Heated concrete floors may be used to keep a home warm. With a floor heating system -- also known as “radiant heated” floors -- the floor works as if a large radiator is warming the room from the ground up. Some flooring materials -- such as tile, hardwood, marble or vinyl -- work well with radiant heating. However, installing carpet over such a floor may prove to be counterproductive in certain circumstances.
How Radiant Heating Works
A floor heating system uses a stream of heated water that flows through tubing that is embedded in a concrete slab. The heat from the water radiates outward from the tubing and into the slab; any flooring materials that are attached to the slab will heat up as well.
Some Materials Transfer Heat Better Than Others
Materials such as tile, wood and marble are able to transfer heat from a slab with relative ease. These materials are solid and transfer heat by being in direct contact with the slab. Vinyl flooring is thin and also generally solid; therefore vinyl flooring will also transfer heat well. Carpet and carpet padding, however, are known for their insulating properties. Good insulators make poor conductors of heat; therefore, a heavy carpet that is installed over a thick urethane pad will prevent much of the heat from transferring from the slab to the top of the carpet.
Carpet Installation Considerations
Many home carpet installations are done over tackless strips and padding. Typically, tackless strips are attached to the floor by nailing the strips to the floor. Since the concrete floor receives heat from heated water passing through embedded tubing, nails pose a puncture hazard to these tubes if the tackless strips are nailed to the floor. To install a carpet to a radiant-heated floor, it is necessary to either glue the tackless strips to the floor before installing the carpet or padding, or the carpet may be glued directly to the floor without using tackless strips or padding.
While it is possible to install carpet over a heated concrete floor, the efficiency of the heating system will be reduced. A radiant-heat floor design that may work well with a tile installation may perform poorly if carpet is installed instead. However, a well-designed radiant-heat floor may perform adequately if a short-pile carpet with thin rubber padding is installed over it.