Wet underfloor heating and Karndean/Amtico flooring

[PleaseHelp]

Hi All, I'm new to the forum and not in the trade, so please excuse my ignorance.

I'm looking to install wet underfloor heating using polypipe overlay plus system (18mm) and then looking to finish with a karndean/Amtico floor finish.
I need some advice on:

• what goes on top of the underfloor polypipe overlay plus (screed, cement board, ply?? ) in preparation for the Karndean/Amtico.
• what thickness does it need to be?
• any other considerations?

Also, there are some areas that I won't be doing underfloor heating (due to cost) but left with the dilemma of uneven floors. Therefore my question is:
- can I use say 20/22mm ply, insulation boards?? To level up the floor to continue my karndean/Amtico floor finish??

Subfloor : floorboards
Coverage Size : circa 100sq/m
Areas: Kitchen, cloakroom and hallway

 

[MiriamT]

Hi, did you ever find answers to this? I'm in exactly the same boat with the same questions! our builder and floorer seem to have conflicting advice