IBC Design 721.1(1) 1-6.2
4-Hour Fire Rated Steel columns and all of primary trusses — Perlite or vermiculite gypsum plaster over self-furring…
IBC Table 721.1(1), Item 1-6.2 (Steel columns and all of primary trusses): protection by Perlite or vermiculite gypsum plaster over self-furring metal lath wrapped directly around column, lapped 1" and tied at 6" intervals with 0.049" (No. 18 B.W. gage) wire. Minimum insulating material thickness — 4-hr: 1-3/4" · 3-hr: 1-3/8" · 2-hr: 1". Prescriptive protection from the adopted building code — see table footnotes for conditions.
Perlite or vermiculite gypsum plaster over self-furring metal lath wrapped directly around column, lapped 1" and tied at 6" intervals with 0.049" (No. 18 B.W. gage) wire.
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