I have an old house with a thick stone facade. The stone is at least 8 inches thick. When built(1938), they used Celotex(Homasote) for sheathing > 2 x 4 framing(real 2 x 4). I just opened all the walls in the room for new wiring and insulation and to repair any rotted wood. Attached are some pictures of areas where the Celotex is missing or completely deteriorated. Amazingly, there are many areas perfectly intact.
I was initially thinking closed cell spray foam, but there is so much conflicting information out there. Looking for some ideas? And no, Iḿ not removing the stone:)
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