From my attic I can see gaps to the outdoors along the outside corners of the chimney. Primarily this is a problem with both wasps and bats squeezing themselves into the attic. Also, a recent rainstorm with lots of wind leaked water into the house although most rains, even heavy ones, are not leaking in.
Climbing on the outside of the house is a non-starter for me, and I'd like to see what I can come up with that I can do myself without hiring someone.
What options do I have to spray up in there that will be both:
- water resistant
- safe/legal to have against a chimney? (likely to be legal in USA – I don't expect absolute confirmation on that point)
I'm hoping that there's some sort of spray foam that will fit the bill but most of what I'm seeing are interior foams meant to retard fire between walls and floors.
Best Answer
Pretty much any fix that you attempt from the inside has the potential to create issues in addition to the primary problem, which is that your chimney isn't properly flashed. Spraying foam or shooting caulking/tar into the gap is very likely to create water traps somewhere in the roof decking, most likely underneath the existing flashing. You would basically be hiding the problem more than correcting it, and could also make it more difficult to fix the underlying issue in future. I would strongly recommend having the flashing corrected.