foot of wall): \r\n \r\n M px = (1/8)(W)(L) 2 = (1/8)(25 psf)<15 \r\n ft) = 703 ft-lb \r\n m py = (1/10)(h/L)(M px ) = (1/10)(16 ft/15 \r\n ft) (703 ft-lb) = 75 ft-lb \r\n V px = (0.5)(25 psf)(15 ft) = 188 lb \r\n \r\n b) For the panel span between caissons, \r\n assume the panel is supported along its entire base by the ground. \r\n c) For an interior steel pier: \r\n \r\n \r\n V = (2)(V px )(h) = (2)(188 lb/ft)(16 ft) = 6016 lb \r\n V u = 1.3V = 1.3 (6016 lb) = 7820 lb \r\n Step 3: Calculate required reinforcement \r\n for the panel for the design moment M px . Assume the distance from the extreme compression face to \r\n the joint reinforcement is 3 inches. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Area of steel \r\n listed is for one wire. \r\n \r\n \r\n \r\n \r\n \r\n Step 4: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n Step 5: Check compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6 : Calculate shear stress. \r\n \r\n Step 7: Check shear stress. \r\n \r\n Step 8: Assume the pier design will \r\n be governed by deflection limitations of the panel, not the required \r\n flexural strength of the pier. Calculate the maximum vertical cantilever \r\n deflection the panel may undergo without exceeding the allowable tensile \r\n stress value for the panel found in Table 2. From Table 2: \r\n \r\n Step 9: Sliding and overturning resistance \r\n of the caisson is a function of the lateral soil pressure and is beyond \r\n the scope of this Technical Notes. \r\n Design Example #3: Reinforced Brick Masonry \r\n Pier and 4 Inch Panel Noise Barrier Wall \r\n \r\n \r\n \r\n \r\n Noise Barrier Wail Design \r\n Example #3 \r\n Reinforced Brick Pier and 4 Inch Panel \r\n \r\n FIG. 5 \r\n \r\n Step 1: Based on acoustical considerations, \r\n the wall height shall be 10 ft minimum. \r\n Step 2: Critical load combinations \r\n result in the following design values: \r\n \r\n Step 3: Calculate the maximum permissible \r\n spacing of piers with the given joint reinforcement based on the design \r\n moment, M px . \r\n Assume the distance from the extreme compression face to the joint \r\n reinforcement is 3 inches. \r\n \r\n Step 4: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n Step 5: Check the compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6: Calculate shear stress. \r\n \r\n Step 7: Check shear stress. \r\n \r\n Step 8: Design the reinforced brick \r\n masonry pier. Repeat steps 3 through 7 with the following design values: \r\n \r\n Step 3a: Calculate required pier \r\n reinforcement. \r\n \r\n Step 4a: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n Step 5a : Check compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6a: Calculate shear stress. \r\n \r\n Step 7a: Check shear stress. \r\n \r\n Step 9: Sliding and overturning \r\n resistance of the caisson is a function of the lateral soil pressure \r\n and is beyond the scope of this Technical Notes. \r\n Design Example #4: Reinforced Brick Pilaster \r\n and 6 inch Panel Noise Barrier Wall \r\n \r\n \r\n \r\n \r\n \r\n Noise Barrier Wall Design Example #4 \r\n Reinforced Brick Pilaster and 6 inch \r\n Panel \r\n FIG. 6 \r\n \r\n Step 1: Based on acoustical considerations, \r\n the wall height shall be 6 ft minimum. \r\n Step 2: Critical load combinations \r\n result in the following design values: \r\n \r\n Step 3: Calculate required reinforcement \r\n for the panel for the design moment, M px . Assume the distance from the extreme compression face to \r\n the joint reinforcement is 4.9 inches. \r\n \r\n Step 4: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n Step 5: Check compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6: Calculate shear stress. \r\n \r\n Step 7: Check shear stress. \r\n \r\n Step 8: Design the reinforced brick \r\n masonry pilaster. Repeat steps 3 through 7. \r\n Step 3a: Calculate required pilaster \r\n reinforcement. \r\n \r\n Step 4a: Calculate the masonry compressive \r\n stress and the steel tensile stress. \r\n \r\n Step 5a: Check compressive stress \r\n in masonry and the tensile stress in steel. \r\n \r\n Step 6a: Calculate shear stress. \r\n \r\n Step 7a: Check shear stress. \r\n \r\n Step 9: Sliding and overturning resistance \r\n of the caisson is a function of the lateral soil pressure and is beyond \r\n the scope of this Technical Notes. \r\n SUMMARY \r\n This Technical Notes discusses the \r\n structural design of brick masonry noise barrier walls. Design procedures \r\n are given following working stress analysis provided in the ACI/ASCE/TMS \r\n standard. Example designs are presented for recommended design of \r\n pier and panel, pilaster and panel and cantilever brick noise barrier \r\n walls. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and \r\n the experience of the technical staff of the Brick Institute of America. \r\n The information and recommendations contained in this publication \r\n must be used in conjunction with good engineering judgment and a basic \r\n understanding of the properties of brick masonry and related construction \r\n materials. Final decisions on the use of the information contained \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project designer and owner. \r\n REFERENCES \r\n 1. Anand, S.C., Brick Masonry Noise Barrier Walls, A Refined Structural \r\n Analysis of Wall Panel for Pier/Panel Case , Submitted to the Brick \r\n Institute of America, December 1991, 16 pp. \r\n 2. Building Code Requirements for Masonry Structures (ACI 530/ASCE \r\n 5/TMS 402-92) and Specifications for Masonry Structures (ACI \r\n 530.1/ASCE 6/TMS 602-92), American Concrete Institute, Detroit, \r\n MI, 1992. \r\n 3. Guide Specifications for Structural Design of Sound Barriers , American \r\n Association of State Highway and Transportation Officials, Washington, \r\n D.C., 1989. \r\n 4. Load and Resistance Factor Design Manual of Steel Construction-First \r\n Edition , American Institute of Steel Construction, Chicago, \r\n IL, 1986. \r\n 5. Minimum Design Loads for Buildings and Other Structures (ASCE 7-88), \r\n American Society of Civil Engineers, New York, NY, 1990. \r\n 6. Noise Barrier Design Handbook, (Report No. FHWA-RD-76-58), United \r\n States Department of Transportation, Federal Highway Administration, \r\n Washington, D.C., 1976. \r\n 7. Technical Notes on Brick Construction 3 , \r\n \"Building Code Requirements for Masonry Structures ACI 530/ASCE \r\n 5 and Specifications for Masonry Structures ACI 530.1/ASCE 6,\" February \r\n 1990. \r\n 8. Technical Notes on Brick Construction 45 , \r\n \"Brick Masonry Noise Barrier Walls - Introduction,\" February 1991. \r\n 9. Uniform Building Code , 1991 Edition, International Conference of \r\n Building Officials, Whittier, California, 1991. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60127,"ResultID":176359,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 4B - Energy Code Compliance \r\n of Brick Masonry Walls \r\n December 1992 \r\n Abstract: All buildings designed \r\n today must comply with energy code requirements. Building energy performance \r\n requirements may be embodied in a model building code or in a separate \r\n energy standard. These documents typically contain requirements for the \r\n building envelope, including walls, windows, doors, roofs and floors. \r\n Brick masonry, as a high mass building material, has the inherent energy \r\n saving feature of thermal storage capacity (thermal mass). This Technical \r\n Notes describes how to quantify thermal mass and calculate the heat \r\n capacity of several brick masonry walls. The procedure for addressing \r\n thermal mass in residential and commercial construction when determining \r\n building envelope compliance with widely used energy standards and codes \r\n is also described. \r\n Key Words: brick, building codes, \r\n building envelope, energy, heat capacity, standards, thermal mass. \r\n INTRODUCTION \r\n All buildings designed today must comply \r\n with energy code requirements. Energy performance requirements may be \r\n found in such documents as the 1992 Model Energy Code (MEC) [8], \r\n the ASHRAE/IES Standard 90.1-1989: Energy Efficient Design of New Buildings \r\n Except New Low-Rise Residential Buildings [4], and the 1990 edition \r\n of the BOCA National Building Code [9]. These standards \r\n and codes specify energy efficient design through overall building performance \r\n criteria or by a component prescriptive approach. The element in overall \r\n building performance discussed in this Technical Notes is the \r\n building envelope. Brick masonry walls provide a uniquely energy efficient \r\n envelope due to their high thermal mass. Thermal mass is the characteristic \r\n of heat capacity and surface area capable of affecting building thermal \r\n loads by storing heat and releasing it at a later time. Materials with \r\n high thermal mass react more slowly to temperature fluctuations and thereby \r\n reduce peak energy loads. Economic, energy efficient designs may be achieved \r\n by recognizing this inherent aspect of brick masonry and incorporating \r\n it in the building envelope design. \r\n The benefits of thermal mass have been \r\n known for a long time. However, their inclusion in energy codes and standards \r\n is a relatively recent development. Research in 1975-76 during the energy \r\n crisis, sponsored by the Masonry Industry Committee, led to the development \r\n of a simplified method for quantifying thermal mass benefits [10]. This \r\n method, called the M Factor, was developed for use by designers to compare \r\n wall systems with respect to energy performance during the heating cycle. \r\n The M Factor was not intended for sizing of mechanical equipment, but \r\n rather as a comparative analysis tool. By knowing the weight of a wall \r\n and the annual heating degree days (HDD), a designer could determine the \r\n correction factor (M Factor) to convert the calculated U- or R-value of \r\n a wall to an equivalent U- or R-value accounting for thermal mass and \r\n its effect of slowing heat transmittance. The U- and R-values are measures \r\n of steady-state heat transmittance. The corrected U- or R-value was then \r\n used to comply with prescribed energy requirements. At that time codes \r\n and standards did not incorporate thermal storage concepts when prescribing \r\n limits on heat transfer. Today, most energy codes and standards specify \r\n a maximum permissible value for the coefficient of thermal transmittance \r\n (U-value) for the building envelope as a function of wall weight. Some \r\n codes additionally specify a maximum overall thermal transfer value for \r\n walls (OTTV w ) of mechanically \r\n cooled spaces. The OTTV w is \r\n also a measure of heat transmittance and is a function of the wall temperature \r\n difference (TD EQ ) which is also \r\n related to wall weight. \r\n This Technical Notes instructs \r\n the user on the methods for determining compliance of various brick masonry \r\n walls with the building envelope requirements of several energy standards \r\n and codes. Those included are the 1989 ASHRAE/IES Standard 90.1, the 1992 \r\n Model Energy Code, the 1990 National Building Code, the \r\n 1991 Standard Building Code [11] , end the 1991 Uniform \r\n Building Code [12]. The methods by which these energy standards and \r\n codes criteria reflect thermal mass properties of brick masonry are explained. \r\n The user of this Technical Notes is \r\n assumed to have a working knowledge of heat transmittance and familiarity \r\n with the energy codes and standards listed. Procedures for calculating \r\n the actual U-values for walls can be found in Technical Notes 4 \r\n Revised, Section 8.4 of ASHRAE/IES Standard 90.1, and in the ASHRAE Handbook \r\n of Fundamentals [5]. \r\n Because of the possible confusion inherent \r\n in showing dual unit systems in calculations, metric (SI) units are not \r\n given in the data, equations, or examples in this Technical Notes. \r\n Table 1 provides metric (SI) conversion factors for the more commonly \r\n used energy units. \r\n \r\n \r\n \r\n NOTATION \r\n A d \r\n door area, ft 2 \r\n A f \r\n fenestration area, ft 2 \r\n A g \r\n glazing area, ft 2 \r\n A o \r\n gross wall area above grade, ft 2 \r\n A w \r\n opaque wall area, ft 2 \r\n c specific heat, Btu/(lb - 0 F) \r\n dt temperature difference between exterior and interior design conditions, \r\n 0 F \r\n HC heat capacity, Btu/(ft 2 - 0 F) \r\n HDD annual heating degree days \r\n HDD65 annual Fahrenheit heating degree days, 65 0 F \r\n base \r\n OTTV w overall thermal transfer value - walls, Btu/(hr-ft 2 ) \r\n SC shading coefficient of the fenestration, dimensionless \r\n SF solar factor value, Btu/(hr-ft 2 ) \r\n TD EQ \r\n temperature difference value, 0 F \r\n U d \r\n thermal transmittance of the door area, Btu/(hr-ft 2 - 0 F) \r\n U f \r\n thermal transmittance of the fenestration area, Btu/(hr-ft 2 - 0 F) \r\n U g \r\n thermal transmittance of the glazing area, Btu/(hr-ft 2 - 0 F) \r\n U o \r\n average thermal transmittance of the gross wall area, Btu/(hr-ft 2 - 0 F) \r\n U ow \r\n overall thermal transmittance of the wall assembly, Btu/(hr-ft 2 - 0 F) \r\n U w \r\n thermal transmittance of the opaque wall area, Btu/(hr-ft 2 - 0 F) \r\n w weight, lb/ft 2 \r\n HEAT CAPACITY \r\n In most energy codes, the thermal characteristics \r\n of high mass walls are quantified by measuring the heat capacity of the \r\n wall. Heat capacity represents the amount of thermal energy which may \r\n be stored by a material. For walls constructed of multiple materials, \r\n total heat capacity is calculated as the sum of the heat capacities of \r\n the individual components. In most energy codes and standards in the United \r\n States, heat capacity (HC) of a wall is calculated as the product of weight \r\n per unit area and specific heat (HC = w x c). Since the specific heats \r\n of most building materials are roughly equal, the heat capacity of a wall \r\n is directly proportional to its weight. Those materials which are relatively \r\n lightweight, such as insulation, do not have a significant effect on heat \r\n capacity and are often ignored when determining heat capacity. Sample \r\n calculations of heat capacity for several brick walls are provided in \r\n Figure 1. \r\n ENERGY CODE COMPLIANCE \r\n Each energy code and standard is slightly \r\n different in scope and criteria for compliance. The ASHRAE/IES Standard \r\n 90.1 is only applicable to non -residential buildings. Both residential \r\n and non-residential criteria may be found in the model building codes \r\n or the CABO Model Energy Code. Each code and standard is discussed \r\n individually below. \r\n ASHRAE/IES Standard 90.1 \r\n The ASHRAE/IES Standard 90.1 covers the \r\n energy performance design of new buildings except residential buildings \r\n of three stories or less. Compliance with this standard may follow one \r\n of two paths: the Building Energy Cost Budget Method or the System/Component \r\n Method. \r\n The Building Energy Cost Budget Method \r\n (BECBM) is to be used with innovative design concepts which cannot be \r\n accommodated by the System/Component Method or when a design fails the \r\n System/Component approach. The BECBM requires a detailed energy analysis \r\n to determine the estimated design energy cost. The BECBM permits any design \r\n whose design energy cost does not exceed the specified energy cost budget \r\n and meets the other requirements of the method. A complete description \r\n of this method can be found in Section 13 of the ASHRAE/IES Standard 90.1. \r\n The System/Component Method can be divided \r\n into two compliance paths for the building envelope: Prescriptive Criteria \r\n found in Section 8.5 and System Performance Criteria found \r\n in Section 8.6. These methods give minimum requirements to satisfy both \r\n heating and cooling cycle conditions. As the use of the ASHRAE/IES Standard \r\n 90.1 may be somewhat confusing, the National Codes and Standards Council \r\n of the Concrete and Masonry Industries is in the process of developing \r\n a handbook which discusses the benefits of thermal mass [2]. This energy \r\n handbook is slated for publication in early 1993. In addition to the examples \r\n given in this Technical Notes, the reader is also urged to refer \r\n to this handbook. \r\n \r\n FIG. 1 \r\n Heat Capacities of Several Brick \r\n Walls \r\n _________________________________________________________________________________ \r\n (a) 4 IN. BRICK AND WOOD STUD WALL \r\n \r\n \r\n 4 IN. BRICK w = (130 lb/ft 3 ) x [(0.75)(3.63 in.) / 12in./ft] = 29.5 \r\n lb/ft 2 \r\n (>75% SOLID) c = 0.20 Btu/(lb- o F) \r\n HC = 29.5 x 0.20 = 5.9 Btu/(ft S 2 - o F) \r\n 4 IN. STUD w = 45 lb/ft 3 x [(3.5 in. x 1.5 in.) / (144 in. 2 /ft 2 )] x (12 in./ft / 16 in.) \r\n = 1.23 lb/ft 2 \r\n c = 0.30 Btu/(lb- o F) \r\n HC = 1.23 x 0.30 = 0.4 Btu/(ft 2 - o F) \r\n (2) 1/2 IN. \r\n w = 50 lb/ft 3 \r\n x [(2)(0.5 in.) / 12 in./ft] = 4.2 lb/ft 2 \r\n GYPSUM BOARD c = 0.26 Btu/(lb- o F) \r\n HC = 4.2 x 0.26 = 1.1 Btu/(ft 2 - o F) \r\n INSULATION NEGLIGIBLE \r\n \r\n \r\n \r\n \r\n TOTAL HC = 5.9 + 0.4 + 1.1 \r\n = 7.4 Btu/(ft 2 o F) \r\n \r\n \r\n \r\n \r\n \r\n _________________________________________________________________________________ \r\n (b) 4 IN. BRICK AND 8 IN. LIGHTWEIGHT \r\n CMU WALL \r\n \r\n \r\n \r\n 4 IN. BRICK HC \r\n = 5.9 Btu/(ft 3 ° F) (from Fig. 1a) \r\n 8 IN. LIGHTWEIGHT CMUw = 90 lb/ft 3 x [(0.52)(7.63 in.) / 12in./ft] = 29.7 \r\n lb/ft 2 \r\n (52% SOLID) c = 0.21 Btu/(lb- ° F) \r\n HC = 29.7 x 0.21 = 6.2 Btu/(ft 2 - ° F) \r\n INSULATION NEGLIGIBLE \r\n \r\n \r\n \r\n \r\n TOTAL HC = 5.9 + 6.2 = 12.1 \r\n Btu/(ft 2 - ° F) \r\n \r\n \r\n \r\n \r\n \r\n _________________________________________________________________________________ \r\n (c) 4 IN. BRICK AND 6 IN. LIGHTWEIGHT \r\n CMU WALL \r\n \r\n \r\n \r\n 4 IN. BRICK HC \r\n = 5.9 Btu/(ft 2 - o F) (from Fig. 1a) \r\n 6 IN. LIGHTWEIGHT CMUw = 90 lb/ft 3 x [(0.55)(5.63 in.) / 12 in./ft] = 23.2 \r\n lb/ft 2 \r\n (55% SOLID) c = 0.21 Btu/(lb- ° F) \r\n HC = 23.2 x 0.21 = 4.9 Btu/(ft 2 - ° F) \r\n INSULATION NEGLIGIBLE \r\n \r\n \r\n \r\n \r\n TOTAL HC = 5.9 + 4.9 = 10.8 \r\n Btu/(ft 2 - ° F) \r\n \r\n \r\n \r\n \r\n \r\n _________________________________________________________________________________ \r\n (d) 6 IN. HOLLOW BRICK WALL \r\n \r\n \r\n \r\n \r\n \r\n 6 IN. BRICK w = 130 Ib/ft 3 \r\n x [(0.60)(5.63 in.) / 12 in./ft] = 36.6 Ib/ft 2 \r\n (60% SOLID) c = 0.20 Btu/ (Ib- ° F) \r\n \r\n \r\n \r\n \r\n TOTAL HC = 36.6 x 0.20 = 7.3 Btu/(ft 2 - ° F) \r\n IF GROUTED, HC WOULD BE EVEN \r\n GREATER \r\n \r\n \r\n \r\n \r\n \r\n \r\n _________________________________________________________________________________ \r\n \r\n Prescriptive Criteria . Section \r\n 8.5 of the ASHRAE/IES Standard 90.1 provides precalculated Alternate Component \r\n Package (ACP) tables based on the System Performance Criteria in Section \r\n 8.6 for a set of climate ranges. These ACP tables list the maximum permissible \r\n percentage of fenestration in a wall area, maximum thermal transmittance \r\n U-values, and minimum thermal resistance R-values as a function of the \r\n buildings internal energy load, type and characteristics of fenestration \r\n and wall construction. The many climatic variables which influence the \r\n building envelope are grouped together in each ACP table for a range of \r\n climates. Thus, the criteria found in the ACP tables address a worst case \r\n condition and may be more stringent than the System Performance Criteria \r\n in Section 8.6. \r\n The maximum permissible overall thermal \r\n transmittance value of an opaque wall (U ow ) using the prescriptive envelope criteria \r\n and the appropriate ACP table. The following example illustrates the benefits \r\n of using a thermal mass wall by comparing the maximum permissible U ow -value \r\n of a lightweight and a high mass wall. The U OW -value \r\n is a function of the wall weight (represented by HC); the buildings internal \r\n cooling loads due to heat generated by lights, equipment, and people (ILD); \r\n the placement of the insulation either internal to or integral with the \r\n wall mass (INT INS) or outside the wall mass (EXT INS); and the percentage \r\n of total wall area consisting of doors, windows and other glazing (PCT \r\n FEN). Refer to Fig. 2 of this Technical Notes and Section 8.6 of \r\n the ASHRAE/IES Standard 90.1 for the tables and terms used in this example. \r\n \r\n \r\n EXAMPLE 1: ASHRAE/IES Standard 90.1- Prescriptive Criteria \r\n \r\n Office Building \r\n \r\n Determine the maximum permissible overall \r\n wall thermal transmittance value (U ow ) \r\n of a 12,000 ft 2 office \r\n building located near Albuquerque, NM. The building is constructed of \r\n 4 in. nominal brick veneer with 8 in. nominal concrete masonry loadbearing \r\n walls with insulation as shown in Fig. 1b. The buildings fenestration \r\n is 30 percent of the total wall area. To determine the maximum permissible \r\n U ow -value, use the following steps. \r\n Step 1: To use the Prescriptive \r\n Envelope Criteria, first determine the appropriate ACP table from the \r\n locations listed in Table 8A-0 in Attachment 8A of the Standard. Find \r\n Albuquerque, NM in Table 2 of this Technical Notes. From Table \r\n 2, determine that the appropriate ACP table is Table 8A-23 of the Standard. \r\n The ACP table for Albuquerque, NM (8A-23) is shown in Fig. 2 of this Technical \r\n Notes. \r\n \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n Step 2: Calculate the heat capacity \r\n (HC) of the wall in question. The HC of the brick and concrete masonry \r\n wall shown in Fig. 1b has already been calculated to be 12.1 Btu/(ft 2 - ° F) . \r\n Step 3: Calculate internal load \r\n density (ILD) of the building. Section 8.5.5.2 of the Standard defines \r\n ILD as the sum of Lighting Power Density (LPD), Equipment Power Density \r\n (EPD) and Occupant Load Adjustment (OLA). Values for LPD are found in \r\n Table 6-5 of the Standard. (Note that Unit Lighting Power Allowance (ULPA) \r\n equals LPD.) For this office building example, LPD equals 1.81 W/ft 2 . The EPD can be selected from Table 8-4 of the Standard. For an office, \r\n EPD equals 0.75 W/ft 2 . \r\n OLA is a measure of the heat generated by living objects and is discussed \r\n in Section 8.5.5.2 of the Standard. For this example, assume OLA equals \r\n 0.0 W/ft 2 . Therefore, \r\n \r\n ILD = LPD + EPD + 0LA = 1.81 + 0.75 \r\n + 0.0 = 2.56 W/ft 2 . \r\n \r\n Using the ACP table for Albuquerque, \r\n NM shown in Fig. 2, enter the appropriate row based on the ILD of the \r\n building. Since ILD for this example is 2.56 W/ft 2 , enter the row for ILD 1.51 - 3.00. \r\n Step 4: The ACP tables contain \r\n criteria for both fenestration and opaque portions of the building envelope. \r\n This example addresses only the opaque wall requirements. Therefore, to \r\n determine the maximum permissible U OW -value \r\n for the wall assembly in this example, move to the far right to the box \r\n under the heading OPAQUE WALL. Since HC of the wall in question is greater \r\n than 5 Btu/(ft 2 -F), \r\n go to the subheading MASS WALL and find the box corresponding to the ILD \r\n row found in Step 3. \r\n Step 5: The maximum U OW -value is also a function of the location of insulation \r\n in the wall assembly. The insulation in this example is placed between \r\n or integral with the wall mass. Therefore, select the column for interior \r\n or integral insulation, INT INS. See Section 8.5.5.3 of the Standard for \r\n a complete discussion of insulation location. \r\n Step 6: Find the appropriate \r\n rows under MASS WALL corresponding to the HC of the wall in question. \r\n In this example, HC equals 12.1 Btu/(ft 2 -F), \r\n so use the rows HC greater than or equal to 10. Follow these rows to where \r\n they intersect the INT INS column. There are two possible values of U ow based on the percentage of fenestration (PCT FEN) \r\n in the envelope. \r\n \r\n Step 7: Follow the rows for HC greater \r\n than or equal to 10 to PCT FEN equal to 11 and PCT FEN equal to 57. Recall \r\n that the buildings fenestration (PCT FEN) equals 30 percent of the wall \r\n area in this example. The U OW -value \r\n corresponding to 11 percent equals 0.15 Btu/(hr-ft 2 - ° F), \r\n and UOW -value corresponding to 57 percent equals \r\n 0.14 Btu/(hr-ft 2 -F). \r\n Linearly interpolate for PCT FEN equal to 30 or use the lower of the two \r\n values. Using the lower value as the maximum permissible value, UOW must \r\n be less than or equal to 0.14 Btu/(hr-ft 2 -F). \r\n Step 8: To comply with the Standard, \r\n the calculated U OW-value of the wall in question may not exceed the maximum \r\n permissible value as determined from the ACP table. Using the steps found \r\n in Technical Notes 4 Revised or the ASHRAE \r\n Hand/book of Fundamentals, the thermal transmittance of the wall \r\n in Fig. 1b is calculated to be 0.10 Btu/(hr-ft 2 -F). Since the \r\n calculated U OW-value is less than the maximum permissible value of 0.14 \r\n Btu/(hr-ft 2 -F), the wall construction complies with the Building \r\n Envelope Requirements of ASHRAE/IES Standard 90.1. \r\n \r\n \r\n TABLE 2 \r\n Climate Data Grouped by ACP Tables 1 \r\n \r\n \r\n Compare \r\n the maximum permissible UOW-value of the thermal mass wall in this example \r\n with the maximum permissible UOW -value \r\n for a lightweight wall with HC less than 5 Btu/(ft 2 -F). The \r\n box under the heading OPAQUE WALL shows that the maximum UOW-value is \r\n only 0.10 Btu/(hr-ft 2 - ° F) for a lightweight \r\n wall. In terms of R-values, this thermal mass wall must have a minimum \r\n R-value of 7.1 (hr-ft 2 -F)/Btu, whereas a lightweight wall must \r\n have an R-value of at least 10.0 (hr-ft 2 -F)/Btu. \r\n \r\n System Performance Criteria. A system \r\n approach for compliance with envelope requirements is provided in Section \r\n 8.6 of the ASHRAE/IES Standard 90.1. This method is more flexible than the \r\n Prescriptive Criteria when considering thermal mass for several reasons. \r\n The external wall criteria are based on annual energy calculations for a \r\n specific location, rather than for a group of climates. Calculations allow \r\n for variations in internal loads and wall heat capacity by separating the \r\n building into zones. Furthermore, wall assemblies with HC greater than or \r\n equal to 7 Btu/(ft 2 - ° F) do not have limits on \r\n the permissible UOW-value as they do in the ACP tables. Compliance with \r\n the System Performance Criteria is achieved if the calculated energy loads \r\n do not exceed the criteria specified in Section 8.6. The System Performance \r\n Criteria approach requires numerous mathematical calculations by hand or \r\n a computer program. Information on an acceptable computer program, ENVSTD, \r\n is part of Appendix D of the ASHRAE/IES Standard 90.1. The program models \r\n the building envelopes performance and fully accounts for the effects of \r\n thermal mass. For this reason, ENVSTD is recommended for use with the System \r\n Performance Criteria when determining energy compliance of brick masonry \r\n walls, particularly when passive solar technologies are employed in the \r\n design. \r\n \r\n \r\n Model Energy Code \r\n The 1992 Model Energy Code (MEC) prepared \r\n by the Council of American Building Officials is applicable to residential \r\n dwellings as well as commercial, institutional and other buildings. This \r\n code sets limits on the permissible thermal transmission (U-value) of \r\n the building envelope. Designers may comply with this code by adhering \r\n to one of three chapters in the MEC: Chapter 4 - Building Design \r\n by Systems Analysis and Design of Buildings Utilizing Nondepletable Energy \r\n Sources; Chapter 5 - Building Design by Component Performance Approach; \r\n or Chapter 6 - Building Design by Acceptable Practice. \r\n Systems Analysis and Nondepletable Source \r\n Analysis. Chapter 4, as its title implies, is separated into two sections: \r\n Systems Analysis and Nondepletable Source Analysis. Both sections require \r\n an analysis of the annual energy usage of the proposed system. Requirements \r\n and procedures for analysis are specified. Compliance is achieved if annual \r\n energy consumption is not greater than that of a similar building designed \r\n according to MEC Chapter 5. This chapter applies to all building \r\n types covered by the MEC \r\n Component Performance Approach . The \r\n component performance approach presented in Chapter 5 of the MEC has \r\n requirements for both residential (Section 502.2) and non-residential \r\n (Section 502.3) construction. \r\n \r\n Residential Construction - Section \r\n 502.2 covers two types of residential construction, A1 and A2. Type A1 is \r\n detached one- and two-family dwellings. Type A2 is all other residential \r\n construction, not greater than three stories in height. Section 502.2 specifies \r\n the maximum thermal transmission U-value for each building component (walls, \r\n roof, slab on grade, etc.). In residential construction, the maximum permissible \r\n UW-value for walls is a function of the heat capacity of the wall in question. \r\n The example which follows illustrates how the maximum permissible U W -value \r\n may be increased if the HC of the wall in question is greater than or equal \r\n to 6 Btu/(ft 2 - ° F). All 4 in. brick veneer walls \r\n have a HC of at least 6 Btu/(ft 2 - ° F). \r\n \r\n \r\n EXAMPLE 2: Model Energy Code - Component Performance Criteria \r\n Single Family Home \r\n \r\n Determine the maximum permissible thermal \r\n transmittance of the opaque wall area (UW-value) of a 2,000 ft 2 \r\n two-story single family home located in a suburb of Washington, D.C. The \r\n house is brick veneer over wood frame constructed as shown in Fig. 1a. \r\n The homes fenestration is 20% of the total wall area: 15% glazing, 5% \r\n doors. Thermal transmittance values for the fenestration are: Ug = 0.48 \r\n and Ud = 0.48. The following steps are suggested to determine the maximum \r\n permissible UW-value. \r\n Step 1: Determine the annual Fahrenheit \r\n heating degree days (HDD, 65 0 F base) for the location given. \r\n For Washington, D.C., HDD equals 4224. HDD for most U.S. cities can be \r\n found in Table B7.1 of Building Control Systems [1] or in \r\n the 1981 ASHRAE Handbook of Fundamentals [5]. A single family home \r\n is classified by MEC Section 502.2 as building Type A1. Using this \r\n information, determine the maximum UO-value for the gross wall area from \r\n Fig. 3 of this Technical Notes to be 0.15 Btu/(hr-ft 2 - ° F). \r\n \r\n \r\n \r\n UO Walls-Group R Buildings-Heating \r\n \r\n FIG. 3 \r\n \r\n Step 2: Calculate Uw using Eq. 1 \r\n and knowing the U-values of the glazing and door areas and the gross wall \r\n area (Uo). Equation 1 in this Technical Notes is Eq. 1 found \r\n at the end of Section 502 of the MEC, solved for Uw. \r\n \r\n \r\n This Uw-value is the maximum permissible value \r\n for wall constructions having a heat capacity less than 6 Btu/(ft 2 -F). \r\n Step 3: Determine the HC of the wall \r\n in question. The HC of the brick veneer and wood stud wall has already \r\n been calculated to be 7.4 Btu/(ft 2 - ° F), see \r\n Fig. 1a. The maximum permissible Uw-value for a wall having a HC of 6 \r\n Btu/(ft 2 - ° F) or greater may be increased to \r\n account for the effects of thermal mass using Tables 3a-3c in this Technical \r\n Notes. The values in these tables, taken from the MEC, are \r\n a function of climate (represented by HDD65); wall construction (HC greater \r\n than or equal to 6 Btu/(ft 2 - ° F)); and the placement \r\n of insulation outside the thermal wall mass (Table 3a), on the interior \r\n of the wall mass (Table 3b) or integral with the wall mass (Table 3c). \r\n In this example, the insulation in the wall \r\n shown in Fig. 1a is placed interior of the wall mass. Therefore, Table \r\n 3b should be used. Enter the row in Table 3b for HDD65 equal to 4000-5500 \r\n and the column for Uw equal to 0.067 Btu/(hr-ft 2 - o F). \r\n Uw equal to 0.067 is between the columns in the table labeled 0.06 and \r\n 0.08. Linearly interpolate the table to determine the maximum permissible \r\n thermal transmittance, Uw, to be 0.077 Btu/(hr-ft 2 - ° F). \r\n This U-value corresponds to an R-value greater than or equal to 13 (hr-ft 2 - ° F)/Btu. \r\n \r\n TABLE 3a \r\n Required Uw for Wall With a Heat Capacity1 \r\n \r\n Equal to or Exceeding 6 Btu/(ft 2 \r\n ° F) \r\n With Insulation Placed on the Exterior \r\n of the Wall Mass \r\n \r\n \r\n TABLE 3b \r\n Required Uw for Wall With a Heat Capacity1 \r\n \r\n Equal to or Exceeding 6 Btu/(ft 2 \r\n ° F) \r\n With Insulation Placed on the Interior \r\n of the Wall Mass \r\n \r\n \r\n TABLE 3c \r\n Required Uw for Wall With a Heat Capacity1 \r\n \r\n Equal to or Exceeding 6 Btu/(ft 2° F) \r\n \r\n With Integral Insulation (Insulation \r\n and Mass Mixed, Such as a Log Wall) \r\n \r\n \r\n \r\n Step 4: To determine if the wall \r\n in question complies with Section 5 of the MEC, compare the maximum \r\n permissible thermal transmittance, Uw-value, determined in Step 3 with \r\n the calculated Uw-value. The calculated Uw-value, determined using the \r\n procedures contained in Technical Notes 4 \r\n Revised or the ASHRAE Handbook of Fundamentals, is 0.071 \r\n Btu/(hr-ft 2 - ° F). Since the calculated Uw-value \r\n is less than the maximum Uw-value (0.077 Btu/(hr-ft 2 - ° F)), \r\n this wall construction meets the requirements of the MEC Section \r\n 5. \r\n For comparison, in this example the maximum \r\n permissible Uw-value for a lightweight wall is 0.067 Btu/(hr-ft 2 - ° F), \r\n but for a thermal mass wall, the maximum Uw-value is 0.077 Btu/(hr-ft 2 - ° F). \r\n The allowable Uw-value for the thermal mass wall is 15 percent greater. \r\n Non-residential Construction - \r\n The requirements of Section 502.3 for non-residential construction \r\n are separated into heating criteria and cooling criteria. \r\n The heating criteria for walls specify the \r\n maximum permissible UO-value. The procedure parallels that outlined above \r\n for residential buildings; however, the maximum UW-value is not a function \r\n of HC and may not be adjusted for thermal mass walls. When permitted by \r\n the governing code, the ASHRAE/IES Standard 90.1 should be used in lieu \r\n of the MEC if the designer wishes to account for thermal \r\n mass effects in heating calculations. This change would permit an analysis \r\n which is closer to actual building performance. \r\n Non-residential buildings which are mechanically \r\n cooled must not exceed the maximum permissible overall thermal transfer \r\n value for walls (OTTVw) given in Section 502.3.2 of the MEC. The \r\n OTTVw is a function of the wall weight. The procedure for determining \r\n the actual OTTVw is a straightforward calculation using Eq. 2. Equation \r\n 2 of this Technical Notes corresponds to MEC Eq. 3. \r\n Eq. 2 \r\n The OTTVw is a function of the amount and characteristics \r\n of the fenestration and opaque wall areas, and the design temperatures. \r\n Consult the glazing manufacturers for the shading coefficient, SC, of the \r\n glazing used. The solar factor value, SF, is a function of location and \r\n is found in Chapter 7 of the MEC. The Uw-value of the opaque wall \r\n should be calculated using the procedures found in Technical Notes \r\n 4 . The capacity insulation effect of thermal mass \r\n walls is reflected in the temperature difference value (TDEQ). TDEQ is a \r\n measure of heat capacity and is inversely proportional to the wall weight, \r\n see Fig. 4. A high thermal mass wall has a lower TDEQ and, consequently, \r\n a lower calculated OTTVw. \r\n \r\n \r\n \r\n Temperature Difference (TDEQ) of Walls1 \r\n \r\n FIG. 4 \r\n \r\n Design by Acceptable Practice. The \r\n requirements for design by acceptable practice are given in Chapter 6 \r\n of the MEC. The consideration of thermal mass for energy conservation \r\n is allowed with the approval of the building official; however, Chapter \r\n 6 does not specify how to account for thermal mass. The Appendix section \r\n referenced in Chapter 6 gives examples of permitted construction details \r\n and corresponding Uw-values; however, no adjustments to the maximum permissible \r\n Uw-value are made in Chapter 6. The designer must use another method to \r\n consider the energy performance effects of thermal mass. The ASHRAE/IES \r\n Standard 90.1, where permitted, or Chapter 5 of the MEC are the \r\n recommended alternatives. \r\n BOCA National Building Code \r\n Article 31 of the 1990 National Building \r\n Code addresses energy conservation. This section gives requirements \r\n for maximum thermal transmission (U-values) for the various components \r\n of the building envelope. It also permits the use of the 1989 CABO Model \r\n Energy Code or the ASHRAE Standard 90A - 1980: Energy Conservation \r\n in New Building Design [3] in lieu of the requirements in Article \r\n 31. Designers wishing to utilize the benefits of thermal storage should \r\n comply with the 1989 MEC as no adjustments are made for thermal \r\n mass in Article 31. Future editions of the National Building Code may \r\n permit use of ASHRAE/IES Standard 90.1. \r\n Standard Building Code \r\n Appendix E - Energy Conservation of the \r\n 1991 Standard Building Code gives the requirements for building \r\n envelope energy compliance. This Appendix does not specify actual criteria \r\n but identifies which energy codes or standards may be used. Specifically, \r\n the Standard Building Code (SBC) allows use of the MEC , \r\n ASHRAE/IES Standard 90.1 for non-residential buildings, or ASHRAE Standard \r\n 90A for residences not exceeding 3 stories. The SBC explicitly \r\n allows the use of thermal mass (capacity insulation) when determining \r\n compliance with the permissible energy codes. Other energy conservation \r\n standards may be used in lieu of Appendix E when specifically adopted \r\n by the local jurisdiction. \r\n Uniform Building Code \r\n Appendix Chapter 53 of the 1991 Uniform \r\n Building Code requires users to comply with the energy requirements \r\n found in the 1989 MEC. No other standard or code may be used, unless \r\n specifically adopted by the local jurisdiction. \r\n SUMMARY \r\n This Technical Notes continues the \r\n discussion of the energy efficiency of thermal mass brick masonry walls. \r\n Direction is provided on how to treat thermal mass when considering the \r\n envelope requirements of several energy codes or standards. Methods for \r\n complying with these requirements are described in detail. Sample calculations \r\n quantifying thermal mass as heat capacity (HC) are given. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used in conjunction with good \r\n technical judgment and a basic understanding of the properties of brick \r\n masonry. Final decisions on the use of the information contained in this \r\n Technical Notes are not within the purview of the Brick Institute \r\n of America and must rest with the project architect, engineer and owner. \r\n REFERENCES \r\n 1. Bradshaw, \r\n V., Building Control Systems, John Wiley & Sons, New York, \r\n NY, 1985. \r\n 2. Concrete \r\n and Masonry Handbook to the ASHRAE/IES Standard 90.1. National Codes \r\n and Standards Council the Concrete and Masonry Industries, Herndon, \r\n VA, 1993. \r\n 3. Energy \r\n Conservation in New Building Design (ASHRAE Standard 90A), American \r\n Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., \r\n Atlanta, GA, 1980. \r\n 4. Energy \r\n Efficient Design of New Buildings Except New Low-Rise Residential Buildings \r\n (ASHRAE/IES Standard 90.1-1989 and Addendum-1992), American Society \r\n of Heating, Refrigerating and Air-Conditioning Engineers, Inc. and Illuminating \r\n Engineering Society of North America, Atlanta, GA. \r\n 5. Handbook \r\n of Fundamentals, American Society of Heating, Refrigerating and \r\n Air-Conditioning Engineers, Inc., Atlanta, GA, 1981 edition and 1989 \r\n edition. \r\n 6. \"Heat \r\n Gain Through Opaque Walls,\" Technical Notes on Brick Construction \r\n 4A Revised, Brick Institute of America, Reston, VA February 1982. \r\n 7. \"Heat \r\n Transmission Coefficients of Brick Masonry Walls,\" Technical Notes \r\n on Brick Construction 4 Revised,, Brick Institute of America, Reston, \r\n VA, January 1982. \r\n 8 . Model \r\n Energy Code, Council of American Building Facials (CABO), Falls \r\n Church, VA, 1992. \r\n 9. National \r\n Building Code, Building Code Officials and Code Administrators International, \r\n Inc. (BOCA), Country Club Hills, IL, 1990. \r\n 10. \"Report \r\n on the Effect of Well Mass on the Storage of Thermal Energy,\" Hankins \r\n and Anderson, Inc., Richmond, VA and Boston, MA, 1976. \r\n 11. Standard \r\n Building Code, Southern Building Code Congress International, Inc. \r\n (SBCCI), Birmingham, AL, 1991. \r\n 12. Uniform \r\n Building Code, International Conference of Building Officials (ICBO), \r\n Whittier, CA, 1991. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60128,"ResultID":176360,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 5A - Sound \r\n Insulation - Clay Masonry Walls \r\n June 1970 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n The sound insulation or sound transmission \r\n loss of a wall is that property which enables it to resist the passage \r\n of noise or sound from one side to the other. This should not be confused \r\n with sound absorption which is that property of a material which permits \r\n sound waves to be absorbed, thus reducing the noise level within a given \r\n space and eliminating echoes or reverberations. Only sound insulation \r\n will be discussed in this Technical Notes. \r\n \r\n MEASUREMENT OF SOUND \r\n The sound insulation of a building \r\n assembly is expressed as a reduction factor in decibels (dB). The decibel \r\n is approximately the smallest change in energy the human ear can detect, \r\n and the decibel scale is used for measuring ratios of sound intensities. \r\n The reference sound intensity used to measure absolute noise levels is \r\n that corresponding to the faintest sound a human ear can hear (0 dB). \r\n However, a difference of 3 or less dB is not especially significant, because \r\n the human ear cannot detect a change in sounds of less than 3 dB. Figure \r\n 1 shows the intensity level of common sounds on the decibel scale. These \r\n data are reproduced from \"How Loud is Loud? Noise, Acoustics and Health\", \r\n by Lee E. Farr, M.D., published in the February 1970 issue of Architectural \r\n & Engineering News. \r\n \r\n SOUND TRANSMISSION LOSS \r\n It is desirable to have a single number \r\n rating as a means for describing the performance of building elements \r\n when exposed to an \"average\" noise. In the past it was customary to use \r\n the numerical average of the transmission loss values at nine frequencies. \r\n This rating, termed the nine-frequency average transmission loss, is \r\n often quite inaccurate in comparing an assembly of materials having \r\n widely differing TL-frequency characteristics. One single number rating \r\n method which has been recently proposed is the sound transmission class \r\n (STC). This rating is based on the requirements that the value of \r\n transmission loss at any of the eleven measuring frequencies does not \r\n fall below a specified TL-frequency contour. The shape of this contour \r\n is drawn to represent the more common types of noise, and generally covers \r\n the requirements for speech privacy. \r\n \r\n \r\n \r\n \r\n FIG. 1 \r\n \r\n The \r\n following are conclusions in a report entitled, \"Measurements of Sound \r\n Transmission Loss in Masonry\", by William Siekman of Riverbank Acoustical \r\n Laboratories, June 1969. \r\n \" In conclusion, changes in results of \r\n transmission loss measurements have been studied. They indicate that deficiencies \r\n in earlier test methods and environments have apparently been corrected. \r\n Although data reported today are lower than ever before, they agree very \r\n well with data taken in field situations, and consequently provide assurance \r\n that laboratory tests can be relied upon to achieve the desired noise \r\n reductions. The performance of walls near the coincidence frequency cannot \r\n be predicted yet on a theoretical basis, nor can the performance of walls \r\n having a compound structure, but test specimen sizes are now large enough \r\n to be representative of typical walls and to provide data over the present \r\n frequency range of interest.\"Since the principal deviation due to specimen \r\n size is apt to occur at the lower frequencies, users of transmission loss \r\n data are urged to avoid dependence upon single figure ratings, even such \r\n a relatively good one as is recommended by the Proposed Classification \r\n for Determination of Sound Transmission Class, ASTM RM 14-2 (1966). The \r\n decision to use a particular construction should always be based upon \r\n the total curve and the requirements at individual frequencies.\" \r\n \r\n DESCRIPTION OF SPECIMENS \r\n The specimens discussed in this issue of Technical Notes were \r\n constructed at the Riverbank Acoustical Laboratories in a testing frame \r\n having inside dimensions of 14 ft 4 in. wide by 9 ft 4 in. high. The joints \r\n were of typical thickness and were staggered. Mortar was mixed in a ratio \r\n by volume of 1 part cement, 2 parts lime and 9 parts sand. All specimens \r\n were constructed by a professional mason. The curing time was 28 days \r\n or more. The transmission area, S. used in the computations was generally \r\n 126 sq ft. \r\n \r\n Following are the descriptions of tests, performed at the Riverbank Acoustical \r\n Laboratories starting with the lowest Sound Transmission Class (STC): \r\n \r\n STC 39. 4-in. Structural Clay Tile Wall \r\n Tile dimensions: 3-9/16 by 4-7/8 by 11-3/4 in \r\n Wall thickness: 3-9/16 in. \r\n Average weight: 22.3 \r\n psf \r\n Test: TL 67-59 \r\n \r\n STC 41. 4 in. Structural Clay Tile \r\n Wall, with 5/8-in. plaster one face \r\n Tile dimensions: 3-9/16 by 4-7/8 by 11-3/4 in. \r\n Wall thickness: 4-3/16 in. \r\n Average weight: 25.3 psf \r\n Test: TL 67-82 \r\n \r\n STC 45. 