Stirotermal Duo 30 is panel of the same shape, but different insulation thicknesses. The top layer represents hard corrugated polystyrene film, which is planted on the molded polystyrene foam. The shape of the knobs allows for a very firm grip of pipes in diameter of 14 to 18 mm at an interval of at least 50 mm. The panels join solidly and waterproof with each other longitudinally and transversely according to the principle ""knob into knob"", therefore they are suitable for installation under cement mortar, as well as under floating screed in spaces with higher pressure loads.