How to Regulate the Humidity in the Basement

  • 4-8 hours
  • Beginner
  • 350-750
What You'll Need
Brush (to clean the coils)
Extenders for downspouts
Splash blocks for downspouts

Humidity in basement rooms should be around 50%, the same as any room in the home. Higher humidity may cause mildew or mold to grow and irritate allergies of the occupants. There may be also be damage from wood rot or mildew on personal belongings. If the humidity is lower then the air will be too dry and cause dry skin and nasal problems. Using a dehumidifier in the basement is a good way to regulate the moisture in a basement.

Step 1 – Determine the Size

A dehumidifier should be purchased to match the size of the room. The box that the dehumidifier comes in will say how large a room it is designed for. Dehumidifiers are rated by the amount of moisture that they can pull out of the air in one day. A very wet basement will require a more powerful dehumidifier. Larger units will have a larger reservoir and will not have to be emptied as often. A smaller unit will use less energy. So strike a balance between the energy used and how often you have to empty the unit.

Step 2 – Decide which Type

Although portable dehumidifiers are the most common there are also ducted and stationary units available. In order to avoid having to empty a reservoir the dehumidifier can be ducted to the outside through a wall. A stationary dehumidifier can make sure the entire home is at the correct humidity.

Step 3 – Decide when to Run the Unit

Warm humid climates are the perfect place to run a dehumidifier and it may be needed all year. A cold weather climate may only need the unit in the warm humid summer months. Dehumidifiers don’t work well when the temperature is too low. Also when the basement is heated the moisturized air rises to the floors above.

Step 4 – Maintain the Dehumidifier

Check the filters and clean them twice per month. There are internal filters and there may be an external foam filter. Examine the coils seasonally to be sure they are clean. Clean the internal filters frequently - as a rule of thumb, every 2 weeks.

Step 5 – Consider Other Solutions

To solve the moisture problem there are some other things that can be implemented to provide a long term solution. Gutters and downspouts can be extended to carry rainwater away from the foundation. Also the grade can be sloped away from the foundation to shed water away from the house. A buried exterior drainage system can be installed to take care of water near the base of the house. There are also drainage systems that are placed at the concrete slab to deal with moisture.

Dehumidifying your basement will make it a more comfortable place. In addition it protects your home and its contents from damage. The simple use of a dehumidifier can help to control the humidity in your basement.