8-in. Structural Clay Tile Wall \r\n Tile dimensions: 7-5/8 by 4-7/8 by 11-3/4 in. \r\n Wall thickness: 7-5/8 in. \r\n Average weight: 40.6 psf \r\n Test: TL 67-69 \r\n \r\n STC 45. 4-in. Face Brick Wall \r\n Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. \r\n Wall thickness: 3-3/4 in. \r\n Average weight: 38.7 \r\n psf \r\n Test: TL 67-70 \r\n \r\n STC 49. 6-in. \"SCR brick\" (Reg. U.S. Pat. Off., SCPI) Wall, with 3/8-in. \r\n gypsum board over 1-in. styrofoam \r\n insulation one face \r\n Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2. \r\n Wall thickness: 6-7/8 in. \r\n Average weight: 57.7 \r\n psf \r\n Test: TL 70-39 \r\n NOTE: The styrofoam was placed with adhesive, \r\n spot applied 12 in. o.c. both vertically and horizontally, to the brick \r\n wall on one side. A single layer of 3/8 in. gypsum board was applied vertically \r\n over the foam with adhesive, spot applied 12 in. o.c. vertically and horizontally \r\n in the field and 6 in. o.c. at the joints. The external joints were finished \r\n with a typical drywall joint system. \r\n \r\n STC 50. 8-in. Face Brick and Structural Clay Tile Composite Wall \r\n Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. \r\n Tile dimensions: 4 in. nominal thickness \r\n \r\n Wall thickness: 8 in. Average \r\n weight: 63.8 psf \r\n Test: TL 67-65 \r\n \r\n STC 50. 10-in. Face Brick Cavity Wall, with 2-in. air space \r\n Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. \r\n Wall thickness: 10 \r\n in. \r\n Average weight: 81.0 psf \r\n Test: TL 68-31 \r\n NOTE: The 2 wythes of masonry were tied \r\n together with metal wall ties. \r\n \r\n STC 50. 4-in. Brick Wall, with 1/2-in. sanded plaster, two-coat one face \r\n Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in. \r\n Wall thickness: 4-1/8 in. \r\n Average weight: 42.4 psf \r\n Test: TL 69-283 \r\n \r\n STC 51. 6-in. \"SCR brick\" (Reg. U.S. Pat. Off., SCPI) Wall \r\n Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2 in. \r\n Wall thickness: 5-1/2 in. \r\n Average weight: 55.8 psf \r\n Test: TL 69-286 \r\n \r\n STC 52. 8-in. Solid Face Brick Wall \r\n Brick dimensions: 2-1/4 by 3-5/8 by 8-1/4 in. \r\n Wall thickness: 8 in. \r\n Average weight: 83.3 psf \r\n Test: TL 67-68 \r\n \r\n STC 53. 8-in. Solid Brick Wall, with 1/2-in. gypsum board on furring strips \r\n one face \r\n Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in. \r\n Wall thickness: 9-1/4 in. \r\n Average weight: 86.7 psf \r\n Test: TL 69-287 \r\n NOTE: The 3/4-in. collar joint was filled with mortar. Metal Z ties were \r\n used between wythes spaced at 24 in. o.c. both vertically and horizontally. \r\n The 1 by 3 wood vertical furring strips were spaced at 16 in. o.c. and \r\n nailed at the mortar joints approximately 12 in. o.c. The gypsum board \r\n was applied vertically and attached with nails spaced 12 in. o.c. in the \r\n field and 8 in. o.c. along the edges. The joints and nail heads were finished \r\n with standard drywall system. \r\n \r\n STC 53. 6-in. \"SCR brick\" (Reg. U.S. Pat. Off., SCPI) Wall, with 1/2-in. \r\n plaster one face \r\n Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2 in. \r\n Wall thickness: 6 in. Average \r\n weight: 60.8 psf \r\n Test: TL 70-70 \r\n \r\n STC 55. 12-in. Face Brick and Structural Clay Tile Composite Wall \r\n Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. \r\n Tile dimensions: 7-5/8 by 4-7/8 by 11-3/4 in. \r\n Wall thickness: 12 \r\n in. Average weight: 84.1 \r\n psf \r\n Test: TL 67-62 \r\n \r\n STC 59. 12-in. Solid Brick Wall \r\n Brick dimensions: Face: 2-1/4 \r\n by 3-3/4 by 8-1/4 in. \r\n Building: 2-1/4 \r\n by 3-5/8 by 8 in. \r\n Wall thickness: 12 in. \r\n Average weight: 116.7 psf \r\n Test: TL 67-32 NOTE: The outside wythes \r\n were of face brick. The interior wythe was of common brick. \r\n \r\n STC 59. 10-in. Reinforced Brick Masonry Wall (RBM) \r\n Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in \r\n Wall thickness: 9-1/2 in. \r\n Average weight: 94.2 \r\n psf \r\n Test: TL 70-6 \r\n NOTE: The 2-1/4-in. grouted cavity contained No. 6 bars at 48 in. o.c. \r\n vertically and No. 5 bars at 30 in. o.c. horizontally. \r\n \r\n SOUND TRANSMISSION CLASS \r\n Sound transmission class contours (see Fig. 2) may be constructed in accordance \r\n with ASTM RM 14-2 on conventional semi-logarithmic paper as follows: a \r\n horizontal line segment from 1250 to 4000 Hz (cycles per second); a middle \r\n line segment decreasing 5 dB in the interval 1250 to 400 Hz; and a low \r\n frequency segment decreasing 15 dB in the interval 400 to 125 Hz. \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n \r\n The STC contour is shifted vertically relative \r\n to the test curve until some of the measured TL values for the test specimen \r\n fall below those of the STC contour and the following conditions are fulfilled: \r\n The sum of the deficiencies (that is; the deficiencies of test points \r\n below the contour) shall not be greater than 32 dB, and the maximum deficiency \r\n of any single test point shall not exceed 8 dB. The sound transmission \r\n class for the specimen is the TL (transmission loss) value corresponding \r\n to the intersection of the sound transmission class contour and the 500-Hz \r\n ordinate. \r\n \r\n Table 1 shows the decibel losses for 18 frequencies of test specimens \r\n listed above. Deficiencies or deviations from the contour (see graph) \r\n are tabulated to correspond with the proper frequencies. \r\n \r\n These measurements were made using a one-third octave bank of pink noise, \r\n swept in 13 min from 100 to 5000 Hz. Runs were made before and after a \r\n system interchange, during which the ratio of sound pressure levels in \r\n the two rooms was directly recorded graphically. The final results were \r\n obtained by averaging the runs, with a resultant precision within a 90 \r\n per cent confidence limit of ┬▒1 dB. \r\n \r\n The sound transmission class is computed \r\n in accordance with the Tentative Recommended Practice for Laboratory Measurement \r\n of Airborne Sound Transmission Loss of Building Partitions, ASTM E 90-66T, \r\n and ASTM RM 14-2. The STC number is intended to be used as a preliminary \r\n estimate of the acoustical properties of the specimen. Final decisions \r\n for design use should be based upon the entire TL curve for the values \r\n at all the test frequencies. \r\n \r\n The sound transmission loss of the tested specimen is shown by the curved \r\n line in the above graph. The broken line is the limiting sound transmission \r\n class contour. \r\n \r\n The theoretical transmission loss of that \r\n limp mass having the same weight per square foot as the specimen can be \r\n located by drawing a straight line between the two slash marks on the \r\n edges of the grid. This was derived from the equation: TL = 20 log W + \r\n 20 log F - 33, where W is weight in pounds per square foot, and F is frequency \r\n in Hertz (cycles per second). \r\n \r\n \r\n \r\n 1 Transmission Loss, decibels \r\n 2 Deficiencies, decibels \r\n MASKING EFFECT \r\n \r\n The sound insulation required in a structure to give satisfactory results \r\n depends not only upon the noise level outside of the building or in adjoining \r\n rooms, but also upon the noise level within the room under consideration. \r\n \r\n If it is to be assumed that there is no \r\n noise within the room to be insulated against sound transmission and the \r\n noise level in the adjoining room is 60 dB, it will require a partition \r\n having a reduction factor of 60 dB to render the noise in the adjoining \r\n room inaudible. However, if the noise level in the room under consideration \r\n is 30 dB, a partition having a sound reduction factor of approximately 40 \r\n dB (see Fig. 3) will make the sound in the adjoining room inaudible. Experiments \r\n have shown that for one sound to mask another, there must be at least 10 \r\n dB difference between the two sounds. This effect of the sound within the \r\n room under consideration is known as the \"masking effect\". Figure 3 illustrates \r\n this \"masking effect\" principle. \r\n \r\n \r\n \r\n Effect of Masking Noise on \r\n \"Listening\" Side of Wall \r\n FIG. 3 \r\n CONCLUSION \r\n This issue of Technical Notes has discussed recent test data for, \r\n and sound insulation performance of, brick and tile walls and partitions. \r\n Future issues of Technical Notes will contain some suggestions and \r\n recommendations for the control of sound transmission through brick and \r\n tile walls and partitions. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60129,"ResultID":176361,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 6 - \r\n Painting Brick Masonry \r\n May 1972 (Reissued Dec. 1985) \r\n \r\n INTRODUCTION \r\n Although some masonry walls \r\n require protective coatings to impart color and help in resisting \r\n rain penetration, clay masonry requires no painting or surface \r\n treatment. Brick are generally selected because, among other characteristics, \r\n they have integral and durable color and, when properly constructed, \r\n are resistant to rain penetration. Clay \r\n masonry walls may be painted to increase light reflection or for \r\n decorative purposes. Most paint authorities agree that, once painted, \r\n exterior masonry will require repainting every three to five years. This \r\n issue of Technical Notes discusses general applications \r\n of paint to interior and exterior brick walls, and a brief discussion \r\n on specific paints suitable for brick masonry. \r\n \r\n GENERAL \r\n It is often erroneously assumed \r\n that brick masonry walls that are to be painted can be built with \r\n less durable materials and, in some instances, with less than \r\n extreme care in workmanship than would normally be used for unpainted \r\n brick walls. This is not the case. When a brick wall is \r\n to be painted, the selection of materials, both brick units and \r\n mortar, and the workmanship used in constructing the wall should \r\n all be of the highest quality; at least as good in quality as \r\n when the walls are to be left exposed. Every care should be taken \r\n to see that joints are properly filled with mortar to avoid the \r\n entrance of moisture into the wall, since it may become trapped \r\n behind the paint and cause problems. Every care should be taken \r\n to see that there are no efflorescing materials in the wall, either \r\n in the mortar, brick units or in the backup, since efflorescence \r\n beneath the paint film can also cause problems. See Technical \r\n Notes 23 Series. \r\n \r\n Brick . \r\n Brick units to be used for walls that are to be painted should \r\n conform to the applicable requirements of the ASTM Specifications \r\n for Building Brick or Facing Brick, C 62 or C 216, respectively. \r\n The grade of units (which designates their durability) should \r\n not be lower than would be used if the wall were not to be painted. \r\n Grade SW is recommended. It may be acceptable to use brick units \r\n which are durable but differ in color in a wall to be painted. \r\n However, care should be taken that the units have similar absorption \r\n and suction characteristics so that the paint applied will adhere \r\n to all of the surfaces and have a uniform acceptable appearance. \r\n \r\n Mortar . \r\n Mortar for brick masonry walls to be painted should conform to \r\n the Specifications for Mortar for Unit Masonry, ASTM C 270, Proportion \r\n Specifications. It is suggested that the mortar consist of portland \r\n cement and lime, and that the mortar type be selected on the basis \r\n of the structural requirements of the wall. See Technical Notes \r\n 8 . \r\n \r\n Paint . \r\n Paint for application to brick masonry walls should be durable, \r\n easy to apply and have good adhesive characteristics. It should \r\n be porous if applied on exterior masonry, thereby permitting the \r\n wall to breathe and preventing the trapping of free moisture behind \r\n the paint film. \r\n \r\n CONSIDERATIONS FOR PAINTING CLAY MASONRY \r\n In selecting a paint system for a brick masonry wall, the \r\n primary concern should be the characteristics of the surface and \r\n the exposure conditions of the wall. A primer coat may be of particular \r\n importance, especially where unusual or severe conditions exist. \r\n \r\n Alkalinity . \r\n The chemical property of masonry which may have a significant \r\n effect on paint durability and performance is the alkalinity of \r\n the wall. Brick are normally neutral, but are set in mortars which \r\n are chemically basic. Paint products, which are based on drying \r\n oils, may be attacked by free alkali and the oils can become saponified. \r\n To prevent this occurrence, an alkaline-resistant primer is recommended. \r\n \r\n Efflorescence . \r\n The deposit of water-soluble salts on the surface of masonry, \r\n efflorescence, is another factor that can hamper the performance \r\n of painted masonry. Efflorescence, which is present on the surface, \r\n should be removed and, once removed, the surface should be observed \r\n for reoccurrence prior to being painted. Methods of preventing \r\n and removing efflorescence are discussed in Technical Notes \r\n 23 Series, \"Efflorescence-Causes, Prevention and Control\". \r\n \r\n Water and Moisture . \r\n Water or moisture in a masonry system will generally hamper the \r\n satisfactory performance of the painted surface. Moisture may \r\n enter masonry walls in any of several ways; through the pores \r\n of the material, through incompletely bonded or only partially \r\n filled mortar joints, copings, sills and projections, through \r\n incomplete caulked joints and improperly installed flashing or \r\n where flashing is omitted. In general, brick wall surfaces should \r\n be dry for painting. Acceptable moisture conditions for masonry \r\n walls to receive paint are listed in Table 1. The use of an electrical \r\n moisture meter may be used to measure the moisture content of \r\n a wall \r\n \r\n \r\n \r\n 1 Some manufacturers offer \r\n special porous, highly pigmented emulsion paints which may give \r\n somewhat better results in very adverse conditions where delay \r\n is not acceptable. \r\n SURFACE PREPARATION General . \r\n \r\n Proper surface preparation is as important as paint selection. \r\n Because each coat is the foundation for all future coats, success \r\n or failure depends largely upon surface preparation. Thoroughly \r\n examine all surfaces to determine the required preparation. Previously \r\n painted surfaces often require the greatest effort. Before painting, \r\n remove all loose matter. Take special care when cleaning surfaces \r\n for emulsion paints and primers. They are nonpenetrating and require \r\n cleaner surfaces than solvent-based paints. Some paints can or \r\n should be applied to damp surfaces. Others must not. Be sure to \r\n follow directions accompanying proprietary brands. \r\n \r\n New Masonry . \r\n As a general rule, new clay masonry is seldom painted. It is difficult \r\n to justify the extra expenditure for initial and future painting. \r\n However, if for any reason painting new masonry is desired, there \r\n are a few precautions necessary for reasonable success. Do \r\n not wash new clay masonry walls with acid cleaning solutions. \r\n Acid reactions can result in paint failures. Use alkali-resistant \r\n paints. If low-alkali portland cement is not used in the mortar, \r\n it may be necessary to neutralize the wall to reduce the possibility \r\n of alkali-caused failures. Zinc chloride or zinc sulfate solution, \r\n 2 to 3 1/2 lb per gal of water, is often used for this purpose. \r\n \r\n Existing Masonry . \r\n Examine older unpainted masonry for evidence of efflorescence, \r\n mildew, mold and moss. While these conditions are not common, \r\n they all indicate the presence of moisture. Examine all possible \r\n entry points for water. Where necessary, repair flashing and caulking; \r\n tuckpoint defective mortar joints. Remove \r\n all efflorescence by scrubbing with clear water and a stiff brush. \r\n A wall which has effloresced for a long time may present difficulties. \r\n The presence of moisture, the deposition of salts and the probable \r\n presence of alkalies are all factors which may contribute to the \r\n deterioration of paints. If moss \r\n has accumulated on damp, shaded masonry, apply an ordinary weed \r\n killer. Wet the wall with clear water before applying weed killers \r\n to prevent them from being drawn into the wall. Chemical weed \r\n killers may contain solubles which can contribute to efflorescence \r\n or react unfavorably with paint, and should be removed after being \r\n used by scrubbing the wall with a stiff brush while rinsing with \r\n clear water. Mildew seldom occurs \r\n on unpainted masonry. However, where present, treat it the same \r\n as on painted surfaces, discussed in the following paragraphs. \r\n Be sure to wet the wall before applying any cleaning solution. \r\n Clean small areas and rinse thoroughly. For further discussion \r\n on cleaning brick see Technical Notes 20 \r\n Revised, \"Cleaning Clay Products Masonry\". \r\n \r\n Painted Surfaces . \r\n Previously painted surfaces normally require extensive preparation \r\n prior to repainting (refer to Table 2 for typical paint \r\n failures). Under humid conditions, mildew may have developed. \r\n Mildew may feed on a paint film or on particles trapped by the \r\n painted surface. If present, remove it completely before applying \r\n paint. Otherwise, growth will continue, damaging new paint. Mildew \r\n has been successfully removed by steam cleaning and sand blasting. \r\n The following is also effective: 3 \r\n oz trisodium phosphate (Soilax, Spic and Span, etc.), plus 1 \r\n oz detergent (Tide, All, etc.), plus 1 \r\n qt 5 per cent sodium hyperchlorite (Chlorox, Purex, etc.), plus \r\n 3 qt warm water, or enough to make 1 gal of solution. Use \r\n this solution to remove mildew and dirt. Scrub with a medium soft \r\n brush until the surface is clean; then rinse thoroughly with fresh \r\n water. For small areas, use an ordinary household cleanser. Scrub \r\n with a medium soft brush and then rinse thoroughly. Use masonry \r\n paints containing a mildewcide to help prevent molds from recurring. Remove \r\n all peeled, cracked, flaked or blistered paint by scraping, wire \r\n brushing or sand blasting. In some instances, old paint may be \r\n burned off, but this should be done only by skilled operators. \r\n Like efflorescence, paint blistering is caused by water within \r\n the masonry. Search for the waters source and take the necessary \r\n corrective measures to keep water out of the wall. If \r\n alligatoring exists, remove the entire finish. There is no other \r\n means of correction. If slight \r\n chalking has occurred, brush the surface thoroughly. However, \r\n if chalking is deep, remove by scrubbing with a stiff fiber brush \r\n and a solution of trisodium phosphate and water. Rinse the surface \r\n thoroughly afterwards. Use a penetrating primer to improve adhesion \r\n of the final coat. Excessive paint \r\n buildup results from too many coats or excessively thick coats. \r\n Where it occurs, remove all paint and treat as a new surface. Completely \r\n remove cement-based paints before repainting with other types. \r\n An exception to this rule is the use of cement-based paints as \r\n primers which will be covered by another paint within a relatively \r\n short time. If the wall will be repainted with another cement-based \r\n paint, wire brushing and scrubbing will suffice, providing treatments \r\n for mildew, efflorescence, etc. are not required. \r\n \r\n TABLE 2 \r\n Types of Paint Failure \r\n \r\n \r\n \r\n MASONRY \r\n PAINTS \r\n Because all paints have distinct properties \r\n and because surfaces vary considerably, even the most experienced \r\n painting contractors carefully examine a surface before making \r\n recommendations. However, the following will generally indicate \r\n the proper use of masonry paints. \r\n \r\n CEMENT-BASED PAINTS \r\n For many years, cement-based \r\n paints have been satisfactory coatings for masonry surfaces. They \r\n achieved popularity because they have relatively good adherence \r\n and tendency to make a wall less permeable to free water. Cement-based \r\n paints are permeable, permitting the wall to breathe. Their main \r\n components are portland cement, lime and pigments. Additives, \r\n binders and sands may be added. Although \r\n cement-based paints are more difficult to apply than other types, \r\n good surface protection results when properly applied. While they \r\n are not complete waterproofers, cement-based paints help to seal \r\n and fill porous areas, excluding large amounts of free water. \r\n White and light colors tend to be the most satisfactory. It is \r\n difficult to obtain a uniform coating with darker shades. Lighter \r\n colors tend to become translucent when wet, and dark colors become \r\n darker. Color returns to normal as the wall surface dries. Cement-based \r\n paints can provide a good base for other paints applied within \r\n a relatively short time. The following \r\n procedure for applying paint on a properly prepared surface generally \r\n applies: \r\n 1. Cure new masonry walls for approximately one month before applying \r\n cement-based paints. \r\n 2. Dampen wall surfaces thoroughly \r\n by spraying with water. \r\n 3. Cement-based paints are packaged \r\n in powdered form. Because their cementitious components begin \r\n to hydrate upon contact with water, mix immediately prior to application \r\n for optimum results. \r\n 4. Apply heavy coats with a stiff \r\n brush, allowing at least 24 hr to elapse between coats. \r\n 5. During this time, keep the \r\n wall damp by periodically spraying it with water. \r\n 6. Apply additional coats in the \r\n same manner. \r\n 7. Keep the final coat damp for \r\n several days to properly cure. \r\n \r\n WATER-THINNED EMULSION PAINTS \r\n General Characteristics . \r\n \r\n Water-thinned emulsion paints, commonly referred to as latex paints, \r\n are relatively easy to apply. Water-thinned emulsions may be brush, \r\n roller or spray-applied. However, brush application is preferable, \r\n especially on coarse-textured masonry. Emulsion paints dry quickly, \r\n have practically no odor and present no fire hazard. They may \r\n be applied to damp surfaces, permitting painting shortly after \r\n a rain or on walls damp with condensation. As \r\n a group, these paints are alkali-resistant. Hence, neutralizing \r\n washes and curing periods are not usually necessary before painting. \r\n Water emulsion paints possess high water vapor permeability and \r\n are known to have performed well on brick substrates that have \r\n been properly prepared. Emulsion \r\n paints will not adhere well to moderately chalky surfaces. If \r\n possible, repainting should be done before the previous coat chalks \r\n excessively. However, specifically formulated latex paints are \r\n available containing emulsified oils or emulsified alkyds which \r\n facilitate wetting of chalky surfaces. This property enables the \r\n paint to bond the chalk together and to the substrate. The \r\n principal water-thinned emulsion paint types are: butadiene-styrene, \r\n vinyl, acrylic, alkyd and multicolored lacquers. \r\n \r\n Butadiene-Styrene Paints . \r\n These relatively low-cost, rubber-based latex paints develop water \r\n resistance more slowly than vinyl or acrylic emulsions. They are \r\n most satisfactory in light tints as chalking rate may be excessive \r\n in deep colors. \r\n \r\n Vinyl Paints . \r\n Polyvinyl acetate emulsion paints dry faster, have improved color \r\n retention and a more uniform, lower sheen than rubber-based latex \r\n paints. \r\n \r\n Acrylic Emulsion Paints . \r\n Acrylic emulsions have excellent color retention, permit recoating \r\n in 30 min or less, and have good alkali resistance. Acrylics have \r\n high resistance to water spotting and may be scrubbed easily. \r\n \r\n Alkyd Emulsion Paints . \r\n Alkyd emulsions are related to solvent-thinned alkyd types, but \r\n have all the general characteristics of latex paints. They do \r\n have more penetration than most water-thinned emulsions, achieving \r\n better adhesion on chalky surfaces. Compared to other emulsion \r\n paints, these are rather slow to dry, have more odor, are not \r\n as resistant to alkalies, and have poorer color retention. Under \r\n normal exposure conditions, alkyd emulsions can serve as a finished \r\n coat over a suitable primer. \r\n \r\n Multicolored Lacquers . \r\n A specialized paint group, multicolored lacquers are applied only \r\n by spray gun. The finished film appears as a base color with separate \r\n dots or particles of contrasting colors. These paints will cover \r\n many surface defects and irregularities. However, they must be \r\n applied over a base coat of another type; for example, polyvinyl \r\n acetate or acrylic emulsion paints. \r\n \r\n FILL COATS \r\n Fill coats are base coats \r\n for exterior masonry. They are similar in composition, application \r\n and uses to cement-based paints. However, fill coats contain an \r\n emulsion paint in place of some water, giving improved adhesion \r\n and a tougher film than unmodified cement paints. Fill coats have \r\n greater water retention, giving the cement a better chance to \r\n cure. This is particularly valuable in arid areas where it is \r\n difficult to keep the painted surface moist during the curing \r\n period. \r\n \r\n SOLVENT-THINNED PAINTS \r\n The five major solvent-thinned \r\n paints are oil-based, alkyd (synthetic resin), synthetic rubber, \r\n chlorinated rubber and epoxy. Oil-based and alkyd paints are not \r\n recommended for exterior masonry. Solvent-thinned paints should \r\n be applied only to completely dry, clean surfaces. They produce \r\n relatively nonporous films and should be used only on interior \r\n masonry walls not susceptible to moisture penetration. The exception \r\n to this is special purpose paint, such as synthetic rubber, chlorinated \r\n rubber and epoxy paints. \r\n \r\n Oil-Based Paints . \r\n Oil-based paints have been used for many years. They are relatively \r\n non-porous and recommended for interior use only. \r\n Although several coats may be required for uniform color and good \r\n appearance, they bind well to porous masonry. As with most solvent-based \r\n paints, they have good penetration on relatively chalky surfaces, \r\n but are highly susceptible to alkalies. New masonry must be thoroughly \r\n neutralized to avoid saponification. Available in a wide color \r\n range, oil-based paints are moderately easy to apply. Several \r\n days drying is generally required between coats. \r\n \r\n Alkyd Paints . \r\n Alkyd paints are similar to oil-based paints in most general characteristics. \r\n They may have slightly less penetration, resulting in somewhat \r\n better color uniformity at the cost of adhering power. Alkyd paints \r\n are more difficult to brush, dry faster and give a harder film \r\n than oil-based paints. These, too, are nonpermeable and are recommended \r\n for interior use only. \r\n \r\n Synthetic Rubber and Chlorinated Rubber Paints . \r\n These paints have excellent penetration and good adhesion to previously \r\n painted, moderately chalky surfaces as well as new surfaces. They \r\n are reported to be more resistant to efflorescence and are generally \r\n good in alkali resistance. They may be applied directly to alkaline \r\n masonry surfaces, but are more difficult to brush on than oil \r\n paints. Darker colored synthetic rubber paints lack color uniformity. \r\n Both types have high resistance to corrosive fumes and chemicals. \r\n For this reason, they are often specified for industrial applications. \r\n Both types require very strong volatile solvents, a fire hazard \r\n which may prove undesirable. \r\n \r\n Epoxy Paints . \r\n Epoxy paints are of synthetic resins generally composed of two \r\n parts, a resin base and a liquid activator. They must be used \r\n within a relatively short time after mixing. Epoxies can be applied \r\n over alkaline surfaces, have very good adhering power, and good \r\n corrosion and fume resistance. However, some types chalk excessively \r\n if used outdoors. Epoxies are relatively expensive and somewhat \r\n difficult to apply. \r\n \r\n \"HIGH-BUILD\" PAINT COATINGS \r\n High-build paint coatings \r\n are generally used on interiors to give the effect of glazed brick. \r\n Some coatings are based on two-component urethane polyesters and \r\n epoxies. Others are of an emulsion-based coat with acrylic lacquer. \r\n These paint systems usually include fillers to smooth out surface \r\n irregularities. \r\n \r\n OTHER COATINGS \r\n Heavily applied coatings of \r\n the so-called \"breathing type\" are available with either a water \r\n or solvent base. They are generally composed of asbestos fiber \r\n and sand, and applied thickly to hide minor surface imperfections. \r\n The presence of moisture on the surface of a masonry wall generally \r\n will not harm the latex type. Lower application temperatures of \r\n 35 F to 50 F on the other hand are less damaging to the solvent \r\n type. For both types, adhesion \r\n is mostly mechanical because of low binder and high pigment content. \r\n Some coatings require special primers to insure adhesion. Although \r\n these coatings are reported to have given good performance on \r\n masonry, they tend to show stains where water runoff occurs. These \r\n coatings are capable of allowing passage of water vapor, but cannot \r\n transmit large quantities of water that may enter through construction \r\n defects. Failure may occur as a result of freezing of water accumulation \r\n behind the film. \r\n \r\n PAINTING NEAR UNPAINTED MASONRY \r\n Often windows and trim of \r\n masonry buildings are painted with self-cleaning paints \r\n to keep surfaces fresh and clean. Unfortunately, self-cleaning \r\n is generally achieved through chalking. The theory is that rain \r\n will wash away chalked paint, constantly exposing a fresh paint \r\n surface. The theory works well, but too often no provision is \r\n made to keep chalk-contaminated rain water away from masonry surfaces. \r\n The result is usually more unsightly than dirty paint on trim \r\n or windows. Avoid this staining by choosing nonchalking paints \r\n for windows and trim and by providing a means of draining water \r\n away from wall surfaces. \r\n \r\n REFERENCES \r\n 1. Manual \r\n on the Selection and Use of Paints , Technical Report #6, \r\n National Research Council of Canada, Division of Building Research, \r\n 1950, Ottawa, Canada. \r\n 2. Paints \r\n for Exterior Masonry Walls , BMS110, National Bureau of Standards, \r\n 1947, Washington, D.C. \r\n 3. Field \r\n Applied Paints and Coatings , Publication 653, Building Research \r\n Institute, 1959, Washington, D.C. \r\n 4. Paints \r\n and Coatings , Publication 706, Building Research Institute, \r\n 1960, Washington, D.C. \r\n 5. Painting \r\n Walls; 1, Building Research Station Digest (2nd Series), \r\n No. 55, Building Research Station, 1965, Garston, Herts., England. \r\n 6. Coatings \r\n for Masonry Surfaces, by H. E. Ashton, Canadian Building \r\n Digest, CBD 131, November 1970, Ottawa, Canada. \r\n 7. Coatings \r\n for Masonry and Cementitious Materials, by Walter Bayer, \r\n Construction Specifier, November 1970, Washington D.C. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60130,"ResultID":176362,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 6A - Colorless Coatings for \r\n Brick Masonry \r\n April 1995 \r\n \r\n Abstract : Colorless coatings are considered \r\n for application to brick masonry walls and floors for several reasons. \r\n This Technical Notes discusses the common reasons for applying \r\n colorless coatings to above-grade brick masonry and the appropriateness \r\n of such actions. The types of products which are often used and the advantages \r\n and disadvantages of their use are considered. Recommendations are provided \r\n when considering the application of a clear coating to brick masonry. \r\n Key Words : colorless coatings, film \r\n former, graffiti-resistant, penetrant, water penetration, water repellent. \r\n INTRODUCTION \r\n Colorless coatings are available in many \r\n types and are designed for a variety of uses. The type of coating applied \r\n to brick masonry is dependent on the desired effect of the coating and \r\n its chemical and physical properties. Products promoted for use on brick \r\n masonry are not always appropriate. Some can be detrimental to brick masonry. \r\n Function of the brickwork plays an important role in coating selection. \r\n Coatings suitable for interior brick masonry may not be suitable for exterior \r\n exposures. Similarly, coatings applied to floors or pavements are subject \r\n to conditions different from coatings applied to brick masonry walls. \r\n Coating selection is also influenced by the material properties of the \r\n substrate. Recommendations for clear coatings on other masonry materials \r\n are not necessarily appropriate for brick masonry. Clay brick masonry \r\n is considerably different than stone, concrete and concrete masonry in \r\n both physical and chemical properties. Brick masonry has a different pore \r\n structure, is generally less absorptive, less permeable and is not as \r\n alkaline as concrete masonry. The recommendations included herein are \r\n applicable only to clay brick masonry. \r\n This Technical Notes examines the \r\n various types of colorless coatings often applied to brick masonry. Specific \r\n recommendations are found under RECOMMENDATIONS FOR USE. Coatings for \r\n below grade masonry, such as damp proofing or waterproofing coatings, \r\n are not addressed. Other Technical Notes in this series cover the \r\n painting of brick masonry. \r\n REASONS FOR USE \r\n Clear coatings may be applied to brick masonry \r\n in an effort to facilitate cleaning, to resist graffiti, to provide gloss \r\n or to reduce water absorption or penetration. Many times a single product \r\n is used to achieve several of these objectives. Selection of a coating \r\n should be based on the desired appearance, resistance to water penetration, \r\n application, material substrate, economics, life span or other criteria \r\n set by the designer or user. In addition, the disadvantages of using colorless \r\n coatings should be considered during selection. \r\n Water Repellency \r\n It is desirable to minimize the absorption \r\n and penetration of water in a brick masonry wall system for many reasons. \r\n Water absorption can lead to staining and efflorescence when soluble salts \r\n are liberated by moisture in a masonry wall. Water penetration is responsible \r\n for many of the problems encountered in walls. Water which freezes in \r\n nearly saturated brick can cause deterioration over time. Corrosion of \r\n metal ties, metal studs and other metal items due to prolonged contact \r\n with water can lead to structural or serviceability failures of a building \r\n wall. Wood members and sheathing are vulnerable to rotting and mold growth \r\n when wetted. Water penetrating an exterior wall can damage interior finishes. \r\n To effectively minimize water penetration, \r\n care must be exercised in the material selection, design and detailing \r\n of brick masonry. Quality construction and proper maintenance are also \r\n important. Under normal exposures, it is nearly impossible for significant \r\n amounts of water to pass directly through the brick units or mortar. Most \r\n water penetrating a brick masonry wall occurs at separations and cracks \r\n between brick and mortar or at junctures with other materials. \r\n Clear water repellent coatings are sometimes \r\n suggested to reduce water absorption and reduce the amount of water that \r\n penetrates the exterior brick masonry wythe. Recent research indicates \r\n the varied effectiveness of clear water repellents in reducing water leakage \r\n through a brick masonry wythe [4,8,11]. Change in the absorption properties \r\n of masonry may have no effect on water penetration of a masonry wall system. \r\n Clear water repellents can seldom stop water penetration through cracks \r\n over 0.02 in. (10 mm) in size. Clear water repellents cannot stop water \r\n penetration through incompletely filled mortar joints or from sources \r\n such as ineffective sills, caps or copings. Their effectiveness under \r\n conditions of wind-driven rain is questionable. As a result, the use of \r\n clear water repellent coatings to eliminate water penetration in a wall \r\n with existing defects is often futile. Clear water repellents are most \r\n effective at reducing the amount of water absorbed by the brick \r\n masonry. Thus, they can help reduce staining and efflorescence caused \r\n by moisture absorption, particularly on highly absorptive masonry. \r\n The applications and limitations of clear \r\n water repellents are described in the sections that follow. Methods for \r\n ascertaining the effectiveness of clear water repellents are discussed \r\n under PERFORMANCE CRITERIA. \r\n New Construction Applications . Clear \r\n water repellents are sometimes specified for newly constructed brick masonry \r\n as an \"insurance measure\" against water penetration and related problems. \r\n The thinking is that clear water repellents will prevent water penetration \r\n which would have otherwise occurred due to imperfections in construction. \r\n Such thinking should be discouraged, because clear water repellents cannot \r\n compensate for poor construction or design. As discussed previously, their \r\n effectiveness in stopping water penetration has limitations. Furthermore, \r\n most brick masonry wall systems do not require a clear water repellent \r\n to remain impervious to rain water. For these reasons, the use of clear \r\n water repellents on newly constructed drainage walls is not recommended. \r\n Clear water repellents can be useful for \r\n brick masonry walls which are particularly vulnerable to water penetration, \r\n especially in climates which receive large amounts of rain. These wall \r\n types include barrier walls, chimneys and parapets. When a clear water \r\n repellent is considered for use on these elements, the benefits must be \r\n weighed against the possible disadvantages. Past successful performance \r\n of the proposed coating, for a number of years in the same exposure conditions \r\n and on the same brick and mortar types, should be required. In climates \r\n which experience freezing and thawing cycles, the effect of a colorless \r\n coating on the durability of the masonry is a particular concern. For \r\n exterior brick pavements subject to repeated freeze/thaw cycling, the \r\n possibility of accelerated deterioration outweighs any benefits of clear \r\n water repellents. \r\n Whenever applying clear water repellents \r\n to newly constructed masonry walls, a minimum of one month should pass \r\n after close-in of the building before application of the coating. This \r\n period will allow the walls to cure sufficiently and, more importantly, \r\n allow the evaporation of moisture from the building materials to occur \r\n naturally, unimpeded by a coating on the masonry. In fact, a relatively \r\n dry substrate is recommended by many colorless coating manufacturers. \r\n A delay of one year is preferred so that efflorescence due to water absorbed \r\n during construction, often known as \"new building bloom,\" is not entrapped \r\n by the coating. For a more complete discussion of efflorescence, refer \r\n to Technical Notes 23 Series. \r\n Remedial Applications . The most common \r\n reason for application of a clear water repellent coating is to reduce \r\n or eliminate water penetration in a building experiencing water penetration \r\n problems. The inability of a coating to eliminate water penetrating through \r\n larger than hairline cracks in the masonry has already been discussed. \r\n When a clear water repellent is being considered as a means to eliminate \r\n water penetration in a brick masonry wall, several items must be addressed \r\n prior to application of a coating. It is paramount that the source of \r\n water penetration be determined. The application of a clear water repellent \r\n in lieu of ascertainable repairs is not recommended. Common repairs \r\n which may be necessary and should be completed include: \r\n 1. Removal of defective sealant and cleaning, \r\n priming and replacement with a good grade of elastomeric sealant at all \r\n windows, copings, sills, expansion joints between brick masonry and other \r\n materials; \r\n 2. Repointing of incompletely filled, cracked \r\n or disintegrated mortar joints; \r\n 3. Removal and replacement of spalled or \r\n cracked brick; \r\n 4. Surface grouting of separations between \r\n the brick units and mortar. \r\n These remedial measures are described in \r\n Technical Notes 7F [15]. \r\n Other repairs, which are generally more difficult \r\n and costly to complete, include: \r\n 1. Clearing mortar blockage from weep holes \r\n and the interior drainage system; \r\n 2. Removal and replacement of damaged, omitted \r\n or improperly installed flashing. \r\n These latter repairs are argued by some people \r\n to be unnecessary or uneconomical if using a clear water repellent. However, \r\n all of these repair techniques can reduce water penetration and are long-term \r\n solutions. Application of a clear water repellent is not considered a \r\n long-term solution. Long-term solutions are preferred. \r\n After remedial measures have been completed \r\n and inspected, it is usually advisable to wait a period of several months \r\n to determine if additional corrective steps are necessary. Many times \r\n the moisture penetration problems will be corrected by these initial repairs \r\n and further consideration of coatings can be dismissed. \r\n If water penetration remains a problem, or \r\n long-term solutions are judged to be uneconomical despite their benefits, \r\n the application of a clear water repellent can be considered. If water \r\n absorption appears to be the problem, a clear water repellent can be particularly \r\n effective. However, clear water repellents are not a permanent solution \r\n and will require reapplication. See the discussion under the Durability \r\n section for further information on the life span of coatings. \r\n Staining and Efflorescence \r\n The use of colorless coatings can reduce \r\n the amount of water absorbed by a brick masonry wall and may help reduce \r\n staining and efflorescence. As a result, colorless coatings are sometimes \r\n used on brick masonry which has a relatively high absorption, such as \r\n walls which have been sand-blasted. Brick manufacturers sometimes apply \r\n colorless coatings to units during manufacture to reduce staining or initial \r\n rate of absorption. ASTM C 216 Specification for Facing Brick requires \r\n that the brick manufacturer report the presence of such coatings. Selection \r\n of a coating for any of these uses should be based on demonstrated successful \r\n performance in similar usages and exposures. Staining and efflorescence \r\n may not be completely eliminated by application of a coating. If staining \r\n or efflorescence occurs on masonry which is treated with a colorless coating, \r\n the stains and salts may be difficult or impossible to remove. \r\n Appearance Change \r\n Another common reason for using a colorless \r\n coating is to achieve a darker, wet or glossy appearance. Gloss is created \r\n by changing the reflectance of the brick masonry surface. In some cases, \r\n change of appearance may be the undesired side effect of an improperly \r\n applied coating or of poor coating selection. Some coatings may give an \r\n undesired sheen or gloss. See Figure 1. Other coatings may impart a yellow \r\n appearance to the masonry. Satisfactory appearance of a treated surface \r\n is best judged by examining a sample panel or test area of masonry before \r\n and after treatment. \r\n \r\n Undesired Gloss Due to a \r\n Colorless Coating \r\n FIG. 1 \r\n Graffiti Resistance \r\n Many structures used by the public are built \r\n with brick masonry. Schools, government buildings, libraries and noise \r\n barrier walls are applications where brick masonry is chosen for its appearance \r\n and low maintenance. Resistance to graffiti and ease of cleaning can be \r\n important. Colorless coatings are sometimes applied to brick masonry to \r\n help achieve these goals. Such coatings work by keeping graffiti or dirt \r\n on the masonry surface for easier removal. Glazed brick are often used \r\n in similar applications to provide the same benefits. \r\n TYPES OF COLORLESS COATINGS \r\n Colorless coatings for brick masonry can \r\n be classified into two general categories: film formers and penetrants. \r\n The two types have significantly different physical properties and performance. \r\n As the name implies, film formers produce a continuous film on the surface \r\n of the masonry. Penetrants enter up to 3/8 in. (10 mm) into the brick \r\n masonry and do not form a surface film. \r\n Most colorless coatings are available in \r\n two formulations: water-borne and solvent-borne. Normally, better penetration \r\n and performance is attained using solvent-borne solutions. However, manufacturers \r\n are increasingly using water-borne solutions which have lower volatile \r\n organic compound (VOC) content. VOC content is regulated by many states \r\n because of the connection with poor air quality. Product data and test \r\n results should be examined to compare performance. Carrier type influences \r\n permissible application conditions. Temperature range, substrate moisture \r\n content, environmental regulations and adjacent materials and vegetation \r\n must be considered. \r\n Colorless coatings are discussed in the following \r\n sections according to generic chemical type. Most colorless coating manufacturers \r\n will provide information on the generic chemical composition of their \r\n products. In addition, handbooks are available which classify many proprietary \r\n