There would be about 12 inches space under the floor. What do I do to create a warm space under that floor? I would like to somehow run the outside sheeting down to the ground, but then I would have the frost heaving problem. I guess one solution would be to leave an air space under the addition and use floor radiant heating.
Answer:
With only a foot under the structure you'll be best off with radiant heat but a skirt should still go almost to the ground. The inside of the skirt would be lined with galvanized sheet metal screening (like they put on houses before applying stucco) which would cover from the bottom of the structure down to about a foot below grade; it gets dug in. This will keep vermin (raccoons, etc.) from nesting there.
