basement mold
A dark, warm and wet basement or crawl space is one of the first places where truly invasive mold can appear in the home.

Basement Mold

Mold loves to grow under your home. Usually, basements and crawl spaces receive little to no sunlight and are cool, humid and poorly ventilated. These conditions create the perfect environment for mold and mildew to thrive.

Basement mold is usually caused by:

Poor Ventilation

A lack of circulation and higher humidity can create the perfect environment for mold to proliferate. You may see signs of growth on the walls and ceiling and a musty smell in the air. Be sure to check behind anything that is sitting against the walls and inside basement closets.

A Direct Leak

Many utilities, such as your plumbing or HVAC, are often run through the basement. Check around all plumbing fixtures, under the bathrooms from the above floors, and around any hot water heaters and HVAC units. Heavy mold growth in these areas is usually a sign of a leak.


Condensation forms when air is rapidly cooled and loses its ability to hold moisture. Your basement is the coolest area of the house and is usually more humid. Cool, humid air with little to no ventilation can create the perfect environment for mold to grow.

how water gets in to the basement to allow for the growth of basement mold

Basement Mold

basement mold

Crawlspace Mold

crawlspace mold

How to Get Rid of Basement Mold

If the basement has vents from your HVAC system, make sure they are open. If you don’t have vents, consider adding them so that the basement air gets the same treatment as the rest of your house.

Consider adding a permanent dehumidifier in your basement. A dehumidifier will remove the moisture and pump it to a drain or outside of your house. A dehumidifier is less expensive than running new HVAC ductwork and is often more effective. Having both the HVAC vents and a dehumidifier would be the best solution.

If you did the condensation test mentioned in the BADGER TIP below and discover that water is seeming through your concrete, you will need to seal the concrete with a specialty sealer such as DryLok. Paint is not waterproof, so a product like DryLok, which is formulated to be waterproof, is crucial to protecting your home from moisture seepage. Once you’ve applied the DryLok, per manufacturer instructions, you can then apply regular paint over the DryLok.

After you have removed the source of the moisture, you will need to clean the mold affected areas in your basement. This will include wiping down walls and joists with the proper mold killing solutions, throwing away or cleaning damaged materials such as carpet and furniture, and making sure a dehumidifier is running so mold doesn’t return.

Please read our section on MOLD KILLERS for treatment solutions and for detailed instructions for:

Badger Tip: Concrete walls with earth behind them frequently seep moisture if not sealed with a speciality paint such as DryLok. The best way to check for seepage versus condensation is to take a 1 foot by 1 foot sheet of plastic and tape it against the wall in the area of your basement with moisture problems. Make sure all 4 edges are taped and sealed. Check over several days. If you find moisture on the wall side, water is seeping through. If it is on the basement side, it is a condensation issue.

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