coatings according to their generic chemical composition [6]. \r\n Film Formers \r\n Acrylics, stearates, mineral gum waxes, urethanes \r\n and silicone resins are among the products which form a film when applied \r\n to brick masonry. The large molecular size of these products prevents \r\n them from penetrating into the masonry. Typically, film-forming products \r\n work by adhering a film to the surface of the brick masonry substrate. \r\n Surface preparation can be important in achieving satisfactory adhesion \r\n of a film-forming coating. Film materials, continuity and product concentration \r\n determine the performance characteristics. \r\n Film-forming products are effective at preventing \r\n water from penetrating into brick masonry. Film formers can bridge the \r\n small hairline cracks which are commonly the source of water penetration. \r\n However, their ability to exclude water from the exterior also inhibits \r\n evaporation of water within the masonry through the exterior face. This \r\n reduction in the water vapor transmission rate, or lack of breathability, \r\n through the brick masonry is of special concern in exterior brick masonry \r\n subject to freezing and thawing cycles. Thus, film-forming products are \r\n generally not recommended for brick masonry in such environments. \r\n A film on a masonry wall may facilitate cleaning \r\n by keeping surface contaminants from penetrating into the masonry. This \r\n characteristic leads to their use as graffiti-resistant coatings. When \r\n an appearance change is desired, film formers are typically used. Film-forming \r\n products, by their nature, tend to produce a sheen or gloss when applied. \r\n In some cases, they may darken the appearance of a wall (the wet look) \r\n when used in high concentrations. \r\n Acrylics . Acrylics can be effective \r\n as water repellents. However, they are vulnerable to cracking due to thermal \r\n fluctuations. They are often used when a high gloss is desired. Acrylics \r\n are available in two forms, water-borne and solvent-borne. Acrylic emulsions \r\n are water-borne. Acrylic solutions are solvent-borne. Because of increasing \r\n regulation of solvent-borne products, acrylic emulsions are more widely \r\n used. Coating manufacturers typically recommend that acrylics be applied \r\n to substrates that are thoroughly dry. If applied to a damp substrate, \r\n the acrylic film can separate from the masonry, giving it a cloudy, or \r\n whitened, appearance. Acrylics in particular tend to create a slippery \r\n surface. This is a concern in pavement applications. When stabilized against \r\n degradation in ultraviolet (UV) light, acrylics can last five to seven \r\n years. \r\n Stearates . Stearates promoted for \r\n use on masonry are generally aluminum or calcium stearates. They are sometimes \r\n known as metallic soaps. Stearates form a water repellent surface by reacting \r\n with free salts in mineral building materials and plugging the pores. \r\n Some formulations are used as integral water repellents in concrete masonry \r\n and mortar. Their effectiveness as water repellents varies, and typically \r\n film-forming stearates must be reapplied every year. Stearates also have \r\n the potential to turn cloudy if moisture gets behind the coating. \r\n Mineral Gum Waxes . Paraffin wax and \r\n polyethylene wax are commonly referred to as mineral gum waxes. These \r\n products are typically solvent-borne and can be good water repellents, \r\n able to bridge hairline cracks. However, they have been known to darken \r\n the substrate and, in cases where moisture gets behind the coating, turn \r\n the surface a milky white. Figure 2 illustrates a case where a mineral \r\n gum wax promoted for use on brick masonry was applied to a building which \r\n had water penetrating through cracks in the masonry and at flashing failures. \r\n The sources of moisture were not addressed, and the coated masonry became \r\n moist. This led to clouding and eventual spalling of the masonry, as shown \r\n in Fig. 3. \r\n \r\n Clouding of Brick Masonry \r\n Wall - Coated With a Mineral Gum Wax \r\n FIG. 2 \r\n \r\n Spalling of Brick Masonry \r\n Wall - Coated With a Mineral Gum Wax \r\n FIG. 3 \r\n \r\n Urethanes . \r\n Urethanes, chemically polyurethanes, are isocyanate resins. They are classified \r\n as either aromatic or aliphatic, depending on the compound reacted with \r\n the isocyanate. They are considered one-part urethanes if cured by moisture \r\n in the substrate or air, and two-part if they require a chemical catalyst \r\n to cure. While urethanes can be excellent water repellents and provide \r\n good gloss, they often break down under UV light. Chemical additives are \r\n often used in urethanes to prevent yellowing and improve gloss retention. \r\n Urethanes with such additives usually last from one to three years. Because \r\n they are not resistant to UV light, urethanes are not the best choice \r\n for exterior applications. \r\n Silicone Resins . Known chemically \r\n as polydimethylsiloxanes (PDMS), silicone resins may form a film in the \r\n presence of moisture when their solids content is between five and ten \r\n percent. The PDMS comes in many weights and forms. The properties of the \r\n resin depend on the molecular weight and structure of the PDMS. Early \r\n silicone resins were known for reducing the durability and changing the \r\n appearance of masonry. They often yellowed and were hard to clean. There \r\n are PDMS manufactured today which do not yellow or contribute to soiling. \r\n Silicones do not chemically bond with the substrate, and as a result, \r\n have a short life. Many silicones require reapplication on a yearly basis, \r\n although some last longer. \r\n Penetrants \r\n Penetrating type coatings are characterized \r\n by their penetration into the substrate, typically to depths up to 3/8 \r\n in. (10 mm). They repel water by changing the capillary force, or contact \r\n angle, of the pores in the face of the masonry from positive (suction) \r\n to negative (repellency). Penetrating coatings are typically more resistant \r\n to UV degradation because of their chemical composition and because they \r\n penetrate below the masonry surface. Because they coat the pores rather \r\n than bridge them, penetrants tend to have better water vapor transmission \r\n characteristics. The solids content of these materials commonly ranges \r\n from five to forty percent by weight. Penetrants can be categorized into \r\n five groups: silanes, siloxanes, silicates, methyl siliconates and blends \r\n of these. \r\n Silanes . Silanes used as clear water \r\n repellents are more accurately known as alkylalkoxysilanes or alkyltrialkoxysilanes. \r\n Their small molecular structure allows good penetration on even dense \r\n substrates. They are used in relatively high concentrations (typically \r\n 20 percent or greater solids content). Silanes chemically bond with silica- \r\n or alumina-containing materials to make the material water repellent. \r\n Silanes are best applied to slightly damp substrates. An alkaline substrate, \r\n such as concrete or concrete masonry, acts as a catalyst to speed the \r\n reaction to form a water repellent surface. Chemical catalysts are also \r\n used with silanes to improve the chemical reaction on less alkaline substrates \r\n such as brick. \r\n Siloxanes . The clear water repellent \r\n coatings known as siloxanes are actually oligomerous alkylalkoxysiloxanes \r\n or silsesquioxanes. Although they have a larger molecular structure than \r\n silanes, good penetration and water repellency can also be achieved by \r\n siloxanes. Like silanes, siloxanes chemically bond with silica- or alumina-containing \r\n materials such as brick. This results in a long life, up to ten years \r\n or more, and makes them more difficult to remove. Siloxanes can also be \r\n applied to a damp surface. Siloxanes are less volatile than silanes and \r\n react with chemically neutral substrates without a chemical catalyst. \r\n Siloxanes are typically used in solutions having five to seven percent \r\n solids by weight. Siloxanes have been known to work well on certain brick \r\n masonry installations. However, siloxanes are highly reactive with silica \r\n and will bond with glass which is not properly protected. \r\n Silicates . Ethyl silicates are commonly \r\n used as consolidants on natural stone and occasionally brick masonry. \r\n They are generally used for restoration of deteriorated masonry. Consolidants \r\n are designed to react with and stabilize the substrate to which they are \r\n applied. Their use on brick is uncommon. Sodium silicates and potassium \r\n silicates are sometimes used in the concrete industry as curing compounds \r\n and accelerators. None are effective water repellents and are not recommended \r\n for this use on brick masonry. \r\n Methyl Siliconates . Methyl siliconates \r\n are alkaline solutions which react slowly with silica-containing materials \r\n in the presence of carbon dioxide to form a water repellent surface. Siliconates \r\n are sometimes injected into brick masonry to form a horizontal barrier \r\n to rising damp. However, because of their slow reaction time, they make \r\n poor water repellents and are not recommended for surface application \r\n to exterior brick masonry walls. \r\n Blends . Colorless coatings are also \r\n made from blends of the materials listed above. Blends are created to \r\n produce products with the benefits of the constituent materials. As such, \r\n they reflect the properties of the constituent materials, but the properties \r\n will be modified somewhat. Thus, it is important that the user review \r\n product data and test results for blended products. \r\n PERFORMANCE CRITERIA \r\n Any coating applied to brick masonry will \r\n change the physical properties of the masonry. Appropriate performance \r\n criteria for colorless coatings are not well defined. Currently, coating \r\n manufacturers rely on test methods developed for common substrates, such \r\n as concrete and brick, to measure the performance of their products. For \r\n example, water repellency is often measured by comparing the cold water \r\n absorption of untreated and treated brick using the method described in \r\n ASTM C 67 Test Methods of Sampling and Testing Brick and Structural Clay \r\n Tile. While easy to perform, the interpretation and use of such laboratory \r\n results, for a single material, has not been determined. Until these tests \r\n are validated with research and correlated to masonry wall performance, \r\n one must rely on good judgment and experience in establishing performance \r\n criteria limits. The following criteria can be useful in comparing several \r\n colorless coating alternatives. The most critical properties of colorless \r\n coatings to be evaluated are water vapor transmission, water penetration \r\n and repellency, durability, reapplication, gloss, slip resistance, graffiti \r\n resistance and environmental considerations. These properties are discussed \r\n in the following sections. A summary of several properties of colorless \r\n coatings is found in Table 1. \r\n \r\n \r\n 1Refs. 6,13 \r\n \r\n Water Vapor Transmission \r\n The most important property to consider when \r\n selecting a coating for application on exterior brick masonry is the water \r\n vapor transmission rate. The water vapor transmission, or breathability, \r\n of exterior brick masonry is important in determining the rate and \r\n amount of water which can evaporate through the face of the masonry. Coatings \r\n which do not breathe well, those not having a high water vapor transmission \r\n rate, can entrap water within the brickwork leading to clouding of the \r\n coating. See Figs. 2 and 4. A minimal reduction in the water vapor transmission \r\n rate through coated brick masonry reduces the possibility of masonry deterioration \r\n due to freeze-thaw cycles or salt crystallization by ensuring that natural \r\n evaporation can occur. Otherwise, water-soluble salts which may be normally \r\n deposited on the surface of the masonry as efflorescence may be trapped \r\n beneath the coating. As salts crystallize, they grow significantly in \r\n size. Accumulation of entrapped salts can lead to spalling. The potential \r\n for these actions may preclude the use of coatings on brick masonry. Additionally, \r\n older brick masonry structures may be subject to damaging moisture problems, \r\n such as rising damp and condensation, which are only aggravated by the \r\n application of a colorless coating. \r\n \r\n Clouding of a Colorless Coating \r\n on a Brick Pavement \r\n FIG. 4 \r\n A method to evaluate the potential of a colorless \r\n coating to entrap damaging salts and cause spalling is proposed by Binda \r\n [3]. Individual brick units are treated with the colorless coating on \r\n their exposed face. The sides of the unit are sealed with rubber to prevent \r\n evaporation except through the treated face. The units are subjected to \r\n cycles of immersion in a salt solution for 4 hours and air drying for \r\n 44 hours. The cross-sectional size is measured after each cycle. Deterioration \r\n is typically by delaminations of the treated brick face. Hence, a reduction \r\n in brick cross section. A correlation of the number of cycles to deterioration \r\n in this test to the durability of a masonry assemblage has not yet been \r\n established. However, this method is one means of assessing salt crystallization \r\n damage potential when evaluating colorless coatings. \r\n Others have also tried to establish the effect \r\n of colorless coatings on the water vapor transmission rate and durability \r\n of brick masonry. At present, there is no definitive test. The water vapor \r\n transmission rate can be measured using ASTM E 96 Test Methods for Water \r\n Vapor Transmission of Materials, desiccant (dry) cup method. A comparative \r\n measurement can be made between an untreated and a treated brick unit \r\n sample, or the water vapor transmission rate of the coating itself can \r\n be determined. Comparative testing of an untreated and a treated brick \r\n sample is advised. For comparative testing, a maximum ten percent reduction \r\n in the rate of vapor transmission is the recommended limit. \r\n Water Penetration and Water Repellency \r\n Water penetration resistance is an important \r\n criterion when selecting a clear water repellent. However, most clear \r\n water repellent manufacturers measure performance of a clear water repellent \r\n based on water absorption. The ASTM C 67 test for cold water absorption \r\n is often used to compare the absorption of treated and untreated brick \r\n units. This approach has two significant limitations. Testing an individual \r\n brick is not a measure of the performance of a clear water repellent on \r\n the brick masonry assemblage. Secondly, changing the absorption of a brick \r\n unit may have no beneficial effect on the water penetration resistance \r\n of the brickwork. Performance of a coating is more accurately evaluated \r\n by measuring water penetration resistance of the constructed brick masonry \r\n wythe. \r\n The water penetration resistance of clear \r\n water repellent coatings should be measured by comparative laboratory \r\n testing in accordance with ASTM E 514 Test Method for Water Penetration \r\n and Leakage Through Masonry. Testing should be performed on a minimum \r\n of three identical wall specimens of the intended materials and construction. \r\n The amount of water penetration should be measured on each specimen in \r\n accordance with ASTM E 514 before and after coating with the clear water \r\n repellent. The percentage reduction in water penetration is a measure \r\n of the water repellent effectiveness. A 90 percent reduction in maximum \r\n leakage rate, percent area of dampness on the back face of the wall and \r\n total water collected after 24 hours of testing [4] as compared to the \r\n untreated wall panel is recommended. However, a specified reduction under \r\n laboratory conditions may not necessarily reflect performance of the clear \r\n water repellent on the actual masonry construction. Variables in construction \r\n can have a significant impact on water penetration resistance of a masonry \r\n wall. Thus, a 90 percent reduction rate for a laboratory test does not \r\n automatically translate into a 90 percent reduction in water leakage through \r\n the exterior brick wythe of a constructed building. \r\n Durability \r\n The life span of colorless coatings is an \r\n important criterion in material selection. The effective life is influenced \r\n by the thickness of the film or depth of penetration into the brickwork, \r\n exposure to UV light, the severity of weather exposure and the form of \r\n masonry construction. There are several test methods which simulate outdoor \r\n exposure. ASTM G 53 Practice for Operating Light- and Water-Exposure Apparatus \r\n (Fluorescent UV-Condensation Type) for Exposure of Nonmetallic Materials \r\n is one often specified. The difficulty with using such tests to measure \r\n life span of a coating is trying to correlate laboratory test results \r\n to field performance. Coating characteristics, such as gloss or water \r\n repellency, can be measured before and after exposure and the results \r\n compared, but such tests have not been correlated to the actual life expectancy \r\n of the coating. Greater depth of penetration or film thickness and greater \r\n resistance to degradation in UV light and harmful environments imply longer \r\n life for an exterior applied colorless coating. Many clear water repellents \r\n are warranted by the coating manufacturer to last ten years or more. \r\n In addition to laboratory testing, monitoring \r\n field performance by comparative testing can determine the effectiveness \r\n of a clear water repellent after several years of service. The water penetration \r\n of a newly coated wall can be measured and recorded in a specified area \r\n using a field test, such as a Masonry Absorption Test (MAT) tube [11], \r\n RILEM tube or other technique [87]. Periodic comparisons can be made using \r\n the same technique in the same location. Such evaluation will indicate \r\n if the coating has met its warranted life and also when recoating may \r\n be necessary. \r\n The durability of a coating applied to an \r\n interior brick pavement is characterized by resistance to abrasion and \r\n yellowing. It is common for film-forming products to require reapplication \r\n to brick floors every few years, depending on the amount of traffic. Evaluation \r\n of a coatings resistance to abrasion is difficult, because there are \r\n no direct test methods for measurement on brick. \r\n Reapplication \r\n Reapplication of clear coatings is another \r\n consideration. Most coatings must be reapplied every 7 to 15 years, and \r\n some last considerably shorter periods of time. Compatibility of coatings \r\n can be a problem. For example, a penetrating coating cannot be applied \r\n over an existing film-forming coating. In some cases, reapplication of \r\n the same coating may cause clouding. In other cases, the hydrophobic nature \r\n of a coating makes reapplication difficult or impossible. It may be necessary \r\n to strip the treated surface of any prior coating according to the coating \r\n manufacturers recommendations before a new or different coating can be \r\n applied. This procedure may involve hazardous chemicals often regulated \r\n or restricted from use by local, state or federal environmental regulations. \r\n Thus, an existing coating may have to remain in place until it wears off, \r\n even if deterioration of the masonry calls for its removal. \r\n Gloss \r\n Gloss can be measured by determining the \r\n reflectance of a coating using Federal Test 141a, Method 6121. However, \r\n desirable gloss is a subjective matter. Gloss is best evaluated by examining \r\n a representative test area of brick masonry including the entire range \r\n of colors and textures, one-half of the area treated with the specified \r\n coating, the other half untreated. Acceptable appearance should be determined \r\n by the designer or owner. An accepted test area should be retained as \r\n a means for judging acceptability of other treated areas. \r\n Slip Resistance \r\n A colorless coating can adversely affect \r\n the slip resistance of an interior brick floor or exterior brick pavement. \r\n Coated floors or pavements should be evaluated for slipperiness for safety \r\n reasons, especially in public access areas and in areas where water may \r\n contact the floor or pavement. The slip resistance of a coating is often \r\n measured using ASTM D 2047 Test Method for Static Coefficient of Friction \r\n of Polish-Coated Floor Surfaces as Measured by the James Machine. Nonhazardous \r\n surfaces have a minimum static coefficient of friction of 0.5 as measured \r\n by this test method [1]. \r\n Graffiti Resistance \r\n Graffiti-resistant coatings may be permanent \r\n or sacrificial in nature. In addition to the properties already mentioned, \r\n they should be evaluated on the basis of their resistance to chemicals \r\n and degradation in UV light. A high resistance to common chemical cleaners \r\n is a necessary property of a permanent coating, so that the graffiti can \r\n be removed without removing the coating. The effect of cleaning chemicals \r\n on the coating can be evaluated by applying the cleaning chemical to a \r\n sample area of coated brick masonry. Always consult the coating manufacturer \r\n prior to such testing for safety precautions, as reactions between the \r\n cleaner and the coating may be hazardous. Many graffiti-resistant coatings \r\n are sold with a special cleaner designed for use with that coating. If \r\n the coating is designed as a sacrificial layer, ease of removal is important \r\n and should be documented by the product manufacturer and evaluated by \r\n application to a test area. Satisfactory performance is indicated by successful \r\n removal of purposely applied graffiti. Resistance to weathering and UV \r\n stability can be evaluated using ASTM Test Method G 53 to simulate exterior \r\n exposure, followed by evaluation of the desired performance characteristics, \r\n such as ease of cleaning. \r\n Environmental Considerations \r\n Possible environmental hazards are also of \r\n concern when considering a colorless coating. Often the chemicals used \r\n in colorless coatings are highly reactive and can etch glass, damage paint, \r\n kill vegetation and emit harmful vapors. This requires attention to worker \r\n safety and proper protection of adjacent surfaces. \r\n RECOMMENDATIONS FOR USE \r\n Selection of a specific product should be \r\n based on recommended performance criteria described herein and any other \r\n criteria set by the designer to address the particular conditions involved. \r\n The possible advantages of colorless coatings should be weighed against \r\n the disadvantages associated with their use. In addition, the brick manufacturer \r\n should be consulted for recommendations on the use of colorless coatings \r\n prior to selection of any coating. Colorless coatings change the physical \r\n properties of the brick masonry on which they are applied. This may be \r\n beneficial or, in many cases, detrimental to the performance of the masonry. \r\n Exterior Walls \r\n In exterior brick masonry walls, one of the \r\n foremost concerns is water penetration. The many factors important in \r\n determining the water penetration resistance of brick masonry walls are \r\n discussed in Technical Notes 7 , 7A \r\n and 7B [15]. Clear water repellents should \r\n never be used as a substitute for good design, construction and maintenance. \r\n When a colorless coating is considered for \r\n a brick masonry wall exposed to freezing, the water vapor transmission \r\n rate is critical to the durability of the masonry. In addition, a condensation \r\n analysis, as described in Technical Notes 7C \r\n and 7D [15], should be performed to determine \r\n the effect of the coating on the location of condensation within the wall \r\n system before applying a colorless coating. \r\n Because they permit more rapid water vapor \r\n transmission, penetrating coatings are preferred over film-forming coatings \r\n for exterior brick masonry walls. If a clear water repellent is to be \r\n used, siloxanes are recommended. Siloxanes provide the advantage of good \r\n water repellency and long term performance and have been shown to be effective \r\n on many brick masonry walls. Silanes containing chemical catalysts have \r\n also been used successfully. \r\n Because of the effect of a film on the breathability \r\n of masonry, film-forming coatings should be used cautiously, particularly \r\n in freezing environments. Only products with known performance in a similar \r\n climate, wall type and exposure on brick masonry with similar physical \r\n properties should be used. In areas where freeze-thaw cycles is a concern, \r\n the possible disadvantages of a colorless coating may preclude their use. \r\n For this reason, film-forming coatings should be avoided on exterior brick \r\n masonry walls in freezing climates. \r\n Prior to applying a colorless coating on \r\n any exterior wall, the wall should first be thoroughly inspected and necessary \r\n repairs made. The inspection should determine the condition and suitability \r\n of: caps and copings, flashing, weep holes, sealant joints, mortar joints \r\n and general execution of details. Technical Notes 7F \r\n provides an inspection checklist for areas of concern. The source of the \r\n problems should be identified and all deficiencies should be carefully \r\n repaired or corrected. For further discussion see the earlier section \r\n entitled Remedial Applications. Only when remedial repairs have been \r\n made, and problems still exist, should a clear water repellent coating \r\n be considered for brick masonry. \r\n Drainage Walls . Drainage-type masonry \r\n walls, such as brick veneer and cavity walls, are designed to accommodate \r\n water penetration of the exterior brick wythe without damage to the interior \r\n components of the wall system. Thus, when designed and constructed properly, \r\n a clear water repellent is not necessary on newly constructed brick \r\n masonry drainage walls. \r\n When the elements essential to successful \r\n performance of a drainage wall are not achieved and water penetration \r\n is a problem, a clear water repellent coating may be appropriate. When \r\n a drainage wall is treated with a colorless coating, the use of vents \r\n at the top and bottom of all wall cavities is recommended to promote evaporation \r\n of moisture from the brick masonry. \r\n Barrier Walls . Barrier walls are exterior \r\n single wythe walls and multiwythe walls with filled collar joints, which \r\n do not contain any provision for internal drainage of water which penetrates \r\n the brick wythe(s). These walls rely solely on the mass of the masonry \r\n to prevent moisture penetration. Proper design, good workmanship and maintenance \r\n are exceedingly important. \r\n Sometimes such walls contain flashing and \r\n drainage spaces formed by interior finishes. For walls without a provision \r\n for drainage of water which does penetrate, prevention of water entry \r\n becomes even more important. Walls without drainage spaces, and walls \r\n in areas subject to large amounts of rain, are prime candidates for the \r\n application of a clear water repellent. A clear water repellent can limit \r\n the amount of moisture which is absorbed by the wall and help reduce the \r\n potential for water penetration. \r\n Chimneys and Parapets . Chimneys and \r\n parapets are other elements where clear water repellents can sometimes \r\n be recommended. These walls can be subject to early deterioration because \r\n of severe exposure. They are often exposed to wind-driven rain, water \r\n rundown on the exterior walls from the crown or coping, water penetration \r\n from failures in the chimney crown or wall coping and incorrect flashing \r\n installations. Good detailing of precast chimney crowns and parapet copings, \r\n properly constructed with overhangs, wall flashing and a drip, prevents \r\n many water penetration problems. However, because of the large amount \r\n of moisture which can contact the surface of a chimney or parapet wall, \r\n a clear water repellent coating can sometimes be effective in reducing \r\n water-related problems. Conditions in which a clear water repellent may \r\n be recommended on chimneys and parapet walls include climates with a driving \r\n rain index above three (see Fig. 5) and on sloped or horizontal projections \r\n of such elements. \r\n \r\n Driving Rain Index \r\n FIG. 5 \r\n \r\n Interior Walls \r\n Colorless coatings are generally applied \r\n to interior walls to facilitate cleaning or provide a gloss. Water repellency \r\n and breathability of an interior wall is generally not a concern. While \r\n some penetrating coatings may provide the desired effect, a film-forming \r\n product will typically give best results when gloss and ease of cleaning \r\n are desired. Water-borne acrylics (acrylic emulsions) and urethanes have \r\n been found to produce the best results for interior brick masonry walls. \r\n Acrylics, in particular, are known to provide a high gloss. Both are durable \r\n in applications with no UV exposure. Finished appearance is best judged \r\n by applying the coating to a test area on the surface to be treated. \r\n In the case of exterior brick masonry walls \r\n which have their interior face exposed, water vapor transmission may be \r\n a concern. Film-forming products should be used cautiously, only after \r\n the effect of the film on the water vapor transmission of the wall system \r\n has been evaluated. \r\n Pavements \r\n Brick masonry pavements are significantly \r\n different from vertical brick masonry. Their exposure is different, as \r\n is their construction. An exterior brick masonry pavement is subjected \r\n to a more severe weathering exposure than an exterior vertical wall. Pavements \r\n have greater contact with moisture due to their horizontal orientation \r\n and are often not protected by overhangs. In addition, the lack of a drainage \r\n cavity or air space to aid in drying further increases the severity of \r\n exposure. \r\n There are several disadvantages associated \r\n with the use of a colorless coating on pavement surfaces. Colorless coatings \r\n can decrease the slip resistance of the pavement or floor, especially \r\n when wet. Also, pavements and interior floors are subject to abrasion \r\n due to foot traffic which shortens the life expectancy of most coatings \r\n compared to vertical applications. \r\n Exterior Pavements . By nature of their \r\n construction, pavements only allow evaporation of moisture from the masonry \r\n through one face, the wearing surface. As a result, the potential for \r\n problems associated with reduced water vapor transmission are significant. \r\n These disadvantages usually outweigh any potential benefit. For this reason, \r\n colorless coatings are not recommended for use on exterior brick \r\n pavements subject to freezing and thawing. In exterior environments not \r\n subject to freezing, water vapor transmission rate of the coating must \r\n be high. Clouding of the coating is a particularly common problem. See \r\n Fig. 4. \r\n Interior Floors . Colorless coatings \r\n are often applied to interior brick floors to provide a glossy finish \r\n and to facilitate cleaning. Mortarless brick pavements are sometimes coated \r\n to help retain the jointing sand in the joints. Urethanes, acrylics, waxes \r\n and some penetrating coatings which meet the performance criteria discussed \r\n herein and those set by the designer can be used on interior brick masonry \r\n floors not subject to freezing. The primary disadvantage of most colorless \r\n coatings used on floors is their tendency to increase the slipperiness \r\n of the floor. Acrylics can be particularly hazardous; however, performance \r\n varies with formulation, and some acrylic solutions have been used successfully. \r\n New epoxy-based coatings show promise in this area. Past successful performance \r\n is the best measure of a satisfactory coating. Another caution is that \r\n film-forming coatings may separate from the brick paving and turn cloudy \r\n if moisture from the brickwork or supporting members migrates through \r\n the brick floor. Consequently, a film-forming coating should only be applied \r\n when the brick floor and supporting members are substantially dry. \r\n CONSIDERATIONS PRIOR TO COATING \r\n Selection of a colorless coating for use \r\n on brick masonry should be based on the desired performance, the information \r\n discussed in this Technical Notes and literature from the coating \r\n manufacturer. Additional items to be considered prior to application of \r\n a colorless coating follow. Whenever possible, consult with the brick \r\n manufacturer for specific recommendations regarding coating of a particular \r\n brick. Properties of each brick are unique and can affect coating performance. \r\n 1. It is suggested that the designer or user \r\n require test reports for relevant performance criteria and a written warranty \r\n from the coating manufacturer for the performance of the coating over \r\n a designated period of time. The application contractor should know precisely \r\n the work to be performed and should protect adjacent and surrounding surfaces \r\n from over-spray as necessary. Qualifications of the contractor should \r\n be verified. \r\n 2. The coating should be that of a well-known \r\n manufacturer who has been in business for a period of at least five years. \r\n It is suggested that a brand name be used that has a good track record \r\n over a period of at least five years. References of projects with similar \r\n applications, materials and exposure should be investigated. \r\n 3. The coating should be applied at the application \r\n rate and under the climatic conditions recommended for clay brick masonry \r\n substrates by the coating manufacturer. Typically, temperatures above \r\n 40 ° F (4°C) and below 100 ° F (38 ° C) \r\n are required. Application on windy days should be avoided when possible. \r\n 4. Repair and replacement of brick and mortar \r\n joints and other necessary repairs should be completed prior to applying \r\n a colorless coating. \r\n 5. There should have been no efflorescence \r\n or, at the maximum, only a minor occurrence of efflorescence on the brick \r\n masonry to be treated. Walls less than one year old should not be treated \r\n because efflorescence, \"new building bloom\", may be entrapped by the coating. \r\n Walls with a history of efflorescence should be coated only after the \r\n source of moisture has been addressed. \r\n 6. The wall must be clean at the time of \r\n application. Heavy accumulations of atmospheric dirt will interfere with \r\n proper penetration or adhesion of the coating and result in poor performance \r\n and shorter life. See ASTM D 5703 Practice for Preparatory Surface Cleaning \r\n for Clay Brick Masonry for a discussion of cleaning techniques which may \r\n be required [2]. In addition, freshly repointed mortar and repaired sealant \r\n joints should cure a minimum of 72 hours before a coating can be applied \r\n [13]. \r\n 7. The brickwork should have a moisture content \r\n consistent with that recommended by the coating manufacturer. Moisture \r\n content of the brick masonry should be checked at several locations by \r\n the method recommended by the coating manufacturer. \r\n 8. Apply samples of the selected coating to test \r\n areas of at least 10 ft 2 (1 m 2 ) on the building at a location representative of the area to \r\n be treated or on a sample panel. Allow these test areas to cure as recommended \r\n by the coating manufacturer. Inspect and test them to determine satisfactory \r\n performance with respect to the performance criteria established. \r\n These steps must be taken in conjunction \r\n with the recommendations contained within the applicable sections of this \r\n Technical Notes. They cannot guarantee successful performance, \r\n but will greatly increase the likelihood that the colorless coating will \r\n perform as intended. The coating manufacturer will often have additional \r\n recommendations regarding coating selection, substrate preparation, curing, \r\n application methods and coverage rates. Failure to consider these items \r\n can result in poor performance of the coating and can cause severe harm \r\n to the masonry or surrounding elements. \r\n SUMMARY \r\n This Technical Notes has discussed \r\n both the reasons for and the suitability of colorless coatings for brick \r\n masonry. For most exterior brick masonry, it is advisable not to use colorless \r\n coatings. Furthermore, clear water repellents are not necessary on properly \r\n designed and constructed brick masonry. However, under certain conditions \r\n clear water repellents and other colorless coatings may be beneficial. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data and the \r\n experience of the engineering staff of the Brick Institute of America. \r\n The information contained herein must be used in conjunction with good \r\n technical judgment and a basic understanding of the properties of brick \r\n masonry. Final decisions on the use of the information contained in this \r\n Technical Notes are not within the purview of the Brick Institute \r\n of America and must rest with the project architect, engineer and owner. \r\n REFERENCES \r\n \r\n 1. \"ASTM D 2047 \r\n Standard Test Method for Static Coefficient of Friction of Polish-Coated \r\n Floor Surfaces as Measured by the James Machine,\" Annual Book of \r\n ASTM Standards , Vol. 15.04, ASTM, Philadelphia, PA, 1994. \r\n 2. \"ASTM D 5703 \r\n Standard Practice for Preparatory Surface Cleaning of Clay Brick Masonry,\" \r\n Annual Book of ASTM Standards , Vol. 6.02, ASTM, Philadelphia, \r\n PA, 1995. \r\n 3. Binda, L., \r\n \"Experimental Study on the Durability of Preservation Treatments of \r\n Masonry Surfaces: Use of Outdoor Physical Models,\" Proceedings of \r\n the Workshop - The Degradation of Brick and Stone Masonries Due to Moisture \r\n and Salt Content and the Durability of Surface Treatments , Politecnico \r\n di Milano, Milan, Italy, January 1991, pp. 1-8. \r\n 4. Brown, R. \r\n H., \"Initial Effects of Clear Coatings on Water Permeance of Masonry,\" \r\n Masonry: Materials, Properties, and Performance, ASTM STP 778, \r\n J. G. Borchelt, Ed., ASTM, Philadelphia, PA, 1982, pp. 221-236. \r\n 5. Clark, E.J., \r\n Campbell, P. G. and Frohnsdorff, G. \"Waterproofing Materials for Masonry,\" \r\n NBS Technical Note 883, National Bureau of Standards, Gaithersburg, \r\n MD, October 1975. \r\n 6. Clear \r\n Water Repellents for Above Grade Masonry and Horizontal Concrete , Sealant, Waterproofing & Restoration Institute, Kansas \r\n City, MO, 1994. \r\n 7. Clear \r\n Water Repellent Treatments for Concrete Masonry , \r\n Concrete Masonry Association of California and Nevada and the Masonry \r\n Institute of America, Los Angeles, CA, 1993, pp. 38-40. \r\n 8. Coney, W. \r\n B. and Stockbridge, J. G., \"The Effectiveness of Waterproofing Coatings, \r\n Surface Grouting, and Tuckpointing on a Specific Project,\" Masonry: \r\n Materials, Design, Construction, and Maintenance, ASTM STP 992 , \r\n H. A. Harris, Ed., ASTM, Philadelphia, PA, 1988, pp. 220-224. \r\n 9. \"Efflorescence: \r\n Causes, Mechanisms, Prevention and Control,\" Technical Notes on Brick \r\n Construction 23 Series, Brick Institute of America, Reston, VA, \r\n 1985. \r\n 10. McGettigan, \r\n E., \"Selecting Clear Water Repellents,\" The Construction Specifier , \r\n Vol. 47, No. 6, Construction Specifications Institute, Alexandria, VA, \r\n June 1994, pp. 121-132. \r\n 11. Roller, \r\n Sandra, \"A Comparison of ASTM E 514 and MAT Tube Water Penetration Testing \r\n Methods Including an Evaluation of Saver Systems Water Repellents,\" \r\n Department of Civil and Architectural Engineering, University of Wyoming, \r\n Laramie, WY, October 1994, 208 pp. \r\n 12. Roth, M., \r\n \"Comparison of Silicone Resins, Siliconates, Silanes and Siloxanes as \r\n Water Repellent Treatments for Masonry,\" Technical Bulletin 983-1, \r\n ProSoCo, Inc., Kansas City, KS, 1985. \r\n 13. Suprenant, \r\n B. A., \"Water Repellents: Selection and Usage,\" Magazine of Masonry \r\n Construction , Aberdeen Group, Addison, IL, December 1993, pp. 527-532. \r\n 14. \"The Cleaning \r\n and Waterproof Coating of Masonry Buildings,\" Preservation Briefs , \r\n No. 1, U.S. National Park Service, Washington, DC, 1976. \r\n 15. \"Water Resistance \r\n of Brick Masonry,\" Technical Notes on Brick Construction 7 Series, \r\n Brick Institute of America, Reston, VA, 1985. