Re: rim joist insulation in a ballon framed house...
Remember that the purpose of firestops (blocking, caulking, etc.) is not to completely stop the spread of fire -- they can't -- but to slow the spread of smoke and fire so all occupants have sufficient time safely exit the building. Secondarily, they may help reduce damage to other portions of the structure -- your insurance company appreciates that. Regardless, without aggressive suppression (fire department), a fire will destroy the entire structure.
Firestops are more critical in commercial and multifamily dwellings due to the extended amount of time required to notify all occupants (a smoke detector at one end of the building won't necessarily alert someone at the other end if they are not interconnected) and the time it takes to clear occupants from a larger building.
The fireblock foam may be flammable, but if it slows the spread of fire by even a minute that can be the difference between life and death.
Last edited by Fencepost; 06-21-2014 at 04:56 PM.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.