PURPOSE: To improve thermal conductivity and cushion effect of a titled material, by so constituting that foamed sheets made of plastics having independent foams are laminated and a great number of air holes which are penetrating from the front surface through to the back surface are provided.

CONSTITUTION: A core material 11 is placed between foamed sheets 12 and 12 made of plastics and having independent foams, which are adhered in a sandwich state thermally to each other, unified for constitution of a groundwork material 1, and a great number of through ventitation holes between the front and back surfaces are provided. This is laid on a hot water pipe 21, a heat insulation material 22 and radiation material 23 provided on a main body part 2, on which a carpet 3 is laid. With this constitution, cushion effect and an improvement of thermal conductivity can be contrived through cooperative action of the ventilators and the independent foams.