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60131,"ResultID":176363,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 7 - Water Resistance of Brick Masonry, Design and Detailing \r\n Part 1 \r\n Feb. 1985 (Reissued Feb. 1998) \r\n \r\n Abstract : Proper design and detailing \r\n of brick masonry walls to allow minimum water penetration into or through \r\n a wall system are absolute necessities. Careful evaluation of several items \r\n is a requirement in order to obtain proper resistance to water penetration. \r\n The selection of the proper type of wall is of utmost importance in the \r\n design process as is the need for complete and accurate detailing. In addition \r\n to discussing various wall types, this Technical Notes illustrates \r\n suggested details which have been found to be acceptable methods of achieving \r\n walls resistant to water penetration. \r\n Key Words : barrier, brick masonry, \r\n design , detailing , drainage, flashing , \r\n installation methods, rain, wall types , weepholes . \r\n INTRODUCTION \r\n Water penetration is responsible for many \r\n of the problems encountered in masonry walls today. If a wall is saturated \r\n with water, freezing and thawing may cause cracking, crazing, spelling \r\n and disintegration. Water can cause masonry to experience dimensional \r\n changes, metals to corrode, insulation to lose its effectiveness, interior \r\n finishes to deteriorate and efflorescence to appear on exterior surfaces. \r\n Water is abundant in many forms. Rain and \r\n snow contact building materials, wetting them. Water vapor is present \r\n in the air from many sources. As a result, since water cannot be completely \r\n eliminated, water penetration must be controlled. When water passes through \r\n brick masonry walls, it invariably does so through minute separations \r\n between the brick units and the mortar joints. Under normal exposures, \r\n it is virtually impossible for significant amounts of water to pass directly \r\n through the brick units or through the mortar. Highly absorbent brick \r\n will absorb some water, but certainly do not contribute to an outright \r\n flow of water through a wall. \r\n Before brick curtain wall systems became \r\n popular, masonry walls usually functioned as both the structural system \r\n and as the exterior skin of the building. As a result, these masonry walls \r\n were quite massive, ranging in thickness from 12 in. (300 mm) up to 6 \r\n ft (1.83 m) of solid brick. These masonry walls, both because of their \r\n thickness and their being in constant compression due to the structural \r\n loads, worked quite well in keeping water out of the interior of the building. \r\n Many older masonry walls were built with cornices and other ornamentation \r\n which helped to protect the faces of the buildings from excessive water \r\n rundown and subsequent water penetration to the interior. \r\n Walls used today are much less massive, and \r\n the masonry may be only 3 in. (75 mm) in thickness. In many cases, they \r\n have minimal overhang at the top, allowing sheeting of the rain water \r\n from the roof or parapet down to the ground. As a result of these newer \r\n wall systems, rain water is allowed to be in contact with the masonry \r\n in larger quantities and for longer periods of time, thus leading to more \r\n opportunity for water penetration problems. \r\n The successful performance of a masonry wall \r\n depends on limiting the amount of water penetration and controlling any \r\n water that enters the wall system. If water penetration can be limited, \r\n for all practical purposes, the wall will remain dry. \r\n Water resistance of a masonry wall depends \r\n on four key factors: \r\n 1. Design, including detailing. \r\n 2. Materials. \r\n 3. Construction. \r\n 4. Maintenance. \r\n Attention to all four factors is necessary \r\n to produce a satisfactorily performing wall. Failure to properly address \r\n any one factor can result in water penetration problems. \r\n This Technical Notes Series addresses \r\n water resistance of brick masonry. The first three Technical Notes \r\n in this series provide detailed guidelines in the above areas of design, \r\n materials and construction. Other Technical Notes in the series \r\n provide information on condensation analysis, and the use of colorless \r\n coatings on brick masonry. The subject of \"Maintenance\" will be covered \r\n in a future issue of this Technical Notes Series. \r\n This Technical Notes deals with proper \r\n design of brick masonry to resist water penetration. \r\n DESIGN \r\n The first factor to evaluate in the control \r\n of water resistance of masonry is that of design. Proper design of masonry \r\n does not mean just proper structural design. Design includes fire resistance, \r\n heat transmission, structural integrity, material compatibility, sound \r\n reduction, aesthetics and water resistance. Other Technical Notes provide \r\n guidance on all of these different design factors. \r\n Design for water resistance requires evaluation \r\n of several items, including: (1) sources of moisture; (2)selection of \r\n wall type; and (3) flashing and weepholes. Each of these items will be \r\n addressed separately. \r\n Sources of Moisture \r\n Moisture is present almost everywhere in \r\n various forms, i.e., rain, snow, condensation, ground water, construction \r\n water, etc. Some of these lend themselves to control; some do not. This \r\n section deals with wind-driven rain. Interstitial condensation and its \r\n control are discussed in Technical Notes 7C \r\n and 7D . \r\n Wind-Driven Rain . The exposure to \r\n which a masonry wall will be subjected is very important to the proper \r\n design of the wall. No single standard design can be expected to perform \r\n equally well under all exposures. \r\n Exposures vary greatly throughout the United \r\n States, from severe on the Atlantic Seaboard and Gulf Coast, where rains \r\n of several hours duration may be accompanied by high velocity winds; \r\n to moderate in the Midwest and Mississippi Valley, where wind velocities \r\n are usually lower; to slight in the arid areas of the West. See Figure \r\n 1. Exposure areas may be defined roughly in terms of wind pressure and \r\n annual precipitation as follows: \r\n \r\n FIG. 1 \r\n Severe: Annual \r\n precipitation 30 in. or over, wind pressure 30 psf or over. \r\n Moderate: Annual precipitation 30 in. or over, wind pressure 20 to 25 psf. \r\n Slight: Annual precipitation less than \r\n 30 in., wind pressure 20 to 25 psf, or annual precipitation less than 20 \r\n in. \r\n More recently, a Driving Rain Index (Grimm, \r\n C.T., \"A Driving Rain Index for Masonry Walls\", Masonry: Materials \r\n Properties and Performance, ASTM STP 778, J.G. Borchelt, Ed, American \r\n Society for Testing and Materials, 1982, pp. 171-177), see Table 1 and \r\n Fig. 2, has been proposed, which is based on the assumption that the likelihood \r\n of rain penetration is proportional to the product of annual average rainfall \r\n and annual average wind speed. The wall exposure (severe, moderate or \r\n sheltered) is then determined by correlating the Driving Rain Index with \r\n the wall relative to its surroundings, using Table 1. \r\n \r\n \r\n \r\n Driving Rain Index \r\n FIG. 2 \r\n Selection of Wall Type . The selection of the proper wall type to use in any given situation is \r\n very important. Under normal conditions, it is nearly impossible to keep \r\n a heavy wind-driven rain from penetrating a single wythe of brickwork, regardless \r\n of the quality of the materials or the degree of workmanship used. \r\n Therefore, a major concern is to control \r\n the moisture once it begins to penetrate the wall. Two basic wall systems \r\n are used for this purpose: the drainage wall and the barrier wall. \r\n \r\n Typical Brick Cavity Wall \r\n Fig. 3 \r\n \r\n Typical Insulated Brick Cavity \r\n Wall \r\n Fig. 4 \r\n \r\n Typical Brick Veneer and \r\n Metal Stud Wall \r\n Fig. 5 \r\n \r\n \"SCR Brick\" Wall \r\n Fig. 6a \r\n \r\n Masonry Bonded Hollow Wall \r\n (Utility Wall) \r\n Fig. 6b \r\n Drainage Wall Systems - Drainage wall systems include cavity walls (metal-tied and \r\n masonry-bonded hollow walls), and anchored veneer walls. See Figs. 3 through \r\n 6. The basic concept behind the drainage wall assumes a heavy, wind-driven \r\n rain may penetrate the exterior wythe of brick. When it does, the moisture \r\n migrates inward to the cavity or air space between the wythes. Here it flows \r\n down the back face of the outer brick wythe, is collected on the flashing, \r\n and is directed out of the wall system through the weepholes. Properly designed, \r\n detailed and constructed drainage wall systems are rated excellent with \r\n respect to water penetration resistance. Specific detailed information on \r\n all aspects of cavity wall systems can be found in Technical Notes 21 \r\n Series. Technical Notes 28 Series addresses anchored veneer wall \r\n systems. \r\n Barrier Wall Systems - Barrier \r\n wall systems, shown in Fig. 7, include multi-wythe walls (including composite \r\n brick and concrete block walls), reinforced brick masonry walls and adhered \r\n veneer walls. The basic concept is that when a wind-driven rain penetrates \r\n the exterior wythe of brick masonry it migrates inward toward the interior \r\n wythe. When this migrating water reaches the filled collar joint, the \r\n joint acts as a barrier to prevent further inward movement. The water \r\n then flows back out of the wall system. The key item is that the collar \r\n joint must be completely filled with grout or mortar to be an effective \r\n barrier. Placing mortar in the collar joint with a trowel after the individual \r\n wythes are laid, commonly referred to as \"slushing\", does not result in \r\n completely filled joints, and is not recommended. Properly designed, detailed \r\n and constructed barrier wall systems are rated very good with respect \r\n to water penetration resistance. \r\n Single-wythe masonry walls can be considered \r\n a special case. In single-wythe walls, the masonry wythe is usually much \r\n thicker than a nominal 4-in. (100 mm) thick exterior brick wythe, and \r\n as a result, the added thickness helps to prevent water from penetrating \r\n to the interior of the wall system. Single-wythe walls are not as good \r\n in preventing water penetration as are drainage wall systems or multi-wythe \r\n barrier wall systems, but with careful detailing and good construction \r\n practices, they can perform very well. Single-wythe brick masonry construction \r\n can be designed with either solid or hollow units. \r\n \r\n Barrier Types: Metal-Tied \r\n Solid Walls \r\n Fig. 7a \r\n \r\n Barrier Types : Reinforced \r\n Brick Masonry \r\n Fig. 7b \r\n Flashing \r\n Flashing is a membrane, installed in a masonry \r\n wall system, which collects water that has penetrated the exterior wythe \r\n and facilitates its drainage back to the exterior. Flashing is essential \r\n in a drainage wall system, and is recommended as a second line of defense \r\n in a barrier wall system. Various types of flashing materials which may \r\n be used in the design of brick masonry and composite walls are covered \r\n in Technical Notes 7A Revised. \r\n Locations . Proper design requires \r\n flashing at wall bases, window sills, heads of openings, spandrels, shelf \r\n angles, projections, recesses, tops of walls and roofs. \r\n Wall Base - Moisture which \r\n does enter a wall gradually travels downward. Continuous flashing must \r\n be placed above grade at the base of all walls to divert this water to \r\n the exterior. In addition, base flashing prevents water from rising up \r\n into the wall system due to capillary action. Once the designer has determined \r\n the level for placing flashing in the wall in accordance with the grading \r\n plans, care should be taken that field modifications do not result in \r\n any section of flashing being below grade. See Fig. 8 for typical details. \r\n \r\n Foundation Details \r\n Fig. 8a and b \r\n \r\n Foundation Details \r\n Fig. 8c and d \r\n Window Sills - Through-wall flashing should be placed \r\n under all sills and turned up at the ends to form dams. See Figs. 9 through \r\n 11 for examples. Soffits and deep reveals may require special flashing considerations. \r\n Technical Notes 36 Series contains further details and information. \r\n \r\n Sill in Frame/Brick Veneer \r\n Construction \r\n Fig. 9 \r\n \r\n \r\n Sill in Cavity Wall Construction \r\n Fig. 10 \r\n \r\n Concrete or Stone Sill \r\n Fig. 11 \r\n Steel Lintels - Through-wall flashing should be installed \r\n over all openings. An exception may be those completely protected by overhangs. \r\n The flashing should be placed directly on top of the lintels and turned \r\n up at the ends to form dams. Fig. 12 shows several examples of lintels which \r\n require flashing. (Note that in some cases, although flashing is not called \r\n for, weepholes are still recommended). \r\n \r\n Types of Structural Steel \r\n Lintels \r\n Fig. 12 \r\n Spandrels and Shelf Angles \r\n - In concrete or steel frame buildings, the entire faces of \r\n the spandrel beams may be flashed or the flashing may be inserted in a continuous \r\n reglet installed in the spandrel beam. When the entire face of the spandrel \r\n is flashed, layered flashing (counter-flashing) should be used. See Fig. \r\n 13. \r\n \r\n Steel Shelf Angles \r\n Fig. 13 \r\n Projections, Recesses and Caps \r\n - Projections, recesses and caps tend to collect rain water and snow. They \r\n should be sloped away from the wall to drain and be flashed where possible. \r\n See Fig. 14. Other details and information can be found in Technical \r\n Notes 36 Series. \r\n \r\n Brick and Precast Concrete \r\n or Stone Caps \r\n Fig. 14 \r\n Tops of Walls - The tops of all walls and parapets \r\n should have an adequate cap or coping, and there should be flashing beneath \r\n the coping. Drainage-type parapet walls are recommended as the best wall \r\n system for resistance to water penetration. See Figs. 15 through 18 for \r\n examples. Technical Notes 36 Series provides more details and information \r\n on these subjects. \r\n \r\n Coping for Cavity Wall Parapet \r\n Fig. 15 \r\n \r\n Rowlock Coping on Solid Masonry \r\n Parapet \r\n Fig. 16 \r\n \r\n Reinforced Parapet Wall \r\n Fig. 17 \r\n \r\n Precast Concrete or Stone \r\n Coping on Cavity Wall Parapet \r\n Fig. 18 \r\n Roof Flashing - Because roof flashing occurs at very \r\n vulnerable points, it must be designed and installed with great care. Roof \r\n flashing design may depend upon the type of roofing used. Where the roof \r\n flashing is metal, the counter-flashing should also be metal, extending \r\n into the wall and overlapping the roof flashing a minimum of 3 to 4 in. \r\n (75 to 100 mm). See Figs. 19 and 20 for examples. \r\n \r\n Masonry Bearing Wall Coping \r\n Fig. 19 \r\n \r\n Non-Parapet Wall \r\n Fig. 20 \r\n Installation Methods . In addition to specific location information, there are other considerations \r\n regarding installation of flashing which the designer must address. These \r\n are discussed in detail in this section. \r\n Continuity - Flashing is not \r\n usually installed in one long, continuous sheet. As a result, pieces must \r\n be fitted together on the job. Flashing pieces should be lapped at least \r\n 6 in. (150 mm) and the laps sealed with mastic or an adhesive compatible \r\n with the flashing material. \r\n End Dams - Where the flashing \r\n is not continuous, such as over and under openings in the wall, the ends \r\n of the flashing should be extended beyond the jamb lines on both sides \r\n and should be turned up into the head joint several inches at each end \r\n to form a dam. See Fig. 21. \r\n \r\n End Dams \r\n FIG. 21 \r\n Extension Through Wall - All flashing should extend \r\n beyond the face of the wall to form a drip. Termination of through-wall \r\n flashing behind the exterior face of the wall is a dangerous practice and \r\n is not recommended. See Fig. 22. \r\n \r\n Flashing Extended Beyond \r\n Face \r\n Fig. 22 \r\n Flashing Around Corners - When flashing around \r\n corners, the flashing should be continuous. To achieve this continuity, \r\n the pieces of flashing may need to be cut, lapped and sealed to conform \r\n to the shape of the structure. \r\n Flashing at Vertical Supports - \r\n In some cases, vertical support angles make it necessary to cut, puncture \r\n or otherwise interrupt the flashing. When this occurs, it is important \r\n to make sure that all openings in the flashing are tightly sealed, and \r\n that the flashing is attached to these supports with mastic. \r\n Gravel Beds - It may be desirable \r\n to provide a layer of gravel several inches deep on top of the base flashing. \r\n This will help keep mortar droppings from falling on the flashing and \r\n clogging the weepholes. Care must be taken in the choice of size and shape \r\n of the gravel to avoid blocking the weepholes and puncturing the flashing. \r\n It is recommended that a bed of mortar, conforming to the curve of the \r\n flashing, be placed under the flashing for additional support of the gravel \r\n bed. Note that gravel should not be placed on top of flashing which covers \r\n bolted shelf angles as the weight of the gravel on the flashing may cause \r\n tearing or puncturing at the bolt head. See Figs. 22 and 23. \r\n \r\n Gravel Beds \r\n Fig. 23 \r\n Bond Breaks - It must be remembered that \r\n mortar bond to flashing is not as good as mortar bond to masonry units. \r\n Where mortar is placed immediately above and below flashing, \r\n flexural strength of the wall may be reduced about 30 to 70 percent. Where \r\n flashing is placed directly on masonry, without mortar, the flexural strength \r\n should be considered as zero. \r\n Weepholes \r\n In order to properly drain any water collected \r\n on the flashing, weepholes must be provided immediately above the flashing \r\n at all flashing locations. The practice of specifying the installation \r\n of weepholes one or more courses of brick above the flashing can cause \r\n a backup of water and is not recommended. In general, weepholes \r\n should be at least 1/4 in. (6 mm) in diameter, and should be spaced no \r\n further apart than 24 in. (600 mm) o.c. horizontally. In other cases, \r\n such as where a wick material is used in the weephole, the spacing should \r\n be reduced to 16 in. (400 mm) maximum. See Fig. 24. \r\n \r\n Flashing and Weepholes \r\n Fig. 24 \r\n SUMMARY \r\n This Technical Notes is the \r\n first in a series on water resistance of brick masonry. It provides the \r\n basic information required to properly design and detail brick masonry \r\n to avoid water penetration problems. Obviously, this Technical Notes \r\n cannot cover all designs or all conditions. The details are provided \r\n to illustrate the principles involved, not as standard details. \r\n The information contained in this Technical \r\n Notes is based on the available data and experience of the \r\n technical staff of the Brick Institute of America. This information should \r\n be recognized as recommendations which, if followed with good judgment, \r\n should result in masonry walls that are resistant to water penetration. \r\n Final decisions on the use of information, \r\n details and materials as discussed in this Technical Notes are \r\n not within the purview of the Brick Institute of America and must rest \r\n with the project designer, owner or both. \r\n REFERENCES \r\n More comprehensive information on specific \r\n design procedures and details for various types of walls beyond those \r\n items discussed in this Technical Notes is contained in \r\n the following publications: \r\n 1. Technical \r\n Notes on Brick Construction 7A \r\n Revised. \"Water Resistance of Brick Masonry-Materials -Part II of III\", \r\n March 1985. \r\n 2. Technical \r\n Notes on Brick Construction 7C , \r\n \"Moisture Control in Brick and Tile Walls-Condensation\", Reissued November \r\n 1981. \r\n 3. Technical \r\n Notes on Brick Construction 7D , \r\n \"Moisture Control in Brick and Tile Walls-Condensation Analysis\", Reissued \r\n November 1981 \r\n 4. Technical \r\n Notes on Brick Construction 21 \r\n Revised, \"Brick Masonry Cavity Walls\", Jan.-Feb. 1977. \r\n 5. Technical \r\n Notes on Brick Construction 21A \r\n Revised, \"Brick Masonry Cavity Walls-Insulated\", May-June 1977. \r\n 6. Technical \r\n Notes on Brick Construction 21B , \r\n \"Brick Masonry Cavity Walls-Detailing\", Jan.-Feb. 1978. \r\n 7. Technical \r\n Notes on Brick Construction 21C , \r\n \"Brick Masonry Cavity Walls-Construction\", May-June 1978. \r\n 8. Technical \r\n Notes on Brick Construction 28 \r\n Revised, \"Brick Veneer-New Construction\", Jul.-Aug. 1978. \r\n 9. Technical \r\n Notes on Brick Construction 28A , \r\n \"Brick Veneer-Existing Construction\", Sept.-Oct. 1978. \r\n 10. Technical \r\n Notes on Brick Construction 28B \r\n Revised, \"Brick Veneer-Panel and Curtain Walls\", Feb. 1980. \r\n 11. Technical \r\n Notes on Brick Construction 36 \r\n Revised, \"Brick Masonry Details-Sills and Soffits\", Jul.-Aug. 1981. \r\n 12. Technical \r\n Notes on Brick Construction 36A \r\n Revised, \"Brick Masonry Details-Caps and Copings, Corbels and Racking\", \r\n Sept.-Oct. 1981. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60132,"ResultID":176364,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 7A - Water Resistance \r\n of Brick Masonry - Materials, Part 2 \r\n March 1985 (Reissued Dec. 1995) \r\n \r\n Abstract : This Technical Notes covers considerations and recommendations \r\n regarding the availability and selection of materials to obtain \r\n a satisfactory degree of water resistance in the design and construction \r\n of brick masonry walls. It is not the purpose of this Technical \r\n Notes to cover all materials or all conditions, but to illustrate \r\n the principles involved. There are undoubtedly materials available \r\n which would accomplish the goal of providing satisfactory water \r\n resistance, but are not addressed in this issue. Lack of specific \r\n reference to a material would not preclude its use providing the \r\n product met the necessary requirements of the specifier in obtaining \r\n water-resistant brick masonry. \r\n \r\n Key Words : brick , coatings, corrosion \r\n resistance , flashing , grout, lintels, mortar , \r\n sealants, shelf angles, ties , weepholes. \r\n \r\n INTRODUCTION \r\n \r\n \r\n Water resistance of brick masonry depends on four key factors: design, \r\n materials, construction and maintenance. This Technical Notes discusses \r\n materials. Design for water resistance is addressed in Technical \r\n Notes 7 Revised and construction \r\n techniques are discussed in Technical Notes 7B \r\n Revised. The discussion of various aspects of maintenance will be \r\n covered in a future issue. \r\n \r\n MATERIALS \r\n \r\n The use of quality materials in the construction \r\n of masonry walls is of prime importance in attaining a satisfactory \r\n degree of water resistance. When water passes through brick masonry \r\n walls, it invariably does so through separations or cracks between \r\n the brick units and the mortar. Under normal exposures, it is virtually \r\n impossible for significant amounts of water to pass directly through \r\n brick units. Highly absorbent brick may absorb some water, but certainly \r\n do not contribute to an outright flow of water through the wall. \r\n The key item is the extent of bond between the brick units and the \r\n mortar. Extent of bond is a measure of the area of contact at the \r\n interface between brick and mortar surfaces. Bond strength, on the \r\n other hand, is a measure of the adhesion between brick and mortar. \r\n High bond strength of brick and mortar combinations may not necessarily \r\n result in an extent of bond that would provide high resistance to \r\n water penetration. It follows that better extent of bond results \r\n in increased water resistance of brick masonry. Tests over the years \r\n have shown that the strongest and most complete bond is achieved \r\n when the suction of the brick unit, at the time of laying, is below \r\n 30 g/min/30 sq in. (30 g/min/194 cm 2 ). As a result, brick with suction more than this value may \r\n have to be wetted prior to laying. \r\n \r\n The standards for the choice of quality construction materials \r\n are those of the American Society for Testing and Materials (ASTM). \r\n ASTM has, for many years, developed standard specifications for \r\n basically all building materials. These specifications are based \r\n on laboratory tests and field experience and, in the case of brick \r\n units, are the result of experience gained over a span exceeding \r\n 100 years. It must be remembered that the use of ASTM specifications \r\n will not guarantee that the desired results will be produced, even \r\n if the product meets the appropriate standard in every respect. \r\n They are consensus standards, and they set minimum quality \r\n levels for products. These standards are the best guides available \r\n for the determination of quality construction materials. \r\n \r\n Brick Units \r\n \r\n The choice of quality brick units is very important. The choice \r\n of a particular unit will normally be based on such things as color, \r\n texture, size and cost. But, there are other, more important, items \r\n that need to be taken into account by the designer. These are durability, \r\n and mortar/brick compatibility. \r\n Because the masonry will be wet during part of its life, the question \r\n of durability is of primary concern. Problems of cracking, crazing, \r\n spalling and disintegration can occur if an improper choice of brick \r\n is made. The ASTM specifications for brick are written to provide \r\n guidance to the designer in choosing the quality of brick unit for \r\n specific exposure conditions. All of the requirements for compressive \r\n strength, absorption and saturation coefficients are specified to \r\n predict the durability level of the units. None of the ASTM requirements \r\n are provided as a guide for determining the degree of water resistance \r\n of the masonry. The degree of water resistance is important \r\n to the durability of the masonry insofar as the more water that \r\n enters the system, the greater the probability that the masonry \r\n will be in a saturated condition during any freeze/thaw cycles. \r\n There is a Note in the ASTM brick unit specifications regarding \r\n the initial rate of absorption (suction) of the brick units which \r\n is provided as a guide only, not a requirement. \r\n Brick Standards. There are several kinds of brick units \r\n used in construction today and each has its own ASTM standard, with \r\n its own specific minimum requirements for Grade and, in some \r\n cases, Type. Grades cover the physical requirements in the \r\n standard while Types cover finish, size and warpage. The \r\n most commonly used brick standards are: \r\n 1. Facing Brick - ASTM C 216 \r\n 2. Building Brick - ASTM C 62 \r\n 3. Hollow Brick - ASTM C 652 \r\n 4 Ceramic Glazed Brick - ASTM C 126 \r\n \r\n Mortar and Grout \r\n \r\n The proper choice of mortar and grout to use in a particular design \r\n situation is very important. The primary concern is to choose a \r\n mortar and/or grout which will bond well with the particular masonry \r\n units chosen. Technical Notes 8 Series provides detailed \r\n information on mortars and grouts for masonry. \r\n Mortar . The two standards for specifying mortars for unit \r\n masonry are ASTM C 270 and BIA M1-72. Four types of mortar (M, S, \r\n N and O) are covered in each of the standards. ASTM C 270 covers \r\n mortars made with portland cement-lime combinations and those made \r\n with masonry cements. BIA M1-72 addresses only mortars made with \r\n combinations of portland cement and lime. \r\n \r\n The Basic Rule - No single type of mortar is best \r\n for all purposes. The basic rule for the selection of a mortar \r\n for a particular project is: Never use a mortar that is stronger \r\n (in compression) than is required by the structural requirements \r\n of the project. Always select the weakest (in compression) mortar \r\n that is consistent with the performance requirements of the project. \r\n This general rule must, of course, be tempered with good judgment. \r\n For example, it would be uneconomical and unwise to continuously \r\n change mortar types for various pieces or parts of a structure. \r\n However, the general idea of the rule should be followed, using \r\n good judgment and economic sense. \r\n \r\n Masonry Cements - Proprietary mortar mixes (masonry \r\n cements) are widely used because of their convenience and generally \r\n good workability. However, there are some drawbacks to such proprietary \r\n mixes. As proprietary materials, their formulae are seldom disclosed \r\n by their manufacturers. \r\n Because of a lack of tight limitations on the type and amount of \r\n ingredients permitted in masonry cements, and the wide variation \r\n permitted in air content, the properties of brick masonry constructed \r\n with masonry cement mortars cannot be predicted with any degree \r\n of assurance. For this reason, masonry cements per se cannot be \r\n recommended. The use of any particular brand should be based on \r\n its performance record and laboratory tests of masonry assemblages. \r\n Grout . The standard for specifying grout for all masonry \r\n work, whether it be unreinforced or reinforced, is ASTM C 476. Two \r\n types of grout, fine and coarse, are addressed in this standard. \r\n Coarse grout differs from fine grout only in that it contains an \r\n addition of #4 aggregate (pea gravel) to the basic mix. The grout \r\n space between the brick masonry wythes or the cells in reinforceable \r\n brick units should be more than 2 in. (50 mm) when pea gravel is \r\n used. Fine grout should be used for dimensions less than 2 in. (50 \r\n mm). A minimum cavity width of 1 in. (25 mm) is recommended for \r\n fine grout use. Code requirements may dictate the minimum size grout \r\n space. \r\n \r\n Ties \r\n \r\n Ties in a masonry wall system are provided to connect two or more \r\n wythes together. In the case of a cavity wall, the ties are the \r\n mechanism for transferring lateral loads between the wythes. Wall \r\n ties can take the form of wire ties, wire joint reinforcing, adjustable \r\n wire ties or masonry bonders. One key item is to make sure that \r\n the type of tie chosen will not decrease the water resistance of \r\n the wall system. \r\n Wire Ties . Wire ties, either Z-ties or rectangular ties, \r\n shall comply with ASTM A 82. They should be corrosion-resistant, \r\n 3/16 in. (4.8 mm) diameter steel or metal wire of equivalent thickness. \r\n Applicable ASTM standards for corrosion-resistant coatings or materials \r\n are discussed in a following paragraph of this section. \r\n Wire Reinforcing . Continuous wall ties (joint reinforcing) \r\n may be used in cavity or solid walls when the wythes are composed \r\n of clay masonry units. These continuous wall ties may be either \r\n truss or ladder-type, with at least one side wire in each wythe. \r\n When the backup, or the inner wythe of a cavity wall, is built \r\n using concrete masonry units, joint reinforcing is needed in the \r\n concrete masonry to control cracking from drying shrinkage. This \r\n control of cracking helps reduce water penetration to the interior. \r\n Reinforcing should be either three-wire joint reinforcing, or two-wire \r\n reinforcing with tab ties. In either case, there should be one wire \r\n for each shell of the concrete masonry wythe. Because of the potential \r\n differential movement between brick and concrete block wythes, the \r\n use of ladder-type rather than truss-type joint reinforcing is recommended. \r\n Adjustable Wire Ties . In some cases, adjustable wire ties \r\n are the only way to tie masonry when courses in separate wythes \r\n do not line up vertically, or to accommodate large anticipated vertical \r\n differential movement between wythes in high-rise buildings. They \r\n should, however, be used with caution. Tests have shown that the \r\n strength and stiffness of such ties are drastically reduced if they \r\n are positioned to their maximum adjustment. This reduction can be \r\n as great as a factor of 10. The ties providing lateral support for \r\n the outer wythe should be capable of resisting both tension and \r\n compression, but should be designed to permit movement parallel \r\n to the plane of the wall in both a vertical and a horizontal direction. \r\n Masonry Bonders . Masonry bonders are not used as much today \r\n as they were in the past. One of their main problems is that they \r\n provide a direct path for water penetration from the outside of \r\n the wall to the interior along the head and bed joints. As a result, \r\n they are recommended only in cases where water penetration is a \r\n minor design consideration, or in some instances where all wythes \r\n of a wall are of brick masonry. \r\n Corrugated Metal Ties . Corrugated metal ties should not \r\n be used in masonry construction with the possible exception \r\n of brick veneer on residential construction, up to three stories \r\n in height. This recommendation is made because of: (1) their shape, \r\n which allows water to flow more freely to the interior; (2) their \r\n susceptibility to corrosion; and (3) their poor structural capacity \r\n for transferring loads between the wythes. \r\n Additional Considerations . Other considerations which are \r\n common to most of the ties mentioned above also must be considered. \r\n Drips - The use of drips in ties should be evaluated \r\n carefully. Drips may help to keep water from traveling across wire \r\n ties to the interior, but they also reduce the compressive and tensile \r\n strength of the tie in transferring the lateral loads between the \r\n wythes. Since this load transfer is very important for the structural \r\n strength of the wall assembly, the spacing of the ties should be \r\n reduced when they are manufactured with drips. \r\n Corrosion Resistance - Corrosion resistance is usually \r\n provided by copper or zinc coatings, or by using stainless steel. \r\n To ensure adequate resistance to corrosion, coatings or materials \r\n should conform to the following specifications: \r\n \r\n \r\n \r\n ASTM A 153 -Specification for Zinc Coating \r\n (Hot-Dip) on Iron and Steel Hardware, Class B-3 \r\n ASTM A 641 -Specification for Zinc-Coated \r\n (Galvanized) Carbon Steel Wire, Class 3 \r\n ASTM B 227-Specification for Hard-Drawn \r\n Copper-Clad Steel Wire, Grade 30 HS \r\n ASTM A 167-Specification for Stainless and \r\n Heat-Resisting Chromium-Nickel Steel Plate, Sheet and Strip, \r\n Type 304 \r\n \r\n \r\n \r\n The use of wire ties conforming to the corrosion resistance specified \r\n in ASTM A 641 should be limited to walls where the entire tie is \r\n embedded in mortar or grout. Where a portion of a tie is not embedded, \r\n i.e., crosses an air space or cavity, only ties conforming to ASTM \r\n A 153, ASTM A 167 or ASTM B 227 should be used. While it is felt \r\n that these are conservative recommendations, they are based on current \r\n available data. \r\n \r\n Shelf Angles and Lintels \r\n \r\n \r\n Shelf Angles . \r\n Where building codes or other factors do not permit the brick to be \r\n self-supporting for its full height, the veneer should be supported \r\n at each floor, or at least every other floor, by shelf angles. The \r\n shelf angles should be made of structural steel and properly sized \r\n and anchored to carry the imposed loads. Additional discussion and \r\n details may be found in Technical Notes 21 \r\n Revised and Technical Notes 28B \r\n Revised. \r\n \r\n Corrosion Resistance - For severe climates and exposures, \r\n consideration should be given to the use of galvanized or stainless \r\n steel shelf angles. Even where galvanized or stainless steel shelf \r\n angles are used, continuous flashing should be installed to cover \r\n the angle. To ensure adequate resistance to corrosion, coatings \r\n or materials should conform to the following specifications: \r\n ASTM A 123 - Specification for Zinc (Hot-Galvanized) Coatings on \r\n Products Fabricated from Rolled, Pressed and Forged Steel Shapes, \r\n Plates, Bars and Strip \r\n ASTM A 167 - Specification for Stainless and Heat-Resisting Chromium-Nickel \r\n Steel Plate, Sheet and Strip, Type 304 \r\n Lintels . The proper specification of material for steel \r\n lintels is important for both structural and serviceability requirements. \r\n The steel for lintels, as a minimum, should comply with ASTM A 36-Specification \r\n for Structural Steel. For harsh climates and exposures, consideration \r\n should be given to the use of galvanized or stainless steel lintels. \r\n If this is not done, then the steel lintels will require periodic \r\n maintenance to avoid corrosion. See corrosion resistance requirements \r\n under shelf angles, preceding this section. Technical Notes \r\n 31B Revised provides additional information on structural steel \r\n lintels. \r\n \r\n Flashing \r\n \r\n Flashing in a masonry wall is important for the proper drainage \r\n of water that may penetrate the wall system. Therefore, the choice \r\n of proper flashing material is of utmost importance. Flashing materials \r\n are generally formed from sheet metals, bituminous membranes, vinyls \r\n or combinations. The selection is largely determined by cost and \r\n suitability. It is suggested that only superior quality materials \r\n be selected, since replacement in the event of failure will be exceedingly \r\n expensive. \r\n Copper . Copper is durable, is available in special, performed \r\n shapes, and is an excellent moisture barrier. Although exposed copper \r\n may tend to stain adjacent masonry, it is not materially affected \r\n by the caustic alkalies present in masonry mortars. It can be safely \r\n embedded in fresh mortar and will not deteriorate in continuously \r\n saturated, hardened mortar, unless excessive chlorides are present. \r\n When using copper flashing, prohibit the use of chloride-based additives \r\n in the mortar. Typical copper flashing is made from 10 to 20-oz \r\n sheet copper. \r\n Plastics . Plastics are probably the most widely used flashing \r\n materials. Plastic flashings are tough, resilient materials, which \r\n are highly resistant to corrosion. However, because the chemical \r\n compositions of plastics vary widely, it is impossible to lump all \r\n plastic flashings into one generalized group. Little information \r\n is available regarding the durability of some of these materials, \r\n so it will be necessary to rely on performance records of the material, \r\n the reputation of the manufacturer, and where possible, test data \r\n to ensure satisfactory performance. Some of the critical areas are: \r\n (1) degradation resistance to ultraviolet light; (2) compatibility \r\n with alkaline masonry mortars; and (3) compatibility with joint \r\n sealants. Typical thicknesses of plastic flashings are 20 mil to \r\n 40 mil (0.5 mm to 1 mm). \r\n Galvanized Steel . Galvanized coatings are subject to corrosion \r\n in fresh mortar. Although the corrosive products apparently form \r\n a very compact film around zinc, the extent of corrosion cannot \r\n be accurately predicted. Bending also reduces their durability by \r\n cracking the coating. Some zinc-alloy flashings are available, but, \r\n like many alloys, these may have properties considerably different \r\n from those of the pure metal. The minimum thickness for this type \r\n of flashing should be about 0.015 in. (0.38 mm). \r\n Stainless Steel . Stainless steel is an excellent flashing \r\n material. It provides a good water barrier, and has excellent chemical \r\n resistance. ASTM A 167, Type 304, should be specified. The minimum \r\n thickness should be at least 0.01 in. (0.25 mm). \r\n Combination Flashings . Combination flashings, such as copper \r\n laminated to felt or kraft paper, were developed to utilize the \r\n better properties of each of the materials making up the flashing \r\n while at the same time lowering their cost. It is beyond the scope \r\n of this Technical Notes to describe the various types of \r\n combination flashings and their properties. The manufacturers literature \r\n should be consulted for the various flashings available. \r\n Asphalt-lmpregnated Felt . Asphalt-impregnated felt is not \r\n recommended as a material to be used for flashing in masonry \r\n construction. It is easily damaged during installation, and in many \r\n cases, turns brittle and decays with time. \r\n Aluminum . The caustic alkalies present in fresh, unhardened \r\n mortar will attack aluminum. Although dry, seasoned mortar will \r\n not affect aluminum, corrosion can again occur if the adjacent mortar \r\n becomes wet. Aluminum should not be used as a flashing material \r\n in brick masonry construction. \r\n Sheet Leads . Lead, like aluminum, is susceptible to corrosion \r\n in fresh mortar. Furthermore, where lead is partially embedded in \r\n mortar, in the presence of moisture, it develops a differential \r\n electrical potential, acting as the positive element of an electric \r\n cell. The resulting electrolytic action gradually disintegrates \r\n the embedded lead. Lead should not be used as a flashing \r\n material in brick masonry construction. \r\n \r\n Weepholes \r\n \r\n \r\n As mentioned in Technical Notes 7 \r\n Revised, weepholes must be used wherever flashing is located. Otherwise, \r\n the collected water has no way to exit the wall system. Weepholes \r\n can be made in a variety of ways. Some of the most common ways are \r\n leaving head joints open, using removable oiled rods, using plastic \r\n or metal tubes, or using rope wicks. There are also plastic or metal \r\n vents which are installed in lieu of mortar in a head joint during \r\n construction. There is no single method which produces the best weephole \r\n for all situations. As long as weepholes are placed at the required \r\n locations in the proper size and spacing, the specific type of weephole \r\n chosen is not critical. See details in Technical Notes 7 Revised \r\n for location and spacing of weepholes. \r\n \r\n Sealants \r\n \r\n One of the most important items for preventing water penetration \r\n is the use of proper sealants and caulking around openings in masonry \r\n walls. Too frequently, caulking is considered a means of correcting \r\n or hiding poor workmanship rather than as an integral part of construction. \r\n The subject of joint sealants is far beyond the scope of this Technical \r\n Notes, but a few comments are in order. For normal joints around \r\n windows and other openings, where little or no movement is expected, \r\n caulking should be done using a solvent-based acrylic sealant or \r\n a butyl caulk. For joints subject to large movements, such as expansion \r\n joints, an elastomeric joint sealant, conforming to the requirements \r\n of ASTM C 920, should be used. This includes silicones, urethanes \r\n and polysulfides. In no case should an oil-based caulking material \r\n be used. Regardless of the type of sealant chosen, proper priming \r\n and backer rods are a must. \r\n \r\n Coatings \r\n \r\n \r\n The use of some type of external coating on the face of a brick masonry \r\n wall, such as paint or clear coatings, is something which should not \r\n be done without a detailed evaluation of the possible consequences. \r\n First, it may not solve the basic water penetration problem, and second, \r\n it could lead to more serious problems. Technical Notes 6 \r\n Revised and Technical Notes 6A \r\n should be consulted before any type of coating is applied to a brick \r\n masonry wall. \r\n \r\n SUMMARY \r\n \r\n This, the second in a series of Technical Notes on water \r\n resistance of brick masonry, has provided information on properly \r\n selecting quality materials for masonry work. Obviously, this Technical \r\n Notes cannot cover all materials or all conditions. The materials \r\n are listed to illustrate the principles involved and may not include \r\n all materials which are available. \r\n The information contained in this Technical Notes is \r\n based on the available data and the experience of the technical \r\n staff of the Brick Institute of America. This information should \r\n be recognized as recommendations which, if followed with good judgment, \r\n should result in masonry walls that are resistant to water penetration. \r\n Final decisions on the use of information, details and materials \r\n as discussed in this Technical Notes are not within the purview \r\n of the Brick Institute of America, and must rest with the project \r\n designer, owner, or both. \r\n \r\n REFERENCES \r\n \r\n For more detailed information on materials and topics discussed \r\n in this Technical Notes, the following publications should \r\n be consulted: \r\n \r\n \r\n \r\n 1. Technical \r\n Notes on Brick Construction 6 \r\n Revised, \"Painting Brick Masonry\", May 1972. \r\n 2. Technical \r\n Notes on Brick Construction 6A , \r\n \"Colorless Coatings for Brick Masonry\", April 1995. \r\n 3. Technical \r\n Notes on Brick Construction 8 \r\n Revised, \"Portland Cement-Lime Mortars for Brick Masonry\", Sept. 1972. \r\n 4. Technical \r\n Notes on Brick Construction 8A , \r\n \"Standard Specification for Portland Cement-Lime Mortar for Brick Masonry\", \r\n Oct.-Nov. 1972. \r\n 5. Technical \r\n Notes on Brick Construction 8B , \r\n \"Mortar for Brick Masonry-Selection and Controls\", July-Aug. 1976. \r\n 6. Technical \r\n Notes on Brick Construction 21 \r\n Revised, \"Brick Masonry Cavity Walls\", Jan-Feb. 1977. \r\n 7. Technical \r\n Notes on Brick Construction 28B \r\n Revised, \"Brick Veneer-Panel and Curtain Walls\", Feb. 1980. \r\n 8. Technical \r\n Notes on Brick Construction 31B \r\n Revised, \"Structural Steel Lintels\", Nov.-Dec. 1981. \r\n 9. Annual \r\n Book of ASTM Standards, American \r\n Society for Testing and Materials: \r\n \r\n (a) \r\n Section 1-Iron and Steel Products, Volumes 01.03, 01.04 and 01.06. \r\n (b) \r\n Section 2-Nonferrous Metal Products, Volume 02.03. \r\n (c) \r\n Section 4-Construction, Volumes 04.01 and 04.05. \r\n (d) \r\n Section 15-General Products, Chemical Specialties and End Use Products, \r\n Volume 15.08. