The preferred option is the new family of Foil Mat Systems (ThermoLAM) which incorporate a narrow diameter heating cable embeded within a laminated foil mat, this foil sheet provides earth screening in compliance with 17th edition wiring regs thus enabling use within Bathrooms and other wet areas. Another significant advantage is the way the mats can be cut and folded to suit a given floor area.Use with XPS SR insulation / underlay either 5mm or 10mm. Another option is the Carbon Film Heating System, this is used in conjunction with an insulating material directly beneath the heating film and is ideal for regular shaped areas and conservatorys. The main limitations of the Carbon system are a lack of earth screening which makes the system un-suitable for Bathroom type wet areas and the lack of flexibility / adjustability in area layout. BOTH HEATING SYSTEMS REQUIRE AN INSULATION MATERIAL SUCH AS XPS SR or DEPRON.