Prepping for insulation
 

Hello,

We are in the process of remodeling our 1930s house. I am planning on tearing out some sheetrock and firring (or is it furring) the studs in about 3 inches, they are only about 2.5 inches right now. Yes you heard that right, 2.5 inches on an exterior wall. Not a lot of insulation.

Anyway, once I tear the sheetrock out and the blown-in insulation, should I prep the wall before I insulate? They used 1x boards back when they built this house. I have seen people prep for insulating by spraying expandable foam in all of the cracks.

Any advice?

The gaps between the boards are not a problem, in fact in new house a gap it required between sheet of plywood. With a vapour bearier on the inside, closing the gaps would be a problem. You can use spay foam for insultion, you just don't want to have to vapour beariers with a wall in between.

Normally with these older houses they were sheeted on the outside with 1X's on a 45% angle called storm sheeting. Then a layer of felt paper over that to help seal the cracks then exterior siding over that. I would not be too concerned with the cracks. Furring the framing out to 3.5" is necessary for R-13 insulation to work properly. Compressed insulation looses its R factor. You need the air space to maintain the R factor. Foam insulation is good around pipe and wire penetrations, doors and windows. Hope this helps.