Gaps opening between hardwood boards in winter
Urgency
1/5
Honest verdict: you can likely DIY this$0–$400Typical repair cost
Likely causes, most common first
- Furnace-dry air shrinking the wood — normal Chicagoland physics, gaps close in summer
- Chronic over-dry house (humidity under ~30%) exaggerating it
- Gaps that DON'T close seasonally: flooring installed too wet or too dry originally
Do this right now
- Add humidification and target 35–45% indoor humidity in winter
- Don't fill seasonal gaps — filler gets crushed out when boards re-expand
DIY or call a pro?
Seasonal gaps are the house breathing — a humidifier is the fix. Call about permanent gaps, cupping (edges up), or crowning (centers up): those are moisture-history problems worth diagnosing before refinishing.