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Home / Assemblies / UL D126
UL D1261-hr Fire RatingFloor/CeilingLoad-BearingSTC 35
Steel JoistFiberglass BattDesign

Steel Joist Floor/Ceiling — single layer Spray-applied fireproofing

UL-listed 1-hour fire-rated steel joist floor/ceiling assembly. C-channel steel joists at 16" o.c. with R-19 fiberglass batt, single layer of Spray-applied fireproofing ceiling.

Cross-Section Diagram

12345FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE5 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")
4R-19 fiberglass batt
5Spray-applied fireproofing(1-1/2")

Specifications

Fire Rating
1-Hour
STC Rating
STC 35
Load Bearing
Yes
Total Thickness
13"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
D126
Assembly Type
Floor/Ceiling
Test Standard
CAN/ULC-S101
Construction Group
Non-Combustible
Number of Layers
5 layers

Applicable Codes

IBC 2021 Table 722.1IBC 2024 Table 722.1

Construction Summary

C-channel steel joists at 16" o.c. with R-19 fiberglass batt, single layer 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"
4R-19 fiberglass batt—
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.