IBC Design 721.1(2) 15-1.6

2-Hour Fire Rated Exterior or interior walls — 2" x 6" fire-retardant-treated wood studs 16" on center. Interior…

IBC Table 721.1(2), Item 15-1.6 (l, m) (Exterior or interior walls): 2" x 6" fire-retardant-treated wood studs 16" on center. Interior face has two layers of 5/8" Type X gypsum with the base layer placed vertically and attached with 6d box nails 12" on center. The face layer is placed horizontally and attached with 8d box nails 8" on center at joints and 12" on center elsewhere. The exterior face has a base 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 self-furred exterior lath attached with 2-1/2", No. 12 gage galvanized roofing nails with a 3/8" diameter head and spaced 6" on center along each stud. Cement plaster consisting of a 1/2" brown coat is then applied. The scratch coat is mixed in the proportion of 1:3 by weight, cement to sand with 10 pounds of hydrated lime and 3 pounds of approved additives or admixtures per sack of cement. The brown coat is mixed in the proportion of 1:4 by weight, cement to sand with the same amounts of hydrated lime and approved additives or admixtures used in the scratch coat. Minimum finished thickness (face-to-face) — 2-hr: 8-1/4". Prescriptive assembly from the adopted building code — thicknesses are code minimums, see table footnotes for conditions.