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Home / Assemblies / UL L173
UL L1731-hr Fire RatingRoof/CeilingLoad-Bearing
Steel StudDesign

Steel Truss Roof/Ceiling — single layer Spray-applied fireproofing

UL-listed 1-hour fire-rated steel truss roof/ceiling assembly. Light gauge steel trusses at 24" o.c., single layer of Spray-applied fireproofing ceiling, 22 ga. steel deck.

Cross-Section Diagram

1234ROOF/CEILING ASSEMBLYSECTION · NOT TO SCALE4 LAYERSsee legend for ① ② ③
Legend
1Roof covering(varies)
222 ga. steel deck(varies)
3Light gauge steel trusses at 24" o.c.(12"-24")
4Spray-applied fireproofing(1-1/2")

Specifications

Fire Rating
1-Hour
Load Bearing
Yes
Total Thickness
15.5"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
L173
Assembly Type
Roof/Ceiling
Test Standard
ASTM E119
Construction Group
Non-Combustible
Number of Layers
4 layers

Applicable Codes

IRC R302.1

Construction Summary

Light gauge steel trusses at 24" o.c., single layer of Spray-applied fireproofing ceiling, 22 ga. steel deck

Material Layers

LayerMaterialThickness
1Roof coveringvaries
222 ga. steel deckvaries
3Light gauge steel trusses at 24" o.c.12"-24"
4Spray-applied fireproofing1-1/2"

Important Notice

This assembly listing is for reference only. Always verify against the current UL Product iQ database before specifying in construction documents. Material substitutions may void the fire rating. Consult with a qualified fire protection engineer for project-specific requirements.