Hardwood Floors and Maryland Humidity: What Homeowners Need to Know
7 min read
Maryland's indoor humidity swings from 15–20% in winter (bone dry) to 60–70% in summer (swampy). Hardwood expands with moisture and contracts without it. Keep your home between 35–55% relative humidity year-round and your floors stay flat.
Winter: run a humidifier
Forced-air heat can drop indoor humidity below 20%. Boards shrink and gaps appear between planks — normal but preventable with a whole-house or portable humidifier.
Summer: run AC and a dehumidifier
Basements and first floors can hit 70% RH in July. Boards absorb moisture, swell and cup (edges rise). Keep AC running and add a basement dehumidifier if needed.
Monitoring
A $15 hygrometer per floor lets you see what's happening. If you see numbers outside 35–55% for weeks at a time, address the source.
Quick answers
- My floors have gaps in winter — is that a problem?
- Usually no. Seasonal gaps close in summer. Permanent gaps can be filled during a refinish.
- My floors cupped after a leak — will they flatten?
- Often yes. Fix the moisture source, let them stabilize for 30–60 days, and re-evaluate. Many cupped floors flatten on their own; the rest sand flat during a refinish.
- Do I need a humidifier if I have hardwood?
- In Maryland winters, yes. It protects your floors and your family's health.