Wood Floors and Radiant Floor Heating: A Good Match?

There's been much debate over the past decade about the use of radiant floor heating under hardwood floors. Many know about the benefits of radiant floors but fear that the WarmlyYours Tempzone™ floor heating system radiant system will damage their wood floors over the long run. As we will see, the evolution of the radiant technology has solved most issues that were typically associated with old hot water radiant floor heating systems, but we will also make some recommendations on what types of wood floors work best with a radiant system.

Understanding the Contraction & Expansion Effects

First, before getting to the specifics of the compatibility between radiant heat and hardwood floors, it is important to be aware of the natural impact moisture and humidity have on hardwood floors. A characteristic of wood floors is that they contract and expand because moisture content in the floor changes. Often, this is the result of changes in the humidity level in the air itself, and explains for instance why a door may get jammed in the summer (Humid conditions lead to wood expansions) to suddenly work again in the winter (Dry conditions lead to wood contractions). The same will happen with your wood floor: gaps between the planks will appear in dry conditions and warping or cupping of the planks may occur in sustained humid weathers.

Generally, whether radiant heat is used or not, it is recommended to maintain a relatively constant room humidity level to limit these contraction and expansion effects. This can be a challenge in climates where humidity can get as high as 80% in the summer and as low as 15% in the winter.

How Does Radiant Floor Heating Impact Hardwood Floors?

Radiant floor heating will increase the wood temperature and as a result decrease the wood’s moisture content. While heat in itself will not damage the wood material, the increase in temperature will potentially contract the wood and increase the gap space between the boards. When the homeowner stops the heating system or decreases the temperature setting, the moisture will increase again and the gaps get narrower.

As Nick Mottet from WarmlyYours.com reports: “In the past, radiant heated floor systems were hard to control to ensure an even temperature across the whole floor. This resulted in the creation of cold and hot spots with excessive temperature points damaging the wood over a long-term use of the system. Today, new improved hydronic or electric radiant floor heating systems now allow for much better control of the floor temperature and improved design techniques help ensure even distribution of heat across the whole floor. The issue with excessive temperature points no longer exists.”

How to Choose Your Hardwood Floor

Overall, now most wood floors will work well with radiant heat. When making your decision, a few points should still be considered:

• A hardwood floor with higher density will conduct heat better and expand less. Density varies depending on the species and the growth characteristics of the trees used. Fast growing tree typically have lower density.
• Planks with a narrower width will leave more room for expansion while wide plank floors have less flexibility.
• Engineered wood floors typically work better than natural wood because engineered products have a thinner natural component, with the remainder made up of processed or plywood the assembly is simply more stable than solid hard wood.
• Thinner hardwood floors will conduct heat faster than thicker wood floors. Launstein, a manufacturer of less than standard solid floors, reports a difference of 6 degrees in tests comparing 3/8” and ¾” wood floors.
• Quarter sawn (and rift sawn) wood is more stable and will expand/contract less than plain sawn wood. For more information about these different cutting techniques, visit this very helpful page.

It is important to give consideration to the factors above. However, overall you can feel confident that radiant floor heating is a good option for your wood floors. New technology and improved design will help you ensure years of comfort with the beauty and elegance a nice wood floor will bring to your home.

WarmlyYours features thorough information on radiant floor heating under hardwood as well as installation case studies, available at http://www.warmlyyours.com/products/floor-heating/hardwood/.

Related Pages:

• Engineered Wood Floors
• Wide Plank Flooring
• Avoiding Hardwood Floor Problems - other tips