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60133,"ResultID":176365,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical \r\n Notes 7B - Water Resistance of Brick Masonry - Construction and Workmanship, \r\n Part 3 \r\n April 1985 (Reissued Apr. 1998) \r\n \r\n Abstract : This Technical Notes covers \r\n essential construction practices needed to assure water-resistant brick \r\n masonry. Included are information and recommendations on the preparation \r\n of materials to be used in brick masonry construction. Consideration is \r\n also given to the need for good workmanship, which requires the complete \r\n filling of all mortar joints. Discussion centers on acceptable types \r\n of tooled mortar joints for exterior exposure and the need to cover unfinished \r\n brick masonry walls. \r\n Key Words : air space, brick, construction , \r\n j oints , maintenance, materials, mortar, suction , \r\n tooling , workmanship . \r\n INTRODUCTION \r\n This is the third of three Technical Notes \r\n addressing water resistance of brick masonry. Technical Notes \r\n 7 Revised covers design and details, while \r\n Technical Notes 7A Revised covers \r\n materials. This issue discusses construction techniques and workmanship. \r\n All of these items are vital in obtaining good water-resistant brick masonry \r\n walls. \r\n CONSTRUCTION \r\n The best design and detailing combined with \r\n the best quality materials will not compensate for poor construction practices \r\n and workmanship. Proper construction practices, including preparation \r\n of materials and workmanship, are essential in attaining a water-resistant \r\n brick masonry wall. \r\n Preparation of Materials \r\n Preparation of the materials before the actual \r\n bricklaying begins is very important. Specific procedures must be followed \r\n to ensure quality masonry and avoid future problems. \r\n Storage of Materials . All materials \r\n at the jobsite should be properly stored to avoid contamination. If possible, \r\n materials should be stored inside an enclosure. When stored outside, all \r\n masonry units, mortar materials, ties and reinforcing should be stored \r\n on platforms, preferably in a high, dry location. In addition, all materials \r\n should be covered with tarpaulins or some other weather-resistant material \r\n to protect them from the elements. \r\n Mixing of Mortar and Grout . A high \r\n water content in the mortar is necessary to obtain complete and strong \r\n bond between mortar and brick units. Therefore, the mortar should be mixed \r\n with the maximum amount of water that it is possible to use and \r\n still produce a workable mortar. It is recommended that all cementitious \r\n materials and aggregates be mixed for at least 3 min and not more than \r\n 5 min in a mechanical batch mixer. If, after initial mixing, the mortar \r\n stiffens due to the loss of water by evaporation, additional water can \r\n be added and the mortar remixed. All mortar and grout should be used within \r\n 2 1/2 hr of initial mixing and no mortar or grout should be used after \r\n it has begun to set. \r\n One of the most common problems with mortar \r\n is oversanding. Oversanded mortar is harsh, unworkable and leads to a \r\n weak bond between mortar and brick, thus inviting water penetration problems. \r\n The cause of the oversanding is frequently due to the use of the shovel \r\n method of measuring the sand. The amount of sand that a shovel will hold \r\n varies, depending on the moisture content of the sand, the person doing \r\n the shoveling and the different size of shovels used on the jobsite. To \r\n alleviate this problem, proper batching methods must be used. Measurement \r\n of sand by shovel should not be permitted. Technical Notes \r\n 8B provides detailed guidelines for various \r\n methods of more accurately batching mortar. \r\n Wetting Brick Units . Brick with suction greater \r\n than 30 gm/min/30 sq in. (30 g/min/194 cm 2 ) may need to be wetted prior \r\n to laying to reduce their initial rate of absorption to an acceptable level \r\n to achieve proper bond of mortar to brick. A rough, but effective, test \r\n for determining whether units need wetting consists of drawing, with a wax \r\n pencil, a circle 1 in. (25 mm) in diameter on the surface of the unit which \r\n will be in contact with the mortar, using a 25-cent piece as a guide. With \r\n a medicine dropper, place 20 drops of water inside this circle and note \r\n the time required for the water to be absorbed. If the time exceeds 1 1/2 \r\n min, the unit need not be wetted; if less than 1 1/2 min, wetting is recommended. \r\n The method of wetting the brick is very important. Sprinkling or dipping \r\n the brick in a bucket of water just before laying may not be sufficient. \r\n The units should be nominally saturated, but surface dry at the time of \r\n laying. See Figure 1. \r\n \r\n Moisture Content of Brick \r\n FIG. 1 \r\n Fig. 1(a) shows the saturated condition which \r\n rarely occurs on the average construction job, except when the brick are \r\n exposed during rainy weather. \r\n Fig. 1(b) shows the dry condition which is \r\n unsatisfactory, except for low-suction brick. \r\n Fig. 1(c) shows the surface-wet condition \r\n which may be satisfactory if the wetness extends to 3/4 in. (18 mm) or \r\n more inside the surface. \r\n Fig. 1(d) shows the ideal situation where \r\n the brick have been saturated, but are surface dry. \r\n A satisfactory procedure for wetting the \r\n brick consists of letting water run on the pile or pallets of brick. This \r\n should be done the previous day, or not later than several hours before \r\n the units will be used so that the surfaces have an opportunity to dry \r\n before the brick are laid. Wetting of low-absorption brick units or excessive \r\n wetting of other brick units may result in saturation and can cause \"bleeding\" \r\n of the mortar joints and \"floating\" of the brick units. When the interior \r\n and exterior wythes of brick have widely different absorption rates, such \r\n as with an extremely dense and hard-burned facing brick backed up with \r\n a relatively porous building brick, it is important to maintain the correct \r\n water content in the two types of brick. \r\n Workmanship \r\n The importance of good workmanship to attain \r\n quality masonry has been stressed by many, sometimes to the point that \r\n it may appear that workmanship alone is responsible for the water permeability \r\n of some masonry walls, regardless of the design or materials used. While \r\n this is by no means true, workmanship is nevertheless a highly important \r\n factor in the construction of watertight masonry. \r\n Filling Mortar Joints . To obtain good \r\n masonry construction, there is no substitute for the complete filling \r\n of all mortar joints that are designed to receive mortar. Partially filled \r\n mortar joints result in leaky walls, reduce the strength of masonry, and \r\n may contribute to disintegration and cracking due to water penetration \r\n and subsequent freezing and thawing. Therefore, all joints to receive \r\n mortar should be completely filled as the brick are laid. See Figs. 2 \r\n through 4. \r\n \r\n Spread a uniform bed of mortar \r\n over only a few brick. \r\n Furrow only lightly, if at all. \r\n Place plenty of mortar on the end of the brick to be placed. \r\n Brick is then shoved into place \r\n so that mortar is squeezed out of top of head joint. \r\n FIG. 2 \r\n \r\n After placing, mortar squeezed \r\n out of bed joint is cut off to prevent staining the wall. \r\n FIG. 3 \r\n \r\n When placing closures, place \r\n plenty of mortar on ends of brick in place and on ends of \r\n brick to be placed. Shove closure \r\n into place without disturbing brick on either side. \r\n FIG. 4 \r\n Collar Joints \r\n - The vertical, longitudinal \r\n joint between wythes of masonry is called a collar joint. The manner in \r\n which these joints are filled is very important. \"Slushing\" of collar \r\n joints is not effective since it is difficult to completely fill all voids \r\n in the joints. Frequently, the mortar is caught and held before it reaches \r\n the bottom of the narrow crevice, leaving openings between the face brick \r\n and the backup units. Even when this space is filled, there is no way \r\n to compact the mortar. The mortar does not bond with the brick over its \r\n entire surface. Channels are left between the mortar and the brick, through \r\n which water can trickle down behind the face brick until it finds a path \r\n along which it can travel to reach the back of the wall (see Fig. 5). \r\n A properly constructed collar joint is completely filled with grout or \r\n mortar. \r\n \r\n \r\n Slushing does not completely \r\n fill the space between the face brick and the back-up work. \r\n FIG. 5 \r\n Bed Joints - A bed joint is the horizontal layer of mortar on which a masonry \r\n unit is laid. Bed joints should be constructed without deep furrowing of \r\n the mortar as full bed joints are an inherent requirement for water-resistant \r\n brick masonry construction. The length of time between the placing of the \r\n mortar on the bed joint and the laying of the succeeding brick units has \r\n an influence on the resulting bond. If too long a time elapses, poor bond \r\n will result. Brick units should be laid within 1 min or so after the mortar \r\n is placed. \r\n Head Joints - A head joint, \r\n sometimes called a cross joint, is the vertical mortar joint \r\n between ends of masonry units. As with bed joints, it is important that \r\n head joints also be completely filled. The best head joints are formed \r\n by completely buttering the ends of the brick with mortar and shoving \r\n the brick into place against previously laid brick. \"Slushing\" of the \r\n interior head space between individual brick in a course of brick is not \r\n effective. Recommended, as well as unacceptable, methods of forming head \r\n joints are shown in Fig. 6. \r\n \r\n Head Joints \r\n FIG. 6 \r\n Keeping Air Spaces Clean . In a drainage wall system, such as a cavity wall or an anchored \r\n veneer wall, it is essential that the air space between the wythes be kept \r\n clean. If it is not, and mortar droppings and protrusions span the air space, \r\n or clog the weepholes, water penetration to the interior may occur. See \r\n Figs. 7 through 10. Technical Notes 21C \r\n and Technical Notes 28 Series provide \r\n further information on the importance of keeping the air space clean, protecting \r\n flashing during construction as well as information on the proper installation \r\n of ties and anchors. \r\n \r\n In cavity wall construction, \r\n mortar droppings should not be permitted to fall into the cavity. \r\n An aid in preventing this is \r\n to bevel the bed joint away from the cavity. \r\n FIG. 7 \r\n \r\n Keeping the Cavity Clean \r\n FIG. 8 \r\n \r\n \r\n \r\n When brick are laid on a beveled \r\n bed joint, a minimum of mortar is squeezed \r\n out of the joint. Brick (1)-beveled \r\n joint; brick (2)-conventional joint. \r\n FIG. 9 \r\n \r\n The mortar squeezed from the \r\n joints on the cavity side may be plastered onto the units. \r\n This same procedure may be used \r\n for laying exterior wythes of reinforced brick walls. \r\n Mortar droppings should not \r\n be permitted in grout core. \r\n FIG. 10 \r\n Disturbance of Newly Laid Masonry . Newly laid masonry units should never be pushed, shoved, tapped \r\n or otherwise disturbed once they are laid in their final position and the \r\n mortar has begun to set. Any disturbance at this point will break the bond \r\n and may lead to a leak. If adjustments are necessary, the incorrectly placed \r\n unit should be removed and re-laid in fresh mortar. \r\n Tooling of Mortar Joints . Weathertightness \r\n and textural effect are the basic considerations for mortar joint finish \r\n selection and execution. Proper \"striking\" or \"tooling\" of the joints \r\n helps the mortar and brick units bond together and seals the wall surface \r\n against moisture penetration. Compression of the mortar produces a denser \r\n mortar at the surface and the most weathertight joint. Only the concave, \r\n \"V\" and compacted grapevine joints are recommended for exterior use. For \r\n interior masonry work, other joints, such as the weathered, beaded, struck, \r\n flush, raked or extruded joints can be used (see Figs. 11 and 12). \r\n \r\n Typical Mortar Joints \r\n FIG. 11 \r\n \r\n \r\n When mortar becomes thumbprint \r\n hard, tool with steel jointer slightly larger than \r\n the mortar joint. Concave or \r\n V joints have best weather resistance. \r\n FIG. 12 \r\n Covering Tops of Walls . Proper covering of masonry walls each night, and especially in time of \r\n inclement weather, is essential for satisfactory performance. Covering of \r\n unfinished walls with tarpaulins or other water-resistant material, securely \r\n tied or weighted in position, should be rigorously enforced. Mortar boards, \r\n scaffold planks and light plastic sheets weighted with brick should not \r\n be accepted as suitable cover. Metal clamps, similar to bicycle clips, are \r\n commercially available in a variety of sizes to meet various wall thicknesses. \r\n These are used in conjunction with plastic sheets or water-repellent tarpaulin \r\n material and offer excellent protection for extended periods of time. In \r\n many cases, after the mason finishes his portion of the work, tops of walls \r\n are left for several months with inadequate or ineffective protective coverings \r\n prior to the attachment of permanent coping. The previously mentioned clamps, \r\n along with proper covering materials, afford an effective solution when \r\n the permanent coping is not attached immediately after the brickwork is \r\n completed. \r\n \r\n MAINTENANCE \r\n Even the best masonry requires periodic maintenance \r\n to ensure its continued successful performance. Although the brick units \r\n are quite durable over time, other materials in the wall system will require \r\n periodic repair and/or replacement. Typical maintenance items which should \r\n be addressed are repairing of cracks in masonry, cleaning clogged weepholes, \r\n removing stains and efflorescence, repainting steel, replacing caps or \r\n copings, repointing mortar joints (tuck-pointing), replacing deteriorated \r\n sealants and caulking, and cleaning the masonry. A more complete discussion \r\n of maintenance of masonry is beyond the scope of this Technical Notes. \r\n The following table provides an estimated life of various building \r\n materials and can be used as a guide in considering the need for periodic \r\n maintenance: \r\n Brick 100 years \r\n or more \r\n Mortar 15-50 years \r\n Paint on Steel 3-5 \r\n years \r\n Sealants (caulking type) 4-10 years \r\n Coping Joints 4-8 \r\n years \r\n SUMMARY \r\n This is the third in a series of Technical \r\n Notes on water resistance of brick masonry. It provides basic information \r\n required for good construction. Obviously, this Technical Notes cannot \r\n cover all construction practices. It does, however, offer basic information \r\n and construction suggestions which, if used with professional judgment, \r\n will result in successfully performing brick masonry walls. Other Technical \r\n Notes in this series discuss design and materials. \r\n The information contained in this Technical \r\n Notes is based on the available data and experience of the \r\n technical staff of the Brick Institute of America. This information should \r\n be recognized as recommendations which, if followed with good judgment, \r\n should result in masonry walls that are resistant to water penetration. \r\n Final decisions on the use of information, details and materials as discussed \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project designer, owner or \r\n both. \r\n REFERENCES \r\n For more comprehensive information on details \r\n and design procedures for various types of walls and detailed information \r\n on materials used to attain water-resistant brick masonry construction, \r\n the following publications should be consulted: \r\n 1. Technical \r\n Notes on Brick Construction 7 \r\n Revised, \"Water Resistance of Brick Masonry-Design and Detailing- Part \r\n I of III\", Feb. 1985. \r\n 2. Technical \r\n Notes on Brick Construction 7A \r\n Revised, \"Water Resistance of Brick Masonry-Materials - Part II of III\", \r\n March 1985. \r\n 3. Technical \r\n Notes on Brick Construction 8B , \r\n \"Mortar for Brick Masonry - Selection and Controls\", July - Aug. 1976. \r\n 4. Technical \r\n Notes on Brick Construction 21C , \r\n \"Brick Masonry Cavity Walls - Construction\", May - June 1978. \r\n 5. Technical \r\n Notes on Brick Construction 28 \r\n Revised, \"Brick Veneer - New Construction\", July-Aug. 1978. \r\n 6. Technical \r\n Notes on Brick Construction 28A , \r\n \"Brick Veneer - Existing Construction\", Sept. - Oct. 1978. \r\n 7. Technical \r\n Notes on Brick Construction 28B \r\n Revised, \"Brick Veneer - Panel and Curtain Walls\", Feb. 1980. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60134,"ResultID":176366,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 7C - Moisture Control \r\n in Brick and Tile Walls - Condensation \r\n Feb. 1965 (Reissued Sept. 1988) \r\n \r\n INTRODUCTION \r\n It is generally agreed that the durability \r\n of masonry depends primarily on its resistance to the penetration of moisture \r\n into the body of the masonry. The source of this moisture may be wind-driven \r\n rains or it may be from interior exposures resulting from various occupancies \r\n which create high humidities. These include, among others, air conditioning \r\n with humidity control, food processing and unventilated space heaters. \r\n Differences in humidity between inside and outside air resulting from \r\n these occupancies will cause vapor flow within the wall and, unless controlled, \r\n either by the use of properly placed vapor barriers or by ventilating, \r\n this vapor may condense within the wall under certain temperature conditions. \r\n When wall surface temperatures are substantially \r\n below air temperatures, condensation may occur on the wall surface. \r\n CONDENSATION ON WALL SURFACES \r\n Atmospheric air is a mixture of dry air and \r\n water vapor. At a given temperature air is saturated when the space occupied \r\n by the mixture holds the maximum possible weight of water vapor at that \r\n temperature. The amount of water vapor necessary to saturate the air at \r\n constant pressure depends upon the temperature-the higher the temperature \r\n the more water vapor will be required. If saturated air at a temperature \r\n of 50 deg, for instance, is warmed to a temperature of 70 deg, the mixture \r\n is no longer saturated but will absorb additional water vapor. However, \r\n if unsaturated air is cooled at constant pressure, a temperature will \r\n be reached at which the air is saturated. This temperature is called the \r\n dew point and, if the mixture is cooled below the dew point, water will \r\n condense from the air. Dew which occurs in the early mornings during the \r\n warmer months in many localities is one of the most common examples of \r\n the effect of cooling unsaturated air to a temperature below the dew point \r\n or to a point where the water vapor which the air contains begins to condense. \r\n The water vapor in air is called humidity, \r\n and relative humidity is the ratio of the amount of water vapor which \r\n a mixture contains to the amount required for saturation at a given temperature. \r\n Obviously, for a fixed amount of water vapor, the relative humidity will \r\n vary with the temperature, increasing as the temperature is lowered and \r\n decreasing as the temperature rises. \r\n While the dew point depends upon the amount \r\n of water vapor in the air and is the temperature at which the water vapor \r\n present is sufficient for saturation, there is also a practically constant \r\n relation between dew point and relative humidity for a considerable range \r\n of temperatures; that is, for a relative humidity of 50 per cent, the \r\n difference between air temperature and dew point is approximately 20 deg \r\n for any air temperature from 60 deg to 90 deg. Similar relations hold \r\n for other relative humidities. A discussion of the reason for this relationship \r\n may be found in the ASHRAE Guide and Data Book, Fundamentals and Equipment \r\n Volume, 1963, published by the American Society of Heating, Refrigerating \r\n and Air-Conditioning Engineers, Inc. \r\n In Fig. 1, the difference in temperature \r\n between the air and the dew point (temperature drop) is plotted for relative \r\n humidities from 50 per cent to 100 per cent. It will be noted from this \r\n curve that for relative humidities above 80 per cent a drop in temperature \r\n of 6.8 deg or over will cause condensation. These high humidities usually \r\n occur during the summer when the difference in temperature between the \r\n air on opposite sides of a wall is small, probably 10 deg or less. For \r\n walls below grade, the temperature difference of the two sides of the \r\n wall may amount to 20 deg or more. \r\n \r\n Temperature Drop Curve for \r\n Relative Humidities \r\n from 50 Per Cent to 100 Per \r\n Cent \r\n FIG. 1 \r\n If condensation occurs, it may be eliminated \r\n by: \r\n 1. Reducing the humidity of the air. This \r\n may be accomplished by adequate ventilation if the high humidity is caused \r\n by conditions inside the building. \r\n 2. Increasing the temperature of the surface \r\n upon which the condensation occurs. Probably the simplest means of increasing \r\n the surface temperature is to increase the movement of air over the surface. \r\n \r\n 3. Increasing the heat resistance of the \r\n wall. This is usually done by the addition of an air space or insulation \r\n back of the interior finish. \r\n The temperature gradient or temperature drop \r\n through a composite wall is directly proportional to the resistance of \r\n the various elements, including surface resistances; that is, if the total \r\n resistance of a wall is 8.0 and the resistance of one element is 2.0, \r\n the temperature drop across this element will be 2/8 of the air temperature \r\n difference on the warm and cold sides of the wall. \r\n Table 1 gives the difference in temperature \r\n between the inside surface of various types of walls and the inside air \r\n temperature for differences between inside and outside air, ranging from \r\n 10 deg to 70 deg Fahr. These figures are based upon the conductivities \r\n and conductances of materials listed in Tables 1, 3 and 4 of Technical \r\n Notes 4 , \"Heat Transmission Coefficients \r\n of Brick and Tile Walls\". \r\n From Table 1, it may be noted that, for a \r\n difference in temperature between inside and outside air of 70 deg, the \r\n inside surface temperature of an exposed brick-and-brick cavity wall is \r\n 16 deg below the temperature of the inside air. Referring to the curve, \r\n Fig. 1, a temperature drop of 16 deg will cause condensation for relative \r\n humidities of 58 per cent or over. The temperature drop for a vermiculite \r\n insulated brick-and-brick cavity wall, exposed, is 6 1/2 deg for which \r\n relative humidities must be 81 per cent or over to cause condensation. \r\n Table 1 may be used in connection with the \r\n \"temperature drop\" curve to select a type of wall construction which will \r\n be free from condensation \r\n \r\n TABLE 1 \r\n Difference in Temperature Betwen Inside Air and \r\n Inside Wall Surface for Various Total Differences \r\n In Temperature Between Inside Air and Outside Air \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Note: Plaster: gypsum and aggregate. \r\n \r\n \r\n \r\n Lath: 3/8 \r\n in. gypsum. \r\n \r\n \r\n 1Reg. U.S. Pat. Off., SCPI \r\n \r\n CONDENSATION WITHIN WALLS \r\n The National Bureau of Standards Report, \r\n BMS63, Moisture Condensation in Building Walls, contains a method \r\n for calculating potential condensation if the temperature and vapor-resistant \r\n gradients of the wall are known. The following summarizes the discussion \r\n and method outlined in the report: \r\n A definite volume of air held at a fixed \r\n temperature can contain permanently no more than a definite amount of \r\n water in the form of vapor. This limiting quantity of water per given \r\n volume is termed \"moisture content at saturation\". If the air contains \r\n a greater proportion of moisture than this at the particular temperature, \r\n the water will start condensing on the surfaces of the container or even \r\n on the dust particles in the air which then fall out in a fine mist. The \r\n ratio of the actual moisture content to the saturation moisture content \r\n for the particular temperature is termed \"relative humidity\". It is customarily \r\n expressed in per cent. \r\n The concentration of water vapor may also \r\n be stated by giving its pressure. If water vapor is present, part of the \r\n atmospheric pressure is maintained by the water vapor and the remainder \r\n of the pressure by the other constituents of the atmosphere. At a particular \r\n temperature and at saturation, the water vapor exerts a definite pressure. \r\n Data on saturated vapor pressures are listed \r\n in tables of the ASHRAE Guide and Data Book and Table 2 gives saturated \r\n vapor pressures for various temperatures as included in the 1963 edition. \r\n \r\n \r\n \r\n TABLE 2 \r\n Saturated Vapor Pressures \r\n \r\n \r\n As may be noted, the variation of vapor pressure \r\n with temperature is not constant but increases rapidly with increased \r\n temperature. \r\n \r\n The ratio of the actual pressure of the water \r\n vapor to the saturation pressure of the water vapor for the particular \r\n temperature is also termed relative humidity. Its value when defined thus \r\n is essentially the same as that given previously. \r\n When a given mixture of air and water vapor \r\n is cooled without loss of moisture, a temperature is eventually reached \r\n where the air becomes saturated with water vapor and condensation can \r\n occur. The temperature then existing is called the dew point. \r\n When a vapor-pressure differential exists, \r\n water vapor will move toward the lower pressure independently of air. \r\n This vapor movement through common building materials is at a relatively \r\n high rate for common pressure differentials. When vapor passes through \r\n pores of homogeneous walls, which are warm on one side and cold on the \r\n other, it may reach its dew point and condense into water within the wall; \r\n but, if the flow of vapor is impeded by a highly vapor-resistant material \r\n on the warm side of the wall, the vapor cannot reach that point in the \r\n wall at which the temperature is low enough to cause condensation. \r\n Permeability to water vapor travel is known \r\n as permeance which is defined as \"the ratio of water vapor flow to the \r\n vapor-pressure difference between the surfaces\". Permeance is measured \r\n in perms. A perm is equal to 1 grain per sq ft per hr per in. of mercury \r\n vapor-pressure difference. A perm-inch is the permeance of 1-in. thickness \r\n of a homogeneous material. The reciprocal of permeance is called vapor \r\n resistance. \r\n Differences in vapor pressure through different \r\n parts of the wall from inside to outside distribute themselves in proportion \r\n to the vapor resistance of the respective parts; that is, the fraction \r\n of the total vapor-pressure drop from inside to outside occurring between \r\n the air indoors and some chosen point within the wall is the same as that \r\n fraction of the total vapor resistance of the wall occurring between the \r\n air indoors and the chosen point. \r\n In this it is analogous to heat flow, in \r\n which differences in temperature through different parts of the wall from \r\n warm to cold side are proportional to the thermal resistance of these \r\n parts. \r\n As an example, assume a brick and tile, vermiculite \r\n insulated cavity wall, unplastered, exposed on the tile side to 75 deg \r\n Fahr, 50 per cent relative humidity, and on the brick side to 20 deg Fahr, \r\n 90 per cent relative humidity. The thermal resistances are: \r\n Inside air 0.68 4-in. tile 1.11 2-in. vermiculite 5.56 4-in. brick 0.44 Outside air 0.17 R = 7.96 U \r\n = 0.125 \r\n The vapor resistances are: \r\n 4-in. tile 0.333 Insulation 0.008 4-in. brick 0.480 0.821 \r\n The vapor pressure differential is 50 per \r\n cent of saturated vapor pressure at 75 deg (0.4375 in. Hg) minus 90 per \r\n cent of saturated vapor pressure at 20 deg (0.0924 in. Hg) equals 0.345 \r\n in. Hg. The temperature difference is 75 deg minus 20 deg equals 55 deg. \r\n From the above resistances, the temperature \r\n gradient and vapor pressure gradient may be plotted as indicated in Fig. \r\n 2. As may be noted, the vapor pressure at the inside face of the brick \r\n wythe is 0.29 and the temperature at this point is 24 deg. \r\n \r\n Temperature and Vapor Pressure \r\n Distribution for a Brick and Tile Cavity Wall \r\n FIG. 2 \r\n \r\n Referring to Table 2, the saturated vapor \r\n pressure at 24 deg is 0.124. Since the actual vapor pressure exceeds this \r\n amount, condensation might be expected to occur in the insulation just \r\n back of the outer wythe. \r\n Vapor transmission tests, sponsored by the \r\n Structural Clay Products Research Foundation, a Division of Structural \r\n Clay Products Institute, were conducted on a wall similar to the above \r\n at Pennsylvania State University. The temperatures and humidities maintained \r\n during these tests were approximately the same as those assumed. Data \r\n obtained from the tests are included in the paper, Review of Recent \r\n Research, by C. B. Monk, Jr., published in the Proceedings of the \r\n BRI Conference on Insulated Masonry Cavity Walls, which was held in New \r\n York City in April 1960. \r\n The results of the tests confirm the above \r\n calculations, since frost formed on the cavity face of the brick wythe. \r\n However, Mr. Monk states: \"The major observation of the heat transfer \r\n data is the relative constant air-to-air conductance of the wall during \r\n the 18 days of steady state conditions, indicating no change in the thermal \r\n characteristics of the wall due to the frost observed at the end of the \r\n test.\" \r\n From the vapor transmission tests, it is \r\n apparent that, insofar as condensation affects heat transfer, a vapor \r\n barrier is not required on the warm side of an insulated cavity wall, \r\n whose permeance is approximately equivalent to the wall tested when vapor \r\n pressure differentials are of the order of 1 in. of mercury. However, \r\n as previously indicated, water in a masonry wall may contribute to disintegration \r\n of masonry units and, where soluble salts are present in the masonry, \r\n it also contributes to efflorescence. For this reason, vapor barriers \r\n are recommended on the warm side of cavity walls with exterior wythes \r\n of glazed brick. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60135,"ResultID":176367,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 7D - Moisture Resistance \r\n of Brick Masonry Walls - Condensation Analysis \r\n May 1988 (Reissued Feb. 1993) \r\n Abstract : Moisture, formed \r\n by the condensation of water vapor, can cause many problems in brick \r\n masonry walls. Among these are: efflorescence, spalling, corrosion \r\n and interior finish damage. \r\n This Technical Notes outlines \r\n a method used by designers to assess the possibility of condensation \r\n occurring in a given wall section; and, describes how to alleviate \r\n condensation problems through the use of vapor barriers and/or ventilation. \r\n Key Words : brick, condensation , \r\n dew point , humidity, permeance , relative humidity , \r\n saturated vapor pressure , saturation, vapor barrier, \r\n vapor pressure , vapor resistance , walls. \r\n INTRODUCTION \r\n When a vapor pressure differential \r\n exists, water vapor will move independently of air. The vapor movement \r\n through common building materials is at a relatively high rate for \r\n common pressure differentials. When vapor passes through pores of \r\n homogenous walls, which are warm on one side and cold on the other, \r\n it may reach its dew point and condense into water within the wall; \r\n but, if the flow of vapor is impeded by a vapor-resistant material \r\n in the wall, the vapor may not reach that point in the wall at which \r\n the temperature is low enough to cause condensation. \r\n Condensation problems are most frequent \r\n during the heating season when buildings of tight, highly insulated \r\n construction have occupancies and/or heating systems which produce \r\n humidity. This gain in moisture content of the interior air increases \r\n the interior vapor pressure substantially above that existing in the \r\n outdoor atmosphere. This tends to drive vapor outward from the building \r\n through any vapor-porous materials that comprise the wall assembly. \r\n This may be controlled either by the use of a properly placed vapor \r\n barrier or by decreasing the vapor pressure differential across the \r\n wall section through the use of ventilation. \r\n Technical Notes 7C \r\n contains a discussion of the principles of condensation of water vapor, \r\n both on the wall surface and within the wall system. This Technical \r\n Notes is devoted to the analysis of wall systems to determine \r\n at what point or points in the wall assembly condensation might be \r\n expected to occur. \r\n EFFECTS OF CONDENSATION \r\n \r\n \r\n \r\n Many building materials are affected \r\n by water. For example, wood expands with increasing moisture content. \r\n If conditions of varying humidity occur in different parts of the \r\n cross-section of a single wood framing member, there will be a tendency \r\n to warp. High humidity can also cause the decay of wood. Water promotes \r\n the corrosion of metal, and many insulating materials show permanent \r\n change over the course of time when in contact with water. The insulating \r\n value of most materials is greatly reduced by the presence of free \r\n water. Volumetric changes in fired clay masonry units due to gains \r\n in moisture content are to be expected and should be given consideration \r\n in the design process. Alternate freezing and thawing of clay products \r\n when saturated may lead to eventual deterioration, such as cracking \r\n and spalling. If soluble salts are present in or in contact with brick \r\n masonry, moisture caused by condensation may contribute to efflorescence. \r\n CONDENSATION ANALYSIS \r\n This Technical Notes describes \r\n the method used to determine the temperature and vapor pressure gradients \r\n of a wall when the exterior and interior design temperatures and relative \r\n humidities are known. Accompanying this method is an example of determining \r\n the points in a wall system where condensation may be expected to \r\n occur. \r\n Method \r\n The step-by-step method outlined assumes \r\n a steady-state heat loss procedure. The wall section and the interior \r\n and exterior temperatures and relative humidities are therefore held \r\n constant. This procedure is easily adapted to the cooling season by \r\n keeping in mind that the temperature and vapor pressure gradients \r\n are always plotted across the wall section from the warm side to the \r\n cool side. \r\n Procedure \r\n An 11-column table is set up, similar \r\n to that shown in Table 3. \r\n The wall components, including the \r\n inside air, inside air film and exterior air film, are listed in Column \r\n 1. \r\n The thermal resistance (deg. F * sq. \r\n ft. * hr/Btu) of each wall component is entered in the rows of Column \r\n 2 respectively. Values of thermal resistance may be found in Technical \r\n Notes 4 Revised, Table 1. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n The component thermal resistances \r\n are totaled and entered at the bottom of Column 2. \r\n The component thermal resistance percentage \r\n is calculated by dividing the component thermal resistance by the \r\n total thermal resistance of the wall assembly and multiplying this \r\n quotient by 100. The results are entered in the rows of Column 3, \r\n respectively. Check the total of the component percentages to make \r\n sure that they equal 100. \r\n The temperature drop across each component \r\n is calculated by multiplying the component thermal resistance percentage \r\n by the total temperature drop across the wall section (Ti - To), an \r\n dividing this product by 100. The results are entered in the rows \r\n of Column 4 respectively. A quick check is to total the component \r\n temperature drops. They must equal the total temperature drop across \r\n the wall section. \r\n The temperature of the inside air, \r\n Ti, is entered in Row 2 of Column 5. \r\n The component temperatures (the temperature \r\n of the components exterior face) are calculated by subtracting the \r\n component temperature drop from the temperature of the component preceding \r\n it. The results are entered in the rows of Column 5 respectively. \r\n Check the calculated temperature of \r\n the outside air film. It must equal the temperature of the outside \r\n air, To. \r\n The component saturated vapor pressures \r\n are taken from Table 1 for the temperature of each component, and \r\n entered in the rows of Column 6 respectively. \r\n The component vapor resistances (in. \r\n Hg * sq. ft. * hr/gr), taken from Table 2, are entered in the rows \r\n of Column 7 respectively. \r\n \r\n \r\n \r\n \r\n \r\n \r\n * In this chapter the permeance, \r\n resistance, permeability and resistance per unit thickness values \r\n are \r\n given in the following units: \r\n Permeance Perm= gr/h.ft 2 .in.Hg \r\n Resistance Rep= in.Hg.ft 2 h/gr \r\n Permeability Perm.in.= gr/h.ft 2 (in.Hg/in.) \r\n Resistance/unit thicknessRep/in. \r\n =(in.Hg.ft 2 h/gr)/in. \r\n a Table 2 gives the water \r\n vapor transmission rates of some representative materials. The data \r\n are provided to permit comparisons of materials; but in the selection \r\n of vapor retarder materials, exact values for permeance or permeability \r\n should be obtained from the manufacturer of the materials under \r\n consideration or secured as a result of laboratory tests. A range \r\n of values shown in the table indicate variations among mean values \r\n for materials that are similar but of different density, orientation, \r\n lot or source. The values are intended for design guidance and should \r\n not be used as design or specification data. The compilation is \r\n from a number of sources; values from dry-cup and wet-cup methods \r\n were usually obtained from investigations using ASTM E96 and C355; \r\n values shown under others were obtained from investigations using \r\n such techniques as two-temperature, special cell, and air-velocity. \r\n Values included were obtained from Ref.14 to 29 and other sources. \r\n Some values were obtained from unpublished tests conducted by Pennsylvania \r\n State University and the Building Research Div., National Research \r\n Council of Canada. \r\n b Depending on construction \r\n and direction of vapor flow. \r\n c Usually installed as vapor retarders, \r\n although sometimes used as exterior finish and elsewhere near cold \r\n side where special considerations are then required for warm side \r\n barrier effectiveness. \r\n d Dry-cup method. \r\n e Wet-cup method. \r\n f Other than dry- or \r\n wet-cup method. \r\n g Low permeance sheets \r\n used as vapor retarders. High permeance used elsewhere in construction. \r\n h Basic weight in lb \r\n per 100 ft 2 (lb per square ft) \r\n i Resistance and resistance/in. \r\n values have been calculated as the reciprocal of the permeance and \r\n permeability values. \r\n j Cast at 10 mils wet \r\n film thickness.31 \r\n k From ASHRAE Handbook \r\n of Fundamentals. \r\n \r\n \r\n \r\n \r\n The total vapor resistance \r\n of the wall section is calculated by totaling the component vapor resistances. \r\n This total is entered at the bottom of Column 7. \r\n The component vapor resistance percentage \r\n is calculated by dividing the component vapor resistance by the total \r\n vapor resistance of the wall section and multiplying this quotient \r\n by 100. The results are entered in the rows of Column 8 respectively. \r\n Check the total of the component vapor resistance percentages to make \r\n sure that they equal 100. \r\n The actual vapor pressure of the interior \r\n and exterior air is calculated by multiplying their saturated vapor \r\n pressures by their respective relative humidities. The results are \r\n entered in the rows of Column 10 respectively. \r\n The total vapor pressure difference \r\n is calculated by subtracting the exterior actual vapor pressure from \r\n the interior actual vapor pressure. The result is entered at the bottom \r\n of Column 9. \r\n The component vapor pressure difference \r\n is calculated by multiplying the component vapor resistance percentage \r\n by the total vapor pressure difference and dividing this product by \r\n 100. The result is entered in the rows of Column 9 respectively. Total \r\n the component vapor pressure differences. This total must equal the \r\n total vapor pressure difference, entered at the bottom of Column 9. \r\n The component actual vapor pressure \r\n is calculated by subtracting the component vapor pressure difference \r\n from the actual vapor pressure of the component preceding it. The \r\n results are entered in the rows of Column 10 respectively. \r\n The component actual vapor pressures \r\n (Column 10) are checked against the component saturated vapor pressures \r\n (Column 6). If any wall component has an actual vapor pressure which \r\n is larger than its saturated vapor pressure, condensation is likely \r\n to occur in that area of the wall section, as indicated by the asterisks \r\n in Column 11. \r\n Table 3 shows an example of this condensation \r\n analysis procedure. The wall being considered is an insulated brick \r\n and block cavity wall system. It is assumed that the wall is located \r\n in Washington, DC. The analysis is for a winter day with an exterior \r\n temperature of 17 deg. F @ 73% relative humidity, and an interior \r\n temperature of 72 deg. F @ 50% relative humidity. \r\n \r\n \r\n TABLE 3 \r\n Example 5 \r\n \r\n Abbreviations \r\n 1. T.R. \r\n Thermal Resistance \r\n 2. T.D. \r\n Temperature Difference ( 0 F) \r\n 3. S.V.P.Saturated Vapor \r\n Pressure (in inches Mercury) \r\n 4. V.R. \r\n Vapor Resistance (in inches Mercury) \r\n 5. V.P.D.Vapor Pressure \r\n Difference (in inches Mercury) \r\n 6. A.V.P.Actual Vapor \r\n Pressure (in inches Mercury) \r\n 7. Ti \r\n Inside Air Temperature ( 0 F) \r\n 8. To \r\n Outside Air Temperature ( 0 F) \r\n 9. RHi \r\n Relative Humidity Inside \r\n 10. RHo Relative Humidity Outside \r\n Notes \r\n 1. See Table 1 of Technical Notes 4 Revised. \r\n 2. See Table 1 \r\n 3. See Table 2 \r\n 4. Condensation is likely \r\n to occur in these areas \r\n 5. Information Required for \r\n this example \r\n Ti = 72 \r\n To = 17 \r\n RHi = 73% \r\n \r\n RHo = 50% \r\n \r\n \r\n \r\n \r\n The temperature gradient, as well as the \r\n saturated vapor pressure and actual vapor pressure gradients, can be plotted \r\n across the wall section, as shown in Figures 2 and 3 respectively. When \r\n plotting the saturated and actual vapor pressure gradients, the areas \r\n where the actual vapor pressure gradient is above the saturated vapor \r\n pressure gradient are where condensation is likely to occur. \r\n \r\n \r\n \r\n Saturated Vapor Pressure Curves \r\n FIG. 1 \r\n \r\n Temperature Gradient \r\n FIG. 2 \r\n \r\n \r\n Saturated Vapor Pressure and \r\n Actual Vapor Pressure \r\n FIG. 3 \r\n \r\n \r\n SUMMARY \r\n The analysis procedure presented in \r\n this Technical Notes may be used as an indicator of where condensation \r\n may occur in a wall section. It may also be used to analyze the effect \r\n on condensation potential of varying wall components and vapor barriers. \r\n The information contained in this Technical Notes is based \r\n on the available data and experience of the technical staff of the \r\n Brick Institute of America. This information should be recognized \r\n as recommendations and should be used with judgment. Final decisions \r\n on the use of the information discussed herein are not within the \r\n purview of the Brick Institute of America, and must rest with project \r\n owner, designer or both. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60136,"ResultID":176368,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 7F - Moisture Resistance of Brick Masonry - Maintenance \r\n Reissued Jan. 1987 (Reissued Oct. 1998) \r\n \r\n Abstract : Even though one of the major advantages of brick masonry \r\n construction is durability, periodic inspections and maintenance can extend \r\n the life of brickwork in structures. This Technical Notes addresses \r\n the use of suggested inspection programs and specific maintenance procedures. \r\n Information is presented on remedial cleaning and various repair methods. \r\n Included in the latter category is the replacement of sealant joints, \r\n grouting of mortar joint faces, tuck-pointing of mortar joints, removal \r\n of plant growth, maintenance and repair of weepholes, replacement of brick \r\n units, installation of a dampproof course, as well as the installation \r\n of flashing in existing walls. \r\n Key Words : cleaning, dampproof \r\n course , efflorescence, flashing, grout, inspection , \r\n maintenance , moisture penetration , \r\n mortar, sealant, tuck-pointing , weepholes. \r\n INTRODUCTION \r\n This is the seventh Technical Notes in \r\n this series addressing moisture control in brick masonry. In this Technical \r\n Notes, maintenance of brick masonry to counteract moisture penetration \r\n is discussed. Generally, if brickwork is properly designed, detailed and \r\n constructed, it is very durable and requires little maintenance. However, \r\n many of the other components incorporated in the brickwork, i.e., caps, \r\n copings, sills, lintels, sealant joints, etc., may require periodic inspection \r\n and repair. \r\n Maintenance of buildings may be broken into \r\n two general categories: 1) general inspection and maintenance to prolong \r\n the life and usefulness of a building; and 2) specific maintenance to \r\n identify and correct problems which may develop. This Technical Notes \r\n addresses both general and specific maintenance procedures. A checklist \r\n is provided for general inspections and specific repair techniques are \r\n described. \r\n GENERAL INSPECTION \r\n A good, thorough inspection and maintenance \r\n program is often inexpensive to initiate and may prove advantageous in \r\n extending the life of a building. It is a good idea to become familiar \r\n with the materials used on a building and how they perform over a given \r\n time period. Table 1 lists various building materials and their estimated \r\n life expectancies with normal weathering. \r\n It is suggested that periodic inspections be \r\n performed to determine the condition of the various materials used on \r\n a building. These inspections can be set for any given time period, i.e., \r\n weekly, monthly, yearly, etc. A suggested inspection period is \"seasonal\" \r\n so that the behavior of building materials in various weather conditions \r\n can be noted. Inspection records, including conditions and comments, should \r\n be kept to determine future \"trouble spots\", problems and needed repair. \r\n The checklist in Table 2 is not all-inclusive; however, it may establish \r\n a guideline for use during inspections. \r\n SPECIFIC MAINTENANCE \r\n General \r\n Problems resulting from moisture penetration \r\n may include: efflorescence, spalling, deteriorating mortar joints, interior \r\n moisture damage, etc. Once one or more of these conditions becomes evident, \r\n the direct source of moisture penetration should be determined and action \r\n taken to correct both the visible effect and the moisture penetration \r\n source. Table 3 lists various problems appearing on brickwork due to moisture \r\n and the most probable source of moisture penetration. The items checked \r\n in the table represent each source that should be considered when such \r\n problems occur in brick masonry. \r\n \r\n \r\n \r\n \r\n \r\n After investigating all of the possible moisture \r\n penetration sources, the actual source may be determined through the process \r\n of elimination. Many times the source will be self-evident as in the cases \r\n of deteriorated and missing materials; however, in instances such as improper \r\n flashing, differential movement, etc., the source may be hidden and determined \r\n only through some type of building diagnostics. In any case, it is suggested \r\n to first visually inspect for the self-evident source before retaining \r\n a consultant as it may save time and money in the detection of the moisture \r\n penetration source. \r\n Once the source is determined, measures can \r\n then be taken to effectively remedy the moisture penetration source and \r\n its effects on the brickwork. This Technical Notes discusses suggested \r\n techniques for the reduction of moisture penetration. \r\n \r\n \r\n \r\n \r\n \r\n Remedial Cleaning \r\n Moisture penetration is a contributing factor \r\n to the formation of efflorescence (see Technical Notes 23 Series). \r\n Generally, efflorescence is easily removed by natural weathering or by \r\n scrubbing with a brush and water. In some cases, acid may be used to remove \r\n stubborn efflorescence (see Technical Notes 20 \r\n Revised). Improper acid cleaning, i.e., absence of pre-wetting, insufficient \r\n rinsing and strong acid concentrations, may be a cause of further moisture \r\n penetration in brick masonry. Cement is soluble in hydrochloric acid (muriatic \r\n acid); therefore, if any hydrochloric acid remains on the brickwork, the \r\n mortar joints may become etched and/or deteriorated. This situation becomes \r\n evident by the formation of one of two types of efflorescence which are \r\n not water-soluble. One type is a white efflorescence, composed of either \r\n sodium chloride or potassium chloride. The other is a white or grayish \r\n haze, referred to as \"white scum\", composed of silicic acid or other silica \r\n compounds. Each of these two types of efflorescence has unique removal \r\n solutions. \r\n The first case, where sodium chloride or potassium \r\n chloride is formed, can be corrected by applying a solution of sodium \r\n hydroxide and water to the dry wall. The solution should consist of 12 \r\n oz (350 ml) sodium hydroxide to 1 qt (950 ml) water. The solution should \r\n be allowed to dry on the wall. The sodium hydroxide will penetrate the \r\n wall surface and neutralize the remaining hydrochloric acid. The wall \r\n will effloresce heavily upon drying. These new water-soluble salt deposits \r\n can be removed by natural weathering or by scrubbing with a brush and \r\n water. \r\n If \"white scum\" has formed on the wall, the \r\n methods of removal as discussed in Technical Notes 20 \r\n Revised may be effective. Table 4 summarizes the removal methods presented \r\n in Technical Notes 20 Revised. \r\n \r\n \r\n \r\n After cleaning, the mortar joints should be \r\n inspected. Tuck-pointing of the joints, as discussed later in this Technical \r\n Notes, may be necessary. It should be noted that these and all cleaning \r\n procedures should first be tried in an inconspicuous area at different \r\n concentrations and judged on effectiveness. \r\n Repair Methods \r\n Sealant Replacement . Missing or deteriorated \r\n caulking and sealants in contact areas between brickwork and other materials, \r\n i.e., window and door frames, expansion joints, etc., may be a source \r\n of moisture penetration. The sealant joints in these areas should be inspected. \r\n If the sealant is missing, a full bead of high-quality, permanently elastic \r\n sealant compound should be placed in the open joints. If a sealant material \r\n was installed, but has torn, deteriorated or lost elasticity, it should \r\n be carefully cut out. The opening must be clean of all old sealant material. \r\n A new sealant should then be placed in the clean joint. All joints should \r\n be properly primed before the new sealant material is applied. A backer \r\n rope material should be placed in all joints deeper than 3/4 in. (19 mm) \r\n or wider than 3/8 in. (10 mm). \r\n Grouting of Mortar Joints . If the mortar \r\n joints develop small \"hairline\" cracks, surface grouting may be an effective \r\n measure in sealing them. One recommended grout mixture is 1 part portland \r\n cement, 1/3 part hydrated lime and 1 1/3 parts fine sand (passing a No. \r\n 30 sieve). The joints to be grouted should be dampened. To ensure good \r\n bond, the brickwork must absorb all surface water. Clean water is added \r\n to the dry ingredients to obtain a fluid consistency. The grout mixture \r\n should be applied to the joints with a stiff fiber brush to force the \r\n grout into the cracks. Two coats are usually required to effectively reduce \r\n moisture penetration. Tooling the joints after the grout application may \r\n help compact and force the grout into the cracks. The use of a template \r\n or masking tape may prove effective in keeping the brick faces clean. \r\n Tuck-pointing Mortar Joints . Moisture \r\n may penetrate mortar which has softened, deteriorated or developed visible \r\n cracks. When this is the case, tuck-pointing may be necessary to reduce \r\n moisture penetration. Tuck-pointing is a process of cutting out old mortar \r\n to a uniform depth and placing new mortar in the joint (see Figure 1). \r\n \r\n \r\n \r\n \r\n Tuck-Pointing Mortar Joints \r\n FIG. 1 \r\n \r\n Prior to undertaking a tuck-pointing project, \r\n the following should be considered: 1) Whether or not to use power tools \r\n for cutting out old mortar. The use of power tools may damage the brick \r\n units surrounding the mortar being cut out. 2) Any tuck-pointing operation \r\n should only be done by a qualified and experienced tuck-pointing craftsman. \r\n An individual who is an excellent mason/bricklayer may not be a \r\n good tuck-pointing craftsman. Skills should be tested and evaluated prior \r\n to the selection of the craftsman. 