IBC Design 721.1(2) 15-1.8

2-Hour Fire Rated Exterior or interior walls — 2" x 6" wood studs 16" on center. The exterior face has a layer of…

IBC Table 721.1(2), Item 15-1.8 (l, m) (Exterior or interior walls): 2" x 6" wood studs 16" on center. The exterior face has a layer of 5/8" Type X gypsum sheathing placed vertically with 6d box nails 8" on center at joints and 12" on center elsewhere. An approved building paper is next applied, followed by 1-1/2" by No. 17 gage self-furred exterior lath attached with 8d by 2-1/2"-long galvanized roofing nails spaced 6" on center along each stud. Cement plaster consisting of a 1/2" scratch coat and a 1/2" brown coat is then applied. The plaster may be placed by machine. The scratch coat is mixed in the proportion of 1:4 by weight, plastic cement to sand. The brown coat is mixed in the proportion of 1:5 by weight, plastic cement to sand. The interior is covered with 3/8" gypsum lath with 1" hexagonal mesh of No. 20 gage woven wire lath furred out 5/16" and 1" perlite or vermiculite gypsum plaster. Lath nailed with 1-1/8" by No. 13 gage by 19/64" head plasterboard glued nails spaced 5" on center. Mesh attached by 1-3/4" by No. 12 gage by 3/8" head nails with 3/8" furrings, spaced 8" on center. The plaster mix shall not exceed 100 pounds of gypsum to 2-1/2 cubic feet of aggregate. Minimum finished thickness (face-to-face) — 2-hr: 8-3/8". Prescriptive assembly from the adopted building code — thicknesses are code minimums, see table footnotes for conditions.