IBC Design 721.1(3) 5-2.1

2-Hour Fire Rated Reinforced concrete — 5/8" Type X gypsum wallboard, 0.018 inch (No.…

IBC Table 721.1(3), Item 5-2.1: Reinforced concrete. Ceiling: 5/8" Type X gypsum wallboard, 0.018 inch (No. 25 carbon sheet steel gage) by 7/8" deep by 2-5/8" hat-shaped galvanized steel channels with 1"-long No. 6 screws. The channels are spaced 24" on center, span 35" and are supported along their length at 35" intervals by 0.033" (No. 21 galvanized sheet gage) galvanized steel flat strap hangers having formed edges that engage the lips of the channel. The strap hangers are attached to the side of the concrete joists with 5/32" by 1-1/4"-long power-driven fasteners. The wallboard is installed with the long dimension perpendicular to the channels. End joints occur on channels and supplementary channels are installed parallel to the main channels, 12" each side, at end joint occurrences. The finished ceiling is located approximately 12" below the soffit of the floor slab. Minimum slab thickness — 2-hr: 2-1/2". Minimum ceiling thickness — 2-hr: 5/8". Prescriptive assembly from the adopted building code — see table footnotes for conditions.