Wood shrinkage gaps between hardwood floor boards during a dry winter are:

Wood is hygroscopic and its dimensions follow the surrounding humidity, so hardwood flooring shrinks in a dry heating season and swells again when humidity rises. Gaps that open between boards in midwinter are the visible result and are normal within limits; the whole reason flooring is installed with expansion allowance at the perimeter is that this movement is expected. What distinguishes normal seasonal movement from a defect is whether it reverses. Gaps that close as humidity returns in spring are seasonal; gaps that remain open through a full cycle indicate something else — flooring installed at the wrong moisture content, a persistent moisture source beneath, or subfloor movement. That is why the inspector notes the condition, the season and the indoor humidity, and frames it as worth monitoring across the year rather than as a finding requiring immediate action.

Wood shrinks as indoor humidity falls in the heating season, so winter gaps are normal seasonal movement; they become a finding only if they persist once humidity returns.

Wood flooring changes dimension with ambient humidity, shrinking in dry heating seasons and swelling in humid periods. Perimeter expansion allowance accommodates this. Gaps that do not close over a full cycle indicate an underlying problem.

Does It Close in Summer? If yes it is the season; if no it is a problem.

Check the perimeter for expansion allowance while you are there. Flooring butted tight to the walls buckles when it swells back.

• •Reporting seasonal gapping as a defect
• •Not recording the season and humidity with the observation
• •Overlooking missing perimeter expansion allowance