Back in 2006, STI engineers watched plumbers struggle with a familiar problem: firestopping toilet drain penetrations, only to have hardened firestop caulk later interfere with proper closet flange installation.

Sealing from below with ladders or scissor lifts was slower. Cutting back firestop caulk from above was messy. Neither respected how the work actually gets done.

So we went back to the office, bought every closet flange we could find, and built something better.

The result was the SpecSeal® Closet Flange Firestop Gasket. A one-piece, intumescent rubber gasket solution that installs from the top side of the floor, fits 3” and 4” flanges, and maintains fire-rated performance without slowing the trade installing it.

Tested to ASTM E814 (UL1479) and CAN/ULC-S115 and UL Certified for up to 2 hours. Approved with cast iron, PVC, and ABS pipes.

A small jobsite problem led to a practical, patented solution now used worldwide. That’s customer-driven design. Learn more about the SpecSeal® Closet Flange Firestop Gasket here.