IBC Design 721.1(1) 1-4.1
2-Hour Fire Rated Steel columns and all of primary trusses — Cement plaster over metal lath wire tied to 3/4"…
IBC Table 721.1(1), Item 1-4.1 (Steel columns and all of primary trusses): protection by Cement plaster over metal lath wire tied to 3/4" cold-rolled vertical channels with 0.049" (No. 18 B.W. gage) wire ties spaced 3" to 6" on center. Plaster mixed 1:2-1/2 by volume, cement to sand. Minimum insulating material thickness — 2-hr: 2-1/2" · 1-hr: 7/8". Prescriptive protection from the adopted building code — see table footnotes for conditions.
Cement plaster over metal lath wire tied to 3/4" cold-rolled vertical channels with 0.049" (No. 18 B.W. gage) wire ties spaced 3" to 6" on center. Plaster mixed 1:2-1/2 by volume, cement to sand.
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