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Home / Assemblies / UL L181
UL L1813-hr Fire RatingRoof/CeilingLoad-Bearing
Steel StudFiberglass BattDesign

Steel Truss Roof/Ceiling — 2 layers Spray-applied fireproofing

UL-listed 3-hour fire-rated steel truss roof/ceiling assembly. Light gauge steel trusses at 24" o.c. with R-30 fiberglass batt, 2 layers of Spray-applied fireproofing ceiling, 20 ga. steel deck.

Cross-Section Diagram

123456ROOF/CEILING ASSEMBLYSECTION · NOT TO SCALE6 LAYERSsee legend for ① ② ③
Legend
1Roof covering(varies)
220 ga. steel deck(varies)
3Light gauge steel trusses at 24" o.c.(12"-24")
4R-30 fiberglass batt
5Spray-applied fireproofing(1-1/2")
6Spray-applied fireproofing(1-1/2")

Specifications

Fire Rating
3-Hour
Load Bearing
Yes
Total Thickness
17"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
L181
Assembly Type
Roof/Ceiling
Test Standard
UL 263
Construction Group
Non-Combustible
Number of Layers
6 layers

Applicable Codes

IBC 2021 Table 722.1IBC 2024 Table 722.1

Construction Summary

Light gauge steel trusses at 24" o.c. with R-30 fiberglass batt, 2 layers of Spray-applied fireproofing ceiling, 20 ga. steel deck

Material Layers

LayerMaterialThickness
1Roof coveringvaries
220 ga. steel deckvaries
3Light gauge steel trusses at 24" o.c.12"-24"
4R-30 fiberglass batt—
5Spray-applied fireproofing1-1/2"
6Spray-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.