3) For tuck-pointing for historic preservation \r\n purposes, refer to ENGINEERING AND RESEARCH DIGEST on \"Tuck-Pointing\", \r\n Brick Institute of America, June 15, 1983. \r\n The old mortar should be cut out, by means of \r\n a toothing chisel or a special pointers grinder, to a uniform depth of \r\n 3/4 in., or until sound mortar is reached (see Fig. 1B). Care must be \r\n taken not to damage the brick edges. All dust and debris must be removed \r\n from the joint by brushing, blowing with air or rinsing with water. \r\n Tuck-pointing mortar should be carefully selected \r\n and properly proportioned. For best results, the original mortar proportions \r\n should be duplicated. If this is not possible, Types N or O mortar should \r\n be used, as mortars with higher cement contents may not properly bond \r\n to the original mortar. Table 5 lists the proper proportions for Types \r\n N and O mortars. \r\n The tuck-pointing mortar should be pre-hydrated \r\n to reduce excessive shrinkage. The proper pre-hydration process is as \r\n follows: All dry ingredients should be thoroughly mixed. Only enough clean \r\n water should be added to the dry mix to produce a damp, workable consistency \r\n which will retain its shape when formed into a ball. The mortar should \r\n stand in this dampened condition for 1 to 1 1/2 hr. \r\n \r\n \r\n \r\n The joints to be tuck-pointed should be dampened, \r\n but to ensure a good bond, the brickwork must absorb all surface water. \r\n Water should be added to the pre-hydrated mortar to bring it to a workable \r\n consistency (somewhat drier than conventional mortar). The mortar should \r\n be packed tightly into the joints in thin layers (1/4 in. [6 mm] maximum). \r\n Each layer should become \"thumbprint hard\" before applying the next layer \r\n (see Fig. 1C). The joints should be tooled to match the original profile \r\n after the last layer of mortar is \"thumbprint\" hard (see Fig. 1D). As \r\n it may be difficult to determine which joints allow moisture to penetrate, \r\n it is advisable to tuck-point all mortar joints in the affected wall area. \r\n Ivy Removal . Ivy growth may be a contributing \r\n factor to moisture penetration. Ivy shoots, sometimes referred to as \"suckers\", \r\n penetrate voids in mortar and may conduct moisture into these voids. If \r\n this is the case, ivy removal may be necessary. \r\n To effectively remove ivy, the vines should \r\n be carefully cut away from the wall. The vines should never be pulled \r\n from the wall as this could damage the brickwork. After cutting, the shoots \r\n will remain. These suckers should be left in the wall until they dry up \r\n and die. This usually takes from 2 to 3 weeks. Care should be taken not \r\n to allow the suckers to rot and oxidize as this could make them difficult \r\n to remove. Once the shoots die, the wall should be dampened and scrubbed \r\n with a stiff fiber brush and water. Laundry detergent or weed killer may \r\n be added to the water in small concentrations to aid in the removal of \r\n the shoots. If these additives are used, the wall must be thoroughly rinsed \r\n with clean water after scrubbing. \r\n It is suggested that a small portion of the \r\n ivy (5-10 sq ft [0.5 to 1.0 m 2 ]) be removed from an inconspicuous \r\n area first to determine how the masonry wall will appear once the ivy \r\n is removed. Tuck-pointing of the mortar joints may be necessary if the \r\n mortar has cracked or deteriorated. \r\n Opening Weepholes . In some instances, \r\n moisture may penetrate walls but is unable to escape to the exterior. \r\n If this is the case, the weepholes should be inspected to determine if \r\n they are clogged or insufficiently spaced. If the weepholes are clogged, \r\n they can be cleaned out by probing with a thin wood dowel, or stiff wire. \r\n If the weepholes were not properly spaced, drilling new weepholes may \r\n be necessary. Technical Notes 21B \r\n outlines suggested types and spacing of weepholes. Table 6 is a summary \r\n of the recommended spacing requirements included in Technical Notes \r\n 21B . \r\n \r\n \r\n \r\n It should be noted that weepholes are placed \r\n directly above flashing; therefore, care must be exercised not to damage \r\n the flashing whenever probing or drilling. The use of a stopper to limit \r\n the depth of penetration of the probe or drill bit may be effective in \r\n reducing the possibility of damaging the flashing. \r\n Replacement of Brick Units . Moisture \r\n may penetrate brick units which are broken or heavily spalled. When this \r\n occurs, replacement of the affected units may be necessary. The following \r\n procedure is suggested for the removal and replacement of masonry units \r\n (see Fig. 2). \r\n \r\n \r\n \r\n \r\n Replacement of Brick Units \r\n FIG. 2a \r\n \r\n \r\n \r\n \r\n \r\n Replacement of Brick Units \r\n FIG. 2b \r\n \r\n \r\n \r\n \r\n \r\n Replacement of Brick Units \r\n FIG. 2c \r\n \r\n A tuck-pointers toothing chisel should be used \r\n to cut out the mortar which surrounds the affected units. For ease of \r\n removal, the units to be removed can be broken. Once the units are removed, \r\n all of the old mortar should be carefully chiseled out, and all dust and \r\n debris should be swept out with a brush (see Fig. 2B). If the units are \r\n located in the exterior wythe of a cavity wall, care must be exercised \r\n not to allow debris to fall into the cavity. \r\n The brick surfaces in the wall should be dampened \r\n before new units are placed, but the masonry should absorb all surface \r\n moisture to ensure a good bond. The appropriate surfaces of the surrounding \r\n brickwork and the replacement brick should be buttered with mortar. The \r\n replacement brick should be centered in the opening and pressed into position \r\n (see Fig. 2C). The excess mortar should be removed with a trowel. Pointing \r\n around the replacement brick will help to ensure full head and bed joints. \r\n When the mortar becomes \"thumbprint\" hard, the joints should be tooled \r\n to match the original profile. \r\n Installation of a Dampproof Course . Moisture \r\n may migrate upward through brickwork by capillary action. This condition \r\n appears as a rising water line or \"tide mark\" on the wall. \r\n All building codes require the use of a dampproofing \r\n material on below-grade masonry walls. If this was omitted or improperly \r\n installed, the insertion of a dampproof course at a level above the ground, \r\n but below the first floor, may stop the rising moisture. The installation \r\n procedure can take one of two forms. One form is the injection of a chemical \r\n dampproof course directly into the masonry wall. Holes are drilled into \r\n the masonry into which a synthetic material is inserted. Through a process \r\n based on electro-osmosis, the synthetic material forms a continuous dampproof \r\n barrier at this level. The other form of installation is the removal of \r\n an entire brick course. A dampproof material, i.e., plastic, metal or \r\n flashing is inserted, and the brick course is replaced. The brick should \r\n be replaced as described in the preceding section. \r\n Installation of Flashing . Flashing, which \r\n has been omitted, damaged or improperly installed, may permit moisture \r\n to penetrate to the building interior. If this is the case, a costly procedure \r\n of removing brick units, installing flashing and replacing the units may \r\n be required. See Technical Notes 7 \r\n Revised. \r\n To install continuous flashing in existing walls, \r\n alternate sections of masonry in 5 to 10 ft (1.5 to 3 m) lengths should \r\n be removed. The flashing is installed in these sections and the masonry \r\n is replaced. The replaced masonry should be properly aged (5 to 7 days) \r\n before the intermediate masonry sections are removed. The flashing can \r\n then be placed in these sections. The lengths of flashing should be lapped \r\n a minimum of 6 in. (150 mm) and be completely sealed to function properly. \r\n The masonry is then replaced. \r\n \r\n \r\n \r\n \r\n A Method of Installing Continuous \r\n Flashing in Existing Walls \r\n FIG. 3 \r\n \r\n SUMMARY \r\n This Technical Notes has presented maintenance \r\n procedures to reduce moisture penetration in brick masonry. It is suggested \r\n that routine inspections of the building be carried out to determine where \r\n future \"trouble spots\" may occur. Once a problem resulting from moisture \r\n penetration occurs, the actual source of moisture should be determined \r\n and corrected before any repairs are initiated. Many moisture control \r\n procedures have been presented; however, all buildings are unique and \r\n may experience individual problems. No one solution will remedy similar \r\n problems on different buildings. It is therefore suggested that a repair \r\n method which will effectively suit the particular needs of a building \r\n be selected when a problem occurs. \r\n The information contained in this Technical \r\n Notes is based on the available data and experience of the \r\n technical staff of the Brick Institute of America. This information should \r\n be recognized as recommendations which, if followed with good judgment, \r\n should result in masonry walls that are resistant to moisture penetration. \r\n Final decisions on the use of this information are not within the purview \r\n of the Brick Institute of America, and must rest with the project designer, \r\n owner or both. \r\n \r\n REFERENCES \r\n \r\n 1. \"A Glossary \r\n of Historic Masonry Deterioration Problems and Preservation Treatments\", \r\n Anne E. Grimmer, Department of the Interior, National Park Service, \r\n Preservation Assistance Division, Washington, D.C., 1984. \r\n 2. \"Basic \r\n Masonry Techniques\", March 1985. \r\n 3. \"Building \r\n Materials and Structures\", BMS 33, Plastic Caulking Materials, National \r\n Bureau of Standards, U.S. Department of Commerce, Washington, D.C., \r\n 1940. \r\n 4. \"Building \r\n Materials and Structures\", BMS 63, Moisture Condensation in Building \r\n Walls, National Bureau of Standards, U.S. Department of Commerce, Washington, \r\n D.C., 1940. \r\n 5. \"Building \r\n Materials and Structures\", BMS 76, Effect of Outdoor Exposure of the \r\n Water Permeability on Masonry Walls, National Bureau of Standards, \r\n U.S. Department of Commerce, Washington, D.C., 1941. \r\n 6. \"Building \r\n Materials and Structures\", BMS 94, Water Permeability and Weathering \r\n Resistance of Stucco-Faced, Gunite-Faced and \"Knap Concrete Unit\" Walls, \r\n National Bureau of Standards, U.S. Department of Commerce, Washington. \r\n D.C.. 1942. \r\n 7. \"Building \r\n Materials and Structures\", BMS 95, Tests of Cement-Water Paints and \r\n Other Waterproofings for Unit-Masonry Walls, National Bureau of Standards, \r\n U.S. Department of Commerce, Washington, D.C., 1943. \r\n 8. \"Maintenance \r\n Engineering Handbook\", 3rd Edition, Higgins, L.R. and Morrow, L.C., \r\n McGraw-Hill Publishing Company, 1977. \r\n 9. \"Paints \r\n for Exterior Masonry Walls\", Building Materials and Structures Report \r\n BMS 110, National Bureau of Standards, U.S. Department of Commerce, \r\n Washington, D.C., 1947. \r\n 10. \"Cleaning \r\n of Clay Masonry\", Soderstrom, W.K., Structural Clay Products Research \r\n Foundation, May 1964. \r\n 11. ENGINEERING \r\n AND RESEARCH DIGEST, \"Ivy on Brick (Pro and Con)\", Brick Institute of \r\n America, McLean, Virginia, May 1980. \r\n 12. ENGINEERING \r\n AND RESEARCH DIGEST, \"Tuck-Pointing\", Brick Institute of America, McLean, \r\n Virginia, 1983. \r\n 13. Old House \r\n Journal, No. 5, Vol. XIII, Brooklyn, New York, June 1985. \r\n 14. \"Penetrative \r\n Stains for Masonry\", Hoskins, R.A., Hodsons Dye Agency P/L. \r\n 15. Preservation \r\n Briefs No. 2, \"Repointing Mortar Joints in Historic Brick Buildings\", \r\n Heritage, Conservation and Recreation Service, U.S. Department of the \r\n Interior, Washington, D.C., 1980. \r\n 16. Research \r\n Report 15, \"The Causes and Control of Efflorescence on Brickwork\", Wayne \r\n E. Brownell, Structural Clay Products Institute, August 1969. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60137,"ResultID":176369,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 8 - Mortars for Brick Masonry \r\n August 1995 \r\n \r\n Abstract : This Technical Notes addresses mortars for brick \r\n masonry. The major ingredients of mortar are identified. Means of specifying \r\n mortar are covered. Mortar properties are described as well as their effect \r\n on brick masonry. Information is provided for selection of the appropriate \r\n materials for mortar and properties of mortars. \r\n Key Words : hardened mortar properties, \r\n mortar, plastic mortar properties, specifications, types of mortar. \r\n INTRODUCTION \r\n Mortar is the bonding agent that integrates \r\n brick into a masonry wall. Mortar must be strong, durable, capable of \r\n keeping the wall intact, and it must help to create a water resistant \r\n barrier. It must accommodate dimensional variations and physical properties \r\n of the brick when laid. These requirements are influenced by the composition, \r\n proportions and properties of mortar. \r\n Because concrete and mortar contain the same \r\n principal ingredients, it is often erroneously assumed that good concrete \r\n practice is also good mortar practice. In reality, mortar differs from \r\n concrete in working consistencies, methods of placement, and structural \r\n performance. Mortar is used to bind masonry units into a single element, \r\n developing a complete, strong and durable bond. Concrete, however, is \r\n usually a structural element in itself. Mortar is usually placed between \r\n absorbent masonry units, and loses water upon contact with the units. \r\n Concrete is usually placed in non-absorbent metal or wooden forms which \r\n absorb little if any water. The importance of the water cement ratio for \r\n concrete is significant, whereas for mortar it is less important. Mortars \r\n have a high water cement ratio when mixed, but this ratio changes to a \r\n lower value when the mortar comes in contact with the absorbent units. \r\n This Technical Notes addresses the materials, \r\n means of specifying and properties of mortars. Other Technical Notes \r\n in this series include a standard specification for portland cement-lime \r\n mortars (BIA M1-88) and the selection and control of mortars. \r\n MATERIALS \r\n Historically, mortars have been made from a \r\n variety of materials. Burned gypsum and sand were used to make mortar \r\n in ancient Egypt, while lime and sand were used extensively in this country \r\n before the 1900s. Currently, the basic dry ingredients for mortar include \r\n portland cement, masonry cement, hydrated lime, and sand. Each of these \r\n materials makes a definite contribution to mortar performance. \r\n Portland Cement \r\n Portland cement, a hydraulic cement, is the \r\n principal cementitious ingredient for mortars. It contributes to durability, \r\n high strength, and early setting of the mortar. Portland cement used in \r\n masonry mortars should conform to ASTM C 150 Specification for Portland \r\n Cement. Of the eight types covered by ASTM C 150, only three are recommended \r\n for use in masonry mortars: \r\n Type I - For general use when the special properties \r\n of Types II and III are not required. \r\n Type II - For use when moderate sulfate resistance \r\n or moderate heat of hydration is desired. \r\n Type III - For use when high early strength \r\n is desired. \r\n The use of blended hydraulic cements, ASTM C \r\n 595 Specification for Blended Hydraulic Cements, such as portland blast-furnace \r\n slag cement, portland-pozzolan cement, slag cement and natural cement \r\n is not recommended unless the mortar containing such cements meets the \r\n property specification of ASTM C 270 Specification for Mortar for Unit \r\n Masonry. \r\n Because high air entrainment can significantly \r\n reduce the bond between the mortar and masonry units or reinforcement, \r\n the use of air-entrained portland or blended hydraulic cements is not \r\n recommended. Most building codes have lower allowable flexural tensile \r\n stress values for mortars made with air-entrained portland cement. \r\n Masonry Cements \r\n Masonry cements are proprietary cementitious \r\n materials for mortar. They are widely used because of their convenience \r\n and good workability. ASTM C 91 Specification for Masonry Cement defines \r\n masonry cement as \"a hydraulic cement, primarily used in masonry and plastering \r\n construction, consisting of a mixture of portland or blended hydraulic \r\n cement and plasticizing materials (such as limestone, hydrated or hydraulic \r\n lime) together with other materials introduced to enhance one or more \r\n properties such as setting time, workability, water retention, and durability\". \r\n ASTM C 91 provides specific criteria for physical requirements and performance \r\n properties of masonry cements. The constituents of masonry cement may \r\n vary depending on the manufacturer, local construction practices and climatic \r\n conditions. \r\n Masonry cements are classified into three types \r\n by ASTM C 91: Types M, S and N. The current edition of ASTM C 91 requires \r\n a minimum air content of 8 percent (by volume) and limits the maximum \r\n air content to 21 percent for Type N masonry cement and 19 percent for \r\n Types S and M masonry cements. Mortar prepared in the field will typically \r\n have an air content 2 to 3 percent lower than that when tested under laboratory \r\n conditions. \r\n In the model building codes, allowable flexural \r\n tensile stress values for masonry built with masonry cement mortars are \r\n lower than those for masonry built with non air-entrained portland cement-lime \r\n mortars. Therefore, the use of masonry cement should be based on the requirements \r\n of the specific application. \r\n Hydrated Lime \r\n Hydrated lime is a derivative of limestone which \r\n has been through two chemical reactions to produce calcium hydroxide Ca(OH) 2 . \r\n Lime, which sets only upon contact with carbon dioxide in the air, contributes \r\n to bond, workability, water retention and elasticity. \r\n Hydrated lime in ASTM C 207 Specification for \r\n Hydrated Lime for Masonry Purposes is available in four types. Only Type \r\n S hydrated lime should be used in mortar. Type N hydrated lime contains \r\n no limits on the quantity of unhydrated oxides. Types NA and SA lime contain \r\n air entraining additives which reduce the extent of bond between the mortar \r\n and masonry units or reinforcement, and are therefore not recommended \r\n for mortar. \r\n Because lime hardens only upon contact with \r\n carbon dioxide in the air, hardening occurs slowly over a long period \r\n of time. However, if small hairline cracks develop, water and carbon dioxide \r\n which penetrate the joint will form calcium carbonate. The newly developed \r\n calcium carbonate will seal the cracks from further water penetration. \r\n This self-perpetuating process is known as autogenous healing. \r\n Aggregates \r\n Sand acts as a filler, providing for an economical \r\n mix and controlling shrinkage. Either natural sand or manufactured sand \r\n may be used. Gradation limits are given in ASTM C 144 Specification for \r\n Aggregates for Masonry Mortar. \r\n Gradation can be easily and inexpensively altered \r\n by adding fine or coarse sands. Sometimes the most feasible method requires \r\n proportioning the mortar mix to suit the available sand, rather than requiring \r\n sand to meet a particular gradation. However, if the sand does not meet \r\n the grading requirement of ASTM C 144, it can only be used provided the \r\n mortar meets the property specifications of BIA M1 Specification for Portland \r\n Cement-Lime Mortar for Brick Masonry or ASTM C 270. \r\n Water \r\n If water is clean, potable, and free of deleterious \r\n acids, alkalies or organic materials, it is suitable for masonry mortars. \r\n Admixtures \r\n Admixtures are sometimes used in mortar to increase \r\n workability, decrease setting time and to retard freezing. Admixtures \r\n to achieve a desired color of the mortar are the most widely used. Although \r\n some admixtures are harmless, some are detrimental to mortar and the resulting \r\n brickwork. Since the properties of both plastic and hardened mortars depend \r\n so largely upon mortar ingredients, the use of admixtures should not be \r\n considered unless their effect on the mortar is known. The use of admixtures \r\n should also be examined for their effect on the wall, masonry units and \r\n items embedded in the wall. \r\n SPECIFYING MORTAR \r\n Masonry mortars are classified into four types: \r\n M, S, N and O. Each mortar type consists of aggregate, water, and one \r\n or more of the three cementitious materials (portland cement, masonry \r\n cement and lime) listed in the previous section. \r\n There are two methods of specifying mortar by \r\n type in ASTM C 270 and BIA M1: proportions or properties. \r\n Proportion Specifications \r\n The proportion specifications require that mortar \r\n materials be mixed according to given volumetric proportions. If mortar \r\n is specified by this method, no laboratory testing is required for the \r\n mortar. Table 1 lists proportion requirements of the various mortar types. \r\n Note that a Type N masonry cement may be combined with portland cement \r\n to produce a Type S or Type M mortar. \r\n TABLE 1 \r\n Proportion Specification Requirements \r\n \r\n \r\n \r\n \r\n Property Specifications \r\n The property specifications require a mortar \r\n mix to meet the specified properties under laboratory testing conditions. \r\n If mortar is specified by the property specifications, compressive strength, \r\n water retention, and air content tests must be performed on mortar mixed \r\n in the laboratory with a controlled amount of water. The material quantities \r\n determined from the laboratory testing are then used in the field with \r\n the amount of water determined by the mason. Table 2 lists property requirements \r\n of the various mortar types. Properties of field mixed mortar cannot be \r\n compared to the requirements of the property specifications because of \r\n the different amounts of water used in the mortars. \r\n Proportion vs. Property Specifications \r\n The specifier should indicate in the project \r\n specifications whether the proportion or the property specifications govern. \r\n If the specifier does not, then the proportion specifications govern by \r\n default. The specifier should also confirm that the mortar types selected \r\n and the materials indicated in the project specifications are consistent \r\n with the structural design requirements of the masonry. \r\n Mortar prepared by the proportion specifications \r\n should not be compared to mortar prepared by the property specifications. \r\n A mortar that is mixed according to the proportion specification will \r\n have higher laboratory compressive strengths than that of the corresponding \r\n mortar type under the property specification. \r\n The volumetric proportions given in Table 1 \r\n or as determined by laboratory tests can be converted to weight proportions. \r\n The assumed weights per cubic foot for the materials are: \r\n Portland cement 94 \r\n lb (42.6 kg) \r\n Hydrated lime 40 \r\n lb (18.1 kg) \r\n Masonry cement Varies, use weight printed on bag \r\n Sand, damp and loose 80 lb (36.3 kg) of dry sand \r\n \r\n \r\n \r\n PHYSICAL PROPERTIES OF MORTAR \r\n Mortars have two distinct, important sets of \r\n properties; those in the plastic state and those in the hardened state. \r\n The plastic properties help to determine the mortars compatibility with \r\n brick and its construction suitability. Properties of plastic mortars \r\n include workability, water retention, initial flow and flow after suction. \r\n Properties of hardened mortars help determine the performance of the finished \r\n masonry. Hardened properties include bond strength, durability, extensibility \r\n and compressive strength. \r\n Bond Strength \r\n Bond strength is perhaps the most important \r\n single physical property of hardened mortar. Both the strength and the \r\n extent of bond are important. Variables which affect the bond strength \r\n include texture of the brick, suction of the brick, air content of the \r\n mortar, water retention of the mortar, pressure applied to the joint during \r\n forming, mortar proportions and methods of curing. \r\n Effect of Brick Texture . Research shows \r\n that bed surface texture is a major factor in determining bond strength. \r\n Mortar bond is greater to roughened surfaces, such as wire cut surfaces, \r\n than to smooth surfaces, such as die skin surfaces. Sanded surfaces can \r\n reduce the bond strength depending upon the amount of sand on the surface \r\n and its adherence to the surface. \r\n Effect of Brick Suction . The laboratory \r\n measured initial rate of absorption (IRA) of brick indicates the bricks \r\n suction and whether it should be wetted prior to use. However, it is the \r\n actual suction at the time of laying which influences bond strength. In \r\n practically all cases, mortar bonds best to brick whose suctions are less \r\n than 30 g/min/30 in. 2 \r\n (1.55 kg/m 2 /min) at the time of laying. If the bricks suction exceeds this value \r\n then the brick should be wetted three to twenty-four hours prior to laying. \r\n Wetted brick should be surface dry before they are laid in mortar. \r\n Several researchers have shown that IRA appears \r\n to have little influence on bond strength. \r\n Effect of Air Content . Available information \r\n indicates a definite relationship exists between air content and bond \r\n strength of mortar. Provided other parameters are held constant, as air \r\n content is increased, compressive strength and bond strength are reduced, \r\n while workability and resistance to freeze-thaw deterioration are increased. \r\n Effect of Flow . An increase in the flow \r\n of mortar at the time of use is beneficial because it can satisfy the \r\n suction of the brick and can allow greater control of the mortar for the \r\n bricklayer. For all mortars, and with minor exceptions for all brick suctions, \r\n bond strength increases as flow increases. However, too much water can \r\n reduce both workability and bond strength. \r\n The time lapse between spreading mortar and \r\n placing brick will affect mortar flow, particularly when mortar is spread \r\n on high suction brick or when construction takes place during hot, dry \r\n weather. In such cases, mortar will have less flow by the time brick are \r\n placed than when it was first spread. Conceivably, bond to brick placed \r\n on this mortar could be materially reduced. For highest bond strength, \r\n reduce this time interval to a minimum. \r\n Because all mortar is not used immediately after \r\n mixing, some of its water may evaporate while it is on the mortar board. \r\n The addition of water to mortar (retempering) to replace water lost by \r\n evaporation should be encouraged. Although compressive strength may be \r\n slightly reduced if mortar is retempered, bond strength may be lowered \r\n if it is not. All mortar should be used within 2 1/2 hours after mixing \r\n since the mortar will begin to set. \r\n Effect of Movement . Once mortar has begun \r\n to harden, tapping or attempting to otherwise move brick can be detrimental \r\n to bond. Movement at this time will break the bond between the brick and \r\n mortar. The partially dried mortar will not have sufficient plasticity \r\n to adhere well to the masonry units. \r\n Effect of Proportions . There is no precise \r\n combination of materials that will always produce optimum bond. Type S \r\n mortar will typically develop the highest flexural bond strength of all \r\n the mortar types, if all other variables are held constant. \r\n Effect of Curing . Wet curing of masonry \r\n generally produces higher bond strength than dry curing, but mortar materials \r\n will influence the result. Bond strength design values, however, are based \r\n on dry curing. \r\n Test Methods . Because many variables \r\n affect bond, it may be desirable to achieve reproducible results from \r\n a small scale laboratory test. The bond wrench test, ASTM C 1072 Method \r\n for Measurement of Masonry Flexural Bond Strength, appears to fulfill \r\n this need. It evaluates the flexural bond strength of each joint in a \r\n masonry prism. The bond wrench test has replaced various tests such as \r\n ASTM E 518 and E 72. The apparatus as shown in Figure 1 consists of a \r\n stack bonded prism clamped in a stationary frame. A cantilevered arm is \r\n clamped to the top brick over the joint to be tested. The free end of \r\n the cantilever arm is loaded until failure, which occurs when the clamped \r\n brick is \"wrenched\" off. \r\n \r\n \r\n \r\n \r\n Bond Wrench Test Apparatus \r\n FIG.1 \r\n \r\n In general, to increase the flexural bond strength: \r\n 1. Bond mortar \r\n to a wirecut or roughened surface rather than a die skin surface. \r\n 2. Use brick \r\n with suction less than 30 grams/min/30 in. 2 (1.55 kg/m 2 /min) when laid. Control high suction \r\n by wetting brick prior to laying. \r\n 3. Use Type \r\n S portland cement-lime mortar or Type S masonry cement mortar with air \r\n content in the low to mid-range of ASTM C 91 limits. \r\n 4. Mix mortar \r\n to the maximum flow compatible with workmanship. Use maximum mixing water \r\n and permit retempering. \r\n Water Content \r\n Water content is possibly the most misunderstood \r\n aspect of masonry mortar, probably due to the similarity between mortar \r\n and concrete materials. Many designers have mistakenly based mortar specifications \r\n on the assumption that mortar requirements are similar to concrete requirements, \r\n especially with regard to the water-cement ratio. Many specifications \r\n incorrectly require mortar to be mixed with the minimum amount of water \r\n consistent with workability. Often, retempering of the mortar is also \r\n prohibited. These provisions result in mortars which have higher compressive \r\n strengths but lower bond strengths. Mixing mortar with the maximum amount \r\n of water consistent with workability will provide maximum bond strength \r\n within the capacity of the mortar. Retempering is permitted, but only \r\n to replace water lost by evaporation. This can usually be controlled satisfactorily \r\n by requiring that all mortar be used within 2 1/2 hours after initial \r\n mixing. \r\n Workability \r\n A mortar is workable if its consistency allows \r\n it to be spread with little effort and if it will readily adhere to vertical \r\n masonry surfaces. Although experienced masons are good judges of the workability \r\n of the mortars, there is no standard laboratory test for measuring this \r\n property. \r\n Water retention, flow and resistance to segregation \r\n affect workability. In turn, these are affected by properties of the mortar \r\n ingredients. Because of this complex relationship, quantitative estimates \r\n of workability are difficult to obtain. Until a test is developed, the \r\n requirements for water retention and aggregate gradation must be relied \r\n upon to ensure satisfactory workability. \r\n Initial Flow and Water Retention \r\n Initial flow is essentially a measure of the \r\n mortars water content. It can be measured by either of two methods: 1) \r\n ASTM C 109 Method of Test for Compressive Strength of Hydraulic Cement \r\n Mortars, or 2) ASTM C 780 Method for Preconstruction and Construction \r\n Evaluation of Mortars for Plain and Reinforced Unit Masonry. \r\n In ASTM C 109, a truncated cone of mortar is \r\n formed on a flow table, which is then mechanically raised and dropped \r\n 25 times in 15 seconds. During this test, the mortar will flow increasing \r\n the diameter of the mortar specimen. The initial flow is the ratio of \r\n the increase in diameter from the initial four inch cone base diameter, \r\n expressed in percent. \r\n In ASTM C 780, a 3 1/2 in. (89 mm) high hollow \r\n cylinder is filled with mortar, and a cone shaped plunger, whose point \r\n is placed at the top of the cylinder, is dropped into the mortar. The \r\n depth of the cone penetration into the mortar is measured. The greater \r\n the penetration of the cone into the mortar the greater its flow or water \r\n content. \r\n Water retention is the ability of a mortar to \r\n hold water when placed in contact with absorbent masonry units. The laboratory \r\n value of water retention is the ratio of flow after suction to the initial \r\n flow, expressed in percent. Flow after suction, as described in ASTM C \r\n 91, is determined by subjecting the mortar to a vacuum and re-measuring \r\n the flow of the mortar. A mortar which has low water retention will lose \r\n moisture more rapidly. The IRA of the brick is considered in order to \r\n determine if this is detrimental to bond. \r\n Laboratory mortars are based on an initial flow \r\n of only 105 to 115 percent. Construction mortars normally have initial \r\n flows in the range of 130 to 150 percent to produce a level of workability \r\n satisfactory to the mason. Requirements for laboratory prepared mortar \r\n should not be applied to field prepared mortar. Further, test results \r\n of laboratory prepared mortar should not be compared to test results of \r\n field prepared mortar without considering the initial flow of each. The \r\n lower initial flow requirements for laboratory mortars were set to allow \r\n for more consistent test results on most available laboratory equipment \r\n and to compensate for water absorbed by the units. \r\n In general, the following will increase water \r\n retention: \r\n 1. Addition of sand fines within allowable gradation \r\n limits. \r\n 2. Use of highly plastic lime (Type S lime). \r\n 3. Increase air content. \r\n Extensibility and Plastic Flow \r\n Extensibility is another term for maximum tensile \r\n strain at failure. It reflects the maximum elongation possible under tensile \r\n forces. High lime mortars exhibit greater plastic flow than low lime mortars. \r\n Plastic flow, or creep, acting with extensibility will impart some flexibility \r\n to the masonry, permitting slight movement. Where greater resiliency for \r\n movement is desirable, increase the lime content while still satisfying \r\n other requirements. \r\n Compressive Strength \r\n As with concrete, the compressive strength of \r\n mortar primarily depends upon the cement content and the water cement \r\n ratio. However, because compressive strength of masonry mortar is less \r\n important than bond strength, workability and water retention, the latter \r\n properties should be given principal consideration in mortar selection. \r\n Effect of Proportions . Compressive strength \r\n increases with an increase in cement content of mortar and decreases with \r\n an increase in water content, lime content or over-sanding. Sometimes \r\n air entrainment is introduced to obtain higher flows with lower water \r\n content. The reasoning here is that lower water cement ratios will provide \r\n higher compressive strengths. However, this generally proves futile since \r\n compressive strength decreases with an increase in air content. \r\n Effect of Retempering . Retempering will \r\n decrease mortar compressive strength, the amount of decrease increasing \r\n with time after mixing. Mortar will begin to stiffen about 2 1/2 hours \r\n after initial mixing. Since mixing after initial set lowers compressive \r\n strength more, reduction in strength will be noticeably less if retempering \r\n occurs within that time. It is frequently desirable to sacrifice some \r\n compressive strength in favor of improved bond strength by permitting \r\n retempering. \r\n Test Methods . Compressive strength is \r\n measured by testing 2 in. (50 mm) mortar cubes or 2 in. (50 mm) and 3 \r\n in. (75 mm) diameter cylinders. Procedures for molding and testing cubes \r\n and cylinders appear in ASTM C 109 and ASTM C 780, respectively. Because \r\n the tests are relatively simple and because they give consistent, reproducible \r\n results, compressive strength is considered one basis for comparing mortars. \r\n Durability \r\n The durability of mortar in unsaturated masonry \r\n is not a serious problem. The durability of mortar is shown in the number \r\n of masonry structures that have been in service for many years. \r\n Although an increase in air content may increase \r\n the durability of masonry mortar, it will decrease bond strength and other \r\n desirable properties. For this reason, and because mortar is normally \r\n quite durable without air entrainment, the use of air-entraining admixtures \r\n to increase air content is not recommended. \r\n Volume Change \r\n Volume changes in mortars can result from four \r\n causes: chemical reactions in hardening, temperature changes, wetting \r\n and drying and unsound ingredients which chemically expand. Differential \r\n volume change between brick and mortar in a given wythe has no important \r\n effect on performance. However, total volume change can be significant. \r\n Volume change caused by hardening is often termed \r\n shrinkage and depends upon curing conditions, mix proportions and water \r\n content. Mortars hardened in absorbent molds or in contact with brick \r\n exhibit considerably less shrinkage than those hardened in non-absorbent \r\n molds. An increase in water content will cause an increase in shrinkage \r\n during hardening of mortar if the excess water is not removed. \r\n Change in temperature will lead to expansion \r\n and contraction of masonry. Thermal expansion and contraction of masonry \r\n and means to accommodate the expected movement are discussed in Technical \r\n Notes 18 Series. \r\n Mortar swells and shrinks as its moisture content \r\n increases and decreases, respectively. Moisture content changes with normal \r\n cycles of wetting and drying. The magnitude of volume change due to this \r\n effect is smaller than that from shrinkage. Unsound ingredients or impurities \r\n can cause mortar to expand. Unhydrated lime oxides or gypsum are examples \r\n of these, and can cause significant volume change. \r\n Efflorescence \r\n Efflorescence is a crystalline deposit of water-soluble \r\n salts on the surface of masonry. Mortar may be a major contributor to \r\n efflorescence since it is a primary source of calcium hydroxide. This \r\n chemical can produce efflorescence on its own and can react with solutions \r\n from the brick to form insoluble compounds. Mortar can contain other soluble \r\n constituents, including alkalies, sulfates and magnesium hydroxide. \r\n Currently there is no standard test method to \r\n determine the efflorescence potential of mortar or of a brick/mortar combination. \r\n Scientists conclude that mortars will effloresce under any standard test. \r\n Color \r\n Colored mortars may be obtained through the \r\n use of colored aggregates or suitable pigments. The use of colored aggregates \r\n is preferable when the desired mortar color can be obtained. White sand, \r\n ground granite, marble or stone, usually have permanent color and do not \r\n weaken the mortar. For white joints, use white sand, ground limestone \r\n or ground marble with white portland cement and lime. \r\n Mortar pigments must be sufficiently fine to \r\n disperse throughout the mix, must be capable of imparting the desired \r\n color when used in permissible quantities and must not react with other \r\n ingredients to the detriment of the mortar. These requirements are generally \r\n met by metallic oxide pigments. Iron, manganese and chromium oxides, carbon \r\n black and ultramarine blue have been used successfully as mortar colors. \r\n Avoid using organic colors and, in particular, those colors containing \r\n Prussian blue, cadmium lithophone, and zinc and lead chromates. Paint \r\n pigments may not be suitable for mortars. Most pigments which conform \r\n to ASTM C 979 Specification for Pigments for Integrally Colored Concrete \r\n are suitable for mortar. \r\n Use the minimum quantity of pigments that will \r\n produce the desired results; an excess may seriously impair strength and \r\n durability. The maximum permissible quantity of most metallic oxide pigments \r\n is 10 percent of the cement content by weight. Although carbon black is \r\n a very effective coloring agent, it will greatly reduce mortar strength \r\n when used in greater proportions. Therefore, limit carbon black to 2 percent \r\n of the cement by weight. \r\n For best results, use cement and coloring agents \r\n premixed in large, controlled quantities. Premixing large quantities will \r\n assure more uniform color than can be obtained by mixing smaller batches \r\n at the job. A consistent mixing sequence is essential for color consistency \r\n when mixing smaller batches at the job. Further, use the same source of \r\n mortar materials throughout the project. \r\n Color uniformity varies with the amount of mixing \r\n water, moisture content of the brick when laid and if the mortar is retempered. \r\n The time and degree of tooling and cleaning techniques will also influence \r\n final mortar color. Color permanence depends upon quality of pigments \r\n and weathering and efflorescing qualities of the mortar. \r\n RECOMMENDED MORTAR USES \r\n Selection of a particular mortar type is usually \r\n a function of the needs of the finished masonry element. Where high winds \r\n are expected, high lateral strength is required and, hence, mortar with \r\n high flexural bond strength should be chosen. For loadbearing walls and \r\n reinforced brick masonry, high compressive strength may be the governing \r\n factor. In some projects considerations of durability, color and flexibility \r\n may be of utmost concern. Factors which improve one property of mortar \r\n often do so at the expense of others. For this reason, when selecting \r\n a mortar, evaluate properties of each type and choose that mortar which \r\n will best meet particular end-use requirements. No single type of mortar \r\n is best for all purposes. See Technical Notes 8B \r\n for selection of mortar types. \r\n SUMMARY \r\n Mortar requirements differ from concrete requirements, \r\n principally because the primary function of mortar is to bond masonry \r\n units into an integral element. Properties of both plastic and hardened \r\n mortars are important. Plastic properties determine construction suitability; \r\n hardened properties determine performance of finished elements. No one \r\n combination of ingredients provides a mortar which is highest in all desirable \r\n properties. Factors that improve one property may do so at the expense \r\n of others. When selecting a mortar, evaluate all properties, then select \r\n the mortar providing the best compromise for the particular requirements. \r\n The information and suggestions contained in \r\n this Technical Notes are based on the available data and the experience \r\n of the technical staff of the Brick Institute of America. The information \r\n and recommendations contained herein must be used in conjunction with \r\n good technical judgment and a basic understanding of the properties of \r\n brick masonry. Final decisions on the use of the information contained \r\n in this Technical Notes are not within the purview of the Brick \r\n Institute of America and must rest with the project architect, engineer \r\n and owner. \r\n REFERENCES \r\n \r\n 1. ASTM C \r\n 270-92a Standard Specification for Mortar for Unit Masonry, Annual \r\n Book of ASTM Standards , Vol. 04.05, American Society for Testing \r\n and Materials, Philadelphia, PA, 1995. \r\n 2. Matthys, \r\n J.H., \"Brick Masonry Flexural Bond Strength Using Conventional Masonry \r\n Mortar\", Proceedings of the Fifth Canadian Masonry Symposium, University \r\n of Vancouver, Vancouver, BC, 1992, pp. 745-756. \r\n 3. Melander, \r\n J.M. and Conway, J.T., \"Compressive Strengths and Bond Strengths of \r\n Portland Cement-Lime Mortars\", Masonry, Design and Construction, \r\n Problems and Repair , ASTM STP 1180, American Society for Testing \r\n and Materials, Philadelphia, PA, 1993, pp. 105-120. \r\n 4. Ribar, \r\n J.W. and Dubovoy, V.S., \"Investigation of Masonry Bond and Surface Profile \r\n of Brick\", Masonry: Materials, Design, Construction and Maintenance , \r\n ASTM STP 992, American Society for Testing and Materials, Philadelphia, \r\n PA, 1988, pp. 33-37. \r\n 5. Robinson, \r\n G.C. and Brown, R.H., \"Inadequacy of Property Specifications in ASTM \r\n C 270\", Masonry: Materials, Design, Construction and Maintenance \r\n ASTM STP 992, American Society for Testing and Materials, Philadelphia, \r\n PA, 1988, pp. 7-17. \r\n 6. Wood, S.L., \r\n \"Flexural Bond Strength of Clay Brick Masonry\", The Masonry Society \r\n Journal , Vol. 13 #2, The Masonry Society, Boulder, CO, February \r\n 1995, pp. 45-55. \r\n 7. Wright, \r\n B.T., Wilkin, R.D. and John, G.W., \"Variables Affecting the Strength \r\n of Masonry Mortars\", Masonry, Design and Construction, Problems and \r\n Repair , ASTM STP 1180, American Society for Testing and Materials, \r\n Philadelphia, PA, 1993, pp. 197-210. