Hi I just got a lead on some cheap "reclaimed" Poly Iso boards and I am considering insulating my attic with them(currently uninsulated). The board has the black backing, not foil, which seems to be known as fiber faced. There are 1000x posts on foil backed but cannot find much info on fiber backed. I live in upstate NY and would like to buy and install this the right way asap. Thanks for the help all!
The fiberglass faced would stop any moisture trying to exit the rooms below to the attic space where it would be removed by ventilation. I would use something more permeable, (over the <1 perm) especially if you already have a vapor barrier/retarder poly/craft-faced next to the ceiling drywall/plaster. http://www.menards.com/main/building...632-c-5779.htm
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