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Home / Assemblies / UL D111
UL D1112-hr Fire RatingFloor/CeilingLoad-BearingSTC 48
Steel JoistDesign

Steel Joist Floor/Ceiling — 2 layers Spray-applied fireproofing

UL-listed 2-hour fire-rated steel joist floor/ceiling assembly. Open-web steel joists at 24" o.c., 2 layers of Spray-applied fireproofing ceiling.

Cross-Section Diagram

12345FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE5 LAYERSsee legend for ① ② ③
Legend
1Floor covering(varies)
23" concrete on steel deck(3")
3Open-web steel joists at 24" o.c.(14.0")
4Spray-applied fireproofing(1-1/2")
5Spray-applied fireproofing(1-1/2")

Specifications

Fire Rating
2-Hour
STC Rating
STC 48
Load Bearing
Yes
Total Thickness
18.5"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
D111
Assembly Type
Floor/Ceiling
Test Standard
CAN/ULC-S101
Construction Group
Non-Combustible
Number of Layers
5 layers

Applicable Codes

IBC 2021 §722IBC 2024 §722

Construction Summary

Open-web steel joists at 24" o.c., 2 layers of Spray-applied fireproofing ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
23" concrete on steel deck3"
3Open-web steel joists at 24" o.c.14.0"
4Spray-applied fireproofing1-1/2"
5Spray-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.