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Will a Dehumidifier Reduce Attic Moisture?

Gary Sprague

Attic moisture can lead to problems including mold, mildew and rotting wood. While a dehumidifier can help get rid of attic moisture, it is not a permanent solution.

Will a Dehumidifier Reduce Attic Moisture

Because most homeowners rarely visit their attic, moisture buildup can go unnoticed for a long period of time. Attic moisture can result in mold and mildew as well as damage to beams, rafters and insulation. Once moisture is detected, it is important to act quickly to prevent further damage.

Causes of Attic Moisture

Cold attics, especially those with inadequate insulation, are most at risk of moisture buildup. If attic bypasses are not properly sealed, warm air rising from the home's living area can condense on beams and rafters in the cold air. Inadequate venting which does not allow moist warm air to escape the attic will lead to moisture, while excessive venting can lower the temperature in the attic and cause condensation against the roof. Homes with air conditioners located in the attic may find moisture buildup if a drainage problem allows water to accumulate in the condensate pan. Clothes dryers and bathroom exhaust fans vented to the attic instead of outdoors are another common cause of moisture buildup.

Signs of Moisture

There are several symptoms of excess attic moisture. These include condensation on windows, glass surfaces and pipes, and a mildew or musty odor. This odor often accompanies discoloration that may be white, orange, black or green on wood, insulation and stored items. Attic moisture can result in a feeling of dampness or sogginess on boxes and other stored items. Soft, rotting wood is an indication of advanced moisture damage.

Removing Attic Moisture With A Humidifier

Humidifiers are a good way to draw excess moisture from the attic but should be used only as a temporary solution. Not only will a continuously running dehumidifier waste electricity, but its storage tank will fill and require emptying several times a day in a wet attic. Depending on the size of the attic, more than one dehumidifier may be needed to remove moisture and dry out the area.

Prevent Moisture From Returning

The most important method of preventing attic moisture is creating a barrier to stop warm air in your home's living area from rising to the attic. Pipes, chimneys, recessed lights and attic stairs are examples of areas that need to be sealed. Having adequate insulation will reduce heat loss and prevent attic condensation. And make sure that the attic is properly vented. Check soffits to make sure that insulation has not slipped into the area, as this can prevent proper ventilation while also damaging the insulation.


Because of the risks associated with mold and fungus, wear protective equipment including safety goggles, gloves and a breathing mask to handle and remove insulation and items stored in the attic.