Trimming a Basement Window


Old 07-13-10, 01:41 PM
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Trimming a Basement Window

I hope this thread belongs here. Maybe it belongs in the window or trim forum. Feel free to move if necessary.

I want to get some opinions on my basement egress windows.
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My windows are about 4' square directly placed on the concrete. Last winter there was some condensation build up on the concrete around the windows. Note: the windows did not leak - it was definitely condensation. I will most likely trim out the windows with oak extension jambs. Here are my questions.

1) Should I use liquid nails to glue the jambs directly to the concrete?
2) Should I put poly film between the concrete and jambs?
3) Should I use pink foam/XPS to cover the concrete and insulate it - thus removing the cold surface and hopefully the condensation?
4) If I cover the concrete with anything, how do I make sure that the oak jambs are firmly attached? Just nail them?

Other ideas?


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Old 07-13-10, 03:39 PM
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From the pic, I would say it will difficult to insulate around the window AND install trim. There is not a lot of space there. There are some very thin, high efficiency insulation products that we use in the car restoration field, they might work here. Dynamat is on.
Old 07-13-10, 04:01 PM
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I'm not sure about what to do about the condensation. For the extension jamb, I would assemble it into a box first and then slide it into the opening. That what you can secure the jamb to the 2x4's and not worry about the corners near the the window opening up.
Old 07-14-10, 03:26 PM
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I had exactly the same situation with the egress windows in my basement. My windows have a metal frame imbedded in the concrete, but it works the same as your situation. I've never actually seen condensation on the inside, but I've felt how cold the surface gets in the winter so I'm sure it happens sometimes.

I ended up doing as drooplug suggests and attached the jambs to the 2x4s. I left a small air gap between the metal frame and the trim materials. I then filled in the gap with caulk to give it a more finished look. I figured this would at least allow a bit of air movement back there to keep the condensation damage to a minimum.

The other thing you could consider if you don't already have them are covers for the top of the window wells. This will keep the air outside the window a bit warmer, which may reduce the condensation on the inside.

A word of caution: Make sure that the trim materials to not get in the way of opening the egress windows if they are the type that open to the inside. If one were to accidently do that then one might have to rip out the trim on a couple of windows and re-do it....

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