Double hung window gap

Old 06-28-13, 07:24 AM
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Double hung window gap

I am re-trimming my windows on the exterior. They are double hung windows with new vinyl windows installed inside the old frame. The old window frames are 1 inch thick. I would like to fill the 2 inch gap between the 2x4 studs and the 1 inch window frame with regular foam insulation. Will that cause the 1 inch frame to bow or should I use the low expanding foam? I like using the regular foam, it is cheaper and I think does a better job.
Old 06-28-13, 07:58 AM
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I'd use window and door foam. Great Stuff makes one, but I like the DAP for the easier cleanup.

If you are very careful...the regular foam could be used...just don't try and fill the gap all at once.
Old 06-28-13, 10:43 PM
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You shouldn't use any of the regular foams. Expanding or low expanding cure to a rigid block and will bow the wood. Use the foam designed for window and door insulating or cut strips of insulation and loosely fill the void.
Old 06-28-13, 11:10 PM
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I would install a high density insulation such as Roxul in the empty weight channels. Vapor barrier installed over it on the interior. It's great insulation and easy to remove later.

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