Radiant floor heating systems offer gradual, room-filling convection heat that is silent and relatively energy efficient. Yet due to the amount of heat generated by these systems' electric wires or hydronic pipes, not all floors can be installed over them.
Radiant floor heating can be installed under a surprisingly large number of floor coverings. Solid hardwood is the main problematic floor covering with respect to radiant floor heating--and not all flooring industry experts agree, either.
- Natural Stone: Any kind of natural stone or aggregate stone is a natural fit for radiant heating systems. Not only is it safe to use over radiant heating, stone retains the heat.
- Porcelain or Ceramic Tile: Tile that is made from minerals is always safe to use over radiant systems and, much like stone, holds heat after the system shuts off.
- Laminate Flooring: Laminate flooring's thinness is an asset when installing radiant heating, allowing the heat to penetrate and dissipate. Precautions must be taken to protect the flooring, though. The most important point is to keep the temperature below the maximum point that is recommended by the laminate flooring manufacturer. Shaw, for example, recommends that the temperature should never exceed 85 degrees F.
- Carpeting: Due to the insulating properties of carpeting, radiant heating systems will experience efficiency reduction and thus may require that the thermostat be turned up higher than it would be with hard flooring. According to a study conducted by the Georgia Institute of Technology School of Textile Engineering, carpeting alone can reach R-values as high as 2.46 for plush wool. When combined with a bonded polyurethane padding (R-value of 2.09), carpeting may be warm enough alone that radiant heating is not even required.
- Linoleum, Sheet or Tile Vinyl Flooring: Check the manufacturer's installation instructions for maximum temperatures. Generally, begin with 70 degree F temperatures during the first 24 hours of use, increasing to no more than 85 degrees.
- Most Species of 3/4" Solid Hardwood: Recommended quarter-sawn wood instead of plain-sawn. Heating element should be embedded within sleeper system subfloor, under traditional subfloor, or embedded within concrete. Narrower floor boards tend to work better than wide-plank because the multiplicity of seams allows for more flexibility if the floor should expand and contract.
- Engineered Wood Flooring: Engineered wood flooring is recommended in place of solid wood flooring.
- Rubber Flooring: Rubber does not react well to high heat and may give off unpleasant odors.
- Directly Under Engineered or Solid Hardwood Flooring: Radiant heating should be separated from solid hardwood (as noted above).
- Very Dense Solid Hardwood: Hardwoods that rank 1,375 or more on the Janka scale are a poor fit for radiant heating systems.
- Glued-Down Carpeting: Radiant heating can dry and loosen carpet adhesive.