UL Design N761
2-Hour Fire Rated Open-Web Steel Joist — SFRM, min 12K5
UL Design N761 — steel joist floor design: min 12K5 open-web steel joist (8K1/10K1 alternates with greater thickness) supporting 1-1/2" to 3" steel floor units with 2-1/2" concrete over welded wire fabric; joists sprayed with SFRM. 12K5, NW concrete on fluted deck: 1 hr = 9/16", 1-1/2 hr = 1", 2 hr = 1-3/8", 3 hr = 2-1/4". Optional metal lath or glass fiber mesh on joist webs.
Min 12K5 joist under 2-1/2" concrete on steel deck, SFRM by rating
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- Layer-by-layer components with thicknesses
- Cross-section diagram
- Applicable code sections and test standard
- 6 related assemblies