Warm Tiles floor-warming system is easily installed on subfloor or concrete slab, in thin set or self-leveling compound materials. Plywood subfloor 71 to 83 sq-ft, use standard spacing on floors that are located above heated areas. Concrete subfloor 55 to 63 sq-ft, use alternating spacing on concrete slab floors or in rooms with excessive heat loss such as solariums. Warm Tiles cables, which are supplied with standard 10 ft cold leads are designed to supply at least 12 W/sq-ft when installed per instructions. Warm Tiles cables are UL listed, CSA certified and conform to European directives. Suitable for warming of stone, ceramic and engineered wood floors.