Hello,
I’m trying to figure out where (or if) I need fire blocking in the structure I am insulating. I’ll try to post pictures if I can but here’s a description:
It’s a garage with an apartment above it. The building is balloon framed, so the stud cavities go from the garage concrete stem walls up past the ceiling/floor joists to about two feet into the apartment walls above before they hit any horizontal blocking.
So to summarize, the longest stretch of wall joist cavity between blocking is about ten feet (although more often only 5 to 8 feet)but there is no blocking between FLOORS and there is no blocking where the stud cavity intersects with the ceiling/floor cavities. Do I need it in those places?
It will not be inspected so compliance is not an issue but I would prefer to follow best practice
Thanks
Edited 11/10/2008 1:41 am ET by snap pea
Replies
Yes.
Think of each stud bay as a small chimney, because in the case of a fire, it will function as one, funneling flame into the space beyond.
Your goal is to stop the draft that makes that happen with the firestop spacers.
You need to keep any fire that starts in the garage from spreading into living quarters too fast, that includes under the floor
So each stud bay gets blocking at the elevation of the bottom of the floor system. And if the floor is framed so that the joists set ON a ledger instead of being surronded by a rim/ledger that separates the floor space from the stud spaces, you need to block there too.
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Thanks for the quick response, thats what I'll do. Yes, the joists sit on a ledger, so after I block the garage wall bays (where they reach the ledger), does it matter which way I isolate the joist bays? I could block the bottom of the apartment walls above, or I could block the end of the joist bays before they enter the wall cavity, does it make a difference?