A great underfloor heating solution for under tile requirements is to use a decoupling membrane suitable for use with electric under tile heating cable.
Decoupling Membrane for Undertile Heating Cable:
Material: Polyethylene (PE) film top; Polypropylene (PP) non-woven bottom.
Weight: 1000g/sqm
Thickness: 5.6mm
Accepted Wire Cable Diameter: 3.6 - 4.2mm
Distance of the studs: 4mm
Waterproof: Yes
Available Roll Sizes:
5m x 1m
10m x 1m
20m x 1m