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Community and Q&A

How to Build a Window Buck

cmcgrath09 | Posted in General Questions on

Dumb question of the day. I have zip sheathing. I plan to install 2in of polysio foil face. Then create a 2in Pt buck to install my triple pane nail fin windows on to. . My plan was to use a 2×6 and rip 2in strips and screw them on edge. (creating lots of waste) Or do I cut the 2×6 in half so its built out to cover the furring strips going over the foam?  Am I doing this wrong? Or do I just put a 2×4 on the flat and built it out with the 1×4  furring strip I will be using over the foam. How do I build my trim out to match the LP smart side siding? I did a quick Q&A search but came up empty.

Thank you


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  1. Expert Member


    Make your bucks 2".

    If you use 2" bucks you then have a completely flat surface (just as you would on an ordinary sheathed exterior wall without foam insulation). You then install the windows on the bucks, and add strapping to form the rain-screen cavity - again just as you would if the insulation and bucks weren't there.

    If you make the bucks deeper so that they are co-planar with the outside of your strapping, you can't run your head-flashing back to the WRB, and your sill pan can't drain into the cavity. You can make it work, but with a lot more gymnastics.

    1. cmcgrath09 | | #2

      Thank you.

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