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What Are the Causes of Brown Mold in Homes?

Rebekah Richards
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Mold, also referred to as mildew, is a type of microscopic fungus that thrives in damp places. Mold frequently appears brown, gray, green or black. Since molds can damage objects and cause respiratory symptoms in some people, removing and preventing all types of mold is important.

Mold grows in damp areas.


Cladosporium, acremonium and aspergillus represent three common indoor molds that can appear brown. However, the U.S. Centers for Disease Control and Prevention does not recommend testing mold samples to determine which type of mold you have; each type can be harmful and should be removed.

Leaks and Moisture

Brown mold requires moisture to grow. Condensation, leaks in roofs or plumbing, humidifiers, flooding or storing firewood indoors can cause moisture.

Lack of Light

Brown mold grows in damp locations, such as bathrooms and basements. Since mold does not reproduce through photosynthesis, it does not require light to grow. Avoid carpeting damp locations or areas near appliances such as washing machines or dishwashers.

Dust and Dirt

Brown mold requires nutrients to survive. Since mold can survive by decomposing small amounts of dust or dirt, keeping areas clean and uncluttered can help prevent mold.


Prevent brown mold growth by using a dehumidifier to keep humidity below 60 percent and fixing any sources of moisture, like leaking roofs or cracked walls. Remove dust or clutter and use fans to increase ventilation.