Insulating Basement Walls
I am looking to start finishing my basement. I thought I understood what I needed to do from past reading of building articles, but am now not sure
I am in downstate NY, zone 5 I believe? Basement is a walk out, with back wall and one side wall about 7 ft below grade. Other sides grade down to a walk out in the front corner
Walls are cavity block walls. Some minor flaking of old paint/white powdery stuff on walls, but no mold per se. There was a gutter issue on one side of the house and then missed for a while and I believe this has contributed to some of this white powdery mildew. But overall for the fifteen years we have lived in the house I don’t believe there’s a significant issue
From past reading on bsc, I was set to use 2 inch xps on walls . Frame in front, seal rim joist. Sheet rock and be done. Idea i thought was that the wall can slowly breathe/dry inwards if needed
Now I am seeing that this is not necessarily the correction approach. I have read posts arguing that walls do not need to be allowed to dry inward. Is this just for concrete walls or cavity block walls also? Should i be using 2 inch foil faced polyiso? Is this not similar to the old method if just putting a plastic sheet over the wall and insulating in front, or is there some breathability in foil faced polyiso?
Should I paint the interior walls with a vapor barrier paint first such as drylock and then polyiso or xps.?
Hope I explained where I am sufficiently and look forward to your input. I’ve been waiting a number of years to get to this project and now I just want to get the insulation portion done the right way
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