Stone is not concrete- most stone used in foundations isn't nearly as porous as concrete. Furthermore most old stone has lots of air spaces, and drain pretty well, so there just isn't much capillary draw from the bottom subsoil on up to the top. There might be splash-back or bulk water issues causing rot to be dealt with first, but if it's under control that won't affect the insulation situation. Snow depth levels might though, if it commonly reaches the sill.
If it's 90 years old and there's no hint of rot on either the exterior or interior side, go for it. A 2" (or more) shot of closed cell foam works.
Stay away from open cell if there's even a hint of water seepage through the foundation anywhere. In colder climates with open cell it's possible to get wintertime moisture accumulation high enough for frost to form within the foam under certain conditions, which may impact long term adhesion, but not with closed cell.
Is there a slab/rat-slab, or is the basement floor dirt? Sometimes it's better to dig in a perimeter drain and put a continuous ground vapor retarder (and insulation, if it's cold climate) under a new slab as part of the whole renovation, making the the wall-insulation continuous with he floor insulation/vapor barrier. See some of the foundation wall & slab details in this retrofit:
https://www.powerofaction.com/media/pdf/DER_CaseStudy_Belchertown_MA.pdf
(Note that they did not insert a capillary break under the sill timber, and sprayed diretly onto the stone, no drainage mat, etc.) |