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Foundation wall insulation

My house is about 10 years old...we moved in about 2 years ago.

The basement foundation walls have existing 1.5" (R-7) pink extruded polystyrene boards (2 x 8) fastened to them from the ceiling to just about a foot off the cement floor slab.

I have tuck-taped most of the joints so far between the sheets of foam.

My question is: If/when I finish the basement, should I fill in the space between the floor and where the existing foam ends? I figured the builder or previous owner didn't insulate this part because it is below the frost line.

Also, since the R-value is seemingly quite low, would it make sense to add additional insulation once the framing is complete (most likely 2 x 4 framing)?


Re: Foundation wall insulation

Yes extend it to the floor, seal the joints, and when you frame your walls fill the cavities with batt insulation. Make sure there are no air gaps between the foam and your studs to avoid convection currents which cause moisture problems.

Re: Foundation wall insulation

Thanks for sharing.

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