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Home / Assemblies / UL L180
UL L1803-hr Fire RatingRoof/CeilingLoad-Bearing
Steel StudGypsum BoardDesign

Steel Truss Roof/Ceiling — 2 layers 5/8" Type X gypsum board

UL-listed 3-hour fire-rated steel truss roof/ceiling assembly. Light gauge steel trusses at 24" o.c. with Rigid insulation board, 2 layers of 5/8" Type X gypsum board on furring channels ceiling, 22 ga. steel deck.

Cross-Section Diagram

123456ROOF/CEILING ASSEMBLYSECTION · NOT TO SCALE6 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")
65/8" Type X gypsum board on furring channels(5/8")

Specifications

Fire Rating
3-Hour
Load Bearing
Yes
Total Thickness
15.25"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
L180
Assembly Type
Roof/Ceiling
Test Standard
UL 263
Construction Group
Non-Combustible
Number of Layers
6 layers

Applicable Codes

IBC 2021 §722IBC 2021 Table 722.1

Construction Summary

Light gauge steel trusses at 24" o.c. with Rigid insulation board, 2 layers 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"
65/8" 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.