Top 5 Fireproof Caulks in Canada for 2026 — What CAN/ULC-S115 Listings Actually Cover
Published on Monday, August 24, 2026
Fireproof caulk is designed to withstand high temperatures and slow the spread of fire and smoke through gaps and penetrations, sealing joints around walls, floors, and service openings. Before anything else, understand the distinction that governs this whole category: a true firestop sealant is one that has been tested and listed in a specific assembly under CAN/ULC-S115 in Canada (equivalently ASTM E814 / UL 1479 for through-penetrations, or ASTM E1966 / UL 2079 for joints), and it carries an F-rating — and often T-, FT-, or W-ratings — for that exact assembly. A caulk merely labelled "high-temperature," "fire resistant," or "intumescent" without a listing is not firestopping and will not satisfy a building official. Critically, the rating belongs to the tested system, not to the tube: the same listed sealant can carry a 1-hour or a 4-hour F-rating depending on the substrate, the annular space, the penetrating item, and the fill depth. Always match the sealant to a published system number (a UL/ULC XHEZ or CAJ/WJ system, or the manufacturer's ULC-listed equivalent) rather than assuming the product alone is code-compliant. With that settled, Canadian buyers weigh listed system coverage, low-VOC formulation, freeze-thaw reliability for cold climates, movement accommodation, and ease of installation.
Top Picks Summary
3M Fire Barrier Sealant CP 25WB Plus
3M Fire Barrier Sealant CP 25WB Plus earns its spot as a best-in-class fireproof caulk by combining reliable, water‑based intumescent performance with low VOCs and paintability, making it a cost-effective choice for general contractors. Compared with the silicone-centric options on this list, 3M’s product offers easier cleanup and better compatibility with painted finishes while delivering industry-standard firestop protection and broad tested-system coverage.
DAP Fire Stop Fire-Rated Silicone Sealant
DAP Fire Stop Fire-Rated Silicone Sealant is a market leader for flexible, silicone-based firestop applications where movement and long-term weather resistance matter, making it well suited for dynamic joints and exterior penetrations. Compared with acrylic and water-based sealants like Tremco and 3M, DAP’s silicone formulation trades easier paintability for superior elasticity and durability, offering a financially attractive option for projects that demand long-life seal performance.
Hilti CP 606 Flexible Firestop Sealant
Hilti CP 606 is the premium choice on this list, prized for its high-performance firestop characteristics, extensive tested system documentation, and strong manufacturer support—features that justify its higher upfront cost for mission-critical projects. Unlike more commodity options, Hilti’s product emphasizes certified system performance and contractor assurance, making it the go-to for specifications that require rigorous documentation and long-term liability protection.
Tremco TREMstop Acrylic Firestop Sealant
Tremco TREMstop Acrylic Firestop Sealant stands out as a practical, budget-friendly solution for interior firestopping where paintability and easy tooling are priorities, offering a balance of performance and value for routine wall and floor joints. Compared with premium Hilti and elastic silicones like DAP, Tremco’s acrylic option is generally less costly and simpler to finish, making it attractive for large-volume commercial interiors that favor economical, paintable sealants.
Where to buy Tremco TREMstop Acrylic Firestop Sealant in Canada: the trusted retailers we track in this market, with the best price we have observed at each. Prices are checked regularly and can change, and the retailer confirms the final price at checkout.
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$15 – $35
Mulco Supra FR Firestop Sealant
We are flagging this entry rather than recommending it. Mulco's published Supra line — Supra Expert and its variants — is a general-purpose thermoplastic/multipurpose construction sealant for exterior joints, not a listed firestop product, and we could not locate a CAN/ULC-S115, ASTM E814 / UL 1479, or ASTM E1966 / UL 2079 listing under the name "Supra FR." Retail listings reached from this entry resolve to Mulco Supra Expert, a general-purpose sealant. Treat any fire-resistance claim attached to this name as unconfirmed: do not install it in a fire separation, a rated wall or floor, or around a service penetration unless Mulco or your distributor supplies a specific listed system number in writing. If you need a fourth option beyond the three above, buy a sealant you can trace to a published listing instead.
Where to buy Mulco Supra FR Firestop Sealant in Canada: the trusted retailers we track in this market, with the best price we have observed at each. Prices are checked regularly and can change, and the retailer confirms the final price at checkout.
We may earn a commission on purchases. It never affects our rankings.
$20 – $50
What Research and Standards Say About Firestop Sealants
Scientific testing and building-code standards form the backbone of evaluating fireproof caulks. Laboratory fire tests assess both the ability of a sealant to prevent flame and hot-gas passage and its resistance to sustained heat, while smoke control tests measure the sealant's effectiveness in limiting toxic smoke migration. Independent test protocols and consensus standards, combined with materials science research on intumescence and polymer stability, provide actionable evidence about which formulations perform best for specific applications.
