7205.3 Wall Height. Bale walls shall not exceed one story in height and the bale portion
shall not exceed a height to width ratio of 5.6 : 1 (for example, the maximum height for
the bale portion of a 23 inch thick wall would be 10 feet - 8 inches), unless the structure
is designed by an engineer or architect licensed by the State to practice as such, and
approved by the Building Official.
Exception: In the non-load bearing exterior end walls of structures with gable or
shed roofs, an approved continuous assembly shall be required at the roof bearing
assembly level.
7205.4 Unsupported Wall Length. The ratio of unsupported wall length to thickness,
for bale walls, shall not exceed 13 : 1 (for a 23 inch thick wall, the maximum
unsupported length allowed is 25 feet), unless the structure is designed by an engineer
or architect licensed by the State to practice as such, and approved by the Building
Official.
7205.5 Allowable Loads. The allowable vertical load (live and dead load) on the top of
load-bearing bale walls shall not exceed 360 pounds per square foot (psf) and the
resultant load shall act at the center of the wall. Bale structures shall be designed to
withstand all vertical and horizontal loads as specified in Chapter 16.
7205.6 Foundations. Foundations shall be sized to accommodate the thickness of the
bale wall and the load created by the wall and roof live and dead loads. Foundation
(stem) walls which support bale walls shall extend to an elevation of not less than 6
inches above adjacent ground at all points. The minimum width of the footing shall be
the width of the bale it supports, except that the bales may overhang the exterior edge
of the foundation by not more than 3 inches to accommodate rigid perimeter insulation.
Footings shall extend a minimum of 12 inches below natural, undisturbed soil, or to frost
line, whichever is lower.
7205.7 Wall and Roof Bearing Assembly Anchorage.
7205.7.1 General. Vertical reinforcing bars with a minimum diameter of 1/2", shall be
embedded in the foundation a minimum depth of 6 inches, and shall extend above
foundation a minimum of 12 inches. These vertical bars shall be located along the
centerline of the bale wall, spaced not more than 2 feet apart. A vertical bar shall also
be located within 1 foot of any opening or corner, except at locations occupied by anchor
bolts.
7205.7.2 Intersecting Walls. Walls of other materials intersecting bale walls shall be
attached to the bale wall by means of one or more of the following methods or an
acceptable equivalent:
1. Wooden dowels at least 5/8" in diameter of sufficient length to provide 12
inches of penetration into the bale, driven through holes bored in the abutting
stud, and spaced to provide one dowel connection per bale.
2. Pointed wooden stakes, at least 12 inches in length and 1-1/2" by 3-1/2" at the
exposed end, fully driven into each course of bales, as anchorage points.
3. Bolted or threaded rod connection of the abutting wall, through the bale wall,
to a steel nut and steel or plywood plate washer, a minimum of 6 inches square
and a minimum thickness of 3/16" for steel and 1/2" for plywood, in at least
three locations.
7205.7.3 Anchor Bolts. Load bearing bale walls shall be anchored to the foundation by
1/2" diameter steel anchor bolts embedded at least 7 inches in the foundation at intervals
of 6 feet or less. A minimum of two anchor bolts per wall shall be provided with one
bolt located within 36 inches of each end of each wall. Sections of 1/2" diameter
threaded rod shall be connected to the anchor bolts, and to each other, by means of
threaded coupling nuts and shall extend through the roof bearing assembly and be
fastened with a steel washer and nut. Bale walls and roof bearing assemblies may be
anchored to the foundation by means of other methods which are adequate to resist
uplift forces resulting from the design wind load. There shall be a minimum of two
points of anchorage per wall, spaced not more than 6 feet apart, with one located within
36 inches of each end of each wall.
The dead load of the roof and ceiling systems will produce vertical compression of the
bales. Regardless of the anchoring system used to attach the roof bearing assembly to
the foundation, prior to installation of wall finish materials, bolts or straps shall be re-tightened to compensate for this compression.
7205.7.4 Moisture Barrier. A moisture barrier shall be used between the top of the
foundation and the bottom of the bale wall to prevent moisture from migrating through
the foundation into the bottom course of bales. This barrier shall consist of one of the
following:
1. cementitious waterproof coating;
2. type 30 asphalt felt over an asphalt emulsion;
3. sheet metal flashing, sealed at joints;
4. other approved building moisture barrier. All penetrations through the moisture
barrier, as well as all joints in the barrier, must be sealed with asphalt, caulking or
an approved sealant.
