I am about to replace a floor in a rural farmhouse in France (or at least try!). My problem is that the house has no foundation as such and appears to be built on compacted limestone soil (as all houses were at that time - mid 1800s). I now wish to lift a tile floor, excavate some of the soil in order to lay a concrete sub floor, then lay flagstones on top. While I will get a tradesman to lay the flagstones, I am prepared to do all the groundworks myself. Does the forum suggest a damp proof membrane over the soil, then lay the concrete, or lay the concrete, then lay a damp proof membrane on top? I also hope to put underfloor electric mat heating below the flagstones, so is a reflective or insulating membrane suggested?
No doubt the tradesman will put me right, however, i would not mind some knowledge of the best way forward with this.
All suggestions greatfully received.
Cheers.

Sorted- no need for any reply.

What answer did you get? Hardcore, blinding, dpm under the slab?.