I have built my basement walls from ICF but now have to give up until after Winter. It is a walk-out basement and part of the footings on the inside of the house are currently exposed, the rest are buried below the frost line. I am worried about frost lifting these footings and have covered them over with 4 inches of styrofoam. Is this enough? Should I add straw as well? The roof of the basement will be covered next week by the ground floor sub-floor and tarpaulins. Any advice welcome. Oh yes, I live near Montreal so it gets pretty cold and snowy here!

richwood, the foam was a good start but to be on the safe side go get yourself some straw an put a good foot or more over top of the foam all the way around the inside of the basement over footing. Better safe than sorry!!
The straw won't cost too much so it is a cheap insurance to prevent a potential very expensive problem.
Paul Stevens

And frost blankets over the straw would help keep the straw dry. Keep water away, frost goes deeper with more heaving in saturated earth.

I have the same situation. My subfloor was covered with 6 mil. plastic and heavy tarps to protect the plastic .the outside was tarped in the front where the sun could hit the foam icf to protect it from the sun until spring and stucco. as of yet , I have no leaks from the subfloor into the foundation. I dug down to the footer base on the inside and installed a digital thermometer probe to monitor the cold temps. Only once did I get a reading of 23F, since that in early winter, I have added 4" of foam board along all suspect walls and the lowest temp I recorded was 31.2F. The #1 stone is dry as dust down to the base of the footer. I feel very confident that I won't have a problem with frost heave. My house is located in western New york about 20 miles north of the Pa line.

Richwood are you on bedrock! If you are there is no need to protect if not ICF said it wright, make sure no water can penetrate the straw.
Cheers! Good luck!