7205.7.5 Stacking and Pinning. Bales in load-bearing walls shall be laid flat and stacked
in running bond where possible, with each bale overlapping the two bales beneath it.
Bales in non load-bearing walls may be laid either flat or on-edge and stacked in running
bond where possible. For non-load bearing walls, bales may be laid either flat or on-edge. Bales in load bearing walls shall be laid flat and stacked in a running bond, where
possible, with each bale overlapping the two bales beneath it. Overlaps shall be a
minimum of 12 inches. Gaps between the ends of bales which are less than 6 inches in
width can be filled by an untied flake inserted snugly into the gap.
The first course of bales shall be laid by impaling the bales on the vertical bars or
threaded rods, if any, extending from the foundation. When the fourth course has been
laid, #4 rebar pins, or an acceptable equivalent, long enough to extend through all four
courses, shall be driven down through the bales, two in each bale, located so that they
do not pass within six inches of, or through the space between the ends of any two bales.
The layout of these pins shall approximate the layout of the vertical bars extending from
the foundation. As each subsequent course is laid, two such pins, long enough to extend
through the course being laid and the three courses immediately below it, shall be driven
down through each bale. This pinning method shall be continued to the top of the wall.
In walls seven or eight courses high, pinning at the fifth course may be eliminated.
Only full-length bales shall be used at corners of load bearing walls, unless exceptions
are designed by an engineer or architect licensed by the State to practice as such, and
approved by the Building Official.
Vertical #4 rebar pins, or an acceptable alternative, shall be located within 1 foot of all
corners or door openings.
Staples, made of #3 or larger rebar formed into a "U" shape, at least 18 inches long
with two 6 inch legs, shall be used at all corners of every course, driven with one leg into
the top of each abutting corner bale. In lieu of staples, corner bales may be tied
together , by a method approved by the building official.
7205.7.5.1 Alternative pinning method. When the third course has been laid, vertical
#4 rebar pins, or an acceptable equivalent, long enough to extend through all three
courses, shall be driven down through the bales, two in each bale, located so that they
do not pass within 6 inches of, or through the space between the ends of any two bales.
The layout of these rebar pins shall approximate the layout of the rebar pins extending
from the foundation. As each subsequent course is laid, two such pins, long enough to
extend through that course and the two courses immediately below it, shall be driven
down through each bale. This pinning method shall be continued to the top of the wall.
7205.7.6 Roof Bearing Assembly. Load bearing bale walls shall have a roof bearing
assembly at the top of the wall to bear the roof load and to provide a means of
connecting the roof structure to the foundation. The roof bearing assembly shall be
continuous along the tops of structural walls.
An acceptable roof bearing assembly option consists of two double 2" X 6", or larger,
horizontal top plates, one located at the inner edge of the wall and the other at the
outer edge. Connecting the two doubled top plates and located horizontally and
perpendicular to the length of the wall shall be 2" X 6" cross members spaced no more
than 72 inches center to center, and as required to align with the threaded rods
extending from the anchor bolts in the foundation. The double 2" X 6" top plates shall
be face nailed with 16d nails staggered at 16 inches on
center, with laps and intersections face nailed with four 16d nails. The cross members
shall be face nailed to the top plates with four 16d nails at each end. Corner
connections shall include overlaps nailed as above or an acceptable equivalent such as
plywood gussets or metal plates. Alternatives to this roof bearing assembly option must
provide equal or greater vertical rigidity and provide horizontal rigidity equivalent to a
continuous double 2 by 4 top plate..
The connection of roof framing members to the roof bearing assembly shall comply with
the appropriate sections of the UBC.
7205.7.7 Openings and Lintels.
All openings in load bearing bale walls shall be a minimum of one full bale length from
any outside corner, unless exceptions are designed by an engineer or architect licensed
by the State to practice as such, and approved by the Building Official.
7205.7.7.1 Openings. Openings in exterior bale walls shall not exceed 50 percent of the
total wall area, based on interior dimensions, where the wall is providing resistance to
lateral loads, unless the structure is designed by an engineer or architect licensed by the
State to practice as such, and approved by the Building Official.
7205.7.7.2 Lintels. Wall and/or roof load present above any opening shall be carried,
or transferred to the bales below by one of the following:
1. a structural frame,
2. a lintel (such as an angle-iron cradle, wooden beam, wooden box beam).
Lintels shall be at least twice as long as the opening is wide and extend at least
24" beyond either side of the opening. Lintels shall be centered over openings,
and shall not exceed the load limitations of section 7205.5 by more than 25
percent.
