Casting the underfloor heating into existing concrete vault

[Gräslig]

Considering embedding underfloor heating in an existing concrete slab. Remove the 95mm joists and insulation currently on the slab leading to the basement.
Lay the pipe, then reinforce and cast about 50 mm.
Will it work, or is it too thin? Of course, stud to the old slab and use primer.
Is insulation unnecessary since there's a basement underneath?

 

[huggan]

I would recommend the underfloor heating pipe in foam insulation and then just a self-leveling compound. It prevents you from getting "ceiling heat" in the basement and I believe it's the same material cost, but you avoid a lot of work with casting which might also need to cure for 2 months before you can turn on the heat.

 

[Gräslig]

How thick would the spackling be?

 

[corre]

Depending on the surface view, but about 20mm above the hose including tiles, for example.