- Small winter gaps that close in spring are normal wood movement.
- Furnace-dried air is the usual cause. A humidifier reduces it.
- Gaps that never close, or come with cupping or soft spots, need a look.
- Most warranties treat humidity-related gaps as not a defect.
Why it happens
Wood takes on and gives off moisture with the air. When the furnace runs in a Lower Mainland winter, indoor air dries, boards shrink and small gaps open. In humid months, they swell and close. Wider solid boards move more than narrow ones. Engineered moves less.
What's normal vs not
| Sign | Likely |
|---|---|
| Thin, even gaps in winter that close in spring | Normal seasonal movement |
| Gaps plus cupping (raised edges) | Moisture from below or high humidity |
| A few wide gaps in one area | Install or fastening issue, or a local moisture source |
| Gaps that keep growing year after year | Get it checked |
What to do
- Keep humidity in the warranty's range (often about 35–55%; some brands differ).
- Don't fill seasonal gaps with rigid filler. It cracks or pushes boards when they swell.
- Persistent problem gaps: find the moisture or fastening cause first.
Common questions
Why do my hardwood floors have gaps in winter?
Heating dries indoor air, and wood shrinks as it loses moisture, so small gaps open between boards. They usually close again in the more humid months.
Should I fill gaps in hardwood floors?
Not seasonal gaps. They open and close with humidity, and rigid filler can crack or cause problems when boards swell. Address humidity instead.
Are gaps in hardwood covered by warranty?
Usually not. Most hardwood warranties treat gaps from humidity changes as environmental, not a defect, which is why they specify a humidity range.
Who's writing this: Rose and Thorn Flooring is a flooring company in Surrey, BC. We install floors for a living, so yes, we'd love to do yours. But nobody pays us to say nice things about a product, and we don't earn commission from any brand. If something here is wrong or out of date, text us at 604-716-4160 and we'll fix it.