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Type XIV EPS for window buck.

user-6952674 | Posted in Green Building Techniques on

Thermalbuck is type XIV foam covered with vinyl material.  The foam itself is 40PSI and with the vinyl its ~50psi.  Why can’t we just install the windows over the Type XIV foam with care not to over compress the foam?  Possibly use some powerhead screws with appropriate nails.  Flash with appropriate tapes.

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  1. Expert Member
    Deleted | | #1


  2. Expert Member

    User ...674,

    I don't think the problem is compressive strength except at the sill. Much as with rain-screen furring through exterior insulation, the contribution of the foam is minor compared to the cantilevered screws, and any foam will do. However windows aren't designed to be supported by their flanges, so something solid needs to be situated underneath their sill, and that something also needs to be fastened so that it stays put. How you would do that with foam boards and how you would shim if necessary would be my concerns.

    One solution I have used is to space small blocks of wood along the sill. These represent a very minor interruption in the continuity of the foam. But I don't have a lot of experience with exterior foam. Hopefully others with better ideas will comment.

  3. user-6952674 | | #3

    Good point, good idea, Thanks.

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