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Using Polyiso foam board in below grade basement

| Posted in General Questions on

I thought that polyiso foam board that doesn’t have fiberglass in it (so it won’t wick up water) is the best rigid foam board product to use in a basement remodel to create a thermal barrier.  However, I’m reading conflicting information about its use.  I also read varying information about polyiso’s ability to hold its R value in cold temperatures – keeping in mind that this will be used inside my home.  I live in Maryland which I think is considered Zone 4 Marine.  I have a poured concrete foundation.  I was going to leave about a half inch gap off the floor.  I’m still trying to find construction adhesive to affix this to the wall, but wanted your thoughts.  I understand that polyiso is better than XPS for fire and its R value/thickness (R-6/inch v R-5/inch for XPS).
I would appreciate your thoughts.
Thank you!

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