All photos link to larger images.

Under floor radiant heat is the most comfortable heating system available. It's also very energy efficient, silent, and doesn't create the problems that forced air does for allergy sufferers. Since it's radiant, you can keep the temperature lower than normal and feel totally comfortable. The first step was installing the tubing for the radiant heating system. It was stapled to the wood subfloor, evenly spaced everywhere except in closets or under built-ins.

After a primer was sprayed on the subfloor, the workmen brought in hoses and pumped in the liquid gypsum underlayment. We protected the wood doors from splatters with plastic, but these guys did a neat job and this turned out to be unnecessary. One man managed the hose while the other smoothed the liquid material with a special rake.that also measured the depth of the Therma-Floor.

Maxxon's 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. Therma-Floor encases the tubes or cables in crack resistant, noncombustible gypsum. Its special formula resists breakdown to 150ºF (66ºC). And because it's poured only 1-1/4" (32 mm) thick, the heating system is more responsive and more comfortable.

This type of floor (radiant heat over a wood subfloor and covered in Therma-Floor) is energy conserving and very comfortable. A wood subfloor with a crawlspace below has flexibility and is easier on the legs and feet. Since the floor is insulated from below, heat from the radiant system can only migrate up into the room. This is more efficient than installing radiant tubes in a slab; especially if the slab isn't insulated below. Therma-Floor sets up in just a couple hours and is self leveling.