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Thermafiber® Safing Insulation - Firestop | Owens Corning Insulation
Owens Corning

Exceptional fire performance

Why choose mineral wool insulation?

Thermafiber® Safing mineral wool insulation products are designed to provide fire protection in perimeter fire containment systems, floor and wall penetrations, construction joints, and other firestopping applications. This type of fire-safing insulation is used to seal gaps where floors meet exterior walls in commercial buildings. It helps slow the spread of fire, heat, and smoke between levels of a building. As part of a firestopping system, safing insulation helps meet building safety codes and protect the people inside.

Key Features of Mineral Wool Fire-Safing Insulation:

  • Fire-Rated Assemblies – Performs in perimeter fire containment systems tested to ASTM E2307
  • High Heat Resistance – Withstands temperatures above 2,000°F (1,093°C)
  • Moisture & Mold Resistant – Resists mold growth and moisture exposure
  • Acoustic Support – Improves sound control in wall and floor systems
  • Recycled Content – Minimum 70% recycled material
  • Green Building Standards – Compatible with LEED® and Green Globes® programs
Download Product Data Sheet
Download Install Guide & Joint Safing Compression Calculator

Step-by-Step Guide: Installing Thermafiber® Safing Mineral Wool Insulation

This video covers tools, prep, and techniques for installing safing insulation securely and effectively

When Life Safety Matters Most

Owens Corning® Thermafiber® is committed to providing solutions that help the commercial building professional confidently design, specify, and install durable perimeter fire containment systems for commercial structures.

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Specifications & Literature

Performance Attributes

Thermafiber® Safing is noncombustible and has been tested for use in perimeter fire containment systems in accordance with ASTM E2307 standards. This fire-safing insulation performs in UL and Intertek listed fire-rated assemblies with 1-, 2-, and 3-hour ratings. Capable of withstanding temperatures above 2,000°F (1,093°C), it is designed for demanding firestopping applications in commercial buildings. Made from dense mineral wool, this safing insulation helps absorb sound in wall and floor assemblies. It supports noise control between rooms and floors, making it a valuable option for commercial spaces that require acoustic separation.

Fire Resistance icon

Fire Resistance

Acoustic Properties icon

Acoustic Properties

Technical Information

Physical Properties

PROPERTY

TEST METHOD

VALUE

Corrosion of Steel, Aluminum, and CopperASTM C665Noncorrosive, Types I, II
Non-CombustibilityASTM E136Non-Combustible
Non-CombustibilityCAN/ULC S114Complies
Water Vapor PermeanceASTM E96

Unfaced, 50 perms as tested
Foil-Faced, 0.02 perms as tested

Water Vapor SorptionASTM C1104Sorption less than 1% by volume
Surface Burning CharacteristicsASTM E84

Unfaced, Flame Spread 0. Smoke Developed 0
Foil-Faced, Flame Spread 25, Smoke Developed 0

Surface Burning CharacteristicsCAN/ULC S102

Unfaced, Flame Spread 0, Smoke Developed 0
Foil-Faced, Flame Spread 25, Smoke Developed 0

Perimeter Fire Containment SystemsASTM E2307

Safing insulation used in conjunction with Thermafiber® FireSpan® insulations and with an approved fill, void, or cavity material sealant in the Perimeter Fire Containment System.
Complies

Penetration Firestop SystemsASTM E814 OR UL 1479

Safing insulation used in conjunction with an approved fill, void, or cavity material sealant or other approved material in through – penetration firestop systems
Complies

Fire Resistance of Building Joint SystemsUL 2079

Safing insulation used in conjunction with an approved fill, void, or cavity material in construction joint systems
Complies

Fire Tests of Firestop SystemsCAN/ULC S115Complies

Safing products are approved by: New York City Board of Standards & Appeals – (under BSA 39-74-SM & accepted by MEA-209-82-M, Vol. 4).

Applications

Thermafiber® Safing is used in commercial wall assemblies where fire-rated penetrations and construction joints require protection to help prevent fire and smoke from moving through gaps in the wall. It can be cut and fitted to seal around framing or other components, creating a continuous barrier that helps maintain the wall’s fire rating and assists with reducing sound transfer between spaces. Its noncombustible and moisture-resistant properties help the insulation stay intact and effective over time, even in challenging building environments such as high-rise structures, healthcare facilities, or areas with varying temperatures and humidity.

  • Facades
  • Facades > Metal
  • Passive Fire Protection

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