I'm looking for framing advice. I'm going to create a dining room in teh back of my oversized garage. The garage floor is a concrete slab over a crawl space with a dirt floor. The crawl space is dry. In order to bring the garage floor up a step to match the floor of the house, I plan to construct 2x8 sleepers to support the subfloor of the new space.

Some of the questions I have are around the space between the concrete and the subfloor. Should I lay a moisture barrier on the concrete floor, under the sleepers? And is spray foam insulation the best to use against that concrete to prevent a chill from rising up through the subfloor? If using spray foam, should the moisture barrier then go between the sleepers and subfloor- or is the spray foam effectify a moisture barrier (except where the sleeper touchess the concerete? So does that mean the sleepers should be raised over the concrete to spray foam is between? Or do I use moisture resistance lumber on the concrete, spray foam, and call it a day?

I keep circling here- if you were framing a floor over a concrete slab, can anyone suggest the best order of materials?