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Community and Q&A

Window installation with 5-inch Roxul Comfortboard outsulation

Jessie Pratt | Posted in Green Building Techniques on

We are having a tough time figuring out the details for window installation. We are going to install 5 inches of Roxul Comfortboard to the outer surface of our sheathing and 8 inches of cellulose in our framing. So we’ll need to figure out how to provide a solid surface for the Roxul to butt up against, and we also need some solid surfaces to attach trim and flashing to.

We are thinking of installing the windows in plywood boxes with a sloped bottom surface to direct water out of the box. What we are realizing is that the finer details of this installation are highly dependent on the window’s construction.

We haven’t chosen a window yet but need to get the order in soon! Anyone out there in a similar situation?

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  1. Karen Babel | | #1

    Hello there,

    You may find the following link from our colleagues at RDH to be useful.
    It shows the stages of completing a similar window installation as what you have described. Situations may vary, but of particular usefulness is the integration of the sheathing, weather resistive barrier, saddle flashing and cladding finishing details. We hope this helps!

  2. GBA Editor
    Martin Holladay | | #2

    Thanks for the link.

    I'll reproducing one of the slides from the document that Karen linked to below. [Click on the image to enlarge it.]

    The slide has a photo of the Building Enclosure Design Guide. Here is a link to that document:


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