Rigid foam and drywall directly on top of plaster/brick interior?
New here, hope this is the right format and question category!
I recently bought an 1887 brick Victorian in Colorado. Unfortuately it is covered with years of ugly previous retrofits such as aluminum siding, very dirty fiberglass bats and such. It felt very drafty and the sheetrock was done very poorly. I tore out the sheetrock, framing, and fiberglass in one room to reveal original plaster walls covered with wallpaper. I have read extensively on rigid foam retrofits in old houses, but have come to no conclusion on better insulation options.
I would like to install rigid foam directly to the plaster and wallpaper, use masonry screws to secure furring to the foam and wall, and then install drywall directly over that. No vapor barrier, because it is brick. Brick needs to breathe I hear. Aluminum siding installed over the brick keeps them dry outside, and I think they are in fine shape (I tore the siding off a small section to inspect the brick). I would like to remove this siding at one point but that is another project. There are no exterior moisture penetration issues I can see. According to some posts foam over plaster/brick would be fine, and a vapor barrier would not be nessassary. Other articles state that a vapor barrier is required when foam is applied directly to brick walls covered in plaster, due to moisture accumulation from changes in air tempuratues.
Vapor barrier, or no vapor barrier? Is this this best solution to insulate these type of walls? I’ve also read that the plaster may have to be removed. Should I take the walls down to brick?
Walls seem to be very dry, but do display very old water damage that I am certain were the result of a past roof issue that has been fixed. I am in the highest city in the country, and relative humidity is always pretty low except in the spring during snowmelt. But the climate zone is probably just under taiga/ arctic because I am above 10000ft.
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