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Home / Assemblies / UL W174
UL W1743-hr Fire RatingFloor/CeilingLoad-BearingSTC 53
Wood JoistGypsum BoardFiberglass BattDesign

Wood Joist Floor/Ceiling — 3 layers 5/8" Type X gypsum board

UL-listed 3-hour fire-rated wood joist floor/ceiling assembly. 2x10 wood joists at 24" o.c. with R-30 fiberglass batt, 3 layers of 5/8" Type X gypsum board ceiling.

Cross-Section Diagram

1234567FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE7 LAYERSsee legend for ① ② ③
Legend
1Floor covering(varies)
23/4" plywood subfloor(3/4")
32x10 wood joists at 24" o.c.(9.25")
4R-30 fiberglass batt
55/8" Type X gypsum board(5/8")
65/8" Type X gypsum board(5/8")
75/8" Type X gypsum board(5/8")

Specifications

Fire Rating
3-Hour
STC Rating
STC 53
Load Bearing
Yes
Total Thickness
12.62"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
W174
Assembly Type
Floor/Ceiling
Test Standard
ASTM E119
Construction Group
Light Frame
Number of Layers
7 layers

Applicable Codes

IBC 2021 Table 722.1IBC 2024 §722IRC R302.1

Construction Summary

2x10 wood joists at 24" o.c. with R-30 fiberglass batt, 3 layers of 5/8" Type X gypsum board ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
23/4" plywood subfloor3/4"
32x10 wood joists at 24" o.c.9.25"
4R-30 fiberglass batt—
55/8" Type X gypsum board5/8"
65/8" Type X gypsum board5/8"
75/8" 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.