Relative Humidity in Your Home

Relative Humidity in Your Home

By Published On: January 4, 2019Categories: HVACComments Off on Relative Humidity in Your Home

Relative Humidity in Your Home

When your home is too humid, it can cause issues, both to the health of your loved ones and to the contents in your home. Though when your home is too dry, you also risk health issues and potential concerns with your personal property. Though how do you know what is the right level of humidity in your home? And how do you best manage your home’s air quality?


Understanding Relative Humidity

We describe how much water vapor is in the air by using the term relative humidity. Relative humidity tells us how much water vapor is in the air, compared to how much it could hold at that temperature. For example, relative humidity of 50 percent means the air is holding one half of the water vapor it can hold. Another example would be at 75 percent relative humidity, the air can hold 25 percent more moisture until it reaches the dew point and can hold no more moisture.

When a specific dew point or capacity is reached, the water vapor in the air will condense as moisture, making the air feel damp. In a closed system, such as your home, the more moisture that is present, the higher your relative humidity will be.


How Humidity Affects Your Home

You need to have a certain amount of moisture in your home in order to be healthy and feel comfortable. Though too much or too little humidity in your air can cause problems. Some of those problems could be things like airborne allergens, mold, bacteria, and more. Every time we shower, cook, or even breathe, we increase the amount of moisture in the air; when these activities occur indoors, we raise the humidity level inside our home.

One of the costliest issues humidity causes is mold. Mold can even begin growing before relative humidity has reached the dew point. Mold and microbes can flourish in relative humidity that is greater than 80%.

  • Some symptoms of high humidity include:
  • Musty odors in your home and/or basement
  • Visible condensation and/or water stains
  • Visible mold growth
  • Allergic reactions to dust mites and/or mold
  • Warped wooden floors

Areas of Concern

Basements and crawl spaces are naturally cool and damp. The walls and floors are in contact with the ground. Humid outdoor air can enter your home through this area on hot days. As a result, the temperature of that air cools and its relative humidity will rise. Moisture condenses and forms on the walls of the foundation. Unless an air-tight vapor barrier is in place, moisture will evaporate from the ground and will increase the moisture content in the air of these closed spaces.

Relative Humidity in Your Home

Attics can also fall victim to relative humidity. Moist air migrates up into an attic during colder months. Mold begins to grow on the wood when the moisture condensates. Bathroom exhausts that vent into the attic or into a soffit can also produce heavy mold. If there are leaky ducts in your attic, and/or if you are using your attic for storage or the attic houses equipment that needs to be accessed for repairs and maintenance, the people in your home can be exposed to mold spores that are aerosolized when air flows or human activity disturbs the mold growth.

Your garage can develop mold growth on the cooler surfaces, including the garage overhead doors. If your garage is attached to your home, you should definitely do as much as possible to control relative humidity.

Furniture can also become a prime breeding ground for mold due to elevated relative humidity. This particularly applies to furniture that is stored in the basement or the garage since these tend to be cooler, damper areas of the home. Depending on the temperature and humidity, spores can die though mold will remain potentially allergenic even once it’s dead.

Relative Humidity in Your Home

Managing Humidity in the Home

With a modern home dehumidifier, you can effectively lower your home’s relative humidity. The humidistat that is built into the device will do all the measurements and calculations for you, and help your home attain an ideal humidity level, usually between 30-60%. Today’s home dehumidifiers promote comfort and health for your loved ones and protect your personal property

Part two of this series will offer additional tips on how to control relative humidity in your home. If you have questions or concerns about your home’s humidity levels, feel free to give us a call at 301-905-9963 to talk to one of our expert technicians about relative humidity in your home. They are also available via or email at Our expert technicians can help guide you to reaching your home’s optimal level of humidity, comfort, and safety.

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Source: Healthy Indoors Magazine Vol. 6 No. 7 December 2018

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Relative Humidity in Your Home
Relative Humidity in Your Home
Relative Humidity in Your Home
Relative Humidity in Your Home
Relative Humidity in Your Home
Relative Humidity in Your Home
Relative Humidity in Your Home