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Community and Q&A

Crawlspace foundation detail for ZIP R6

LRC253 | Posted in Green Building Techniques on

Good afternoon, I’ve searched the forum however I was unable to find the answer.  I’m in the early stages of planning for a single story home build and the new requirements for Washington State is continuous insulation.  

I’m likely going the ZIP R6 route and that obviously makes the exterior sheathing an inch thicker.  What would be the best option for the foundation thickness?  Standard 6″ and let the extra inch overhang?  or go with 8″ and flush the extra inch of sheathing thickness with the foundation?

Also, I’m concerned about the exterior doors (and windows) since there will be no foundation support for the extra 1″ overhang.   What detail is everyone doing to eliminate this? Or is that not a big deal?


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  1. Expert Member
    Michael Maines | | #1

    There are regional differences as to how far sheathing typically projects past the foundation, and in seismically active areas there are structural concerns as well. Here in the northeast US, we usually align the face of framing with the face of foundation. In other areas they tend to make them flush. In any case, with insulating sheathing, you can choose--either have the sheathing overhang the foundation or inset the framing, depending on your aesthetic preferences and the construction details.

    Likewise, there are many ways to handle windows and doors in thick walls. I wrote a couple of articles showing the basics of a few ways I've approached it:,

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