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Frost protected shallow foundation under unheated building

user-7350559 | Posted in General Questions on

I’m a builder in climate zone 6. Currently we’re reviewing plans for a house with detached garage. For cost reasons we’d like to do a shallow frost protected foundation under the garage. Only the shell of the garage will be going up at this point, with plans to finish it down the road along with an apartment above. My concerns are, the garage will not be heated until it’s finished in a few years, we are in a fairly dry climate with very well draining soil but I’m still concerned about frost heaves. Has anyone ever used detail ASCE 32-01, in which a continuous layer of high density foam is laid over a 6” base of well draining fill, then the foundation goes over top of it? Or has anyone ever detailed a SFPF under an unheating building that could offer some advice?

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  1. Expert Member
    Michael Maines | | #1

    Caleb, questions like yours come up often here: The design guide attached is simpler than ASCE 32-01 but more thorough than what's in the IRC code book. I'm in CZ6 and usually find that I need 5' wings around unheated garages.

    1. user-7350559 | | #2

      Thank you Michael! I appreciate the link and the response. I’ll look this over and see what my engineer thinks

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