Water/Condensation Basement Window

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SodFace
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Water/Condensation Basement Window

Post by SodFace »

I am having an issue with 1/3 basement windows this winter now that it has been finished.

Every morning there is significant buildup of condensation at the top of the wwindow frame. It happens during the day too but mostly bad overnight when it's coldest. Not sure why this one window of the 3 is having this and the others are not. There is a vent in the ceiling about 1 metre away which I tried taping up to prevent excessive heat in the vicinity of the window.

Humidity is on the higher side but no other window in the house is having this issue.

Any ideas? Wiping it up every day doesn't seem like a good long term solution heh.

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Re: Water/Condensation Basement Window

Post by markrazzy »

Do you see most of your issues on the north-facing windows?

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Re: Water/Condensation Basement Window

Post by dicko1 »

I'd say the builder either neglected to insulate or did a really bad job of insulating above that window.

Pull the upper trim piece off the wall, dig out whatever insulation is in there, and squirt in some expanding door and window foam insulation. Make sure it gets all the way to the outside wall surface. Dont go overboard because it will distort the window frame if too much is used.

Then wait for it to harden, clean it up with a knife and put the trim piece back on.

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Re: Water/Condensation Basement Window

Post by SodFace »

markrazzy wrote:
Fri Dec 10, 2021 1:00 pm
Do you see most of your issues on the north-facing windows?
This one faces North, yes. And the only one with this issue so far.
Last edited by SodFace on Fri Dec 10, 2021 6:25 pm, edited 1 time in total.

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Re: Water/Condensation Basement Window

Post by SodFace »

dicko1 wrote:
Fri Dec 10, 2021 2:49 pm
I'd say the builder either neglected to insulate or did a really bad job of insulating above that window.

Pull the upper trim piece off the wall, dig out whatever insulation is in there, and squirt in some expanding door and window foam insulation. Make sure it gets all the way to the outside wall surface. Dont go overboard because it will distort the window frame if too much is used.

Then wait for it to harden, clean it up with a knife and put the trim piece back on.
Great suggestion thank you.

Basement was previously unfinished and due to some mold issues they tore out all insulation and put in good spray foam insulation. It was after all that we finished it. I think this window had a crevice above which was spray foamed. Could be wrong though.

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Re: Water/Condensation Basement Window

Post by SodFace »

Got to the bottom of it! Builder sent someone even though we've been in 3 years now to take a look. Turns out there is a gap between the rigid insulation on the side of the house and the window frame. He checked all the windows on the outside and this one problem one had a 3/4" gap with no rigid insulation. This allows the cold air to come at the top of the frame causing this condensation. They're going to send a crew to fix 2 basement windows(3rd had no gap and we noticed no condensation).

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Re: Water/Condensation Basement Window

Post by SodFace »

Update: after some days -20C (-4 F) I have noticed zero condensation at the top of said window. Looks like the missing insulation right above the window was the issue.

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