Design question for slab on grade – GreenBuildingAdvisor

Suppose you have an insulated slab-on-grade foundation (example in attached image: Joe Latiburek, BSI-118, fig. 3), but you don’t want to live on a concrete floor (I don’t), can you build a wood floor with some ‘give’ on top of the slab?

I’m thinking of a couple possibilities:

1) Install 2×4 sleepers on the slab, theoretically at same height as the mudsill, attach subfloor, then build the walls on top of that.  Would you do anything to seal the top of the slab, which already has poly, rigid, and crushed rock beneath?

2) Can you build a framed floor system (joists) attached to the mudsill, then sub-floor and walls?  Again, would you seal the top of the slab?  What about insulation?  You already have rigid under the slab.  Maybe just air seal and insulate the rim joists?  The slab wouldn’t be doing much structurally, so maybe a thinner slab would be adequate.  The slab would provide air-barrier continuity and help keep digging wildlife out of the floor system, good things both.  I assume all utilities would be run under the slab, as if the wood over-floor wasn’t there.

Or would it be better to just insulate on top of the slab?  Numerous examples, including some in BSI-118.

This would be for CZ 5B (Colorado front range).

Thank you,

Donald Christensen