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Home / Assemblies / UL J121
UL J1214-hr Fire RatingJoint System
Design

Perimeter Fire Barrier Joint — Silicone System

UL-listed 4-hour fire-rated perimeter fire barrier joint system. Perimeter Fire Barrier Joint, 1" max width, Silicone firestop sealant with ceramic fiber backer.

Cross-Section Diagram

12FIRE-RATED JOINTSECTION · NOT TO SCALE2 LAYERSsee legend for ① ② ③
Legend
1Ceramic fiber backer(3")
2Silicone firestop sealant(3/8")

Specifications

Fire Rating
4-Hour
Load Bearing
No
Total Thickness
Varies
Source / Publisher
UL (Underwriters Laboratories)
Design Number
J121
Assembly Type
Joint System
Test Standard
ASTM E814
Construction Group
N/A
Number of Layers
2 layers

Applicable Codes

IBC 2021 §714IBC 2024 §714

Construction Summary

Perimeter Fire Barrier Joint, 1" max width, Silicone firestop sealant with ceramic fiber backer

Material Layers

LayerMaterialThickness
1Ceramic fiber backer3"
2Silicone firestop sealant3/8"

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.