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Home / Assemblies / UL W146
UL W1464-hr Fire RatingFloor/CeilingLoad-BearingSTC 58
Wood JoistMulti-Layer GypsumMineral WoolHigh STCDesign

Wood Joist Floor/Ceiling — 4 layers 5/8" Type X gypsum board

UL-listed 4-hour fire-rated wood joist floor/ceiling assembly. TJI wood I-joists at 16" o.c. with R-30 mineral wool, 4 layers of 5/8" Type X gypsum board ceiling.

Cross-Section Diagram

12345678FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE8 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 16" o.c.(11.875")
4R-30 mineral wool
55/8" Type X gypsum board(5/8")
65/8" Type X gypsum board(5/8")
75/8" Type X gypsum board(5/8")
85/8" Type X gypsum board(5/8")

Specifications

Fire Rating
4-Hour
STC Rating
STC 58
Load Bearing
Yes
Total Thickness
15.88"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
W146
Assembly Type
Floor/Ceiling
Test Standard
UL 263
Construction Group
Light Frame
Number of Layers
8 layers

Applicable Codes

IRC R302.1IBC 2024 §722

Construction Summary

TJI wood I-joists at 16" o.c. with R-30 mineral wool, 4 layers 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 16" o.c.11.875"
4R-30 mineral wool—
55/8" Type X gypsum board5/8"
65/8" Type X gypsum board5/8"
75/8" Type X gypsum board5/8"
85/8" 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.