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Community and Q&A

Using below grade SIP for full basement

cabinflyer | Posted in Energy Efficiency and Durability on

We are planning our single level lake home in northern Minnesota. 1200 sq. ft. walkout. 11000 HDD Zone 7.

I’m fully aware of the traditional basement options; block, poured, and ICF their plusses and minuses having worked in the masonry field when I was younger.

Question: Has anyone had any experience using SIP’s for below grade?



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  1. GBA Editor
    Martin Holladay | | #1

    A South Dakota company called Enercept makes below-grade SIPs. You probably know about Enercept, but for those who don't, here is a link to a relevant document:

    Enercept's below-grade SIPs are faced with pressure-treated plywood. In essence, this type of basement is detailed like a Permanent Wood Foundation (PWF).

    Some real estate agents think that homes with wood foundations are harder to sell than homes with concrete foundations.

    I have no direct experience with this type of SIPs, but I'm not tempted to try them out.

  2. user-1137156 | | #2

    You might check out .
    The Enercept product is hardly what should be called a SIP as it uses 2x8 12" OC and has no structural advantage over a stick built PWF. The Extrempanel is much more a SIP and has much less thermal bridging. They are also closer to you. You would be well advised to learn all you can about PWF techniques and requirements. Here is a place to start:: Sips are a way of saving some on site labor labor but "stick" building a PWF foundation is also possible using carpentry and appropriate (foundation grade pressure treated and stainless fasteners) materials. In some ways PWF is less tolerant of some poor practices. Drainage and granular backfill are areas where best practices really need to be followed.

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