Details on a rigid foam chainsaw retrofit

I am retrofitting a century old, uninsulated house with exterior rigid insulation. It is in zone 6a in northern MT.  The plan is to put 9 inches of polyiso foam… I am retrofitting a century old, uninsulated house with exterior rigid insulation. It is in zone 6a in northern MT.  The plan is to put 9 inches of polyiso foam…Read MoreGreenBuildingAdvisor