How to Clean Mold From Concrete (And Keep It From Coming Back)

Say goodbye to grimy green patches! Learn how to clean moldy concrete and keep it gone for good.

Mold on your concrete is more than just a cosmetic nuisance – it’s a red flag that moisture is overstaying its welcome. Mold and mildew thrive in cool, moist environments. The shaded corner of your patio? Yep. Your damp basement slab? Check. The sidewalk buried beneath fall leaves? Absolutely.

The good news? You can close out the Amazon tab you’ve got open for a hazmat suit, because in this guide, we’ll walk you through everything you need to know to clean mold from your concrete.

Why Mold Loves Your Concrete (And What It’s Doing There)

Let’s break down the science. Mold spores are floating through the air pretty much all the time until they land somewhere damp and shaded. Concrete, a porous material, acts like a sponge absorbing moisture within its pores, especially if it’s not properly sealed.

Common mold hot spots include:

• Basement floors and garage slabs
• Driveways shaded by trees
• Sidewalks buried in leaves or snow
• Outdoor patios with poor drainage

If moisture is seeping into your concrete, and there’s little sunlight or airflow to dry things out, mold will gladly make itself at home…

… and invite its friends.

Safety First: Protect Yourself From Mold and Mildew

Okay, you may actually need to reopen that Amazon tab because we need to talk protection. The process of mold cleanup can release spores into the air, and they’re not something you want in your lungs or eyes.

Your Mold-Cleaning Personal Protective Equipment (PPE):

• Long sleeves and gloves to prevent skin irritation
• N95 mask to avoid breathing in spores
• Goggles for eye protection
• Open windows or doors if you’re working indoors (ventilation is key!)
  
  

Supplies You’ll Need For Cleaning Mold Off Concrete

Here are a few essentials you may want on hand before you get down and dirty:

• A stiff-bristled brush or broom
• A bucket and clean water
• Mold-killing detergent (choose one labeled for outdoor mold and mildew)
• White vinegar or bleach
• A spray bottle
• A hose or pressure washer for exterior concrete

Cleaning Mold From Concrete Step-by-Step

1. Clear the Surface

Remove any loose dirt, leaves, or debris with a broom or leaf blower. Mold loves to hide under organic matter, so start with a clean slate and expose where the mold is most concentrated.

2. Choose Your Cleaning Solution

Pick the best method for your mold situation:

• Detergent: Mix a solution of water and mold-killing detergent. Apply it to the moldy area using a spray bottle.
• White Vinegar: Vinegar is a natural cleaning agent that can kill mold. Pour white vinegar into a spray bottle and apply it directly to the moldy area. Let it sit for about an hour before scrubbing.
• Bleach Solution: For heavy mold growth, mix 1 part bleach with 10 parts water. Apply generously and allow it to sit for 10 to 15 minutes.

Safety Tip: Never mix bleach and vinegar. This could create dangerous fumes known as chlorine gas.

3. Scrub Thoroughly

After the cleaning solution has soaked in for a while to ensure that all the mold is killed, use your stiff brush or broom to scrub deep into the concrete’s pores. You’ll want to be thorough here – mold clings on tight.

4. Rinse Away the Residue

Using a garden hose or a pressure washer, rinse the entire surface. Indoors, use buckets of clean water or a wet/dry vacuum to remove both the cleaner and the loosened mold.

5. Let It Dry Completely

To prevent the mold from returning, you’ll need to seal it. But the concrete must be completely dry before applying a sealer. Give your concrete a chance to dry out in at least 2 to 3 days of dry, sunny weather.

Step 6: Seal the Concrete

If the area you just cleaned is prone to mold, it’s important to seal the concrete with a high-quality penetrating sealer to prevent it from coming back. Sealing creates a moisture barrier that prevents water from being absorbed into the pores and protects against mold.

Prevent Moldy Concrete: Your Concrete Maintenance Checklist

Mold prevention is all about keeping the concrete dry and protected. Here’s how to keep your surfaces mold-free:

• Seal your concrete: Make sure your concrete is protected by applying a high-quality penetrating sealer to block moisture and mold growth.
• Fix leaks and drainage problems: Ensure water flows away from slabs, not toward them. Fix any drainage issues causing water to pool on the surface.
• Clean regularly: Don’t wait for mold to appear. Routine cleaning helps prevent mold spores from building up.
• Maintain good airflow: Making sure your concrete has air is especially important in basements and garages.

Related Resource: How to Maintain Concrete

When to Call in the Pros

Sometimes mold problems go beyond DIY territory. Here’s when it’s time to contact professionals:

• You’d rather not deal with chemicals or power washing yourself
• The mold has spread across large areas or keeps coming back even after multiple cleanings
• You suspect black mold or health risks are involved

Our team at A-1 Concrete Leveling offers professional cleaning, sealing, and concrete maintenance services to help protect your investment and give you peace of mind.

Say Goodbye to Moldy Concrete

Mold on concrete isn’t permanent, and it doesn’t have to be a recurring nightmare. With a little know-how and elbow grease (plus the right tools), you can send mold packing. And when you pair your efforts with expert sealing from A-1, you’ll have a mold-resistant surface that stays clean and dry for the long haul.

Need help tackling mold, or just want to clean and protect your concrete the professional way? Request a free estimate from your local A-1 Concrete Leveling team.