Is my slab at risk left unheated through the winter?

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Is my slab at risk left unheated through the winter?

I had grand plans for getting my garage closed in, and the rough mechanicals installed before winter. Life (uh... work, actually...) intervened.

I live in MN zone 6, and am building on alluvial sand from the Mississippi River. I built a block stem well on poured footings four feet deep (below frost line), 12 inches of compacted sand was placed on top of undisturbed sandy soil.

I was then compelled by local building codes to put down 4" of 3/4" river rock - known colloquially around here as "radon rock" - followed by 6 mil polyethylene for radon gas mitigation. I then placed 2" rigid foam panels to which I stapled PEX for in-floor radiant heat. (I know... the foam should be first, THEN the poly... sadly, despite protracted arguing and supporting literature from Joe L. inspector said "No, you will put poly UNDER your foam if you are stapling PEX") Rebar 24" OC was laid over the PEX, followed by poured slab 5" thick.

I have my garage framed, roofed and shingled, but that's as far as I've gotten. It is closed in with windows and door, but no rough plumbing, electrical or insulation is in. Well, except for 1.5" rigid foam on exterior, and WRB wrap. It's now November, and I fear I will not be able to get these things in and the boiler running before things freeze around here.

Should I worry if my slab is left unheated through the winter?

Any advice, or experience of others, appreciated. Thanks!

Asked by Kent Jeffery
Posted Wed, 11/07/2012 - 22:23