I have insulation surrounding the opening of two of my egress windows in the basement. I am noticing a good deal of condensation where this insulation is in contact with the radiant barrier which is fastened to the concrete wall. If you reach further in about 4 inches and feel around, there is no moisture. enter image description here

there are two other smaller windows that are not doing this same thing.

For context, it is very cold here, 10 degrees Fahrenheit, and we are currently adding drywall mud/tape.

Will this moisture continue to be an issue and should I not have insulation surrounding the windows? or is it a result of the added humidity in the basement from drywall compound drying?

  • The humid air is condensing on the cold material. If you close off or seal so there is no air movement you eliminate the condensation at that point, better yet dehumidifiers reduce the moisture in the air and may be enough to reduce the condensation it’s all about how cold and the moisture content in the air.
    – Ed Beal
    Feb 24, 2022 at 19:56

1 Answer 1


IMO, this moisture will continue to be a problem. Even if you seal the wall up, moisture will migrate through the drywall and insulation until it reaches the radiant barrier or the outside, cold wall. Sealing the wall cavities will help, but not eliminate the problem.

Like Ed Beal said, reducing the humidity level in the basement by using a dehumidifier will help.

What kind of insulation is in the wall cavities? If it's Rockwool, then you're in better shape than if it's fiberglass because the Rockwool is more forgiving if it gets a bit damp.

  • Prior to the drywall going up the humidity was fairly low in the basement, below 40%. I realize adding sheetrock would change that some. It's also winter and the whole house humidifier is on. Maybe dial it back a scoshe.
    – EMAW2008
    Feb 24, 2022 at 21:46
  • 1
    Dialing back the humidifier will help. But with the outside wall being 10 deg F, any moisture in a 65 F or 70 F basement will condense on that surface. Only way you can prevent that is by 1) preventing the moisture from reaching that cold surface - that is, a vapor barrier, or 2) lowering the relative humidity in the basement until the dewpoint is below 10 F - not practical.
    – SteveSh
    Feb 24, 2022 at 22:24

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