I installed some vapour barriers on the windows recently due to it getting a bit cold, but have been noticing that I've been getting a fair bit of condensation on the inside facing part of the plastic. Now the temperature has gone down about thirty degrees since I installed these, so I'm wondering if it's just not up to the task, or I've installed them improperly/poorly, or maybe something else that I've missed? Here's a picture of one installation. as you can see there's condensation on the lower part of the window.

window with condensation on the plastic vapour barrier

  • Condensation on the inside just means your windows aren't doing much in terms of keeping the cold out (hence you wanting to add the weatherstripping/plastic).
    – DA01
    Commented Jan 27, 2013 at 6:32

1 Answer 1


I don't see that there's anything wrong. Condensation happens... on any surface that's colder than the dew point of the adjacent air. If anything, it's showing that it was worth doing. Despite only being a few mils thick and easily heated, it's much colder than the inside air due to heat loss through the windows. Without it, the windows would be sucking heat out of your house instead of just the interstitial space. The only thing you can do to reduce condensation is reduce the humidity in your house and/or turn the heat up.

  • Thanks for the reassurance. As this is the first place that I've debated doing this with, didnt' know if I was doing it right or not. Commented Jan 26, 2013 at 21:46

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