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Home / Assemblies / UL L174
UL L1741.5-hr Fire RatingRoof/CeilingLoad-Bearing
Steel StudDesign

Steel Truss Roof/Ceiling — single layer 5/8" Type X gypsum board

UL-listed 1.5-hour fire-rated steel truss roof/ceiling assembly. Light gauge steel trusses at 24" o.c. with Rigid insulation board, single layer of 5/8" Type X gypsum board on furring channels ceiling, 22 ga. steel deck.

Cross-Section Diagram

12345ROOF/CEILING ASSEMBLYSECTION · NOT TO SCALE5 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")
4Rigid insulation board
55/8" Type X gypsum board on furring channels(5/8")

Specifications

Fire Rating
1.5-Hour
Load Bearing
Yes
Total Thickness
14.62"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
L174
Assembly Type
Roof/Ceiling
Test Standard
CAN/ULC-S101
Construction Group
Non-Combustible
Number of Layers
5 layers

Applicable Codes

IBC 2021 Table 722.1

Construction Summary

Light gauge steel trusses at 24" o.c. with Rigid insulation board, single layer of 5/8" Type X gypsum board on furring channels ceiling, 22 ga. steel deck

Material Layers

LayerMaterialThickness
1Roof coveringvaries
222 ga. steel deckvaries
3Light gauge steel trusses at 24" o.c.12"-24"
4Rigid insulation board
55/8" Type X gypsum board on furring channels5/8"

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.