IBC Design 721.1(2) 14-1.5

2-Hour Fire Rated Wood studs—interior partition with gypsum wallboard each side — 2" x 4" wood studs 16" on center with two layers 5/8" Type X gypsum…

IBC Table 721.1(2), Item 14-1.5 (l, m) (Wood studs—interior partition with gypsum wallboard each side): 2" x 4" wood studs 16" on center with two layers 5/8" Type X gypsum wallboard (e) each side. Base layers applied vertically and nailed with 6d cooler (n) or wallboard (n) nails at 9" on center. Face layer applied vertically or horizontally and nailed with 8d cooler (n) or wallboard (n) nails at 7" on center. For nail-adhesive application, base layers are nailed 6" on center. Face layers applied with coating of approved wallboard adhesive and nailed 12" on center. Minimum finished thickness (face-to-face) — 2-hr: 6". Prescriptive assembly from the adopted building code — thicknesses are code minimums, see table footnotes for conditions.