It can be a tape type film — one of such materials, it is very convenient and attached between the beams with a stapler, enveloping the insulation from the bottom. A layer of thermal insulation is placed on the waterproofing film. Basalt cotton wool in sheets is also excellent. There are products on the market that have already proven themselves excellently, possessing non -combustibility, moisture resistance, is cut without difficulty. Therefore, all these qualities are undoubtedly suitable for material that can perfectly warm the floor.