Limestone + UFH Spec check please

[Rookery]

I would normally do a heated stone floor to the following spec:
Marmox stuck to screed with RSF
UFH Matt
Floorflex slc over cables
Uncoupling membrane stuck down with RSF
Tiles fixed with RSF

I'm quoting for 50+ sq mtrs of limestone but only 15 - 20 mtrs to be heated. In this instance the marmox and slc in the unheated area is adding significant cost. How would you do it?

 

[Time's Ran Out]

If they want it level it's the only way!

 

[Ajax123]

What type of screed???

 

[Lee@emctiles]

I would convince the customer that the marmox type board will also insulate the non heated area as well, they WILL feel warmer without the heating mat (i know as we tried this a conservatory company s showroom, part was heated, part not and to feel the benefit of both, we also left and area that turned out to be a lot colder)

 

[Rookery]

It occurred to me that I could do the heated area with 6mm board and the unheated area with 10mm and bring the heated area up to the level of the unheated area with the UFH/SLC. It would cut down on the amount of floorflex I'd need but, perversely, the heated area would have the least insulation. Its a sand/cement screed btw.