Listing beats labelling: in Canada the governing test is CAN/ULC-S115; internationally, ASTM E814 / UL 1479 covers through-penetrations and ASTM E1966 / UL 2079 covers construction joints. A product without a listing number for your assembly is not firestopping, no matter what the tube says.
Read the ratings, not the marketing: an F-rating is the time the seal resists flame passage; a T- or FT-rating adds a temperature-rise limit on the unexposed side; a W-rating indicates a water-resistant seal. Inspectors ask which rating the assembly needs, then which listed system delivers it.
The rating is a property of the assembly: substrate, opening size, annular space, penetrant type, backer/mineral-wool packing, and fill depth all change the outcome. Copying a bead detail from another job voids the listing.
Intumescent mechanisms: intumescent materials expand and form insulating char layers under heat, blocking openings and reducing heat transfer; this is a primary mode of protection for many acrylic and water-based firestop caulks, and it is why they suit combustible penetrants like plastic pipe.
Silicone and high-temperature silicones retain flexibility and adhesion at elevated temperatures and are often preferred where movement and temperature cycling are significant factors.
Acrylic and water-based firestop sealants are generally more paintable and lower-VOC, making them attractive for occupied spaces, but they may offer different movement or temperature performance than silicones.
Lab aging and cyclic movement tests indicate that long-term performance depends on both material chemistry and proper installation; poor joint preparation or incorrect joint width-to-depth ratios reduces effectiveness regardless of the tested rating.
Firestopping in fire separations is usually inspected work. In many Canadian jurisdictions it is expected to be installed by a trained applicator and documented against the system number; treat DIY firestopping in a rated wall as something to confirm with your local authority having jurisdiction first.
Frequently Asked Questions
What's the difference between fireproof caulk and a real firestop sealant?
"Fireproof caulk" is a shopping term; the code term is firestop sealant, and it means a product tested and listed in a specific assembly under CAN/ULC-S115 in Canada (or ASTM E814 / UL 1479 and ASTM E1966 / UL 2079 internationally). A high-temperature or fire-resistant caulk with no listing number is not firestopping and will not pass inspection in a fire separation. Note too that the F-rating belongs to the tested assembly, not the tube — the same sealant can earn a 1-hour or a 4-hour rating depending on substrate, annular space, and penetrant.
Which caulk should I buy for firestopping jobs?
Start from the listed system your assembly needs, then buy the sealant that system names. Among the picks here, 3M Fire Barrier Sealant CP 25WB Plus (rated 4.5) is the easy default for common joint and penetration work: it's a water-based, low-VOC intumescent that is paintable and toolable, and it appears in a wide range of tested systems.
What exact feature does Hilti CP 606 provide?
Hilti CP 606 Flexible Firestop Sealant (rated 4.7) maintains long-term adhesion and flexibility on concrete, metal, and masonry, and it's supplied in both cartridges and sausages for trade use. Its practical advantage is breadth of tested-system documentation, which matters when a specification or inspector requires you to cite the system number you installed to.
Is Hilti CP 606 or DAP Fire Stop silicone better value?
DAP Fire Stop Fire-Rated Silicone Sealant sits in roughly the $119.99 CAD–$119.99 CAD range and is rated 3.9; Hilti CP 606 runs about $119.99 CAD–$119.99 CAD and is rated 3.9. DAP is the better value for occasional work and dynamic or damp joints — it's classified to ASTM E814 / UL 1479 and ASTM E1966 / UL 2079, accommodates about ±25% joint movement, and is tested to as much as a four-hour F-rating in the right system. Hilti earns its premium on repeat commercial work through system breadth and documentation support.
Conclusion
In Canada, choosing the right fireproof caulk means balancing tested fire performance, code compliance, and practical jobsite needs — and the single most useful habit is to shop for a listed system, then buy the sealant that system calls for. Of the five options covered here, four are genuine firestop sealants with published listings: 3M Fire Barrier Sealant CP 25WB Plus, DAP Fire Stop Fire-Rated Silicone Sealant, Hilti CP 606 Flexible Firestop Sealant, and Tremco TREMstop Acrylic Firestop Sealant. For high-performance, code-compliant installations where system documentation and long-term flexibility matter most, Hilti CP 606 is often the best overall choice; for paintability and low-VOC needs consider 3M CP 25WB Plus or Tremco TREMstop; for movement and wet-location resilience consider DAP Fire Stop Silicone, which is classified to ASTM E814 / UL 1479 and ASTM E1966 / UL 2079 and tested to as much as a four-hour F-rating in the appropriate system. The fifth entry, listed here as Mulco Supra FR, we could not verify: Mulco's published Supra line is a general-purpose multipurpose sealant, not a listed firestop, and we found no CAN/ULC-S115 listing under that name — do not use it in a fire separation unless the manufacturer supplies a system number in writing. I hope you found what you were looking for — refine or expand your search to compare technical data sheets, listing directories, and local distributor availability.