Not all species of wood are good candidates for an installation over radiant heating. When possible, choose a species that is known for its stability. Quarter sawn or rift-sawn flooring is preferable to plain sawn in the search for stability. Strip flooring is also a better choice than plank flooring, because narrow boards expand and contract less than wide boards do. Using narrow boards also means there are more seams in a floor to take up movement. Engineered flooring and laminates work the best with radiant heat because of their dimensional stability. Floating floors that are either engineered or solid are also highly recommended because they tend to move as a unit to help accommodate moisture content changes.

No. Under any kind of carpet it is a fire hazard. Also, laminate would melt and be a fire hazard. Concrete is a definate yes and is actually the best medium. Gypsum wood is another good flooring as it is light and resistant to shrinking or cracking. Most wood flooring is okay - the only concerns are with shinking or cracking. It is mostly a question of saftey and effectiveness. http://www.concretenetwork.com/concrete/radiantfloorheating/index.html

Radiant floor heating is practical in most parts of the country (world) for most types of flooring. For space heating, regions of extreme cold such as Northern Minnesota, rooms with high ceilings such as 16' vaulted areas, rooms with large window areas, such as window walls, and rooms with high outside wall area vs. floor area such as projecting rooms can create design problems for radiant heat. In my experience as a designer of these systems if you have 2-3 of the factors I've mentioned you have a good chance of requiring special means to provide sufficient heat. Each case is assessed on a design basis. The assumptions behind this answer are: 1. You have a temperature of at least 180 degrees F available in the heat source which most often is hot water. 2. Your heat loads are for average quality commercial or residential buildings. Typically these loads are between 10 and 30 btu / sq. ft/ hour throughout North America. The two basic radiant heat systems are embedded and underfloor. Embedded describes the typical cement floor with embedded tubing, or, thin concrete layer poured over some kind of substrate, typically either wood sub floor or corrugated metal. As the insulation value of the flooring material above the heat source increases the temperature of the heat source increases. Flooring insulation values typically vary up to R=3.5 for thick carpet and pad. As the heat load increases the required heat source temperature increases. Typical residential and commercial radiant heat applications involve flooring surface temperatures less than 10 degrees above desired room temperature. Thus, to maintain a room at 70 degrees F you'd need a floor surface temperature of less than 80 degrees. The precise surface temperature required varies with heat load. These temperatures do not create fire hazard for materials used in flooring, whose flash points are generally above 350 degrees F. These temperatures do not generally cause degradation of flooring materials such as carpet, pad, wood laminates, vinyl, tile, stone, marble, cement etc. These temperatures can cause damage to real wood flooring, but this effect can be minimized by moderate introduction of heat at the beginning of the heat season. In this way the flooring has a gradual period of drying and you avoid the worst effects of rapid movement. A device called an "outdoor reset" can provide this graduated heating automatically. Snow melt systems are special, in that their heat loads can exceed 125 btu/sq.ft./hr and so require heat sources far beyond normal space heating. I am not aware of snow melt systems using surfaces other than cement, tile, brick, or similar materials, all of which tolerate extremely high temperatures. Typical snow melt systems are designed to achieve surface temperatures of 35 degrees F.

You can put some electric radiant floor heating systems under any kind of flooring. Just make sure that it is UL-listed for under carpeting and complies with manufacturer guidelines for under laminate. I know that WarmlyYours.com has an under carpet system, but I am not sure about laminate. Speedheat has a system for under all floor coverings and I know that they have a product called Lamimate for under laminate and CarpetMate for under carpeting. They use a lower wattage system for both and a limiting smart thermostat to comply with manufacturer guidelines for laminate flooring. You can find out more about WarmlyYours at http://www.warmlyyours.com and Speedheat at http://www.speedheat.us. Speedheat also has a heater for under area rugs. WarmlyYours had one, too, but theirs was recalled for safety reasons. They may come up with a new, safe product soon, but you would have to check with them.