With the cold weather we had here, I'm suddenly busy with drywall repairs. This particular job involves a master bath over an unheated garage. Plumber was there and did what he had to do, and I followed removing wet drywall and insulation. 2 pipes burst at the head end of the tub and ran thru the floor soaking the garage ceiling and a 5 foot section of wall. Heres a couple pics.
#1 Location of burst pipes in relation to party wall. This is a 2x4 wall in front of the party wall.
#2 View of same area but in the garage directly below tub.
#3 View of 1" gap between inside wall and party wall.
#4 Same gap from garage.
Now, what I suspect happened was very cold air was moving from the garage area, thru this gap, and freezing the pipes.
My question is, does anybody see a problem with spray foaming this gap closed? I almost think it should've been fire stopped, but I've never built a twin dwelling and I don't know if this area was left open for a reason or not.