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Frost-protected slab on a moderate slope

ethant | Posted in Green Building Techniques on

I’ve been reading through the “Revised Builder’s Guide to Frost Protected Shallow Foundations” (http://cdnassets.hw.net/10/9d/3808b4b94676968c59b8548815f3/revisedfpsfguide.pdf) and notice that they recommend FPSF on “low slope sites.” I’m assuming that this would preclude using on a site of about 15% slope, but not sure what is generally thought of as “low slope.” Any thoughts on FPSF on a 15% slope (Zone 5A), building is a split level with slab on grade, double stud walls with a concrete foundation wall serving as the uphill wall on the house and garage.

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Replies

  1. ethant | | #1

    I should add that my structural engineer kind of dismissed the whole concept of the Frost Protected Shallow Foundation out of hand, but I think he is just too busy to be bothered... perhaps I can find another structural engineer who can wrap his head around the concept and give me/us guidance?

  2. GBA Editor
    Martin Holladay | | #2

    Ethan,
    As you guessed, the person to advise you in this instance is an engineer, not readers of an internet forum. Good luck.

    I will say that it's possible to install a frost-protected shallow foundation on a steep slope, because I've done it. That doesn't mean it's easy. Get the details right, or the foundation will fail. Your engineer is your friend.

  3. ethant | | #3

    Martin, thank you. My concern is that the structural engineer is very busy and from what I could gather, did not feel like working on anything that did not fit neatly into his computer modeling software... He first told me that I should modify the foundation layout even though we both knew it made sense because his software couldn't account for certain factors. So maybe I need to find a different engineer. It is surprisingly difficult, in a sea of architects, to find a structural engineer.

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