7205.7.8 Moisture Protection. All weather-exposed bale walls shall be protected from
water damage. An approved building moisture barrier shall be used to protect at least
the bottom course of bales, but not more than the lower one-third of the vertical exterior
wall surface, in order to allow natural transpiration of moisture from the bales. The
moisture barrier shall have its upper edge inserted at least 6 inches into the horizontal
joint between two courses of bales, and shall extend at least 3 inches below the top of
the foundation. Bale walls shall have special moisture protection provided at all window
sills. Unless protected by a roof, the tops of walls shall also be protected. This moisture
protection shall consist of a waterproof membrane, such as asphalt-impregnated felt
paper, polyethylene sheeting, or other acceptable moisture barrier, installed in such
manner as to prevent water from entering the wall system at window sills or at the tops
of walls.
7205.7.9 Wall Finishes. Interior and exterior surfaces of bale walls shall be protected
from mechanical damage, flame, animals, and prolonged exposure to water. Bale walls
adjacent to bath and shower enclosures shall be protected by a moisture barrier.
Cement stucco shall be reinforced with galvanized woven wire stucco netting or an
acceptable equivalent. Such reinforcement shall be secured by attachment through the
wall at a maximum spacing of 24 inches horizontally and 16 inches vertically, using a
method approved by the Building Official.
Where bales abut other materials the plaster/stucco shall be reinforced with galvanized
expanded metal lath, or an acceptable equivalent, extending a minimum of 6 inches onto
the bales.
Earthen and lime-based plasters may be applied directly onto the exterior and interior
surface of bale walls without reinforcement, except where applied over materials other
than straw. Weather-exposed earthen plasters shall be stabilized using a method
approved by the building official.
Lime based plasters may be applied directly onto the exterior surface of bale walls
without reinforcement, except where applied over materials other than straw.
7205.7.10 Electrical. All wiring within or on bale walls shall meet all provisions of the
National Electrical Code adopted by this jurisdiction. Type NM or UF cable may be
used, or wiring may be run in metallic or non-metallic conduit systems.
Electrical boxes shall be securely attached to wooden stakes driven a minimum of 12
inches into the bales, or an acceptable equivalent.
7205.7.11 Plumbing. Water or gas pipes within bale walls shall be encased in a
continuous pipe sleeve to prevent leakage within the wall. Where pipes are mounted on
bale walls, they shall be isolated from the bales by a moisture barrier.
7206 - PRIVACY/LANDSCAPE WALLS
7206.1 General. This section covers free-standing or attached bale privacy or landscape
walls, not exceeding 6 feet in height, from final grade to top of wall. Bales may be
stacked either flat or on-edge. Alternate methods, other than those listed in this section,
may be approved by the building official.
7206.2 Foundations. The minimum foundation shall consist of an 8 inch thick
reinforced concrete stem wall, over an approved footing. Minimum width of the stem
wall shall be equal to the width of the bottom bale. Stem walls shall have continuous
horizontal reinforcement consisting of two #4 bars with 24 inches minimum lap at
splices.
7206.2.1 Reinforcement. Vertical reinforcing bars, a minimum 3/8" in diameter, shall
be placed in the center of the stem wall, two per bale, and extend up a minimum of 24
inches, and be embedded a minimum of 4 inches into the concrete stem wall. Bales
shall be pinned, using two 3/8" diameter bars per bale, and use pins long enough to
provide at least one vertical bar from stem wall to top of wall, with a minimum of one
full bale overlap where not continuous.
For the purpose of attaching stucco mesh to the wall, 12d or larger galvanized common
double-headed nails shall be embedded in the concrete a minimum of 1 inch below the
top of the stem wall, with the heads embedded a minimum of 2 inches into the concrete,
and the points extending a minimum of 3/4" from the face of the stem wall, and spaced
a minimum of 6" on center on both sides of the wall.
7206.2.2 Moisture Barrier. A moisture barrier shall be used between the top of the
stem wall and the first course of bales. A moisture barrier shall also be used to protect
the tops of bales at the top of walls, and shall extend 6 inches down on either side of the
wall.
7206.2.3 Stucco Mesh. Stucco mesh, 20 gauge or heavier, shall be attached by means
of clinching the embedded nails on one side of the wall, stretching a continuous piece
of netting tightly over the top of the wall, and fastening the netting in the same manner
on the opposite side of the wall.
7206.2.4 Wall Finish. Walls shall be finished with cement stucco, or stabilized mud
