Hardwood flooring is a natural product that responds to its environment by expanding and contracting. During the heating season, indoor humidity levels often drop below the recommended 30-50% range, causing the wood to lose moisture content and shrink. This is the most common cause of small gaps appearing during the winter. These gaps typically close up again when humidity rises during the spring and summer. However, gaps that do not close, or gaps that appear during humid seasons, often point to a failure in the initial acclimation process or an underlying moisture problem with the subfloor that was never addressed during installation. To minimize gapping, it is critical to ensure that the wood flooring is properly acclimated to the home's permanent environment before installation. The NWFA provides rigorous guidelines for checking the moisture content of the wood flooring against the subfloor. For solid wood, the difference in moisture content between the flooring and the subfloor should be within 2-4%. For engineered flooring, it should be within 2%. If the flooring is installed while too wet, it will inevitably shrink as it dries. If you are concerned about persistent gaps that exceed the thickness of a business card, it is advisable to have a professional check the ambient humidity in your home and verify the moisture levels of the wood to rule out long-term subfloor issues.
Key considerations
- why do gaps form in hardwood floors
- seasonal gapping hardwood
- hardwood floor spacing issues
- solid-wood
- engineered-wood
- wood-movement