
Target Humidity Levels
EPA recommends keeping indoor relative humidity below 60%, with an ideal range around 30-50%. When humidity stays high, mold growth becomes much more likely.
Common Sources of High Humidity
- Long showers and poor bathroom ventilation
- Cooking without a vented range hood
- Basements or crawlspaces with poor airflow
- Drying clothes indoors
- Unvented gas appliances
- Seasonal outdoor humidity
Humidity Control Strategies
Ventilation
- Run bathroom fans during and after showers
- Use kitchen exhaust fans that vent outside
- Open windows when outdoor air is drier
- Keep interior doors open for airflow
Moisture Reduction
- Use dehumidifiers in damp rooms
- Fix plumbing leaks quickly
- Seal foundation cracks and improve drainage
- Insulate cold pipes to reduce condensation
Room-by-Room Tips
Basements
Run a dehumidifier, keep items off the floor, and improve air circulation behind storage.
Bathrooms
Use the exhaust fan and wipe down wet surfaces to prevent lingering moisture.
Bedrooms
Avoid blocking vents, and keep furniture slightly away from exterior walls.
Signs Humidity Is Too High
- Condensation on windows or pipes
- Musty odors that return quickly