I am doing a weatherization project on my house where I am installing polyisocyanurate below the ceiling rafters. I have an existing stove pipe and chimney in place for the fireplace that came with the house. I want to get rid of the fireplace and install a wood stove. The existing stovepipe/chimney are double walled and I think the interior pipe is 6" (not sure) and the exterior is 10" or 12" (unsure on that too). What specials precautions must I take to install the polyiso around the stovepipe? The polyiso is 14 feet above where the top of the stove would be.