Silicone Firestop Sealant
This information reflects our best understanding of product composition in 2022.
Firestop sealants are used to seal through penetrations and joints in walls and floors to control the spread of fire, smoke, toxic gases, and water during a building fire. These products can be caulk-type or spray-applied and are most commonly...
Firestop sealants are used to seal through penetrations and joints in walls and floors to control the spread of fire, smoke, toxic gases, and water during a building fire. These products can be caulk-type or spray-applied and are most commonly acrylic- or silicone-based. Silicone firestopping sealants are typically one-component, low modulus, neutral-curing silicone sealants that cure upon contact with moisture in the air. These sealants can be gun grade (nonslump) or self-leveling. Intumescent varieties are also available but are less common. This CP focuses on gun grade, non-intumescent silicone firestop sealants. Self-leving and intumescent silicone firestopping sealants will differ and may include additional additives (for example, graphite and melamine make up a large percentage of silicone intumescent sealants and solvents may be used in self-leveling sealants). Neutral-curing systems can vary - most common in these sealants is an oxime crosslinking system that releases butanone oxime, a suspected carcinogen, when it cures.
Silicone firestop sealants can be used for a variety of applications including to seal electrical, plumbing, and HVAC penetrations, expansion joints, and top-of-wall joints. They can be used in static or dynamic joints in both interior and exterior applications. Priming is not necessary for adhesion to most common building materials. Silicone firestop sealants can typically be used in areas subject to high levels of moisture and many meet Class I W rating requirements (W-rating refers to a firestop system’s ability to resist water passage through a floor assembly). Firestop products are fire rated as part of systems including the assembly or construction, penetrating item, and firestop product(s). Silicone firestop sealants are part of systems that carry fire ratings from 1 to 4 hours for any given product application. They are UL Classified fill, void, or cavity materials for use in through-penetration firestop systems and joint systems. See UL fire resistance directory for specific sealants and assemblies.