Looking for a reliable 4 hour fire rated joint sealant for your next project? Before confirming the price or placing a bulk order, make sure the product suits the joint design and the project’s requirements.
Joint type, joint width and depth, substrate, joint movement, fire rating, and installation conditions are key to consider when selecting sealant.
What Is Fire Resistant MS Sealant?
Fire-rated MS polymer sealant is a silane-modified polymer sealant designed to seal building joints against fire. It helps limit the spread of flame, smoke, and hot gases through joints.
Compared with PU and silicone sealants, this MS sealant offers a balance of flexibility and weather resistance, with up to 4 hours of fire resistance.
When choosing an MS sealant, project managers should check substrate compatibility, joint width, movement, environments, and backer.
Key Features of MS Polymer Fire Rated Caulking
Joint Movement and Seal Performance
Building joints expand and contract with temperature changes, while some structural joints may also experience minor movement. Firestop MS polymer needs sufficient elasticity to accommodate these movements and maintain the seal without cracking or debonding.
Substrate Bonding and Compatibility
Fire Rated MS Polymer Sealant is for common building substrates such as concrete, metal, and stone. Before using MS sealant, make sure it is compatible with the substrate and application.
High Fire Rating
Depending on the sealant depth and backer material, these sealants can provide a certified fire rating of up to 4 hours.
MS Polymer vs. Polyurethane (PU) vs. Silicone Sealant
| Comparison | MS Polymer | PU | Silicone |
| Primer Requirement | Often primer-free | May require primer | Substrate dependent |
| Joint Movement | Good | Good | Excellent |
| UV & Weather Resistance | Good | Moderate | Excellent |
| Wet & Humid Conditions | Suitable | Foaming may occur with some formulations | Suitable |
| Paintability | Paintable | Some grades | Generally not paintable |
| Isocyanate | Isocyanate-free options available | Typically based on isocyanate chemistry | Generally isocyanate-free |
