Understanding
the UL Fire Resistance Directories
6
Furring
Channels:รก Resilient channels, 3/8 in. deep by 2-3/8 in. wide at the base and 1-3/8 in. wide
at the face, formed from 0.020 in. thick galv steel, spaced 12 in. OC. Channels secured to each truss with 1-1/4 in. long Type S
steel screws. Channels
overlapped 4 in. at splices. Channels oriented opposite at wallboard butt
joints (spaced 6 in. OC) as shown in the above illustration.
Ceiling
Damper: Maximum nominal area, 324 sq in. Maximum
square size, 18 in. by 18 in. Rectangular sizes not to exceed 324 sq in. with a maximum
width of 18 in. Maximum
damper height is 14 in.
Installed in accordance with the manufacturers installation instructions
provided with the damper. Maximum
damper openings not to exceed 324 sq in. per 100 sq ft of ceiling area.
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