I was just wondering if insulation foam (I used regular Great Stuff from HD) can expand in dry conditions around a window (frame) and cause warping and damage to the window up to and including breakage.

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6 Answers 6


I have personally seen it bow "trimmer" studs in a framed window opening. It could easily warp, bow, or move a window frame itself. Breakage would likely be caused by users messing with/forcing the out of plumb/square/true window?

Note: you can buy "low expansion" foam specifically designed to avoid this issue.

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    ...but you still should apply it in layers. Problems tend to occur when folks fill it up while spraying, not realizing (as is written in the instructions most people don't read) that the foam (even low-ex) expands for a while after it's been sprayed.
    – Ecnerwal
    Commented Nov 12, 2015 at 3:20

From experience, yes it can cause windows, doors, etc. to stick because the pressure pushes the frame closer to the door or sash. I just completed the finish work in a house and had to use my sawzall like a rasp around window frames to relieve the pressure before I could put the trim on them. I am not sure if the stuff can generate enough force to actually do damage though.


I have seen it warp a window frame to the point that makes it difficult to operate, but, I have not seen it expand to the point it breaks a window.


Indeed it can, aggressively. So if you are using it to install door frames, for example, wedge a piece of wood the required size in the doorway while it expands. Several pieces of wood. You need helpers.


I came across a YouTuber a while back who had some filler foam damage a door of his, so he did some back yard pressure tests:


He ended up with 90lbs of pressure against his bathroom scale after 5 days of the foam setting. It's not exactly the most refined experiment, but 90lbs is pretty startling.


Yes, definitely. As others have stated some detail oriented builders will actually use wood blocking in windows with deep integral jambs to prevent warping of the jambs as the foam sets up. I had issues with some settling and had the marvin reps out for a set of sliders,they basically told me that they have so many issues with it that they see that they recommend installing a bead of foam as a vapor barrier toward the exterior of the space between the jamb and the framing, and then stuffing the remainder of the space with scraps of loose fiberglass batts.

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