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How to Clean Mold on Cement Outside on the Foundation

By Michael Davidson ; Updated September 21, 2017
Mold loves to coexist with concrete.

Two elements common to construction are cement and mold. Cement is a frequently used building material, while mold is a blight in many buildings because it can grow wherever a source of moisture exists. Since both mold and cement are found so abundantly, it should come as no surprise they are often found together. Mold spreads quickly across cement if given a chance to grow, forming stains on the concrete and endangering the air quality for anyone in the vicinity. If you find mold on the concrete foundation of a building, it should be cleaned off as soon as possible.

Spray mold off the foundation with a power washer. Keep the pressure at 3,000 psi or less to help prevent damage to the concrete. The hot temperature of the water combined with the force of the water pressure will blast most of the mold off the foundation in seconds.

Pour 3 qts. of warm water into a bucket and mix in 1 qt. of chlorine bleach and 1/3 cup of powdered laundry detergent. Wear rubber gloves to prevent chemical burns.

Dip a sponge into the bucket and apply the mixture to any remaining stains on the cement foundation. Let the mixture soak into the stains for several minutes.

Apply force with a scrub brush to any remaining mold to remove it from the foundation.

Rinse the affected areas of the foundation to remove any remaining traces of bleach. Once the cement dries, the mold stains should be gone.


Things You Will Need

  • Power washer
  • Warm water
  • Bleach
  • Powdered detergent
  • Bucket
  • Rubber gloves
  • Sponge
  • Scrub brush


  • Mold will come back if there is still moisture exposure on the foundation. Repair leaks to prevent mold from respawning.

About the Author


Michael Davidson started writing screenplays in 2003 and has had a screenplay professionally produced. He has also studied martial arts since 1990 and has worked as a licensed security specialist. Davidson has written articles for various websites. He is a graduate of Michigan State University and holds a Bachelor of Arts in advertising.