Do-It-Yourself (DIY) underfloor heating has become a popular replacement for the ducted or baseboard types of home heating. Improperly installed, DIY underfloor heating can be expensive to maintain and very expensive to repair. The best and most efficient DIY underfloor heating system uses long-lasting materials impervious to corrosion and is designed into zoned areas to control heat flow and energy use. DIY underfloor heating is best installed with a floor covering that retains heat for longer periods of time and slowly releases it into the room.
Before planning an underfloor heating do-it-yourself project, the homeowner should first understand how the system transfers heat. Also called radiant heating, DIY underfloor heating takes advantage of the natural properties of radiation and convection. Unlike a typical forced-air and water baseboard heating systems, radiant heating heats the floor instead of the air. As the floor is heated, heat waves radiate to other objects throughout the room, eliminating drafts and efficiently warming occupants of the room.
Early DIY underfloor heating systems used copper piping embedded in concrete slabs. These systems failed miserably because the corrosive chemicals in the cement caused the copper pipes to deteriorate. The development of cross-linked polyethylene (PEX) pipes gave new life to radiant heating. Unlike copper, PEX pipes do not contract and expand, and are impervious to the corrosive effects of concrete.
While PEX is widely used for new construction, PEX is also an excellent choice for retrofitting an existing floor. The tubes are attached to metal tracks installed on the underside of existing floors. PEX uses a hydronic heating system, where a boiler heats water and pumps the hot water through the pipes. This type of system is very affordable, as PEX piping is less expensive than copper and needs only a few DIY tools for installation. If the PEX pipes are installed in an unheated room, such as a basement ceiling to heat the first floor, the joist cavities should be insulated with fiberglass batting.
Electrical resistance wiring is another common material for the DIY project. Easily installed, electrical wiring can be expensive to run as electricity costs are usually more expensive than natural gas or oil. This type of underfloor heating requires no special tools or intricate do-it-yourself plans. The wiring is embedded in rolled mats. The homeowner simply unrolls and secures the mat on top of the subflooring and installs the finished flooring over the mat.
A zoned heating system, each with its own thermostat, provides customized heating zones that can be turned on or off independent of each other. This saves money and energy, as rooms that are used frequently can receive more heat, while rooms used infrequently can be unheated or receive less heat. An underfloor heating system works best with a solid floor that retains and slowly conducts heat. Tile floors are the best choice, followed by laminate wood flooring. Thick carpeting, hardwood flooring, and linoleum are less efficient, as these floors absorb heat but do not radiate it very efficiently; hardwood may also shrink or crack from the heat.