Radiant Heat & Wood Flooring: Part 2

A strange phenomenon occurring in radiant heat floors is color change directly over the tubes, typically happening with oily woods (often exotics). Over time, the difference in heat exposure directly over the tubes, compared to the rest of the floor, causes a color change in the warmer areas, usually darker, and reveals the exact pattern of the tubes. This is damage to your flooring that cannot be sanded out of the floor.

Before the wood flooring arrives at your job site, the radiant heat system must be running. How long depends on the moisture conditions necessary to bring the wood flooring inside. Some say 2 weeks, others say 30 days minimum. Turning the system on will ensure it is functioning properly, there are no leaks, and it is driving moisture out. If it is not turned on, and the subfloor sufficiently dried before the wood flooring is installed, it is a virtual certainty that when winter arrives, and the system is turned on for the first time, the wood flooring will cup and buckle as the moisture is driven out of the subfloor and into the wood flooring.

Once the flooring has been installed and it is time to apply the finish, it is important that prior to the finishing, the radiant heat is turned off long enough to allow time for the floor surface to reach a normal temperature, usually a minimum of 6 hours. If not, the entire floor will act like one big “hot spot”, similar to any spot where sunlight is directly hitting the floor. This will cause the finish to dry too fast, leaving applicator marks and causing bubbles. Once the finish is dry, the radiant heat can be turned back on.

Lastly, what happens after the installation is just as important as before and during. The environment must be maintained at optimal levels. Stabilizing humidity is the key. Whether that means adding moisture in winter or drier months or dehumidifying in summer or warmer months – this is critical to the success of the floor. Speak with you contractor to understand what the optimal environment is for your floor. Understand that even with humidity controls, it’s natural for wood floors to shrink and swell. It is also important that after being turned off for the season, the radiant heat is gradually turned back on. By its nature, radiant heat warms up slowly and it will be hard to resist the urge to turn it up higher and faster. This will cause a drastic temperature change for the floors and potentially irreversible damage. There are safeguards available to ensure this does not happen. Outdoor thermostats automatically and gradually turn radiant heat up or down in response to outdoor temperature changes. You should be educated by you contractor or installer as to how the heat works and why it shouldn’t be turned up too much at once. Finally, controls can be included in the system that prevent anyone from turning up the system too much at any one time.

For more helpful information on hardwood flooring options, or to buy the right flooring for your radiant system, please visit www.GateWoodFloors.com.

Radiant Heat & Wood Flooring: Part 1

Wood floors are successfully installed over radiant heat every day. When deciding to install a hardwood floor over a radiant heating system, you will need to consider the experience of your installer, his understanding of the radiant heat system and his knowledge of the hardwood flooring being used, and most importantly – moisture. These variables need to be controlled or your dream floor will be a disaster.

Moisture is hardwood flooring’s most-feared and intimidating nemesis. Even without radiant heat, moisture is the leading cause of wood flooring problems. Add radiant heat, and the potential for moisture problems is exponentially increased because the radiant heat dramatically exacerbates the moisture fluctuations in a wood floor.

To understand better, some basic information about radiant heat may be helpful. Radiant heating consists of "radiant energy" being emitted from a heat source; this radiant energy (commonly known as
heat) then penetrates all objects in its path, including people. For example, the heat felt from the sun or fireplace is radiant heat. Radiant energy travels through a space without heating the space itself (unlike forced-air heating systems which actually warm the air). When radiant heat comes across a cooler surface (like a human being), it attempts to equalize the temperature difference, thus giving off heat. Most radiant heat systems used in the United States today are hydronic, meaning the subfloor has plastic tubes through which hot water flows. The water may be heated by anything from natural gas or electricity, to solar energy. A radiant heat system heats all the materials around it. In the process, it drys everything out, while driving moisture from the joists, slab, subfloor and flooring.

There are many product choices you can make to increase the chances of a successful radiant heat flooring installation. However, there are no guarantees.

• Quartersawn & Rift-sawn Floors: More dimensionally stable than plain sawn wood flooring. They expand in height, whereas, plain sawn boards expand in width.

• Narrower Boards: Shrink and swell less than wider boards. Less than 3” wide is recommended.

• Engineered Floors: More dimensionally stable than solid wood flooring. The more plies, the more stable the product.

• Reclaimed Woods: Have a tighter pattern of growth rings, making them more stable.

• Parquet: Less expansion and contraction tendencies.

• Dark floors: Darker colors make seasonal gaps in boards less noticeable.

• Floors with Obvious Grain Patterns: They also downplay the appearance of seasonal gaps between boards.

• Distressed Flooring: Minimize the appearance of seasonal gaps.

• Beveled Edges: Make seasonal gaps less obvious.

• Tongue and Groove Strips

• Dimensionally Stable Species: North American Oak, American Cherry, and American Walnut are known for their inherent dimensional stability. Species that are more dense, such as Beech, Australian Cypress, Maple, Brazilian Cherry, and some Bamboo products are less stable. Exotic species can be particularly susceptible to problems resulting from bad drying practices.

• Products made Specifically for Radiant Heat

In Part 2 of our series on Radiant Heat, we will talk about the best ways to stabilize your floor and avoid disaster.

For more helpful information on hardwood flooring options, or to buy the right flooring for your radiant system, please visit www.GateWoodFloors.com.