Floor Covering
Any floor covering can be used with a radiant heat system. The key is to ensure the radiant design uses the correct floor covering. Different floor coverings will have different R-values (their ability to restrict energy transfer). Carpet is more restrictive than tile, but can still be used. The difference is usually a slightly higher supply water temperature.
Tile
One of the main concerns with regard to tile is cracking. There are three main reasons why tile cracks: deflection, moisture and crack migration from the substrate. Some simple guidelines can be followed to minimize these concerns.
- Always install the substrate per TCA (Tile Council of America). This may include a cement backerboard, thick set, double layer of plywood or a thin slab.
- Do not run the radiant system until the substrate has cured. A minimum of 7 days is required, 15 days is better and 28 days is ideal.
- Install a crack suppressant membrane. This will help retard any crack progress that may originate in the substrate.
Hardwoods
Wood is what is referred to as being hydroscopic, or basically it will act like a sponge. If the wood is installed dry, it will absorb moisture and expand. The following guidelines will help eliminate errors associated with hardwood floor installations:
- Use strips, not planks. Ideal width is 3" to 3.5" in width.
- Use kiln dried wood.
- Make sure the wood is between 7% and 10% moisture content when it is installed.
- Make sure the support floor below the wood is no higher than 4% moisture content than the hardwood.
- Quarter sawn wood will respond better than a plain sawn wood.
- Try to keep the room's relative humidity between 35% and 50%.
Carpet
There are various reports that carpet can not be used over a radiant system. The truth to the matter is that carpet works just fine, if the system is designed with carpet in mind. There is a greater range for error with carpet, depending on the combination of pad and carpet used. An ideal R-value for a carpet and pad is around 2.0 or less.
