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BXUV.U450
Fire Resistance Ratings - ANSI/UL 263

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Fire Resistance Ratings - ANSI/UL 263


See General Information for Fire Resistance Ratings - ANSI/UL 263

Design No. U450

April 11, 2005

Nonbearing Wall Rating — 1, 3 or 4 HR. (See Items 1, 2, and 4)

    1. Floor and Ceiling Runners — Channel shaped 1/2 in. deep by 3-5/8 in. wide, No. 25 gauge painted or galvanized steel. Secured with 3/4 in. long concrete fasteners spaced 18 in. OC. For the 1 hour rating, width may be reduced to 2-1/2 in. to accommodate the 2-1/2 in. wide studs.
    2. Metal Studs — Channel shaped, 3-5/8 in. wide with 1-1/4 in. legs, with 1/4 in. folded back return flange legs, galvanized steel, spaced not more than 16 in. OC. Stud length 3/8 in. less than assembly height. Min. No. 25 MSG for the 1 and 3 hour rating. Min. No. 18 MSG for the 4 hour rating. For the 1 hour rating, width may be reduced to 2-1/2 in.

    3. Metal Mesh — (Used with Item 5) — Diamond mesh, expanded steel, 3.4 lbs/sq yd, 27 by 96 in. sheets tied to iron bands (Item 7) and at laps with No. 18 SWG wire spaced 6 in. OC. As an alternate to the diamond mesh and iron bands, 3/8 in. rib, 3.4 lbs/sq yd expanded metal lath. Fastened to studs (ribbed side against studs) with No. 18 SWG wire spaced 6 in. OC. Fastened to runners with 1/2 in. long self-drilling, self-tapping steel screws spaced 6 in. OC. Laps 6 in. min and tied with No. 18 AWG wire spaced 6 in. OC min. The metal lath may be provided with a paper backing. When provided with the paper backing, the paper backed side of the lath shall face the metal studs.
    4. Gypsum Board* — Any Classified 5/8 in. thick wallboard with beveled, square or tapered edges.

    For 1 Hr rating — One layer of wallboard on each side applied vertically with joints centered over studs. Fastened to studs with 1 in. long, Type S, self-tapping, self-drilling, wallboard screws spaced 8 in. OC at the joints located 3/8 in. from the edges and 12 in. OC in the field. Joints to be staggered from the inner layer.

    For 3 Hr rating — Two layers of wallboard on each side. The inner layer to be applied vertically with joints centered over studs. Fastened to studs with 1 in. long, Type S, self-tapping, self-drilling, wallboard screws spaced 8 in. OC at the joints located 3/8 in. from the edges and 12 in. OC in the field. The outer layer also applied vertically to be fastened to the studs (through the inner layer) using 1-5/8 in. long, Type S, self-drilling, self-tapping, wallboard screws spaced 8 in. OC at the joints located 3/8 in. from the edges and 12 in. OC in the field. Fasteners to be spaced 8 in. OC at the runners. Joints to be staggered from the inner layer.

    For 4 Hr rating — (Not Shown)— Three layers of wallboard on each side. Two inner layers to be applied in the same manner as the 3 hr rating. The outer layer may be applied vertically or horizontally and fastened to each stud through the two previous layers with 2-1/4 in. long, Type S, self-drilling, self-tapping steel screws spaced 3/8 in. from the edges, 8 in. OC in the field. Joints in each wallboard layer to be staggered from the joints in the adjacent layer and on opposite sides of studs.

    See Gypsum Board (CKNX) Category for names of manufacturers.

    5. Portland Cement Plaster — (Not Shown) — May be used in lieu of the layers of wallboard (Item 4) on metal lath side, 3/4 in. thick, applied in scratch coat consisting of 100 lb cement to 50 lb lime to 5-1/2 cu ft of sand and brown coat consisting of 100 lb cement to 50 lb lime to 6 cu ft of sand.
    6. Spray-Applied Fire Resistive Materials* — Sprayed in stud cavities to completely fill interior of walls. Min avg and min ind densities of 13 and 11 pcf, respectively for Types D-C/F and II. Min avg and min ind densities of 22 and 19 pcf, respectively, for Type HP. For method of density determination, refer to Design Information Section.

    ISOLATEK INTERNATIONAL — Types D-C/F, II or HP. Type EBS or Type X adhesive/sealer is optional.


    7. Joint Tape and Compound — (Used with Item 4; Not Shown) — Vinyl or casein, dry or premixed joint compound applied in two coats to joints and screw heads. Paper tape, 2 in. wide, embedded in first layer of compound over all joints.
    8. Building Paper — (Not Shown-Optional) — May be used on the exterior face of the wall assembly, between the metal studs and the metal mesh or lath, as a backing for the application of the plaster (Item 5). The building paper may be a single-ply asphalt saturated sheathing, woven polyolefin sheathing or similar vapor barrier materials.

    *Bearing the UL Classification Mark

Last Updated on 2005-04-11

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