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Home / Assemblies / UL L148
UL L1481-hr Fire RatingRoof/CeilingLoad-Bearing
Steel JoistFiberglass BattDesign

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

UL-listed 1-hour fire-rated steel truss roof/ceiling assembly. Steel bar joists at 48" o.c. with R-30 fiberglass batt, single layer of 5/8" Type X gypsum board on furring channels ceiling, 20 ga. steel deck.

Cross-Section Diagram

12345ROOF/CEILING ASSEMBLYSECTION · NOT TO SCALE5 LAYERSsee legend for ① ② ③
Legend
1Roof covering(varies)
220 ga. steel deck(varies)
3Steel bar joists at 48" o.c.(12"-24")
4R-30 fiberglass batt
55/8" Type X gypsum board on furring channels(5/8")

Specifications

Fire Rating
1-Hour
Load Bearing
Yes
Total Thickness
14.62"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
L148
Assembly Type
Roof/Ceiling
Test Standard
ASTM E119
Construction Group
Non-Combustible
Number of Layers
5 layers

Applicable Codes

IBC 2024 Table 722.1NFPA 5000

Construction Summary

Steel bar joists at 48" o.c. with R-30 fiberglass batt, single layer of 5/8" Type X gypsum board on furring channels ceiling, 20 ga. steel deck

Material Layers

LayerMaterialThickness
1Roof coveringvaries
220 ga. steel deckvaries
3Steel bar joists at 48" o.c.12"-24"
4R-30 fiberglass batt
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.