Radiant Heat and Hardwood Floors: A Dynamic Duo
10/20/2005Energy-efficient and comfortable, radiant heat systems and hardwood floors are a natural -- and increasingly popular -- combination. These helpful tips for selecting floors and systems are courtesy of the American Hardwood Information Center.
What is radiant heat?
A series of heating tubes warms the floor in a radiant heat system. The floor then radiates heat to the room. Radiant heat, which is draft-free, can be more comfortable than forced-air heat because it cleanly and silently warms not only the floor but the entire room as well. Radiant heat systems also are typically more energy-efficient than conventional systems, making them more popular than ever.
What type of radiant heat system should I install in my home?
Ideally, experienced installers of radiant-heat systems and hardwood floors work together to choose the system that best suits your needs. Electric systems use thin electric mats that work much like electric blankets. They often are used to heat small rooms like kitchens, bathrooms and entryways. Larger rooms often justify the more costly initial expense of installing a hydronic system, which involves heating water that runs through plastic tubes under the floor. Hydronic systems can be powered by gas, oil, electricity or solar energy.
Are American hardwood floors compatible with radiant heat systems?
Absolutely. Natural hardwoods warm quickly and are cozy for bare feet because they conduct heat more efficiently than thick, padded carpets. Solid hardwood or engineered wood floors work fine with today's high-tech radiant heat systems -- whether on subfloors or concrete slabs. You can add inlays to new or existing wood floors over radiant heat, and you also can paint and stencil the floors.
What about tropical woods?
The Radiant Panel Association, a trade organization for the radiant heating industry, warns against pioneering the use of a wood with little information on its dimensional stability. If you're importing a tropical or exotic wood, you must pay close attention to the source and age of the wood as well as the method used in drying it. Quick drying creates stresses that can affect the wood later as it expands and contracts.
What types of hardwood floors work best with radiant heat?
Extensive laboratory testing by Launstein Hardwood Floors in Mason, Mich., found that American hardwoods -- including cherry, oak, ash, maple, hickory and walnut -- are good choices for radiant-heat flooring.
For best results, use narrow boards, preferably not wider than 3 inches. Narrow boards will better accommodate wood's expansion and contraction across a floor.
Consider using quarter-sawn wood for planks wider than 3 inches, regardless of species, for enhanced dimensional stability.
The Launstein testing found that quarter-sawn planks up to 7 inches across (when properly installed) can work well with radiant heat systems. The testing also found that hardwood flooring that is three-eighths of an inch thick conducts heat better than thicker floors and resists gapping.
How will moisture affect the installation of a radiant heat system?
Wood naturally expands and contracts to reach balance with the relative humidity of its surroundings. That's why it's important to avoid installing wood flooring when moisture levels typically rise sharply, especially during painting or the installation of sheet rock. When radiant heat is installed in concrete, mortar beds or gypsum cement, operate the heating system until these are completely dry before topping with wood floors. This can take several weeks.
Before hardwood floor installation, operate the heating system until the relative humidity in the space stabilizes to the average level expected for seasonal conditions in the area in which the wood floor will be installed. For example, if the space is expected to average 30 percent relative humidity in the winter and 50 percent in the summer, the average would be 40 percent. In especially dry regions like the American Southwest, a humidifier may be recommended. Likewise, a dehumidifier may be called for in especially humid climates.
Experienced flooring installers will ensure that the wood floor's moisture content is appropriate for your area. A 6 to 8 percent moisture content is average in most parts of the country.
How warm should a wood floor get?
The maximum surface temperature of a wood floor is 85 F. Make sure your installer chooses a control strategy that assures this limit will not be exceeded, and gradually takes the floor through temperature changes.
What about the care and maintenance of American hardwood floors over radiant heat systems?
Caring for a hardwood floor with radiant heat is no different from caring for any other hardwood floor. Radiant heat systems also typically have no effect on refinishing guidelines. (It is, however, always best to check with the finish manufacturer.)
How much do radiant heating systems cost?
Prices vary based on the size of the room and type and quality of equipment, ranging from $3 to $10 per square foot plus installation. Robert Starr, president of Radiantec, a radiant-heat system manufacturer in Lyndonville, Vermont, estimates a system large enough to heat a 2,500-square-foot home would run about $5,000, excluding installation costs.