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60138,"ResultID":176370,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 8A - Standard \r\n Specifications for Portland Cement - Lime Mortar for Brick \r\n Masonry \r\n Sept. 1988 \r\n \r\n 1. SCOPE \r\n 1.1 This specification covers \r\n mortars for use in the construction of non-reinforced and \r\n reinforced brick masonry. Four types of mortar are covered \r\n in this specification. Each mortar type may be specified by \r\n proportion specifications or by property specifications. \r\n 1.2 The proportion or property \r\n specifications shall govern as specified. The mortar type \r\n shall be specified by letter designation. \r\n 1.3 When neither proportion \r\n or property specifications are specified, the proportion specifications \r\n shall govern, unless data are presented to and accepted by \r\n the specifier to show that the mortar meets the requirements \r\n of the property specifications. \r\n 2. MORTAR TYPES \r\n 2.1 Four types of mortar \r\n are covered. \r\n \r\n 2.1.1 Type M . A high \r\n compressive strength mortar specifically recommended for masonry \r\n below grade and in contact with earth. \r\n \r\n 2.1.2 Type S . A mortar \r\n recommended for use in masonry where maximum flexural strength \r\n is required. \r\n \r\n 2.1.3 Type N . A medium \r\n strength mortar suitable for general use in exposed masonry \r\n above grade and specifically recommended for parapets, chimneys \r\n and exterior walls subjected to severe weathering conditions. \r\n \r\n 2.1.4 Type O . A low \r\n strength mortar suitable for use in non-loadbearing walls of \r\n solid masonry units, loadbearing walls of solid units in which \r\n the axial compressive stresses developed do not exceed 100 psi \r\n (7 kgf/cm 2 ) and where the masonry will not be subject to severe weathering. \r\n 3. REFERENCED DOCUMENTS \r\n 3.1 American Society for \r\n Testing and Materials (ASTM) Standards \r\n C91 Specification for Masonry Cement \r\n (For determination of water retention and air content, see \r\n Section 7.2 and 7.3) \r\n C109 Test Methods for Compressive \r\n Strength of Hydraulic Cement Mortars (Using 2-inch or 50-mm \r\n Cube Specimens) \r\n C144 Specification for Aggregate \r\n for Masonry Mortar \r\n C150 Specification for Portland \r\n Cement \r\n C207 Specification for Hydrated \r\n Lime for Masonry Purposes \r\n C511 Specification for Moist Cabinets, \r\n Moist Rooms, and Water Storage Tanks Used in the Testing of \r\n Hydraulic Cements and Concretes \r\n C780 Method for Preconstructed and \r\n Constructed Evaluation of Mortars for Plain and Reinforced \r\n Unit Masonry \r\n 3.2 International Masonry \r\n Industry All-Weather Council \r\n Recommended Practices and Guide \r\n Specifications for Cold Weather Masonry Construction: Section \r\n 04200 Unit Masonry, Article 3 of the Guide Specifications, \r\n Ninth Printing, June 6, 1984. \r\n 4. MATERIALS \r\n 4.1 Materials used as ingredients \r\n in mortar shall conform to the requirements specified in 4.2 \r\n to 4.5. \r\n 4.2 Cementitious Materials . \r\n Cementitious materials shall conform to the following ASTM \r\n specifications: \r\n \r\n 4.2.1 Portland Cement . \r\n Types I, II or III of ASTM Specification C150. \r\n \r\n 4.2.2 Hydrated Lime . \r\n Type S of ASTM C207. Type N may be permitted if shown by test \r\n or performance record not to be detrimental to the soundness \r\n of the mortar. \r\n 4.3 Aggregates. ASTM Specification \r\n C144, except that the grading shall comply to the following \r\n limits: \r\n Sieve Size \r\n Percent Passing \r\n No. 4 (4.75-mm) \r\n 100 \r\n No. 8 (2.36-mm) \r\n 95 to 100 \r\n No. 16 (1.18-mm) \r\n 60 to 100 \r\n No. 30 (600- m m) 35 \r\n to 70 \r\n No. 50 (300- m m) 15 \r\n to 35 \r\n No. 100 (150- m m) 2 \r\n to 15 \r\n No. 200 (75- m m) 0 \r\n to 2 \r\n \r\n 4.4 Admixtures . No \r\n air-entraining admixtures or cementitious materials containing \r\n air-entraining admixtures or agents shall be used in the mortar. \r\n Antifreeze compounds, accelerators, \r\n retarders, water-repellent agents or other admixtures shall \r\n not be added to mortar (see Note 1). Calcium chloride or admixtures \r\n containing calcium chloride shall not be added to mortar. \r\n Mortar colors may be added to the mortar if specified. Mortar \r\n containing such colors shall conform to the physical requirements \r\n in Table 2. \r\n Note 1 - This specification \r\n is not applicable to extended-life mortars that are mixed \r\n under controlled conditions in a central batching plant. \r\n 4.5 Water . Water shall \r\n be clean and free of amounts of oils, acids, alkalies, salts, \r\n organic materials, or other substances that may be deleterious \r\n to mortar or any metal in the wall. \r\n 5. REQUIREMENTS \r\n 5.1 Proportion Specifications . \r\n Mortar conforming to the proportion specifications shall consist \r\n of a mixture of cementitious material, aggregate, and water \r\n all conforming to the requirements of Section 4 and shall \r\n be proportioned within the limits given in Table 1 for each \r\n mortar type specified. See Appendix A.1 for a guide to the \r\n selection of mortar type. \r\n \r\n 5.1.1 Mortar of a known higher \r\n compressive strength shall not be substituted where a mortar \r\n type of an anticipated lower compressive strength is specified \r\n without the consent of the specifier. \r\n \r\n \r\n \r\n Note 4 - When necessary, \r\n testing of a wall section or a masonry prism from the completed \r\n construction is generally more desirable than attempting to \r\n test individual components. \r\n 5.2 Property Specifications . \r\n Mortar conformance to the property specifications shall be \r\n established by test of laboratory prepared mortar in accordance \r\n with Section 6 and 8.2. The laboratory prepared mortar shall \r\n consist of a mixture of cementitious material, aggregate, \r\n and water all conforming to the requirements of Section 4. \r\n The physical properties of the laboratory prepared mortar \r\n shall conform to the requirements of Table 2. See Appendix \r\n A.1 for a guide to the selection of mortar type. \r\n \r\n \r\n 5.2.1 No change in the laboratory \r\n proportions established for mortar accepted under the property \r\n specifications shall be made, except for the quantity of mixing \r\n water. Materials with different physical characteristics shall \r\n not be used in the mortar prepared for the work unless compliance \r\n with the requirements of the property specifications is re-established \r\n and accepted by the specifier. \r\n \r\n TABLE 2 \r\n Property Specification Requirements A \r\n \r\n \r\n \r\n \r\n \r\n \r\n ALaboratory prepared mortar only \r\n (See Note 2). \r\n BWhen structural reinforcement \r\n is incorporated in mortar, the maximum air content shall \r\n be 12%. \r\n 6. PHYSICAL PROPERTIES \r\n 6.1 Laboratory Prepared Mortar . \r\n Laboratory mortar samples prepared and tested in accordance \r\n with Section 7 shall conform to the physical requirements \r\n for each type specified as prescribed in Table 2. \r\n 6.2 Field Prepared Mortar . \r\n Field prepared mortar meeting the requirements of Sections \r\n 4 and 5 shall not be required to meet the physical requirements \r\n of Table 2. When quality control testing is specified, ASTM \r\n Standard C780 shall be used (see Note 2). \r\n Note 2 - The required properties \r\n of the mortar in Table 2 are for laboratory prepared mortar \r\n mixed with a quantity of water to produce a flow of 1105 percent. \r\n This quantity of water is not sufficient to produce a mortar \r\n with a workable consistency suitable for laying masonry units \r\n in the field. Mortar for use in the field must be mixed with \r\n the maximum amount of water, consistent with workability, \r\n in order to provide sufficient water to satisfy the initial \r\n rate of absorption (suction) of the masonry units. The properties \r\n of laboratory prepared mortar at a flow of 1105 percent are \r\n intended to approximate the flow and properties of field prepared \r\n mortar after it has been placed in use and the suction of \r\n the masonry units has been satisfied. The properties of field \r\n prepared mortar mixed with the greater quantity of water, \r\n prior to being placed in contact with masonry units, will \r\n differ from the property requirements in Table 2. Therefore, \r\n the property requirements in Table 2 cannot be used as requirements \r\n for quality control of field prepared mortar. ASTM C780 may \r\n be used to measure consistency in field sampled mortar. \r\n 7. METHOD OF TESTING \r\n 7.1 Compressive Strength . \r\n Compressive strength shall be determined in accordance with \r\n ASTM Standard C109. The mortar shall be composed of materials \r\n and proportions that are to be used in the construction with \r\n mixing water to produce a flow of 110┬▒5 percent. \r\n \r\n 7.1.1 Specimen storage . \r\n Keep mortar cubes for compressive strength tests in the molds \r\n on plane plates in a moist room or cabinet meeting ASTM Standard \r\n C511 for 48 to 52 h in such a manner that the upper surfaces \r\n shall be exposed to the moist air. Remove mortar specimens from \r\n the molds and place in a moist room or cabinet until tested. \r\n 7.2 Water Retention . Water \r\n retention shall be determined in accordance with ASTM Standard \r\n C91, except that the laboratory mixed mortar shall be of the \r\n materials and proportions to be used in the construction. \r\n 7.3 Air Content . Determine \r\n air entrainment in accordance with Specification C91 except \r\n calculate the air content to the nearest 0.1% as follows (see \r\n Note 3): \r\n \r\n where: \r\n D = density of air-free mortar, g/cm 3 , \r\n W 1 = weight of portland cement, \r\n g, \r\n W 2 \r\n = weight of hydrated lime, g, \r\n W 3 = weight of sand, g, \r\n V w = millilitres of water used, \r\n P 1 \r\n = density of portland cement, g/cm 3 , \r\n P 2 = density of hydrated lime, \r\n g/cm 3 , \r\n P 3 \r\n = density of and, g/cm 3 , \r\n A = volume of air, %, and \r\n W m = weight of 400 mL of mortar, g. \r\n \r\n Note 3 - The weights per \r\n cubic foot (kg/m 3 ) of the materials are considered \r\n to be as follows: \r\n Material \r\n Weight, lb per cu ft (kg/m 3 ) \r\n Portland cement \r\n 94 (1504) \r\n Hydrated lime \r\n 40 (640) \r\n Sand, damp and loose \r\n 80 lb (1280) of dry sand \r\n \r\n \r\n 8. CONSTRUCTION PRACTICES \r\n 8.1 Storage of Materials . \r\n Cementitious materials and aggregates shall be stored in such \r\n a manner as to prevent deterioration or contamination by foreign \r\n materials. \r\n 8.2 Measurement of Materials . \r\n The method of measuring materials for the mortar used in construction \r\n shall be by either volume or weight, and such that the specified \r\n proportions of the mortar materials can be controlled and \r\n accurately maintained. Measurement of sand by shovel shall \r\n not be permitted. \r\n 8.3 Mixing Mortars . All cementitious \r\n materials and aggregate shall be mixed for at least 3 min \r\n and not more than 5 min in a mechanical batch mixer, with \r\n the maximum amount of water to produce a workable consistency. \r\n 8.4 Retempering . Mortars \r\n that have stiffened because of evaporation of water from the \r\n mortar shall be retempered by adding water as frequently as \r\n needed to restore the required consistency. Mortars shall \r\n be used and placed in final position within 2 1/2 hr after \r\n initial mixing. \r\n 8.5 Climatic Conditions . \r\n Unless superseded by other contractual relationships or the \r\n requirements of local building codes, cold or hot weather \r\n masonry construction practices relating to mortar shall conform \r\n to Sections 8.5.1 or 8.5.2. \r\n \r\n 8.5.1 Cold Weather . \r\n Cold weather masonry construction relating to mortar shall comply \r\n with the International Masonry Industry All-Weather Councils \r\n \"Guide Specification for Cold Weather Masonry Construction\", \r\n Section 04200 Unit Masonry, Article 3. \r\n \r\n 8.5.2 Hot Weather . When \r\n the ambient air temperature exceeds 100 o F (38 o C) \r\n or 90 o F (32 o C) with a wind velocity greater \r\n than 8 m.p.h. (13 Km/hr), mortar beds shall not be spread more \r\n than 4 ft (1.2m) ahead of masonry units. Units shall be laid \r\n within one minute of spreading mortar. \r\n 9. COST OF TESTS \r\n 9.1 Unless otherwise specified, \r\n the costs of test shall be borne as follows: \r\n \r\n 9.1.1 If the results of the \r\n tests of laboratory prepared mortar show that the mortar \r\n does not conform to the requirements of this specification, \r\n the costs shall be borne by the seller. \r\n \r\n 9.1.2 If the results of the \r\n tests of laboratory prepared mortar show that the mortar \r\n does conform to the requirements of this specification, the \r\n costs shall be borne by the purchaser. \r\n \r\n 9.1.3 If the job specifications \r\n require that the construction mortar be sampled and tested for \r\n the purpose of quality control, the responsibilities for the \r\n costs of such sampling and testing shall be clearly stated in \r\n the specifications. \r\n 10. SPECIFICATION LIMITATIONS \r\n 10.1 BIA Specification M1-88 \r\n is not intended and shall not be used to determine physical \r\n properties of mortar through field testing. \r\n 10.2 ASTM Standard C780 is \r\n acceptable for pre-construction and construction evaluation \r\n of mortars for non-reinforced and reinforced masonry. \r\n 10.3 Tests of Hardened \r\n Mortars. There are no accepted standard methods of measuring \r\n the composition or physical properties of hardened mortar \r\n removed from a structure (see Note 4). \r\n APPENDIX \r\n (Nonmandatory Information) \r\n A1. Selection of Mortar Type \r\n A1.1 The performance of masonry \r\n is influenced by various mortar properties such as workability, \r\n water retentivity, bond strength, durability, extensibility, \r\n and compressive strength. Since these properties vary with \r\n mortar type, it is highly important that the mortar type selected \r\n for a particular application is the one that best meets the \r\n end-use requirements. Table A1 is a general guide for the \r\n selection of mortar type for various masonry wall construction. \r\n Selection of mortar type should also be based on the type \r\n of masonry units to be used as well as the applicable building \r\n code and engineering practice standard requirements such as \r\n allowable design stresses, and lateral support. \r\n \r\n \r\n \r\n \r\n A This table does not provide for \r\n many specialized mortar uses, such as reinforced masonry, and \r\n acid-resistant mortars, fire box mortar. \r\n B Type O mortar is recommended for \r\n use where the masonry is unlikely to be frozen when saturated \r\n or unlikely to be subjected to high winds or other significant \r\n lateral loads. Type N or S mortar should be used in other \r\n cases. \r\n \r\n C Masonry exposed to weather in \r\n a nominally horizontal surface is extremely vulnerable to \r\n weathering. Mortar for such masonry should be selected with \r\n due caution. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60139,"ResultID":176371,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 8B - Mortars for Brick \r\n Masonry - Selection and Controls \r\n Reissued Sept. 1988 \r\n \r\n INTRODUCTION \r\n \r\n Since the introduction of engineered \r\n brick masonry in early 1966, the trend of masonry specifications \r\n nationwide has been towards the use of higher cement content, \r\n so-called stronger, mortars. The result of this trend has \r\n been more expensive masonry construction that is not necessarily \r\n higher in performance characteristics. It has also been noted \r\n that many masonry specifications require inordinately expensive \r\n provisions for control or no control for the batching of the ingredients \r\n and mixing of the mortar. \r\n This issue of Technical Notes discusses \r\n the selection of the proper mortar dependent upon its use. It \r\n also discusses some of the methods and procedures suggested for \r\n the control of proportion batching and mixing of mortar at the \r\n project site. \r\n This Technical Notes does not \r\n discuss mortar ingredients or specific mortar specifications. \r\n Information on these subjects can be found in Technical Notes \r\n 8 Revised and 8A \r\n of this series. \r\n SELECTION OF MORTAR \r\n Since the contemporary bearing wall \r\n of engineered brick masonry has become widely accepted and used, \r\n the trend in masonry specifications has been toward higher cement \r\n content, higher compressive strength mortars. It appears that \r\n many architects, engineers and specifiers believe inherently in \r\n the adage that stronger is better. This could not be farther \r\n from the truth for mortar for brick masonry. \r\n As stated in previous issues of this \r\n Technical Notes series, mortar is the bonding agent that \r\n integrates a masonry wall. It must be strong, durable, capable \r\n of keeping the wall intact, and it must create a water-resistant \r\n barrier. It could also have been stated that the mortar must have \r\n certain resilient properties and be both economical and easy to \r\n use by the mason. \r\n The specifications and requirements \r\n for use of high compressive strength mortars can, in fact, work \r\n contrary to the above desirable properties and performance. It \r\n is of no value if a mortar has huge compressive strength and does \r\n not bond to the masonry units or cannot be properly and easily \r\n placed by the mason. Neither is it acceptable if the mortar has \r\n high cement content, high compressive strength and shrinkage characteristics \r\n that will cause separation cracking between masonry units and \r\n mortar, resulting in wind-driven rain penetration of the wall \r\n elements. \r\n Selection \r\n Selection of a particular mortar for \r\n a particular project is the function of balancing the needs of \r\n the finished element with the properties of the various available \r\n mortar mixes. For example, for areas of high winds, high lateral \r\n strengths may be required and, hence, a mortar that develops high \r\n tensile bond strength. For heavily loaded loadbearing walls, high \r\n compressive strength may be required, and hence high compressive \r\n strength mortar. Other considerations may be durability (below \r\n grade or retaining wall use), color uniformity, flexibility (parapet \r\n walls and exterior wythes), and other considerations. For these \r\n reasons, the selection of a mortar requires the careful evaluation \r\n of the properties of each type of mortar and the selection of \r\n that mortar which will best meet the particular in-use \r\n performance requirements for the project. \r\n The Basic Rule . No \r\n single type of mortar is best for all purposes. The basic \r\n rule for the selection of a mortar for a particular project is: \r\n Never use a mortar that is stronger (in compression) than is \r\n required by the structural requirements of the project. Always \r\n select the weakest (in compression) mortar that is consistent \r\n with the performance requirements of the project. \r\n This general rule must, of course, be \r\n tempered with good judgment. For example, it would be uneconomical \r\n and unwise to continuously change mortar types for various pieces \r\n or parts of a structure. However, the general idea of the rule \r\n should be followed, using good judgment and economic sense. \r\n General Properties of Mortar Types \r\n The following are the recommended general \r\n uses for various mortars to be applied, using the basic rule \r\n as stated above. (Also, see Table 1.) \r\n \r\n \r\n \r\n Type N Mortar . Type N mortar is specifically recommended \r\n for exterior walls wherever they are subject to severe exposure, \r\n for chimneys and for parapet walls. It is a medium strength mortar \r\n suitable for general use in exposed masonry above grade. \r\n \r\n Type S Mortar . Type \r\n S mortar is recommended for use in reinforced masonry, for unreinforced \r\n masonry where maximum flexural strength is required, and for use \r\n where mortar adhesion is the sole bonding agent between facing \r\n and backing. It is a reasonably high compressive strength mortar, \r\n which tests indicate has a high tensile bond strength with most \r\n brick units. \r\n Type M Mortar . Type \r\n M mortar is specifically recommended for unreinforced and reinforced \r\n masonry below grade and in connect with earth, such as foundations, \r\n retaining walls, walks, sewers and manholes. It has high compressive \r\n strength and excellent durability. \r\n Type O Mortar . Type \r\n O mortar may be used for loadbearing walls of solid masonry where \r\n compressive stresses do not exceed 100 psi, provided that the \r\n exposure is not severe. It is a relatively low compressive strength \r\n mortar suitable for limited exterior use and general interior \r\n use in loadbearing and non-loadbearing masonry. Type O mortar \r\n should not be used where it will be subject to freezing in the \r\n presence of moisture. \r\n Special Mortar Applications \r\n Cavity Walls . In \r\n general, Type N mortar is suitable for cavity walls, except where \r\n wind velocities are expected to exceed 80 mph. For high wind areas, \r\n use Type S mortar. \r\n Tuck-Pointing Mortar . \r\n Use only prehydrated mortars. To prehydrate mortar, thoroughly \r\n mix all ingredients except water; then mix again, adding only \r\n enough water to produce a damp unworkable mix which will retain \r\n its form when pressed into a ball. After 1 to 2 hr. add sufficient \r\n water to bring it to the proper consistency; that is somewhat \r\n drier than conventional masonry mortars. \r\n For best results, duplicate the original \r\n mortar proportions. When in doubt, use prehydrated Type N mortar. \r\n For a more complete discussion of tuck pointing, see Technical \r\n Notes 7F , \"Moisture Resistance \r\n of Brick Masonry - Maintenance\". \r\n Dirt-Resistant Mortar . \r\n Where resistance to staining is desired, aluminum tristearate, \r\n calcium stearate or ammonium stearate may be added to the construction \r\n mortar in an amount not to exceed 2 percent of the weight of the \r\n portland cement. \r\n Where maximum dirt resistance is desired, \r\n such as in glazed structural clay unit installations, use mortar \r\n or grout consisting of 1 part portland cement, 1/8 part lime and \r\n 2 parts graded fine (80 mesh) sand, proportioned by volume. To \r\n this add aluminum tristearate, calcium stearate or ammonium stearate \r\n equal to 2 percent of the portland cement by weight. \r\n MIX CONTROLS \r\n Mortar is perhaps the last building \r\n material in history that is still manufactured at the project \r\n site. Almost all other materials with the possible exception of \r\n plaster, are manufactured in highly sophisticated, often automated, \r\n quality controlled industrial plants or factories. Yet many contractors, \r\n architects and engineers often entrust the manufacturing of this \r\n product; i.e. mortar; to untrained and often unqualified personnel, \r\n utilizing measuring systems that are inaccurate by their very \r\n nature; i.e., the shovel. \r\n After the proper mortar has been specified, \r\n it may be reasonably assumed that the proper materials (cement, \r\n lime, sand) are delivered to the project site, properly stored, \r\n and are available at the mortar mixing station. It is not unusual \r\n for specifiers to require that each of these materials be subjected \r\n to rigorous tests that will certify their conformance with standard \r\n specifications (see Technical Notes 8 \r\n Revised and 8A ). The specifier may \r\n then divorce himself of further responsibility by entrusting the \r\n manufacture of this product to possibly untrained and often poorly \r\n equipped personnel. \r\n BATCHING CONTROLS \r\n The method of measuring and batching \r\n materials shall be either by volume or by weight, such that the \r\n specified proportions for the mortar can be accurately controlled \r\n and maintained. For material weights and recommended proportions, \r\n refer to Technical Notes 8 \r\n Revised and 8A of this series. \r\n Measurement of sand exclusively by shovel should not be permitted. \r\n The cementitious materials (cement and \r\n lime) should be placed in the mixer in whole or minimum of half \r\n bags. This will require the mixer to be of suitable size, depending \r\n upon the project requirements and the size of the mason crew. \r\n The primary problem comes from the addition of sand, generally \r\n measured by the shovels full which is an unacceptable procedure. \r\n The following illustrations, taken from actual projects, show \r\n some examples of batching and measurement control methods that \r\n are both economical and accurate. \r\n Example 1. \r\n Figure 1 is a photograph of a project \r\n in Lawrence, Kansas; the site of the construction of several mid-rise \r\n loadbearing brick masonry dormitories and student apartments. \r\n Because of the size of the project and the fact that mortar, grout \r\n and concrete were to be site-mixed under strict controls of both \r\n the university and the state, the contractor used a leased weight-measuring \r\n and batching system. It is obvious that such a system, when operated \r\n by trained personnel, assures absolute control over mortar, grout \r\n and concrete. \r\n \r\n \r\n \r\n \r\n FIG. 1 \r\n \r\n Example 2. \r\n Figure 2 illustrates a simpler approach \r\n with less control. The mortar batchman has the use of several \r\n 1-cu ft plywood boxes constructed at the site. \r\n The procedure for determining the number \r\n of shovels full of sand was spelled out in the specification. \r\n The batchman was required to count the shovels full necessary \r\n to fill the boxes. This was performed at least twice a day - \r\n first thing in the morning and again after lunch. Better control \r\n could be obtained if the boxes were used for each batch. \r\n \r\n \r\n \r\n \r\n FIG. 2 \r\n \r\n Example 3. \r\n Figure 3 illustrates a system using \r\n a concrete bucket on a pivot arm and post. With proper baffles \r\n for desired volume, the concrete bucket can be used for precise \r\n measurement of the sand required for each mixer full of mortar. \r\n The investment is relatively small in terms of the consistency \r\n obtained by this procedure. \r\n \r\n \r\n \r\n \r\n FIG. 3 \r\n \r\n Example 4. \r\n Figure 4 shows a site constructed sand \r\n measuring tilt box for the mortar station at the site of a 15-story \r\n high-rise loadbearing brick masonry apartment structure in Reading, \r\n Pennsylvania. All the mortar batchman had to do was to fill the \r\n box with sand (9-cu ft volume), place it in the mixer, to which \r\n he added two bags of cement, one bag of lime and one measure of \r\n color additive for a carefully controlled Type S colored mortar. \r\n \r\n \r\n \r\n \r\n FIG. 4 \r\n \r\n CONCLUSION \r\n The proper selection of mortar to achieve \r\n desired performance, along with the proper selection of masonry \r\n units, placed with care in accordance with the specifications, \r\n should assure better performing masonry walls. It is also necessary \r\n to assure that proper mixing procedures and batching procedures \r\n are used for the mortar manufactured at the job site. \r\n This Technical Notes sets forth \r\n general basic rules for the selection of mortar types for particular \r\n uses. It is important to remember - \r\n never use a mortar stronger than is necessary to do the job. \r\n This Technical Notes also illustrates \r\n some economical and relatively simple procedures to control the \r\n batching of mortar. \r\n If the recommendations and suggestions \r\n contained in this Technical Notes are followed with judgment \r\n and care, the result will be better performing brick masonry with \r\n less leaky walls, less cracking, less efflorescence and fewer \r\n problems all around. \r\n REFERENCES \r\n \r\n 1. Technical Notes on Brick Construction, 8 Series, \"Mortar for Brick \r\n Masonry\", BIA. \r\n 2. Brick and Tile Engineering, Handbook, by Harry C. Plummer, SCPI \r\n (BIA), 1962. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60140,"ResultID":176372,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 9 - Manufacturing, Classification, \r\n and Selection of Brick, Manufacturing, Part 1 \r\n March 1986 \r\n \r\n Abstract : This Technical Notes presents \r\n some of the fundamental procedures for the manufacture of clay brick. \r\n Discussion centers on the types of clay used; the various phases of manufacturing, \r\n from mining through storage of the finished units; along with descriptions \r\n of the three principal processes for forming brick. Further information \r\n is provided regarding the properties that may be of interest to the user. \r\n These are durability, color, texture (including coatings and glazes), \r\n size variation, compressive strength and absorption. \r\n Key Words : absorption, brick , \r\n clays, color , compressive strength, drawing, drying , \r\n durability , firing , forming, preparation, \r\n shales, size variation , texture , winning. \r\n INTRODUCTION \r\n Brick manufacturing still follows the basic \r\n steps of centuries past. However, technological advancements over the \r\n years have made the modern brick plant substantially more efficient than \r\n the plants of yesterday and have also improved the overall quality of \r\n the products. A more complete knowledge of raw materials and their properties, \r\n better control of firing, improved kiln designs and more advanced mechanization \r\n have all resulted in the development of a progressive, modern industry. \r\n Other Technical Notes in this series \r\n will address the classification of brick, as well as the selection of \r\n the proper brick as to the type of use, exposure to the elements and durability \r\n of the finished assembly. \r\n RAW MATERIALS \r\n Clay is one of the most abundant mineral \r\n materials on earth. Clay for the production of brick must, however, possess \r\n some specific properties and characteristics. To satisfy modern production \r\n requirements, clays must have plasticity, which permits them to be shaped \r\n or molded when mixed with water; and they must have sufficient wet and \r\n air-dried tensile strength to maintain their shape after forming. Also, \r\n when subjected to rising temperatures, the clay particles must fuse together \r\n (see Firing and Cooling). \r\n Types of Clay \r\n Clays occur in three principal forms, all \r\n of which have similar chemical compositions but different physical characteristics. \r\n They are: \r\n Surface Clays . Surface clays may be \r\n the upthrusts of older deposits or of more recent, sedimentary formation. \r\n As the name implies, they are found near the surface of the earth. \r\n Shales . Shales are clays that have \r\n been subjected to high pressures until they have hardened almost to the \r\n form of slate. \r\n Fire Clays . Fire clays are usually \r\n mined at deeper levels than other clays and have refractory qualities. \r\n As a rule, they contain fewer impurities than shales or surface clays \r\n and have more uniform chemical and physical properties. \r\n Clays are complex materials; surface clays \r\n and fire clays differ from shales more in physical structure than in chemical \r\n composition. Chemically, all three are compounds of silica and alumina \r\n with varying amounts of metallic oxides and other impurities. Although \r\n technically metallic oxides are impurities, they act as fluxes, promoting \r\n fusion at lower temperatures. Metallic oxides (particularly those of iron, \r\n magnesium and calcium) influence the color of the finished fired product. \r\n The manufacturer minimizes variations in \r\n chemical composition and physical properties by mixing clays from different \r\n locations in the pit and from different sources. However, because clay \r\n products have a relatively low selling price, it is not economically feasible \r\n to refine clays to produce uniform raw materials. Since variations in \r\n properties of raw materials must be compensated for by varying manufacturing \r\n processes, properties of finished products from different manufacturers \r\n will also vary somewhat. \r\n MANUFACTURING \r\n Although the basic principles of manufacture \r\n are fairly uniform, individual plants deviate from these basics to fit \r\n their particular raw materials and methods of operation. Essentially, \r\n brick are produced by mixing ground clay with water, forming them into \r\n the desired shapes, then drying and firing them. In ancient times, all \r\n molding was performed by hand. However, since the invention of brick-making \r\n machines during the latter part of the 19th Century, practically all brick \r\n produced in the United States have been machine made. \r\n Phases of Manufacturing \r\n The manufacturing procedure has six general \r\n phases: 1) winning and storage of raw materials, 2) preparing raw materials, \r\n 3) forming units, 4) drying, 5) firing and cooling, and 6) drawing and \r\n storing finished products (see Figure 1). \r\n \r\n Diagrammatic Representation \r\n of the Manufacturing Process \r\n FIG. 1 \r\n \r\n \r\n Winning and Storage . To win originally meant to obtain. The term, carried to \r\n the present with its original meaning, is applied to mining procedures \r\n in the clay industry. Surface clays, shales and some fire clays are mined \r\n in open pits with power equipment; some fire clays are taken from underground \r\n mines. The clay or shale mixtures are then transported to plant storage \r\n areas. \r\n It is common practice to store enough raw \r\n material for several days operations, thus insuring continuous operation \r\n regardless of weather conditions. Normally, several storage areas (one \r\n for each source) are provided to permit some blending of the clays. Blending \r\n produces more uniform raw materials, helps to control color and permits \r\n some control over raw material suitability for manufacturing a given type \r\n of unit. \r\n Preparation . The clay is crushed to \r\n break up large chunks and remove stones, after which large grinding wheels, \r\n weighing 4 to 8 tons each, revolve in a circular pan, grinding and mixing \r\n the raw material. Most plants then screen the clay, passing it through \r\n inclined vibrating screens to control particle sizes. \r\n Forming . Tempering, the first step \r\n in the forming process, produces a homogeneous, plastic mass ready for \r\n molding. It is most commonly achieved by adding water to the clay in a \r\n pug mill, a mixing chamber which contains one or more revolving shafts \r\n with blades. After pugging, the now plastic clay mass is ready to go to \r\n the forming step. At the present time, there are three principal processes \r\n for forming brick: the stiff-mud, the soft-mud and the drypress processes. \r\n Stiff-Mud Process - In the \r\n stiff-mud process, clay is mixed with only sufficient water to produce \r\n plasticity, usually from 12 to 15 percent by weight. After thorough mixing, \r\n i.e., \"pugging\", the tempered clay goes through a de-airing chamber in \r\n which a vacuum of 15 to 29 in. (375 to 725 mm) of mercury is maintained. \r\n De-airing removes air holes and bubbles, giving the clay increased workability \r\n and plasticity, thus resulting in greater strength. \r\n Next, the clay is extruded through a die \r\n to produce a column of clay in which two dimensions of the final unit \r\n are determined. The column then passes through an automatic cutter to \r\n make the final dimension of the brick unit. Cutter-wire spacings and die \r\n sizes must be carefully calculated to compensate for normal shrinkage \r\n during wet stages through drying and firing (see Size Variation). As the \r\n clay column leaves the die, textures or surface coatings may be applied \r\n (see Textures, Coatings and Glazes). \r\n Soft-Mud Process - The soft-mud \r\n process is particularly suitable for clays which contain too much natural \r\n water to be extruded by the stiff-mud process. It consists of mixing clays \r\n so that they contain 20 to 30 percent water and then forming the units \r\n in molds. To prevent clay from sticking, the molds are lubricated with \r\n either sand or water. When sand is used, the brick are \"sand-struck\"; \r\n but if water is used, they are \"water-struck\" brick. Brick may be produced \r\n in this manner by a machine or by hand process. \r\n Dry-Press Process - This process \r\n is particularly adaptable for clays of very low plasticity. Clay is mixed \r\n with a minimum of water (up to 10 percent), then formed in steel molds \r\n under pressures from 500 to 1,500 psi (3.4 to 10.3 MPa) using hydraulic \r\n or compressed air rams. \r\n Drying . When wet clay units come from \r\n molding or cutting machines, they contain from 7 to 30 percent moisture, \r\n depending upon the forming method. Before the firing process begins, most \r\n of this water is evaporated in dryer chambers at temperatures ranging \r\n from about 100 o F to 400 o F (38 o C to 204 o C). \r\n Drying time, which varies with different clays, is usually from 24 to \r\n 48 hr. Although heat may be generated specifically for dryer chambers, \r\n it is more commonly supplied as exhaust heat from firing kilns. In all \r\n cases, heat and humidity must be carefully regulated to avoid excessive \r\n cracking in the ware. \r\n Firing and Cooling . Firing, one of \r\n the most specialized steps in the manufacture of brick, requires from \r\n 40 to 150 hr. depending upon kiln type and other variables. Several kilns \r\n are in use, the chief types being tunnel and periodic kilns. Fuel may \r\n be natural gas, propane, oil, sawdust, coal or combinations of these fuels. \r\n Dried units are set in periodic kilns according \r\n to a prescribed pattern that permits free circulation of hot kiln gases. \r\n A periodic kiln is one that is loaded, fired, allowed to cool and unloaded, \r\n after which the same processes are repeated. In a tunnel kiln, units are \r\n similarly loaded on special cars which pass through various temperature \r\n zones as they travel through the tunnel. The heat conditions in each zone \r\n are carefully controlled and the kiln operates continuously. \r\n Firing may be divided into six general stages: \r\n 1) water-smoking (evaporating free water), 2) dehydration, 3) oxidation, \r\n 4) vitrification, 5) flashing and 6) cooling. All except flashing and \r\n cooling are associated with rising temperatures in the kiln. Although \r\n the actual temperatures will differ with the clay or shale, water-smoking \r\n takes place at temperatures up to about 400 o F (204 o C), \r\n dehydration from about 300 o F to 1800 o F (149 o C \r\n to 982 o C), oxidation from 1000 o F to 1800 o F \r\n (538 o C to 982 o C) and vitrification from 1600 o F \r\n to 2400 o F (871 o C to 1316 o C). \r\n Clays are unlike metals in that they soften \r\n slowly and melt or fuse gradually when subjected to rising temperatures. \r\n It is this property of clay, its fusibility, which causes it to become \r\n hard, solid and of relatively low absorption when properly fired. Fusing \r\n takes place in three stages: 1) incipient fusion, that point when the \r\n clay particles become sufficiently soft that the mass sticks together; \r\n 2) vitrification, when there is extensive fluxing and the mass becomes \r\n tight, solid and non-absorbent; and 3) viscous fusion, the point at which \r\n the clay mass breaks down and tends to become molten. The key to the firing \r\n process is to control the temperature in the kiln so that incipient fusion \r\n and partial vitrification are complete but viscous fusion is avoided. \r\n The rate of temperature change must be carefully \r\n controlled, depending on the raw materials, as well as the units being \r\n produced. Kilns are normally equipped with recording pyrometers or other \r\n temperature sensors to provide a constant check on the firing process. \r\n Near the end of the firing process, the units may be \"flashed\" to produce \r\n color variations (see Properties of Brick, Color ). \r\n After the temperature has reached the maximum \r\n and is maintained for a prescribed time, the cooling process begins. Forty-eight \r\n to 72 hr required for proper cooling in periodic kilns; but in tunnel \r\n kilns, the cooling period seldom exceeds 48 hr. Because the rate of cooling \r\n has a direct effect on color and because excessively rapid cooling will \r\n cause cracking and checking of the ware, cooling is an important stage \r\n in the firing process. \r\n Drawing . Drawing is the process of \r\n unloading a kiln after cooling. It is at this stage that units are sorted, \r\n graded, packaged and taken to a storage yard or loaded onto rail cars \r\n or trucks for delivery. The majority of brick today are packaged in self-contained, \r\n steel-strapped cubes, which can be broken down into individual strapped \r\n packages for ease of handling on the jobsite. The packages and cubes are \r\n formed in such a manner as to provide openings for handling by fork lifts. \r\n Brick manufactured and selected to produce characteristic architectural \r\n effects resulting from non-uniformity in size, color and texture may not \r\n lend themselves to self-contained packaging, and are usually shipped on \r\n wooden pallets. \r\n PROPERTIES \r\n All properties of brick are affected by composition \r\n of the raw materials and the manufacturing processes. It is for this reason \r\n that most manufacturers blend clays to reduce the possibility of impurities \r\n from one clay source affecting the overall quality of the finished product. \r\n Similarly, the standardization of the manufacturing processes permits \r\n the manufacturer to limit variations due to processing and to produce \r\n a more uniform product. \r\n Product Use \r\n The properties that most concern the users \r\n of brick are 1) durability, 2) color, 3) texture, 4) size variation, 5) \r\n compressive strength and 6) absorption. \r\n Durability . The durability of brick \r\n results from incipient fusion and partial vitrification during firing. \r\n Since compressive strength and absorption are also related to the firing \r\n temperatures, these properties, together with saturation coefficients, \r\n are taken as predictors of durability. However, because of differences \r\n in raw materials, a single value of compressive strength or absorption \r\n will not reliably indicate the degree of firing. \r\n Color . \r\n The color of fired clay depends upon its chemical composition, the firing \r\n temperatures and the method of firing control. Of all the oxides commonly \r\n found in clays, iron probably has the greatest effect on color. Regardless \r\n of its natural color, clay containing iron in practically any form will \r\n burn red when exposed to an oxidizing fire, due to the formation of ferrous \r\n oxide. When fired in a reducing atmosphere, the same clay will take on \r\n a purple cast. Creating a reducing atmosphere in the kiln is known as \r\n \"flashing\". \r\n For the same raw materials and methods of \r\n manufacture, the darker colors are associated with firing at higher temperatures, \r\n with lower absorptions and with increased compressive strengths. However, \r\n for products made from different raw clays, there is no direct relationship \r\n between strength and color or absorption and color. \r\n Textures, Coatings and Glazes . Many \r\n brick have smooth or sand-finished textures produced by the dies or molds \r\n used in forming. Smooth texture, commonly called a die skin, results from \r\n pressure exerted by the steel die as the clay passes through the die. \r\n In the stiff-mud process, many textures may be applied by attachments \r\n which cut, scratch, roll, brush or otherwise roughen the surface as the \r\n clay column leaves the die. Today, many plants apply engobes (slurries) \r\n of finely ground clay, coloring agents and water to the roughened column. \r\n Sands, with or without coloring agents, can be rolled into the slurry \r\n coating to create interesting and distinctive patterns in the finished \r\n product. Engobes are defined as clay slips that develop a hardness which \r\n adheres to the brick but usually allows the coating to breathe. With high-fired \r\n units, engobes may be almost impervious. \r\n Although not common to all manufacturing, \r\n ceramic glazing is a highly specialized, carefully controlled procedure, \r\n having two basic variations, high-fired and low-fired glazing. High-fired \r\n glazes are sprayed on units before or after drying and then kiln-fired \r\n at the normal firing temperatures of the units. Low-fired glazes are used \r\n to obtain colors which cannot be produced at high temperatures. They are \r\n applied after the unit has been fired to maturity and cooled; then they \r\n are glazed and refired at relatively low temperatures. Unlike many engobes, \r\n glazes are impervious and do not allow the surface to breathe. \r\n Size Variation . Because clays shrink \r\n during both drying and firing, allowances must be made in the die size \r\n and in the length of cut to achieve the desired size of the finished product. \r\n Both air (dryer) shrinkage and firing shrinkage vary for different clays, \r\n usually falling within the following ranges: \r\n Air Shrinkage 2 \r\n to 8 percent \r\n Firing Shrinkage 2.5 \r\n to 10 percent \r\n The principal shrinkage problem is not so \r\n much the total shrinkage as the variation in shrinkage of the clays or \r\n shales. \r\n Firing shrinkage increases with higher temperatures \r\n which, in turn, produce darker shades. Consequently, when a wide range \r\n of colors is desired, some variation between the sizes of the dark and \r\n light units is inevitable. To obtain products of uniform size, manufacturers \r\n attempt to control factors contributing to shrinkage. However, because \r\n of variations in raw materials and temperature variations within kilns, \r\n absolute uniformity is impossible. Consequently, specifications for brick \r\n include permissible size variations to permit economical manufacture. \r\n Compressive Strength and Absorption . \r\n Both compressive strength and absorption are affected by properties of \r\n the clay, method of manufacture and degree of firing. Although there are \r\n exceptions to the rule, the stiff-mud process generally produces units \r\n having higher compressive strengths and lower absorptions than units \r\n produced by the soft-mud or dry-press process. \r\n For a given clay and method of manufacture, \r\n higher compressive strengths and lower absorptions are associated with \r\n higher firing temperatures. Although absorption and compressive strength \r\n can be controlled to a degree by manufacturing and firing methods, these \r\n properties depend largely upon the properties of the raw materials. Consequently, \r\n they vary widely for different products. \r\n SUMMARY \r\n This Technical Notes on manufacturing \r\n brick is the first in a series covering the manufacturing, classification \r\n and selection of brick. It provides a synopsis of the manufacturing processes \r\n and discusses the various properties which are a function of these processes. \r\n More detailed descriptions of the ceramic properties of brick are not \r\n within the purview of the Brick Institute of America. This type of information \r\n is more readily available through ceramic engineers and educators. