Hardwood Floors and Maryland Humidity: What Homeowners Need to Know
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.
Written by
Daniel Santos
Owner, CDS Hardwood Floors
Daniel Santos is the owner of CDS Hardwood Floors and has spent 15+ years sanding, staining and installing hardwood in Maryland, Virginia and Washington DC homes. He personally walks most projects, specializes in HEPA-contained dustless sanding, premium water-based finish systems and custom installations, and believes homeowners make better decisions when the process is explained plainly before a single board is touched.
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