I currently have a built-in porch that sits on a low crawl space on an uninsulated stone-paved concrete slab. This crawl space was ventilated with indoor air from the basement, but outdoor air leaked through gaps in the slab, leading to mold on dense parts of the blind floor. The vertical construction was as follows: uninsulated stone-paved concrete slab/ 20 cm air space/joist base with 20 cm insulation, sawdust, and fiberglass, and then came the floor.
Now to the question; Could one lay a Platon mat on the stone-paved concrete slab and up along the wall/sill and in this "box" place 40 cm of cell plastic, on which a heated floor is cast?
Unfortunately, I don't dare to break away the slab and lay a capillary-breaking layer with gravel, as it stands on a steep slope, and destroying the slab might cause everything to collapse.
