Casting floor heating above basement

[Albindoh]

I was planning to pour a new underfloor with floor heating above the existing concrete floor, which is approximately 120-180mm today. I have removed the joists, insulation, and rough board that accounted for about 80mm, so now this needs to be replaced. Since I don't want to pour directly onto the slab as it is now and have to heat up all the concrete, my first thought was a layer of foam insulation first and then add floor heating and pour, but since I have a bit of rough concrete and many pipes for electricity, maybe it won't work well with foam insulation directly on it? I considered eps concrete as a first layer, but it's very expensive and not so easy to get a large quantity as it's 80sqm to be poured.

What are the other options? Leca balls? Or cut out from the foam insulation for pipes and then lay it on the "uneven" concrete?

 

[Karl-Ove Qvarfordt]

80 mm in construction height is too little to achieve a sensible solution for what you want to accomplish.

 

[Jansson69]

I was planning to cast a new subfloor with underfloor heating above the existing concrete ceiling which is about 120-180mm today. I have torn out the joists, insulation, and raw boards which built up about 80mm, so now this needs to be replaced. Since I don't want to cast directly on the slab as it is now and need to heat up all the concrete, my first thought was a layer of foam first and then put on underfloor heating and cast. But since I have some rough concrete and many pipes for electricity, maybe it's not so good with foam directly on? I considered EPS concrete as a first layer but it's very expensive and not easy to get a large amount as it's 80sqm that needs to be cast.

What other alternatives are there? Leca beads? Or cut out on foam for pipes and then lay on the "uneven" concrete?

There are grooved EPS boards in which you lay plates and underfloor heating pipes. LK has 30mm, 50mm, and 70mm ready-made or you can use 30mm and lay an additional layer underneath..

https://golvvarmebutiken.se/vattenburen-golvvarme/sparskivor/eps/lk-combiboard-eps