Radiant Heating System and Wood Floors - Tamalpais Hardwood Floors

radiant heating system

With more homeowners looking to have a custom look for their homes, wood flooring has increased in popularity. When choosing a heating system, underfloor heating has become a popular choice. It is well suited for use with a wooden floor. With a radiant heating system, the key is to ensure thermal conductivity, which is best with dense wood. So the thinner the flooring material and the higher the density, the shorter the heat-up time and more responsive the system will be. It’s useful to also note that with some softwood flooring, you should take care as some softwoods may create a thermal barrier, blocking the heat rather than transferring it to the floor surface. Over the years, we at Tamalpais Hardwood Floors have installed a lot of wood flooring over different types of radiant heat systems. Click here to see our projects. 


Radiant heating system advantages

Combine economical heating with the beauty of hardwood flooring simply by installing hardwood floors over radiant heating. As a long-term economic investment, installing hardwood floors over radiant heating will enhance the value and aesthetics of your home and provide a warm, cozy and comfortable environment during cold winter months. Radiant heating is also a good choice for allergy sufferers. It helps to avoid the dust blown about by forced air heating systems.


How does radiant heating work?

Radiant heating system does not heat air directly, unlike conventional forced air heating systems, where warm air rises and much is lost, making them less energy efficient. Rather, radiant heating system works by transferring heat directly to objects. When placed beneath wood flooring it heats the floor. Since less heat is lost through the air, a radiant heating system is more energy efficient than forced air heating systems.

Electric radiant heating systems are good for heat small rooms like bathrooms and kitchens. They use thin electric mats that work much like electric blankets. A hydronic radiant heating system is usually is a good choice for larger rooms, involving tubing that is within a concrete slab, or under plywood subfloors. Heated water goes through the tubing network, where it releases its heat energy into the floor.

Here are some commonly asked questions and answers about installing hardwood floors over radiant heating system:


* Which wood is best for radiant heating?

In general, it is best to choose a wood species known for stability. American hardwoods such as cherry, oak, ash, maple, hickory, and walnut are good choices. Because of its dimensional stability, we recommend engineered flooring. Engineered wood flooring employs high-quality plywood as a base for its top layer of hardwood veneer. This type of plywood is dimensionally stable and does not quickly respond to temperature spikes or drops. However, wood is a poor thermal conductor. This means that heat from the system will not transmit as quickly or as thoroughly as with thinner floors that are more thermally conductive.


  • * Can the heat harm the wood?

    While the heater’s temperature will not harm the wood, it will affect its moisture content. With the heat source being directly beneath the flooring, it can dry out or gain moisture far faster than flooring in a home with a conventional heating system. Therefore it is important that the surface temperature of the wood floor does not exceed 85 degrees. Also, it is important that the temperature variations are smooth and gentle. These are easy to achieve with the following climate controls:

    • exterior thermostat – protects the perimeter of the system from condensation absorption during rapid temperature changes.
    • mechanical humidity control – this ensures that the moisture content of the floor will remain stable by keeping the relative humidity at an even level.
    • heat transfer point control – prevents overheating by monitoring the floor temperature.


* Is there a recommended board width?

It is best to use narrow boards, no wider than 3 inches. Narrow boards expand and contract less than wide boards do. They will better accommodate the wood’s expansion and contraction across a floor. The larger number of seams on a floor also helps in absorbing movement. If you must use planks wider than 3 inches, consider using quarter-sawn wood for enhanced dimensional stability. The wider the board, the greater the potential for gaps between the boards. It happens when they contract with seasonal changes in temperature and humidity.


* Does the wood need to acclimate to the site?

Laying down the wood flooring at a correct moisture content is key to having beautiful and long-lasting wood floors. As the material will move over time, expand and contract with the relative humidity caused by the seasons, you need to fit the plans with sufficient room for expansion. Achieve it by letting the flooring acclimate to the environment inside the room you will fit it to. You must store the hardwood in the house for 7 to 10 days before installation so it can acclimate. You should ideally turn on the radiant heating system for several weeks before the hardwood flooring installation.


*How should the subfloor be prepared for hardwood?

The most important factor in successfully installing hardwood floors over the radiant heating system is a dry subfloor. A flooring professional can check the moisture content of your subfloor to determine whether it is acceptable for a hardwood flooring installation. If you don’t maintain the acceptable moisture content, moisture left in the subfloor will enter the wood flooring as soon as the heat is turned on. This will result in the floor excessively expanding, contracting, cracking and warping. The only sure way to do avoid this is to turn on the radiant heating system before installing the wood flooring.  You should also install a high-quality vapor retardant over the subfloor to help protect your hardwood floor from moisture.


* What if there is excessive moisture?

You can tape a 4×4 foot section of polyethylene plastic sheeting to the slab. Turn on the heat to check for the presence of excessive moisture in the slab. If moisture appears under the plastic, heat the slab for another 24 hours. Keep repeating the test until no moisture is visible.


For additional consultation on installing hardwood flooring over radiant heat, please call Tamalpais Hardwood Floors at (866) 987-8686 and ask for Dermot. Click here to see the contact information.  Tamalpais Hardwood Floors not only install hardwood floors but provide maintenance and other flooring services. We have experience serving in San Francisco Bay Area and Marin for all of your flooring needs.