Removing Mold from Concrete

Driveway stains from mold and mildew can significantly impact a home's curb appeal. For driveways in constant shade or damp climates, mildew buildup is often inevitable. 

Attempting to rinse away mold with a standard garden hose or scrubbing it with a push broom often yields temporary or ineffective results. The following sections outline two effective methods for removing mold and mildew from concrete surfaces using bleach or a pressure washer. 

Scrubbing Mold with Bleach 

When mold severely covers a driveway or sidewalk, the most effective solution is to fully disinfect the area to kill all bacteria and prevent further spread. Precautions must be taken whenever using harsh chemicals, such as bleach. Proper protective equipment should be worn, and the user must remain conscious of the surrounding environment. 

Necessary Supplies: 

• Rubber gloves 
• Chlorine bleach 
• Large bucket 
• Push broom or brush with rigid bristles 
• Garden hose 

Pro Tip: Watering the lawn thoroughly before cleaning can help minimize bleach absorption into the grass. 

Before beginning, put on rubber gloves. The cleaning solution is made by combining 1/4 cup of liquid bleach with 1 gallon of hot water in a bucket. To avoid damaging lawns or walkways, bleach should always be diluted, and runoff must be controlled during the rinsing process. 

The brush should be soaked in the solution and used to scrub the entire area until it is fully saturated. The solution should soak for at least several minutes before cleaning up. Bleach should never be used in a pressure washer, as it will damage the internal components. 

Pressure Washing Mold with Detergent 

As an alternative to bleach, a mold and mildew house and siding detergent labeled safe for pressure washers can be used. This option often makes the task much easier. 

To use this method, the detergent tank is filled and switched to the "On" position. The concrete is then sprayed with the soap solution. After allowing the detergent to soak into the mold and mildew, the surface is ready for a high-pressure rinse. 

Blast It Away 

Once either the bleach solution or the specialized detergent has had a chance to work, the pressure washer can be powered up. Using a powerful spray tip or a turbo nozzle, the wand should be held approximately 10–12 inches from the concrete to begin blasting the surface. 

The mold should break up and wash away quickly, restoring the concrete to a clean appearance. To avoid leaving streaks, the entire walkway should be washed using smooth, overlapping strokes to remove all dirt and mildew buildup. 

After the cleaning is complete, the driveway should be allowed to dry fully to verify that no spots were missed.