Ceramic tile is the most common floor covering for radiant floor heating. It's easy to install, cheap, safe and with a good heat conduction. Ceramic is the best choice for radiant floor heating.
Some floor coverings - namely carpeting - are not really advantageous, to say the least. Picking the right flooring is critical.
Ceramic covering or Carpeting Covering - Radiant Floor heating
Products like wool blankets, plush pads and carpets simply do not "match" with radiant floor heating systems. Their thermal value reduces heat transmission.
Some radiant heating experts recommend a thin carpeting with dense padding for lower thermal resistance, but ceramic tile is a much better choice.
Ceramic covering vs Vinyl and Linoleum coverings in Radiant Heating
Vinyl is another relatively common floor covering in radiant heating - but it doesn't work as well as ceramic tile. It's true that vinyl flooring is thin and doesn't slow significantly heat transfer. Anyway, vinyl has not the right heat conducting properties, and it may decrease (even if slightly) the efficiency of the radiant floor system (besides being not recommended on environmental grounds).
And the same goes for linoleum: though an environmentally-friendly option, its thermal insulation may slow the transfer of heat.
Ceramic Covering vs Wood flooring covering
Wood coverings are now common in radiant heating systems, especially laminated wood... Recent improvements in the floor industry technology make some wood choices reasonable alternatives to ceramic tile.
Be cautious, anyway. Using multiple layers of plywood under thick hardwood floor will be disadvantageous.
Besides, using an inadequate wood flooring - or even an inadequate installation method - over your hot-water or electric radiant heat system can have disastrous results. Wood flooring should be able to withstand temperatures of 80ºF/27ºC or higher.
Laminate, cherry, oak, hickory, ash, maple or walnut are tested choices for radiant wood floor coverings. But their use is not devoid of risk. If the surface temperatures exceed 85ºF/30ºC, the floor covering can get damaged.
The source and age of the woods, or the methods used in their drying are also important, since these features affect the expanding and contracting properties of wood.
Using narrow boards, with a maximum wide of 3 inches, is recommended. Narrow wood boards respond better to the wood’s expansion and contraction.
Tests cited by the Hardwood Information Center found that thick hardwood floors are a common cause of gapping. Three-eighths of inch thick hardwood flooring is ideal for heat conduction and to avoid gaps. This organization also recommends quarter-sawn wood flooring. See, for more detailed information on wood floors over radiant heating systems: Hoskinghardwood.
If you do want to use a floor covering for your radiant floor heating system, make sure you choose an experienced flooring installer, able to assess whether the moisture content of the flooring is appropriate for your region. Before installing the wood covering, also make sure that the concrete, gypsum cement and other materials used on radiant floor are completely dry.