How to Control High Humidity in Rooms

Updated February 21, 2017

Humidity refers to the amount of moisture in the air. Some rooms tend to have higher humidity than others; they include basements, crawl spaces, bathrooms and attics. In addition to being uncomfortable, high humidity can cause a host of problems, including mould and mildew growth, wood rot, paint peeling and allergic reactions. High humidity is manageable.

Run a dehumidifier during the winter and an air conditioner during the summer. The goal is to keep the relative humidity (RH) between 30 and 50 per cent. This will make your home comfortable while avoiding many of the problems associated with low and high humidity. Running your air conditioner on humid days, rather than opening your windows, will help reduce humidity.

Ventilate your house. This may be as simple as opening a window. However, in some rooms that are prone to high humidity, this will take more work. For example, soffit vents should be installed in combination with at least one other vent at the top of your roof to ventilate your attic.

Install vapour barriers. Vapour barriers, available at most home supply stores, prevent moisture from seeping into your home. Vapour barriers can be laid under concrete slabs, on the warm side of walls, and across crawl spaces to prevent ground moisture from seeping into your home.

Install storm windows. Storm windows serve as a buffer, keeping the outside air from coming into contact with the regular window. This reduces humidity and moisture condensation.

Run an exhaust fan after activities that make the air more humid, such as showering, laundering and cooking.

Things You'll Need

  • Dehumidifier
  • Air conditioner
  • Vapour barrier
  • Storm windows
  • Exhaust fan
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About the Author

Thomas King is a graduate of the University of Pittsburgh School of Law where he served as managing editor of the "Pittsburgh Journal of Environmental and Public Health Law." He currently lives in Aberdeen, Washington where he writes and practices law.