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Home / Assemblies / UL W148
UL W1481-hr Fire RatingFloor/CeilingLoad-BearingSTC 45
Wood JoistFiberglass BattDesign

Wood Joist Floor/Ceiling — single layer 5/8" Type X gypsum board

UL-listed 1-hour fire-rated wood joist floor/ceiling assembly. TJI wood I-joists at 24" o.c. with R-30 fiberglass batt, single layer of 5/8" Type X gypsum board ceiling.

Cross-Section Diagram

12345FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE5 LAYERSsee legend for ① ② ③
Legend
1Floor covering(varies)
21-1/8" T&G plywood subfloor(1-1/8")
3TJI wood I-joists at 24" o.c.(11.875")
4R-30 fiberglass batt
55/8" Type X gypsum board(5/8")

Specifications

Fire Rating
1-Hour
STC Rating
STC 45
Load Bearing
Yes
Total Thickness
14"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
W148
Assembly Type
Floor/Ceiling
Test Standard
ASTM E119
Construction Group
Light Frame
Number of Layers
5 layers

Applicable Codes

IRC R302.1IBC 2024 §722NFPA 5000

Construction Summary

TJI wood I-joists at 24" o.c. with R-30 fiberglass batt, single layer of 5/8" Type X gypsum board ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
21-1/8" T&G plywood subfloor1-1/8"
3TJI wood I-joists at 24" o.c.11.875"
4R-30 fiberglass batt—
55/8" Type X gypsum board5/8"

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.