IBC Design 721.1(2) 15-2.2

2-Hour Fire Rated Exterior or interior walls — 3-5/8" No. 16 gage steel studs at 24" on center or 2" x 4" wood…

IBC Table 721.1(2), Item 15-2.2 (d) (Exterior or interior walls): 3-5/8" No. 16 gage steel studs at 24" on center or 2" x 4" wood studs at 24" on center. Metal lath attached to the exterior side of studs with minimum 1"-long No. 6 drywall screws at 6" on center and covered with minimum 3/4" thick Portland cement plaster. Thin veneer brick units of clay or shale complying with ASTM C1088, Grade TBS or better, installed in running bond in accordance with Section 1404.10. Combined total thickness of the Portland cement plaster, mortar and thin veneer brick units shall be not less than 2". Interior side covered with two layers of 5/8"-thick Type X gypsum wallboard. Bottom layer attached to studs with 1"-long No. 6 drywall screws at 24" on center. Top layer attached to studs with 1-5/8"-long No. 6 drywall screws at 12" on center. Minimum finished thickness (face-to-face) — 2-hr: 6-7/8". Prescriptive assembly from the adopted building code — thicknesses are code minimums, see table footnotes for conditions.