UL Design U419
1-Hour Fire Rated Steel Stud Partition — 1 to 4 hr by layers (the workhorse commercial partition)
UL Design U419 — non-bearing steel stud wall listed for 1, 2, 3 or 4-hour ratings. Channel-shaped steel studs (min 25 MSG, depths 1-5/8" to 3-5/8") at max 24" o.c., cut 3/8"–3/4" short of assembly height. Canonical 1-hour configuration: 3-1/2" min studs with one layer of 5/8" gypsum board each side. 2 hr = two layers of 1/2" or 5/8" over 1-5/8" studs; 3 hr = three layers; 4 hr = four layers (or two layers 3/4" over 2-1/2" studs with 2" mineral wool). Some thin-stud options require mineral wool batts. Vertical joints staggered one stud cavity on opposite sides.
Steel studs (25 MSG) @ 24" o.c., 1–4 layers gypsum each side by rating, insulation per option
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- Layer-by-layer components with thicknesses
- Cross-section diagram
- Applicable code sections and test standard
- 6 related assemblies