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Are ICF foam window bucks a good choice?

user-2340595 | Posted in Energy Efficiency and Durability on

I’ve decided on using icf’s as a basement/ foundation for a timber frame wrap&strap home. The manufacturer offers a foam window/door buck with an integrated plastic flange in the foam to screw the window flange to. I’m curious if anyone has used something similar or has any experience using this type of foam buck. My concerns are more of durability vs the thermal bridging that the foam prevents.
Any thoughts would be greatly appreciated.

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  1. jackofalltrades777 | | #1

    On my ICF windows I had concrete window bucks. I just had the contractor install temporary wood bucks and then those were removed once the concrete cured. I then used windows without nailing flanges and used brackets with screws. Tapcon screws were used to screw into the concrete and the brackets hold the window in place by attaching to the fiberglass window frame.

    What you DO NOT want to do is use wood window bucks with an ICF wall. The wood, even if treated, will twist and turn as it dries out. In addition, the long term strength and possible issues are removed when you do a concrete buck. Nothing can rot when you have a vinyl or fiberglass window frame and a concrete attachment surface.

    What you MUST make sure to do is leave enough space between the window and concrete buck. There are no "re-do's" with concrete so go 1" wider and 1" taller on the rough opening. Fill the space with a can of window spray foam and I taped the interior and exterior with SIGA tape. Outside is stucco. 60mph rain driven winds and not a leak. I trimmed it off with some nice premium pine wood trim

  2. jackofalltrades777 | | #2


    Did my post help you out?

  3. user-2340595 | | #3

    Yes it did Peter
    Thanks for your help.
    Like most questions throughout our design phase, every answered question leads to more questions. I'm now trying to re draw the window profile without the wood bucks.
    What type of screws/anchors do you recommend?

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