Your right but if you introduce the heat mat on top of the ditra your creating an area of greater lateral stress rendering the ditra less effective.
Ditra mat electric underfloor heating.
If the heat mat is under the ditra then you allow the product to do it s job properly allowing the tile to heat up at a different rate to the substrate.
Schluter ditra heat matting is polyethylene membrane with a cut back stud structure and an anchoring fleece laminated on the underside.
Schluter ditra heat is an integrated uncoupling and underfloor heating system for use under tiles and natural stone on walls and floors.
Ditra heat combines the benefits of schluter ditra decoupling matting with easy to install electric underfloor heating cables for a system that will save you time and money when installing over problematic substrates.
Floor warming ditra heat combines the flexibility of loose heating cables with the ease of installation of mat systems.
The suntouch floor heating mat measures 10 ft.
It is a universal substrate for tile coverings which serves as an uncoupling layer bonded waterproofing and moisture vapour barrier and is designed for the attachment of the matching heating cables of the system for floor heating.
I would install 10 mm marmox insulated backer boards fixed with spf adhesive then slc over heatmat minimum 6 mm imo then install ditra with spf adhesive then tile.
It is a universal substrate for tile coverings which serves as an uncoupling crack bridging waterproofing vapour pressure equalization layer and is designed to be used as a carrying membrane for the schluter ditra heat e hk heating cable.
Substrates for ditra matting substrates on which the matting can be installed must always be checked for their suitability to make sure they are level load bearing clean and compatible with the materials to be used.
I would do the same on the first floor but also use screws and marmox washers to install insulated backer board and as long as the floor is deflecton free and the chipboard has been screwed to the joists.
Uncoupling waterproofing vapor management and support to ensure a long lasting installation.
And offers an ultra thin low profile system that installs beneath tile stone and even vinyl or laminate flooring.
Schlüter ditra heat has been developed offering unique electrical underfloor heating within the uncoupling matting layer system that eradicates sticky situations measuring mistakes and self levelling and primer layers.
Schlüter ditra heat is a polypropylene membrane with a cut back stud structure and an anchoring fleece laminated on the underside.
Schluter ditra heat integrates customizable comfortable electric floor warming with the functions associated with ditra.
Ditra matting is particularly useful when installing underfloor heating and provides a decoupling layer between the underfloor heating and the tiles.