IBC Design 721.1(3) 19-1.1

4-Hour Fire Rated Floor and beam construction consisting of 3"-deep… — Suspended envelope ceiling of perlite…

IBC Table 721.1(3), Item 19-1.1: Floor and beam construction consisting of 3"-deep cellular steel floor unit mounted on steel members with 1:4 (proportion of Portland cement to perlite aggregate) perlite-concrete floor slab on top.. Ceiling: Suspended envelope ceiling of perlite gypsum plaster on metal lath attached to 3/4" cold-rolled channels, secured to 1-1/2" cold-rolled channels spaced 42" on center supported by 0.203 inch (No. 6 B.W. gage) wire 36" on center. Beams in envelope with 3" minimum airspace between beam soffit and lath have a 4-hour rating. Minimum slab thickness — 4-hr: 2". Minimum ceiling thickness — 4-hr: 1". Prescriptive assembly from the adopted building code — see table footnotes for conditions.