DuraVent FasNSeal Firestop and Flat Flashing: covers the opening at each floor crossing
The DuraVent FasNSeal Firestop and Flat Flashing is a flat plate that covers the framed opening where a vent passes through a floor or ceiling. DuraVent requires one at every floor the vent crosses. It can also cover the opening where the vent enters a masonry chimney. Choose a size from 3 to 16 inch on this page to match your vent. FasNSeal is DuraVent’s stainless steel vent for high efficiency gas boilers, furnaces, and water heaters, built to carry pressurized exhaust and its acidic condensate outside.
This plate is not needed at the roof. That opening takes roof flashing instead. On a single wall run, a roof jack fits inside the flashing, and a storm collar seals around the pipe. The vent must reach at least 2 feet above the roof and extend above any wall less than 8 feet away. A vent standing more than 6 feet above the roof needs extra support. Using double wall vent? See the DuraVent FasNSeal Firestop and Flat Flashing for W2. The DuraVent FasNSeal Firestop and Flat Flashing ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.








Commercial projects may require custom parts and unique system designs. Duravent offers complete project assistance:








































