Radiant floor heating can be installed on a wood subfloor, but there are specific considerations and methods to ensure the system operates efficiently and safely. Wood is a natural material that can expand and contract with temperature fluctuations, so it’s essential to ensure that the radiant heating doesn’t damage or warp the wood.
Types of Wood Subfloors:
- Plywood: Common in many homes, it provides a stable base for both the heating system and the flooring material.
- OSB (Oriented Strand Board): Another common type of wood subfloor, it’s slightly denser than plywood.
- Tongue–and–Groove: This can be made from plywood or other types of wood and provides a tight interlocking system.
Considerations for Radiant Heating on Wood Subfloors:
- Thermal Conductivity: Wood has lower thermal conductivity than materials like concrete. This means the heat might not spread as quickly or evenly. Using a system designed for wood subfloors can help address this issue.
- Expansion and Contraction: Wood expands and contracts with temperature changes. A too-rapid temperature change can cause warping or cracking. Therefore, the heating system should heat gradually.
- Moisture Content: Wood can be affected by moisture. Ensure that the wood subfloor’s moisture content is suitable before installation. Also, the use of a vapour barrier might be necessary to prevent moisture from reaching the wood from below.
Installation Methods
Above the Subfloor
Many hydronic systems, particularly those in retrofit scenarios, will place the tubing above the wood subfloor.
This could be within lightweight concrete, specialized panels, or thin-set mortar. Electric radiant mats or cables can be laid directly onto the wood subfloor.
Between Joists
If you have access from below, such as in a basement or crawl space, hydronic tubing can be installed between the joists under the wood subfloor.
It’s essential to use aluminium heat transfer plates for even heat distribution and to insulate beneath the tubes to direct heat upwards.
