Are polyisocyanurate materials considered vapor barriers and to be avoided for insulating basements?
I live in Central Minnesota. Our home was newly built roughly 3 years ago. It was not insulated on the exterior, but foil-faced DOW Thermax Sheathing was installed on the entire basement interior. This has a permeability rating of 0.03. This is basically an impermeable material. If we want to avoid moisture problems when finishing our basement, do we need to take this down and put up something with more permeability like EPS? We do try keep the humidity below 50 or 55 degrees in the basement.
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