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60141,"ResultID":176373,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 9A - Manufacturing, Classification, and Selection \r\n of Brick - Classification, Part 2 \r\n June 1989 \r\n \r\n Abstract : This Technical Notes describes the various \r\n kinds of brick and their classification. Specific requirements \r\n including physical properties, efflorescence, dimensional \r\n tolerances, distortion, chippage, and coring are described. \r\n Additional requirements for each kind of brick are also covered. \r\n Key Words : appearance, ASTM \r\n Standards , brick, chippage, classification , \r\n cores, dimensional tolerances, distortion, efflorescence, \r\n exposure, frogs, grades, physical properties, types, uses. \r\n INTRODUCTION \r\n The classification of brick is determined by the usage of brick in specific \r\n applications. Brick used in the wrong application can lead \r\n to failure or an unpleasing appearance. Standard specifications \r\n have been developed to produce uniform requirements for brick. \r\n The standard specifications include strength, durability and \r\n aesthetic requirements. \r\n The American Society for Testing \r\n and Materials (ASTM) publish the most widely accepted standards \r\n on brick. These standards are voluntary consensus standards. \r\n All have been through a review process by various segments \r\n of the construction industry - producers, users and general interest \r\n members. Most of the model building codes reference ASTM standards. \r\n Many of the requirements in the brick standards aid in predicting \r\n the durability of the product in actual use. These predictors, \r\n and other requirements in ASTM standards, are not infallible. \r\n All ASTM standards are reviewed and updated periodically to \r\n obtain optimal performance. \r\n This Technical Notes addresses \r\n the specific requirements for various classifications of brick. \r\n Other Technical Notes in this series provide the fundamentals \r\n of brick manufacturing and the proper selection of brick. \r\n \r\n \r\n Fig. 1 \r\n \r\n BRICK CLASSIFICATION \r\n Depending on its use, brick can be classified by one of several \r\n specifications. \r\n \r\n \r\n Since chemical resistant brick and \r\n industrial floor brick are special applications, they will \r\n not be addressed in this Technical Notes . \r\n Uses \r\n As the names imply, the uses of brick \r\n are similar to their respective ASTM designations. \r\n Building Brick . Building \r\n brick are intended for use in both structural and non-structural \r\n masonry where appearance is not a requirement. Building brick \r\n are typically used as a backing material. \r\n Facing Brick . Facing brick \r\n are intended for use in both structural and non-structural \r\n masonry where appearance is a requirement. \r\n Hollow Brick . Hollow brick \r\n are identical to facing brick but have a larger core area. \r\n Most hollow brick are used in the same application as facing \r\n brick. Hollow brick with very large cores are used in walls \r\n that are reinforced with steel and grouted solid. Larger cores \r\n or cells in hollow brick allow reinforcing steel and grout \r\n to be placed in these units whereas it would be difficult \r\n to do so with building brick, facing brick or some hollow \r\n brick. \r\n Paving Brick . Paving brick \r\n are intended for use as a paving material to support pedestrian \r\n and light vehicular traffic. \r\n Ceramic Glazed Brick . Ceramic \r\n glazed brick are units with a ceramic glaze fused to the body \r\n and used as facing brick. The body may be either facing brick \r\n or other solid masonry units. \r\n Thin Brick . Thin brick veneer \r\n units are fired clay units with normal face dimensions, but \r\n a reduced thickness. They are used in adhered veneer applications. \r\n Sewer and Manhole Brick . \r\n Sewer and manhole brick are intended for use in drainage structures \r\n for the conveyance of sewage, industrial wastes, and storm \r\n water; and related structures, such as manholes and catch \r\n basins. \r\n GENERAL REQUIREMENTS \r\n There are several terms in each standard used for classification \r\n which may include exposure, appearance, physical properties, \r\n efflorescence, dimensional tolerances, distortion, chippage, \r\n cores and frogs. Brick can be classified by use, grade, type \r\n and/or class in most specifications. All options should be \r\n specified, as each ASTM brick standard has requirements for \r\n grade and type which apply automatically if an option is omitted. \r\n By not specifying the desired requirements, a delivery may \r\n contain brick not suitable for the intended use. \r\n Exposure \r\n \r\n Because of the varying climates throughout \r\n the country, and the different applications of brick, specific \r\n grades of brick are required. Brick must meet a grade of SW, \r\n MW, or NW based on the weathering index and the exposure of \r\n the brick. The weathering index is the product of the average \r\n annual number of freezing cycle days and the average annual \r\n winter rainfall in inches (see Figure 1). The exposure is related \r\n to either a vertical or horizontal surface and whether the unit \r\n will be in contact with the earth (see Table 1). A higher weathering \r\n index or a more severe exposure will require a face brick to \r\n meet the SW requirements. The grade is typically based on physical \r\n properties of the brick. See Technical Notes 9B \r\n for selection of grades. The grades for each specification are \r\n listed in Table 2, and the physical requirements are listed \r\n in Table 4. \r\n \r\n \r\n \r\n \r\n \r\n Appearance \r\n Brick types are related to the appearance of the unit, and specifically \r\n to limits on dimensional tolerances, distortion tolerances \r\n and chippage of the units. The brick type can be selected \r\n depending upon whether: a high degree of precision is necessary; \r\n a wider range of color or size is permitted; or a characteristic \r\n architectural effect is desired. The types of brick for each \r\n specification are listed in Table 3, and requirements for \r\n size variation, distortion, and chippage are listed in Tables \r\n 5, 6 and 7, respectively. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 No requirements \r\n for durability \r\n 2 Based on durability \r\n and abrasion \r\n \r\n \r\n \r\n \r\n \r\n \r\n Physical Property Requirements \r\n The physical property requirements \r\n in most specifications are compressive strength, water absorption \r\n and saturation coefficient. These properties must be determined \r\n in accordance with ASTM C 67, Standard Methods of Sampling \r\n and Testing Brick and Structural Clay Tile . The minimum \r\n compressive strength, maximum water absorption and maximum \r\n saturation coefficient are used in combination to predict \r\n the durability of the units in use. The saturation coefficient, \r\n also referred to as the C/B ratio, is the ratio of 24 hour \r\n cold water absorption to the 5 hour boiling absorption. The \r\n physical property requirements for each standard are listed \r\n in Table 4. \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Hollow brick in bearing \r\n position. \r\n 2 Numbers in parentheses \r\n are for molded brick and apply provided the requirements \r\n for saturation coefficient are met. \r\n 3 Where a high and uniform \r\n degree of resistance to frost action in the presence of \r\n moisture is required. See C 32 for waiver of saturation \r\n coefficient. \r\n \r\n Alternates . Because of the \r\n variability of raw materials and production methods throughout \r\n the country, it is difficult to use only these requirements \r\n to classify all brick. Therefore, in each standard there are \r\n waivers which include those brick which are durable but cannot \r\n be classified under the physical requirements. Using the waiver \r\n permits the use of brick which are known to perform well. \r\n It does not signify that the brick are of a lower quality. \r\n Waivers include: waiving the saturation coefficient and water \r\n absorption requirements if brick are intended to be used where \r\n the weathering index is less than 50; waiving the saturation \r\n coefficient requirement if the cold water absorption is less \r\n than 8% on an average of five units allowing one brick of \r\n the sample to exceed 8% but be less than 10%; waiving the \r\n saturation coefficient and water absorption requirements if \r\n the sample complies with the 50 cycle freeze and thaw test \r\n requiring no breakage and not greater than 0.5% loss in dry \r\n weight of any individual brick (Grade SW only). Freeze-thaw \r\n requirements apply only if the units do not meet the saturation \r\n coefficient and absorption requirements. For waivers specific \r\n to each type of brick, consult the appropriate ASTM Specification. \r\n Efflorescence \r\n Efflorescence is a crystalline deposit \r\n of water-soluble salts which forms on the surface of masonry. \r\n The principal objection is an unsightly appearance, though \r\n it typically is not harmful to brick. The test for efflorescence \r\n is described in ASTM C 67. The brick is given a rating of \r\n \"effloresced\" or \"not effloresced\". ASTM standards (C 216, \r\n C 652, C 902, C 1088) require the rating for brick to be \"not \r\n effloresced\". \r\n Although brick is the only material \r\n in masonry construction that is tested for efflorescence, \r\n brick itself is not a major source of efflorescing salts. \r\n Dimensional Tolerances \r\n Because of the variations in the \r\n raw materials and the manufacturing process, brick may vary \r\n in size. The permitted size variation is based on the brick \r\n type and the dimension being measured. These variations in \r\n size are listed in Table 5. The variation is plus or minus \r\n from the specified dimension. Generally, \"through-the-body\" \r\n colored brick with a wide color range will also have a wide \r\n variation in dimensions. Brick without a wide color range \r\n may vary one way or another. Size variation becomes important \r\n when constructing an assembly with units aligned vertically \r\n or in wall sections with short horizontal dimensions. \r\n \r\n \r\n \r\n TABLE 5 \r\n Dimensional Tolerances \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 As specified by the \r\n purchase \r\n \r\n 2 Over 5 in. to 8 in. \r\n \r\n 3 No limit \r\n \r\n 4 Special Requirements \r\n -- see ASTM C 126 \r\n \r\n \r\n Distortion \r\n Permitted distortion, or warpage, \r\n of brick is listed in Table 6. The amount of distortion is \r\n based on the brick type and face dimension. Other terms for \r\n distortion are \"bowed\" or \"banana\" brick. A brick that is \r\n over the distortion limitations is difficult to lay and is \r\n easily noticeable in the finished wall. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 As specified by \r\n the purchaser \r\n \r\n 2 Special requirements \r\n - see ASTM C 126 \r\n \r\n \r\n \r\n Chippage \r\n Brick may be damaged or chipped \r\n during packaging, shipping or on the jobsite. Limitations \r\n to the size and number of chips on individual units are listed \r\n in Table 7. The amount of chippage is based upon the brick \r\n type. \r\n A delivery of brick may contain \r\n up to 5% broken or chipped brick beyond the limits in Table \r\n 7. The chippage requirements in Table 7 are based on the remaining \r\n 95% of the shipment. The chips are measured from an edge or \r\n a corner, and the total length of these chips may not be greater \r\n than 10% of the perimeter of the face of the brick. Chips \r\n are more noticeable on brick that have a surface color different \r\n from the body of the brick. Chips on \"through-the-body\" color \r\n brick are less noticeable. \r\n \r\n \r\n TABLE 7 \r\n Maximum Permissible Range of \r\n Chippage 1 \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 There are no chippage \r\n requirements for C 62, or C 32. \r\n \r\n 2 Smooth texture -- die \r\n skin finish. \r\n \r\n 3 Rough texture - sanded, \r\n combed, scratched, wire cut. \r\n \r\n Cores \r\n Brick are generally classified as solid or hollow . A solid \r\n brick unit is defined as a unit whose net cross-sectional \r\n area in every plane parallel to the bearing surface is 75% \r\n or more of its gross cross-sectional area measured in the \r\n same plane. Thus, a solid brick unit has a maximum coring \r\n of 25%. A hollow brick unit is defined as a unit whose net \r\n cross-sectional area in every plane parallel to the bearing \r\n surface is less than 75% of its gross cross-sectional area \r\n measured in the same plane. A hollow brick unit has a minimum \r\n coring of 25%, and a maximum coring of 60%. \r\n Holes in brick, referred to as cores, \r\n are used to aid in the manufacturing process and shipping \r\n of brick. The cores create more uniform drying and firing \r\n of the units, reduce the amount of fuel necessary to fire \r\n the units and reduce shipping costs by reducing weight. Additional \r\n advantages, such as aiding in mechanical bond in a wall, easier \r\n laying of the units, etc., may also result from brick manufactured \r\n with cores. Cores are only found in brick manufactured by \r\n the extrusion or dry-press process. Limits to the amount of \r\n coring allowed in brick, the distance from a core to a face, \r\n and web thickness where applicable are listed in Table 8. \r\n Cells are similar to cores except \r\n that a cell is larger in cross-section than a core. Some requirements \r\n for cells are shown in Table 8. Additional requirements for \r\n cells can be found in ASTM C 652 and C 126. \r\n Frogs \r\n Frogs are depressions in brick usually \r\n located on one bed surface and are included for the same reasons \r\n as cores. Frogs are found in brick manufactured by the molded \r\n process. Panel frogs are limited to a specified depth and \r\n a specified distance from a face. Requirements for panel frogs \r\n are listed in Table 8. Deep frogs are frogs that are deeper \r\n than 3/8\" (10 mm) deep, and must conform to the requirements \r\n for coring, hollow spaces and void area of the applicable \r\n standard. \r\n \r\n \r\n TABLE 8 \r\n Requirements for Cores and Frogs 1 \r\n \r\n \r\n \r\n \r\n __________________________________________________________________________ \r\n \r\n \r\n \r\n \r\n \r\n \r\n 1 Deep frogsshall meet \r\n coring requirements of the applicable standard (see ASTM C \r\n 62, C216, C 652) \r\n 2 Additional coring \r\n requirments for cored-shell and double-shell hollow brick \r\n in ASTM C 652 \r\n \r\n 3 Based on 3\" and 4\" \r\n nominal width (For 6\", 8\", 10\" and 12\" see C652 \r\n \r\n 4 Additional Requirements \r\n for cells in ASTM C 126 \r\n \r\n 5 See C 126 for web \r\n thickness in cored units \r\n \r\n \r\n \r\n \r\n \r\n \r\n ADDITIONAL REQUIREMENTS \r\n Paving Brick, ASTM C 902 \r\n Not only must paving brick conform \r\n to the physical requirements in Table 4, but they must meet \r\n additional requirements for abrasion resistance or alternate \r\n performance requirements. \r\n Alternate Performance Requirements. \r\n If information on the performance of units in an application \r\n of similar exposure and similar traffic is given, then the physical \r\n requirements in Table 4 may be waived. \r\n Paving brick manufactured by the molded \r\n process have different physical requirements. See Table 4. \r\n An optional test for the freeze and \r\n thaw test is ASTM C 88 Test Method for Soundness of Aggregates \r\n by Use of Sodium Sulfate . The sulfate soundness test, like \r\n the freeze/thaw test is not required, and the requirements apply \r\n only if the paving units do not meet the saturation coefficient \r\n and absorption requirements. \r\n Abrasion Requirements . Since \r\n paving brick are used in a horizontal application and are exposed \r\n to traffic, brick must meet a specified abrasion limit. Paving \r\n brick are assigned a type by the traffic or abrasion expected. \r\n Type I pavers are exposed to extensive abrasion, such as driveways \r\n or public entries. Type II pavers are exposed to high levels \r\n of pedestrian traffic, such as in stores, restaurant floors \r\n or exterior walkways. Type III pavers, are exposed to pedestrian \r\n traffic, such as floors or patios in homes. The abrasion resistance \r\n can be determined in either of two ways: 1) an abrasion index \r\n is calculated by dividing the absorption by the compressive \r\n strength and multiplying by 100, or 2) by determining the volume \r\n abrasion loss in accordance with ASTM C 418 Test Method for \r\n Abrasion Resistance of Concrete by Sandblasting . The abrasion \r\n requirements for Type I, II, and III are listed in Table 9. \r\n \r\n \r\n \r\n Ceramic Glazed Brick, ASTM C 126 \r\n Since this specification is for ceramic \r\n glazed brick and tile, there are requirements for properties \r\n of the finish. These are imperviousness, opacity, resistance \r\n to fading, resistance to crazing, flame spread, fuel contribution \r\n and smoke density, toxic fumes, hardness and abrasion resistance. \r\n Requirements for each of these are included in the specification. \r\n SUMMARY \r\n This Technical Notes describes \r\n the classification of brick and the specific requirements found \r\n in ASTM standard specifications. It attempts to clarify some \r\n of the wording in ASTM specifications, although an official \r\n interpretation from ASTM must be received from the appropriate \r\n subcommittee. Problems and confusion can be eliminated if a \r\n basic understanding of the ASTM specifications is known. \r\n The information and suggestions contained \r\n in this Technical Notes are based on the available data \r\n and the experience of the technical staff of the Brick Institute \r\n of America. The information contained herein should be used \r\n with good technical judgment and an understanding of the properties \r\n of brick masonry. Final decisions on the use of the information \r\n discussed in this Technical Notes are not within the \r\n purview of the Brick Institute of America and must rest with \r\n the project designer, owner or both. \r\n REFERENCES \r\n More detailed information on subjects discussed here can be found in the \r\n following publications: \r\n 1. ASTM Standard Specifications for Brick, Mortar and Applicable Testing \r\n Methods for Units Reprinted by the Brick Institute of America. \r\n \r\n 2. ASTM C 88 Test Method for Soundness of Aggregates by Use of Sodium Sulfate. \r\n Annual Book of ASTM Standards, Volume 04.02. \r\n 3. ASTM C 418 Test Method for Abrasion Resistance of Concrete by Sandblasting. \r\n Annual Book of ASTM Standards, Volume 04.02. \r\n 4. Technical Notes on Brick Construction 9B , \r\n \"Manufacturing, Classification and Selection of Brick - Selection \r\n - Part III of III\", January 1989. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "},{"TextID":60142,"ResultID":176374,"Text1":" \r\n \r\n Technote \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Technical Notes 9B - Manufacturing, Classification, \r\n and Selection of Brick, Selection, Part 3 \r\n Reissued December 1995 \r\n \r\n Abstract : This Technical Notes addresses the selection of brick. \r\n Evaluation of the properties and applications of brick determines the \r\n durability, appearance, and impression of a project. Information is provided \r\n regarding aesthetics, cost and availability. \r\n Key Words : abrasion, absorption, aesthetics , \r\n availability , brick , color , \r\n compressive strength, cost , durability , size, \r\n texture. \r\n INTRODUCTION \r\n The selection of brick is important in that \r\n it determines a projects durability and appearance, and results in a \r\n lasting impression. It is necessary to identify which qualities and properties \r\n of brick are appropriate to consider in selecting a brick. Brick with \r\n a wide variety of strength, color, texture, size, shape and cost are available. \r\n The owner or designer must decide which characteristics of brick are most \r\n critical. This selection process can dictate the success of any project. \r\n This Technical Notes addresses the properties \r\n and characteristics which must be considered in the selection of the appropriate \r\n brick for a project. Other Technical Notes in this series provide \r\n the fundamentals of brick manufacturing and classification of brick. \r\n GENERAL \r\n Brick selection is based on a number of factors. \r\n Not only are aesthetics and durability important, but strength, absorption, \r\n availability and cost are important to the owner, designers and contractors. \r\n The selection process can be difficult since each group is trying to satisfy \r\n different requirements. Typically, the final selection is based on a compromise \r\n from all parties involved. \r\n Aesthetics \r\n The use of brick as a building material dates \r\n back centuries. Because of bricks enduring qualities and limitless appearances, \r\n designers can satisfy their creative styles with brick. Brick is readily \r\n available in many sizes, colors, textures and shapes. These can be adapted \r\n to achieve virtually any desired style or expression. \r\n The variety of sizes available are shown in \r\n Figure 1. Bricks small module can be related to the scale of the wall. \r\n These sizes can be combined in such a way as to create different appearances \r\n and patterns. Not only does brick size influence scale and appearance, \r\n but the size of brick influences wall cost because larger units require \r\n fewer brick, normally resulting in less labor. When specifying the size \r\n of units, dimensions should be listed in the following order: thickness \r\n by height by length. \r\n \r\n \r\n \r\n \r\n Brick Sizes (Nominal Dimensions) \r\n FIG. 1 \r\n \r\n Brick manufacturers also offer a wide variety \r\n of colors to choose from. Units whose colors range from reds and burgundies \r\n to whites and buffs are manufactured today. Many manufacturers produce \r\n over 100 colors. Many of these color variations are created during the \r\n firing process. Temperature variations and the order in which the units \r\n are stacked in the kiln determine shades of light and dark. Ceramic glazes \r\n or slurries can be applied to the surface to achieve colors not possible \r\n with some clays. The possibilities of using units of contrasting colors \r\n in bands or other patterns are endless. Sample panels, or mockups, can \r\n aid in selecting the desired color by showing the finished appearance. \r\n Another aesthetic feature to consider when selecting \r\n brick is the texture. Textures on brick can be smooth, wirecut (velour), \r\n stippled, bark, brushed, and more. The texture interacts with light and \r\n creates differing and interesting shadows. \r\n Unique design features can easily be achieved \r\n by using special brick shapes. Brick can be molded and formed into any \r\n shape, from simple sloped sill shapes to fancy watertable brick. For most \r\n manufacturers, molded shapes are easier to produce than extruded shapes, \r\n because the molded, or soft-mud process is more adaptable to making brick \r\n shapes than the extruded process. Making very large shapes can be difficult \r\n in either process because of problems with proper drying and firing. \r\n Physical Properties \r\n There are many physical properties which may \r\n influence the selection of brick. Some of these include durability, absorption, \r\n compressive strength and abrasion resistance. This Technical Notes \r\n will provide a basic understanding of these properties to aid in selection \r\n of the proper brick. Physical properties required for proper performance \r\n are given in the appropriate American Society for Testing and Materials \r\n (ASTM) specification for brick. \r\n Durability . Currently, there are two \r\n accepted methods for demonstrating durability under ASTM standards: 1) \r\n durability as predicted by compressive strength, absorption, and saturation \r\n coefficient, or 2) durability as determined by compressive strength and \r\n passing 50 cycles of the freeze and thaw test. Specific criteria in each \r\n ASTM specification determines grade or class designations. Because of \r\n the varying climates and applications of brick, specific grades are required. \r\n Brick is assigned a grade of severe, moderate, or negligible weathering. \r\n Fig. 2 indicates areas of the U.S. with differing weather conditions. \r\n Table 1 defines where each grade is required. Technical Notes 9A \r\n describes this in more detail. Most manufacturers make brick to meet the \r\n severe weathering (SW) grade so they may ship brick to all parts of the \r\n country. Some manufacturers produce brick complying only to the moderate \r\n weathering (MW) grade. Brick manufacturers can furnish certification that \r\n their product will meet a certain grade or class. \r\n \r\n \r\n \r\n \r\n Weathering Indexes in the United States \r\n FIG. 2 \r\n \r\n Absorption . Absorption can be broken \r\n into two distinct categories - absorption and initial rate of absorption (IRA). Both are important in \r\n selecting the appropriate brick. Absorption of a brick is expressed as \r\n a percentage, and defined as the ratio of the weight of water that is \r\n taken up into its body divided by the dry weight of the unit. Water absorption \r\n is measured in two ways: 1) submerging the test specimen in room temperature \r\n water for a period of 24 hours, and 2) submerging the test specimen in \r\n boiling water for five hours. These are known as the 24 hour cold water \r\n absorption, and the 5 hour boiling water absorption, respectively. These \r\n two are used to calculate the saturation coefficient by dividing the 24 \r\n hour cold water absorption by the 5 hour boiling. The saturation coefficient \r\n is used to help predict durability. \r\n \r\n \r\n \r\n The initial rate \r\n of absorption (IRA) or suction is the rate of how much water a brick draws \r\n (sucks) in during the first minute after contact with water. The suction \r\n has a direct bearing on the bon between brick and mortar. It has been \r\n shown by test results that when a brick has high suction (over 30 grams/min/30 \r\n in 2 ), a strong, watertight \r\n joint may not be achieved. Therefore, high suction brick should be wetted \r\n prior (3 hrs to 24 hrs) to laying to reduce the suction and allow the \r\n bricks surface to dry. Very low suction brick should be covered and kept \r\n dry on the jobsite. Brick manufacturers can furnish values of IRA and \r\n saturation coefficient of the selected units. The material specifier or \r\n supplier should inform the mason contractor about the suction of the brick \r\n prior to construction. \r\n Compressive Strength . The strength of \r\n a unit is used to determine durability and also compressive strength of \r\n a wall assembly. Typically, most materials are judged on the basis of \r\n strength. However, it is important not to sacrifice properties of durability \r\n and bond for higher compressive strengths. Most brick currently produced \r\n have strengths ranging from 3,000 psi to over 20,000 psi, averaging around \r\n 10,000 psi. Achieving sufficient compressive strength with brick is seldom \r\n a problem. \r\n Abrasion Resistance . This property is \r\n important when brick is used as paving. The resistance to abrasion is \r\n affected by the degree of burning and by the nature of the raw material. \r\n Abrasion is evaluated in terms of cold water absorption and compressive \r\n strength. These two properties produce an abrasion index which is used \r\n to determine the type of traffic which is suitable for a particular brick. \r\n Application \r\n A building must perform the functions for which \r\n it is designed. The materials selected for a project must also perform \r\n as intended. The designer must consider all factors which a wall or material \r\n must withstand. Some of the more important factors include moisture penetration, \r\n temperature variations and structural loads. No one standard assembly \r\n is suitable for all localities, occupancies, or designs; therefore, the \r\n designer must evaluate each factor and its relative effect on the selection \r\n of a material or assembly. \r\n Moisture Penetration . The use of quality \r\n materials and workmanship is essential in obtaining a satisfactory degree \r\n of water resistance. When water passes through brick masonry walls, it \r\n invariably does so through separations or cracks between the brick units \r\n and the mortar. It is virtually impossible for significant amounts of \r\n water to pass directly through a brick unit. Therefore, brick units which \r\n develop a complete bond with mortar offer the best moisture resistance. \r\n Brick and mortar properties should be compared to provide compatible materials \r\n which result in more watertight walls. Currently, there are no requirements \r\n for the degree of water resistance of a wall. \r\n Temperature Variations . Brick must withstand \r\n daily temperature cycles and seasonal extremes (-30 ° F to \r\n 120 ° F) depending on location, throughout its life. Thermal \r\n expansion and contraction of brick is not critical to the selection of \r\n brick, but it is important to designers and this movement should be provided \r\n for in design and construction. Brick also withstands temperature extremes \r\n in fires. Since brick is a fired material, it will not burn and acts as \r\n an excellent barrier to fire because it is non-combustible. \r\n Structural Loads . Ability to withstand \r\n either gravity or lateral loads relies heavily on brick strength, mortar \r\n strength and strength of the wall assembly. Compressive strength requirements \r\n found in the ASTM specifications for brick are based on durability performance. \r\n Structural analysis may require a higher compressive strength in order \r\n to resist the applied loads. It is common to use high strength units in \r\n loadbearing or reinforced brick masonry projects. \r\n Cost \r\n Material selection is often based on cost, usually \r\n initial cost only. Although initial cost is important, lifecycle cost \r\n is a better tool for making critical decisions. When deciding between \r\n different materials, all costs involved including labor and maintenance \r\n costs, future value and life expectancy should be considered. The selling \r\n price of brick is governed by many factors, including manufacturing methods \r\n and appearance of the unit. When considering different brick, one must \r\n take into account shipping costs. Since most prices quoted are plant prices, \r\n distance between the manufacturing plant and the jobsite is a major determinant \r\n of these shipping costs. Brick manufacturers and distributors can supply \r\n brick prices and shipping prices. Many of the Masonry Institutes throughout \r\n the country provide cost comparisons between different materials. \r\n Availability \r\n The availability of brick fluctuates with the \r\n time of the year and current construction trends and demands. On the average, \r\n brick production time runs about 5 days from pugging of the clay to the \r\n finished, fired product. This can change depending on many factors such \r\n as variations in raw materials, forming process, and kiln types. Many \r\n brick manufacturers have stockpiles of brick, but usually only a small \r\n quantity of each brick type. This may satisfy smaller jobs, but for large \r\n projects requiring large quantities of brick, a special production run \r\n must be made for the job. Most manufacturers have a set schedule as to \r\n when they produce a certain brick shade. It is at this time that the size \r\n of the run will be increased to accommodate the large order. It is wise \r\n to question the manufacturer as to a bricks availability. \r\n It is best to purchase all brick from the same \r\n production run because there are typically slight color variations between \r\n runs. All manufacturers have quality controls to keep this at a minimum. \r\n SUMMARY \r\n This Technical Notes has described which \r\n characteristics of brick are important in selecting a particular unit. \r\n There is a wide selection of brick from which to choose. Selecting the \r\n appropriate material is important to the projects longevity and appearance. \r\n The remainder of this Technical Notes \r\n is \"Recommended Practices Relating to the Responsibilities and Relationships \r\n in Brick Construction\". This document, developed jointly by the Brick \r\n Institute of America, National Association of Brick Distributors, and \r\n the Mason Contractors Association of America, explains some potential \r\n problems that may occur during and after the selection process, and how \r\n to avoid them. \r\n The information and suggestions contained in \r\n this Technical Notes are based on the available data and the experience \r\n of the technical staff of the Brick Institute of America. The information \r\n and recommendations contained herein should be used along with good technical \r\n judgment and an understanding of the properties of brick masonry. Final \r\n decisions on the use of the information discussed in this Technical \r\n Notes are not within the purview of the Brick Institute of America \r\n and must rest with the project designer, owner or both. \r\n REFERENCES \r\n More detailed information on subjects discussed \r\n here can be found in the following publications: \r\n 1. Brick Institute of America Technical Notes 7 Series - Water Resistance \r\n of Brick Masonry \r\n 2. ASTM Standard Specifications for Brick. \r\n \r\n \r\n \r\n \r\n Most brick construction projects are completed \r\n with the result that building owner, architect, contractor and brick supplier \r\n are completely satisfied with the final product. In a few instances, however, \r\n mistakes are made or misunderstandings occur that spoil what would otherwise \r\n be a rewarding and profitable experience for all concerned. \r\n Recognizing this fact, the brick industry, \r\n including representatives from the manufacturing, sales and installation \r\n segments, have developed this \"Recommended Practice\" which identifies \r\n the areas in which misunderstandings are most likely to occur and suggests \r\n a procedure to be followed that will minimize the effects when mistakes \r\n do occur. \r\n The \"Recommended Practices Relating to the \r\n Responsibilities and Relationships in Brick Construction\" was developed \r\n through the cooperative efforts of the Brick Institute of America, the \r\n National Association of Brick Distributors and the Mason Contractors Association \r\n of America. Draft copies of the complete document were distributed to \r\n other construction industry associations for review and, where appropriate, \r\n their advice was included in the final \"Recommended Practice\". \r\n INTRODUCTION \r\n The purpose of this recommended practice is \r\n to prevent misunderstandings which might result from improper ordering, \r\n sampling procedures, or ill-timed examination of field work. \r\n As in all business relationships, there is a \r\n responsibility among the parties involved - manufacturers, distributors, \r\n contractors, mason contractors, architects, engineers, owners and/or their \r\n respective representatives or agents in producing an acceptable masonry \r\n project. It is to the mutual advantage of all concerned that problems, \r\n when encountered, be identified and addressed in a timely manner. \r\n Contract Allowances \r\n The practice of using only dollar value allowances \r\n for brick in construction specifications and/or contracts is not recommended \r\n because this method does not provide sufficient information to make an \r\n informed bid. If an allowance is used in a construction contract, the \r\n size and grade or other specifications of the unit should be stated so \r\n that an informed bid may be given by the contractor or supplier. In the \r\n initial establishment of an allowance, the parties should take into consideration \r\n the extra cost of special shapes and other special units required by the \r\n project. \r\n Selection and Sampling \r\n Brick is subject to variations in color between \r\n production runs and occasionally within the same run. Modern manufacturing \r\n processes encompass the use of automatic equipment, the use of which may \r\n also result in minor imperfections in color and texture. \r\n The selection of the color, texture and type \r\n of brick, tile or paving is the responsibility of the owner and/or his \r\n representative. Usually, small samples are used for the preliminary selection \r\n and may not exactly represent the complete range of colors and textures \r\n encountered in production runs. \r\n Sometimes, a small sample is sufficient for \r\n determining the final selection. However, when large amounts of brick \r\n are to be erected on a flat plain surface, the prudent owner, contractor, \r\n distributor or manufacturer should direct or request that the final selection \r\n be made from a field panel (also called a \"mock-up\"). A field panel is \r\n typically constructed as a free-standing sample which will later be torn \r\n down when the project is complete. Usually, a quantity of brick equal \r\n to 100 standard-size brick will be used for the construction of the free-standing \r\n field panel. \r\n If an owner or the owners representative requires \r\n the field panel or sample, the distributor or manufacturer may not have \r\n control over the actual erection which is frequently performed by a separate \r\n mason contractor. The party or parties who have control over the work \r\n of the mason contractor (either by direct contract or by other powers) \r\n should take appropriate action during the erection of the field panel \r\n or sample to assure that no additions or deletions are made to the brick \r\n supplied by the distributor and manufacturer, unless written approval \r\n has been received from the manufacturer for such a change. \r\n Field panels should be constructed from the \r\n production run that is intended for shipment to the project. In the event \r\n that the field panel has to be constructed for inspection and final selection \r\n before the production run for that project, the owner and the manufacturer \r\n should agree in writing upon such a use. The manufacturer may reserve \r\n the right to resample from the actual run before shipment commences. \r\n When the field panel has been formally approved, \r\n it is the manufacturers responsibility to provide brick as represented \r\n in the sample panel. A strap or control sample is normally retained at \r\n the plant. \r\n Typically, the contractor and mason contractor \r\n are responsible for preserving and maintaining the integrity of the field \r\n panel which is considered the project standard for bond, mortar, workmanship \r\n and appearance, and as the standard for comparison until the masonry has \r\n been completed and accepted by the owner or the owners representative. \r\n If the owner or his representative elects not to have a field panel erected, \r\n the parties may choose to use the first 100 square feet of actual construction \r\n as the field panel. \r\n The owner or a designated representative is \r\n responsible for acceptance of the work and, therefore, should inspect, \r\n as necessary, while the work progresses. This is especially critical at \r\n the start of the project to ensure that the color, texture and workmanship \r\n are representative of the sample field panel and is acceptable. \r\n The selling party, whether the manufacturer, \r\n distributor or dealer, should visit the jobsite, as necessary, and, in \r\n addition, should be available for meetings and consultation in the event \r\n the owner or the owners representative discovers a problem. \r\n In the event the work does not meet with the \r\n approval of the owner or the owners representative, the owner should \r\n immediately notify the contractor in writing, and appropriate action should \r\n be taken to correct the problem. If necessary, this may require that the \r\n work be stopped and that all interested parties meet to resolve the problem. \r\n Ordering \r\n All brick orders should be submitted in writing \r\n by the purchaser to the distributor or manufacturer, whichever is appropriate. \r\n The order should include and clearly identify the following: \r\n A. Job name and type; \r\n B. Location; \r\n C. Owner; \r\n D. Architect; \r\n E. General contractor; \r\n F. Material quantities, including types and quantities of special or non-standard \r\n items, should be accurately determined so that the order may be shipped \r\n in its entirety. Brick should be described by actual dimensions rather \r\n than by generic or trade name; \r\n G. Unit prices, including conditions such as escalation of prices, freight \r\n rates and terms; \r\n H. Delivery schedules, including anticipated start date and rate of shipments; \r\n I. Other information pertinent to the order such as a copy of that portion \r\n of the specifications which applies to the brickwork. \r\n \r\n If special shapes are required, detailed large-scale \r\n drawings should be supplied by the purchaser through appropriate channels. \r\n Most orders are processed through a chain of purchasing which begins with \r\n the signing of the owner-contractor agreement and ends with the receipt \r\n of an order by the manufacturer. Other parties may be involved in this \r\n process as intermediaries or secondary parties, including, among others, \r\n the owners representative, the contractor, the mason contractor and the \r\n distributor. Each party in the chain should endeavor to promptly process \r\n the order and give approvals as necessary so as to cause minimal delays \r\n in the schedule of the project. Upon receipt of the order, the manufacturer \r\n typically acknowledges the order and should promptly advise the parties \r\n through the chain of purchasing about any unacceptable or impractical \r\n terms. \r\n It should also be understood by all parties \r\n that by the placement of a written order the purchaser incurs the specific \r\n payment responsibility for all special and non-standard items. \r\n References \r\n Brick Industry Association, 11490 Commerce \r\n Park Dr., Reston, VA 20191, (703) 620-0010. \r\n Mason Contractors Association of America, \r\n 1910 South Highland Avenue, #101, Lombard, IL 60148, (708) 782-6786. \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n "}]}
