IBC Design 721.1(3) 9-1.1

4-Hour Fire Rated 3"-deep cellular steel deck with concrete slab on… — Suspended ceiling of vermiculite gypsum…

IBC Table 721.1(3), Item 9-1.1: 3"-deep cellular steel deck with concrete slab on top. Slab thickness measured to top.. Ceiling: Suspended ceiling of vermiculite gypsum plaster base coat and vermiculite acoustical plaster on metal lath attached at 6" intervals to 3/4" cold-rolled channels spaced 12" on center and secured to 1-1/2" cold-rolled channels spaced 36" on center with 0.065" (No. 16 B.W. gage) wire. 1-1/2" channels supported by No. 8 gage wire hangers at 36" on center. Beams within envelope and with a 2-1/2" airspace between beam soffit and lath have a 4-hour rating. Minimum slab thickness — 4-hr: 2-1/2". Minimum ceiling thickness — 4-hr: 1-1/8". Prescriptive assembly from the adopted building code — see table footnotes for conditions.