IBC Design 721.1(3) 11-1.1

2-Hour Fire Rated 1-1/2"-deep steel roof deck on steel-framing wood… — Ceiling of gypsum plaster on metal lath.…

IBC Table 721.1(3), Item 11-1.1: 1-1/2"-deep steel roof deck on steel-framing wood fiber insulation board, 17.5 pcf density on top applied over a 15-lb asphalt-saturated felt. Class A or B roof covering.. Ceiling: Ceiling of gypsum plaster on metal lath. Lath attached to 3/4" furring channels with 0.049" (No. 18 B.W. gage) wire ties spaced 6" on center. 3/4" channels saddle tied to 2" channels with doubled 0.065" (No. 16 B.W. gage) wire ties. 2" channels spaced 36" on center suspended 2" below steel framing and saddle tied with 0.165" (No. 8 B.W. gage) wire. Plaster mixed 1:2 for scratch coat and 1:3 for brown coat, by weight, gypsum-to-sand aggregate for 1-hour system. For 2-hour system, plaster mix is 1:2 by weight, gypsum-to-sand aggregate. Minimum slab thickness — 2-hr: 1-1/2" · 1-hr: 1". Minimum ceiling thickness — 2-hr: 7/8" · 1-hr: 3/4". Prescriptive assembly from the adopted building code — see table footnotes for conditions.