How to Get Rid of Mold on Basement Block Walls

A overabundance of moisture in your basement, whether from a flood or from gradual seepage through your walls and floor, can result in mold growth.

Prepare for mold removal

If the basement has a musty smell, you probably have mold. Mold sometimes appears as a black film on surfaces such as block wall---a surface you'll find easier to clean than more porous materials such as wood or drywall.

Put on old clothes. (Throw these away after working around mold.)

Open the windows. When disrupted, mold spores will enter the air, making them easier to inhale. The more ventilation, the better, since you may also be working with bleach. Ventilation will also help dry the basement and surface.

Wear a mask over your mouth and nose. The mask, which you can purchase at a hardware store, will also prevent you from inhaling spores. Throw the mask away after using it around mold.

Mold removal

Remove the mold by thoroughly scrubbing the block wall with a hard, dry brush. Do not apply water during this step. Sweep or vacuum the floor. Make sure you've removed the surface mold from the block wall.

Disinfect the area with bleach. Add about a 1 cup of bleach to 1 gallon of water. You may need more water and bleach, depending on how large the surface. Generously apply the water and bleach solution to the block wall with a coarse sponge.

Rinse the area with clean, clear water. Dry the surface with towels and rags immediately.

Run one or more electric fans facing the surface for further drying. Turn on a dehumidifier, and keep windows open.

Things You Will Need

  • old clothes
  • face and nose mask
  • scrub brush
  • 1 gallon water
  • 1 cup bleach
  • coarse sponge
  • fan
  • dehumidifier


  • To prevent mold, keep surfaces dry. Moisture and water cause for mold. Getting rid of them and decreases the chances of mold growth.


  • Keep children and people with respiratory problems far away from mold.

About the Author

Brendan O'Brien is a professional journalist in Milwaukee, Wis. He has worked for several news organizations, newspapers such as the "Milwaukee Journal Sentinel" and trade magazines during his career of more than 15 years. He is currently a freelance writer who works for several publications.