Abstract: A heating element includes two flexible plastics layers connected in overlying relationship with first and second conductors each running along the element between the layers the side edges with a row of printed conductive strips at right angles to the conductors. A grounding layer comprising a sheet of foil laminated to a carrier is laminated to the heating element. A reinforcing layer in the form of a bitumen anti-fracture membrane is applied on one surface and a reinforcing layer of a fiber reinforced material is applied on the opposite surface for engagement into a tile adhesive layer. A resistor is provided between the grounding layer and the ground terminal of a GFI or similar device for controlling the heating current so as to avoid false triggering of the GFI.