Therma-Floor® is a gypsum underlayment designed to pour over hot water tubes or electric heating cables. It acts as the thermal mass for any radiant floor system. Therma-Floor encases the tubes or cables in crack resistant, noncombustible gypsum. Its special formula resists breakdown to 150 degrees F (66 degrees C). And because it's poured only 1-1/4" (32 mm) thick, the heating system is more responsive and more comfortable.
Flooring Underlayment: Gypsum Based