I'm sealing gaps around my furnace vent that goes from my garage up through my house to the roof. I was going to use fire caulk for this but the gaps are a little big for that. Does anybody know if 'Great Stuff Fireblock Foam' sealant would be a good for an application like this? It doesn't really state on the can that it is for high temperatures like the caulk does. If not, does anybody have another suggestion? Thanks!
Fire caulk and fire stop foam materials are not designed for sustained high heat. They are made to stop fire. The foam will char on the surface when exposed to fire. The char then protects the rest of the foam undeneath from the effects of the fire. Fire caulk can work the same way or it can expand under high temperatures to fill a void and prevent fire penetration. You don't want to use products like that in a situation where they will be constantly exposed to high heat. Fire stop sealants are not really good for exposure to the weather either.You need a high temperature sealant. Many of these are silicones and are designed for sealing exhaust stacks through roofs. A gas furnace sales place should have some.
Last edited by Maintenance 6; 03-30-2012 at 03:04 PM.