Firestop Sealants
Firestop sealant (fire caulk) is the workhorse of passive fire protection: it seals through-penetrations and construction joints in fire-rated walls and floors so flame and smoke cannot pass. Every sealant here is a UL Classified Metacaulk® product from RectorSeal, tested to ASTM E814 (UL 1479) for penetrations and ASTM E1966 (UL 2079) for joints, with ratings up to 4 hours.
Which one you need depends on the assembly. Intumescent sealants (MC 150+, Metacaulk 1000, 350i) expand when heated and are the default for penetrations — cables, conduit, metallic and plastic pipe. Elastomeric MC 1200 flexes with moving joints and comes in caulk-grade, self-leveling and spray versions. Silicone 835+ handles weather exposure and Class 25 movement for curtain-wall and exterior joints. RS136 is the budget pick for basic penetrations, and SAS adds smoke and sound sealing where an STC rating matters.
Firestop-USA is an authorized Metacaulk master distributor: distributor pricing by the case or pallet, volume discounts, same-day shipping on in-stock items ordered before 11 AM, and free freight over $2,500 — with free UL system matching and submittal support.
Which one do I need?
Firestop Sealants — the lineup
Metacaulk® MC 150+ Firestop SealantSingle component, general purpose firestop sealant for a wide range of applications.View product, specs & TDS →
Metacaulk® 1000 Intumescent Firestop SealantSingle component, water-based intumescent sealant for construction joints and through-penetrations.View product, specs & TDS →
Metacaulk® 350i Firestop SealantSingle component, water-based intumescent sealant for a wide range of vertical and horizontal applications.View product, specs & TDS →
Metacaulk® 1200 Firestop SealantSingle component, water-based firestop sealant formulated for caulk, spray, and self-leveling applications.View product, specs & TDS →
Metacaulk® 835+ Firestop Silicone SealantSingle component, low modulus, non-slumping silicone firestop sealant.View product, specs & TDS →
Metacaulk® RS136 Firestop SealantEconomical general-purpose firestop sealant and smoke block for basic through-penetration applications.View product, specs & TDS →
Metacaulk® SAS Smoke & Acoustic SealantHigh-grade acrylic latex sealant for permanent seal of penetrations, membrane openings, and joints in smoke or sound rated assemblies.View product, specs & TDS →Firestop Sealants — frequently asked
What is the difference between firestop sealant and regular caulk?
Regular caulk burns or melts in a fire. Firestop sealant is tested in specific UL Classified systems to maintain the fire rating of the wall or floor — intumescent types expand up to 18× when heated to close gaps around burning penetrants. Building codes require tested firestop systems, not generic caulk, in rated assemblies.
Which firestop sealant should I use for plastic (PVC/CPVC) pipe?
Plastic pipe needs an intumescent product that expands to crush the melting pipe — MC 150+ or Metacaulk 1000 in the appropriate UL system, often combined with a wrap strip or collar on larger diameters. Call (732) 757-4552 and we will match the exact UL system for your pipe size and assembly.
Are Metacaulk sealants UL Classified?
Yes — Metacaulk firestop sealants are UL Classified and tested to ASTM E814 (UL 1479) and ASTM E1966 (UL 2079) with ratings up to 4 hours, covering hundreds of UL systems. We provide the specific UL system documentation for your submittal at no charge.
How much firestop sealant do I need?
Coverage depends on the annular space and depth of the system. As a rule of thumb, a 10.1 oz tube fills about 18 cubic inches; a 20.2 oz sausage about 36. Send us your penetration schedule and we will take off the quantities for you — and pallet pricing kicks in fast on production jobs.
Need the right UL system?
Send your penetration schedule or a photo — we match the UL Classified system, provide submittal documentation free, and ship same-day from New Jersey at distributor pricing.
More firestop categories: Putty Pads & Electrical Box Protection · Pipe Collars, Wrap Strips & Sleeves · Cast-In Devices & Cable Pathways · Pillows, Mortar & Composite Sheet · Cable Coating, Foam & Accessories · Hilti / 3M / STI cross-reference