Remodeling the upstairs 1 1/2 story Can I use expanding foam without using vents?

Question

The ceiling goes from the top to the floor Like an A frame. There are no vents can I use the expanding foam without putting in vents. There is no Insulation just bare ceiling/roof. This house is a 1939 model

Answer 1

I suggest you contact an insulation company and have them come down and give you FREE ideas on how to insulate that room, and the cost involved.

Applying expanding foam can be tricky, and poor coverage can result...plus the stuff is a MESS to work with.

And, due to off-gassing, not all of it can be used in dwellings.

Answer 2

I don't see why it wouldn't work if it's a A frame construction, So there are no roof vents at all? The foam will fill in the whole cavity in from top to bottom, is what your wanting to do? I would think your good to go, if that's what you have. as long as there is no need for air to get to the back side of the roof, then it should work good, what size are the rafters 2x8 or 2x10? that will give you a good R rating.

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