I live in MN. This winter I noticed a cold draft coming from under the baseboard trim along my patio home's exterior walls. Today as I began pulling off the trim I noticed that there was a gap between the 1" rigid foam and the poured slab. In some spots the gap was as wide as 1/2 cm. Is this normal?

Also, in one corner of the room I noticed that the foam was missing. As I peered into the 2"x2" cavity it appeared that there was simply dirt below. Considering that I have in floor heat and my patio home is in MN, shouldn't there be foam insulation laid horizontally directly beneath the poured concrete slab? If I should indeed have insulation beneath the slab, what can I do to remedy the situation?

Thanks for your help!

Also, the water that runs in the PEX tubing seems to reach 145 degrees before my room is sufficiently heated and the boiler turns off.

The water temp in the floor should ideally not exceed 120, yes there should have been plastic down and then 1 in foam board. Get some squirt foam to fill the wholes