I am putting in radiant floor heat in a basement. The slab is going to be poured so that the finished elevation is the same as the top of the footing (to maximize ceiling height). If I insulate the perimeter of the slab so that I create a thermal break from the footing I am concerned that I will have a 4" strip around the perimeter of the floor (the uninsulated, unheated top face of the footing) that will be cool and condense water and potentially create mold or damage the flooring (I am planning on using cork). Specifically, I am going to stop the perimeter insulation about a half inch from the top of the footing elevation so that I can caulk the joint to prevent gas movement up into the building. If I use 1" EPS or XPS will there be enough heat from the slab moving through the insulation and/or the caulking to keep the footing warm enough so that moisture won't gather? If I use rebar doweled into the side of the footing every 24" oc will I risk damaging the footing from expansion/contraction? If not, would there be enough heat transfer through the rebar to keep the footing warm enough to prevent condensation? So many questions. And, if any of you reading this see other problems please voice them. Also, I live in a zone 2 climate, Southern BC Canada (same weather as Northern Montana) and the slab is about 7 feet underground.

Pour the basement walls 1 ft higher.

Use stone under the slab even with the top of footing, add 2-4" XPS from wall to wall over the footing.  Concrete is cheap, 1 ft taller walls is not a big deal in most cases.

eric

If you are putting in radiant floor heat then that "unheated" portion of the footing will be warmer than it would be in a basement warmed by forced air. The walls as you go up will also be colder and therefore more prone to condensation than the footing. Insulate your walls properly for your climate and you should have no issues with condensation.

What I'm not understanding is why you think you'll have moisture problems in the basement during the winter when interior air is at it's driest? You must have some uncorrected moisture source that needs to be fixed before you proceed.

BTW I think the slab next to footing is a bad idea and you should go with taller walls if at all possible as Eric suggested. You'll likely have more issues with water intrusion than with condensation.