Managing seasonal moisture changes in wood floors, including floors over radiant heat.
Wood loses moisture and shrinks in dry conditions, which can open gaps between boards. Some seasonal gaps close again when humidity rises.
Keep indoor conditions stable and follow your flooring manufacturer’s requirements. As general homeowner guidance, the National Wood Flooring Association recommends 30–50% relative humidity and 60–80°F room temperature throughout the year. These are indoor-air conditions, not a permitted floor-surface temperature for a radiant heating system.
For a heated floor, also follow the flooring and heating manufacturers’ temperature and operating instructions. Engineered construction can improve dimensional stability, but it does not eliminate the need to control moisture.
If gaps are large or remain open during more humid months, have a wood-flooring professional assess the cause before attempting repairs.
Sources: NWFA moisture-management guidance and NWFA radiant-heat guidance.