I have a 1950's era ranch house that is in Delaware (zone 4). I am starting a renovation where I have to replace the roofing, siding, windows and doors.
The sheathing on the house is 1x6 t&g boards that have large gaps between them. I also do not have any insulation in the walls. I should also add that my inside walls are not conventional drywall or plaster lathe. It is some type of 16" wide strips of 1/2" drywall-like material that is covered with another 1/2" of mortar. It is strange (and hard as concrete) but I have seen it in a few houses in my area.
My question is, should I keep the sheathing and blow cellulose into the walls, then cover with tyvek? OR, should I remove the old sheathing and replace with Zip sheathing and then blow the cellulose. Does anyone have any better ideas? I would love to use closed cell foam, but it is probably out of my price range.
If I kept the t&g sheathing, would it cause problems with air infiltration?
What if I filled the framing cavities with foam board and used canned foam to fill in the gaps? I haven't done the math from a cost perspective, but would that be a better idea?