I recently became aware of this document:

http://www.dli.mn.gov/CCLD/PDF/sbc_1322_foundation.pdf

It would seem that a bottom-of-the-range R16 ICF foundation would violate the letter of the code as outlined, since more than R10 is expressly prohibited, unless using an underperforming fiber insulation like batts, (and you're limited to a mere R13 with those.)

I can't quite fathom the rationale behind it- I'm speculating that it's to protect against buckling from frost pressures (heat leakage from the house raises the local frost line) or potential frost heaving of the footings or something, which could be arguably protected against with other measures.

Do ICF foundations need other frost protection measures in very-cold climates?

Anyone have insight into the prescribed limits?  It was news to me- R10 isn't a very big number.

Dana1,

That is interesting.  I noticed on the second page that the energy code leaves it up to each manufacturer's requirements as how to do the "Integral Foundation Insulation".  I think this would allow a system like Thermomass to use more than an R10 if they have specific requirements to follow.

Maybe but the note at the bottom of the unfaced batt option is pretty explicit:

"NOTE: This is the only application
where exceeding R‐10 foundation
insulation is permitted. In this
application, it is allowable to install
up to an R‐13 fiberglass batt."

Which seems to preclude even center-insulated poured concrete from exceeding R10.  The document's presence on the MN department of Labor & Industry site is barely a year old.  I'm trying to dig in, see if there's any backstory to the prescriptions, or if they're even truly part of the building code.  In this document pn p.11 they state

"4. Insulating concrete form
materials shall meet the
requirements of Section R611."

But Section R611 doesn't appear elsewhere in that document.  In section N1102.2.6.11 they're all about the R13 limits for batts again.

Dana1,  Can't fathom what they are thinking or perhpas not thinking.   Other than the extra text I would assume it's a typo.  E.g. minimum vs. maximum etc.

I agree heat leakage from the house raises the local frost line.   Thus the better envelope (higher r-value) would allow less leakage and result in lowering the frost line -- or allowing it to go down somewhere nearing where it might be if the house was not present.   Frost is not made by freezing dew but is formed by sublimation so frost heave may not really have anything to do with frost itself -- it requires a water source below a frozen upper layer.

The only thing i know for sure about R-value is that few that throw it around understand how it's derived and etc.  I am encouraged by the new (2009) International Energy Conservation Code (just voted in Texas for next year effective April 1st 2011.    They appear to understand r-value e.g. putting something like foam inside a CMU cavity is a waste of time and it's no longer permitted.   It really requires another thread but i would be very interested in your opinion in regard to this new code that is now being voted in by multiple states might impact ICF.   Regards.

That is crazy, and I just violated it, and the ICF frost wall was inspected twice.

This is the Scandinavian foundation method and they have no problems with frost-heave. There is no water under the houses so no frost-heave.

I've been around long enough to remember when the Canadian Codes started to require insulation in the basement. At first it was just the first 4' (actually something like - to 12" below ground level. I was in Ontario at that time and one of the first things that got noticed was the # of cracked basements. In the heavy wet soils with no heat loss to stop the frost, the clay soils expanded and cracked the walls. The same happens when people insulate old stone foundations that don't have good outside drainage. I suspect that this is what the MN code is trying to prevent. However, the ICF wall should act similiar to void form or frost cushion in that it will absorb the expansion of the soil. Having said that I recently read a blog about a net zero in Edmonton were the writer did not think ICF's were cost effective. He used standard 8" concrete with R40 inside (glued on foam and stud wall with f.f. I wonder if he will experience any problems with this.