B
HomeLibrariesCopilotSearchProjectsBookmarks
FeedbackHelp Desk
Libraries
Building Codes
Code LibraryIBC — BuildingIRC — ResidentialIFC — FireIPC — PlumbingIMC — MechanicalIFGC — Fuel GasIECC — EnergyNEC — ElectricalModel Codes
Specifications
CSI SpecificationsDOT SpecsTransit SpecsUSACE
Standards
TransportationRailroadFire SafetyAccessibilityStructural
Tools & References
DiagramsAssembliesProductsCalculatorsChecklistsPermits
PricingLog in
Home / Assemblies / UL D171
UL D1714-hr Fire RatingFloor/CeilingLoad-BearingSTC 38
Steel JoistDesign

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

UL-listed 4-hour fire-rated steel joist floor/ceiling assembly. Open-web steel joists at 48" 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")
3Open-web steel joists at 48" o.c.(14.0")
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 38
Load Bearing
Yes
Total Thickness
21.5"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
D171
Assembly Type
Floor/Ceiling
Test Standard
ASTM E119
Construction Group
Non-Combustible
Number of Layers
7 layers

Applicable Codes

IBC 2021 Table 722.1IBC 2021 §722

Construction Summary

Open-web steel joists at 48" o.c., 4 layers of Spray-applied fireproofing ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
22-1/2" lightweight concrete on steel deck2-1/2"
3Open-web steel joists at 48" o.c.14.0"
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.