Schluter®-Systems does not recommend the installation of floor warming systems over DITRA or DITRA-XL. Install heating cable systems per heating manufacturer’s directions; encapsulate heating cables in a skim coat of Schluter ALL-SET™, FAST-SET™ or modified thin-set mortar or cement-based leveling compound and allow to cure before installing DITRA or DITRA-XL with Schluter SET™ or unmodified thin-set mortar. If installing an electric thin-mat, install it per heating manufacturer’s directions and install DITRA or DITRA-XL with unmodified thin-set mortar. See detail D-RE in the DITRA Installation Handbook for complete requirements.
Another solution would be to use our electric floor warming system with integrated uncoupling technology. Schluter®-DITRA-HEAT integrates customizable, comfortable electric floor warming with the functions associated with DITRA: uncoupling, waterproofing, vapor management and support, to ensure a long lasting installation. DITRA-HEAT combines the flexibility of loose heating cables with the ease of installation of mat systems. Cables can be placed wherever heat is desired, without creating height differences in the floor. Self-leveling compounds are not required to encapsulate the cables, significantly reducing installation time and effort compared to uncoupling membranes over other electric floor warming systems.