Kitchen floor construction, elec underfloor heating

[CharlieB1981]

Previously planned to use water fed underfloor so planned a floor construction of 100mm insulation on top of the sub floor with pipes in 60mm screed and tiles in top, can no longer use this for numerous issues so looking at elec underfloor.

I'm assuming it would therefore be more efficient to use thinner insulation above the sub base and insulated tile backer board directly under the tiles- so layed on top of the final screed

 

[CharlieB1981]

After though, would adding a further layer of screed onto the current floor, 100mm of kingspan on this then tile back board and tiles, would this provide a stable enough base for kitchen units?