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Home / Assemblies / UL D147
UL D1474-hr Fire RatingFloor/CeilingLoad-BearingSTC 55
Steel JoistHigh STCDesign

Steel Joist Floor/Ceiling — 4 layers Spray-applied fireproofing

UL-listed 4-hour fire-rated steel joist floor/ceiling assembly. C-channel steel joists at 16" o.c., 4 layers of Spray-applied fireproofing ceiling.

Cross-Section Diagram

1234567FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE7 LAYERSsee legend for ① ② ③
Legend
1Floor covering(varies)
22-1/2" lightweight concrete on steel deck(2-1/2")
3C-channel steel joists at 16" o.c.(10.0")
4Spray-applied fireproofing(1-1/2")
5Spray-applied fireproofing(1-1/2")
6Spray-applied fireproofing(1-1/2")
7Spray-applied fireproofing(1-1/2")

Specifications

Fire Rating
4-Hour
STC Rating
STC 55
Load Bearing
Yes
Total Thickness
17.5"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
D147
Assembly Type
Floor/Ceiling
Test Standard
CAN/ULC-S101
Construction Group
Non-Combustible
Number of Layers
7 layers

Applicable Codes

IBC 2021 §722

Construction Summary

C-channel steel joists at 16" o.c., 4 layers of Spray-applied fireproofing ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
22-1/2" lightweight concrete on steel deck2-1/2"
3C-channel steel joists at 16" o.c.10.0"
4Spray-applied fireproofing1-1/2"
5Spray-applied fireproofing1-1/2"
6Spray-applied fireproofing1-1/2"
7Spray-applied fireproofing1-1/2"

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.