Mold on your concrete patio isn’t just an eyesore — it can stain the surface, weaken the concrete, and even spread into your home if left untreated. The longer you wait, the harder it is to remove.
Concrete holds moisture and stays cool, making it a prime target for mold, especially in shaded or poorly drained areas. The good news? You can get rid of it fast — often in one afternoon — using a mix of simple household cleaners and powerful mold killers.
In this guide, we’ll walk you through six proven mold removal methods using tools like pressure washers, scrub brushes, and sprayers — plus cleaners like bleach, vinegar, Simple Green, and ammonia-based solutions. You’ll also learn how to stop mold from coming back with a few smart maintenance tips.
Is Mold on Concrete Patio Dangerous?
Not all mold is created equal: exposure to some types of mold can prove fatal, while other species are benign in human exposure. For instance, toxic black mold may be incredibly dangerous if it spreads to an inhabited area, but most other black-colored molds are relatively harmless.
But harmless or not, once mold finds a good place to propagate and begins to spread, it’s only a matter of time until it finds its way into the home, which is never a good thing. Here are some of the side effects of mold exposure to humans and dwellings:
- Staining: If left to propagate long-term, mold can cause staining to a concrete patio that can’t be reversed.
- Corrosion: Not only can mold cause discoloration, it can cause the concrete to corrode, ruining the smooth, flat texture it once had.
- Spreading: Mold grows. It procreates rapidly under the right conditions, and it can eventually spread into the home if not remediated.
- Health Concerns: Even on outdoor surfaces like a concrete patio, mold can prove harmful to those who are allergic.
How to Remove Mold From Concrete Patio: 6 Options
Unfortunately, cement mold removal is sometimes more involved than power-washing away all visible evidence of the fungus and calling it a day. Because individual spores are invisible and can begin to repopulate the entire area rapidly, it’s important to truly cleanse black mold off cement in its entirety or make sure it is killed at the root, so here are six full-proof ways to eliminate mold from any concrete surface.
1. Pressure Washer Mold Removal
Best for mild mold problems. A power washer removes visible mold and dirt, but it doesn’t kill mold spores. Use it as a first step before applying a mold-killing solution.
- Non-toxic, no chemicals needed
- By far the quickest, easiest form of mold removal
- Will not kill mold spores, only removes them
- Must be followed by mold prevention
The cost of time contributed to this form of remediation is minimal, and if you have a power washer the total cost of equipment is $0. But renting one can cost up to $50 and hiring a professional can cost between $80 and $350, depending on the size of the project.
2. Bleach and Power Wash
The first line of defense for many, thanks to its tried and true reputation, is to saturate the area with a bleach spray. Concrete is hardy enough to withstand a power washer, and unfinished concrete isn’t susceptible to discoloration from bleach meaning there’s limited risk to your property.
Mix 1 cup of bleach per gallon of water. Spray the solution on the affected area and let it sit for 1–3 hours. Then pressure wash or scrub it off.
- Bleach is known to kill mold on contact, eliminating the problem from the source
- Affordable and relatively simple for the layman
- Bleach may be corrosive to finished concrete
- Unless the source of the issue is addressed, bleach and power washing is a band-aid solution
- Bleach solution can be be harmful if inhaled
Using bleach and a power washer is relatively cheap if you already own a power washer, in which case the only cost associated is the bleach itself, bringing the entire project to a total of about $10 or less. However, if you require the help of a professional it can cost anywhere between $100 and $400, depending on the size of your mold infestation. It is not recommended to remove the bleach solution by hand without a pressure washer, as doing so could result in skin burns and respiratory overexposure to chlorine bleach.
3. Vinegar Solution
While the bleach and power wash method is a go-to for many, a great deal of property owners would rather begin with a solution that’s less harsh and more natural. Vinegar is the perfect option in such cases. Used similarly to bleach, vinegar is known to kill many species of fungus including harmful mold.
Mix 1 cup of white vinegar with 1 gallon of water. Spray the area thoroughly, let it sit for an hour, then scrub or rinse it off.
- Non-toxic and not harsh on skin or lungs
- Vinegar is available everywhere, and no power sprayer is required
- While vinegar kills many species of fungi, it isn’t a one-size-fits-all solution; research your mold variety to ensure vinegar is an effective option
- Like bleach, vinegar can corrode colored concrete finishes
Thanks to the fact that vinegar can be washed off by hand, no power washer is required. If you have a small mold infestation, your cost of remediation could total around $3 for vinegar, $2 for a concrete scrubbing brush, and add in some elbow grease for a total of $5.
4. Mixing Laundry Detergent and Bleach
If bleach alone isn’t effective in remediating your concrete patio mold problem, consider adding laundry detergent into the mix. While bleach kills mold effectively, it is slick and non-penetrating and may not reach the root of a thick mold infestation. But laundry detergent acts as a trojan horse, ushering the bleach to the very core of your concrete pad mold infestation.
Combine 1 cup of bleach, 1 cup of laundry detergent, and 1 gallon of water. The detergent helps the bleach penetrate deeper into porous surfaces. Let it soak, then power wash or scrub.
- More effective than bleach alone
- All ingredients are already readily available in most households and businesses
- Mixing chemicals can be dangerous, so this should be done outdoors and with plenty of ventilation
- Not recommended for use without a power washer; physical interaction with this mixture can cause skin burns and irritation to eyes and respiratory tracts.
Other than the cost of a power washer, this solution can range from $8 to $15, depending on the scope and product brands used.
5. Ammonia Mold Solution
Ammonia is probably the most effective chemical against mold. It kills on contact and it cuts to the source. While it’s incredibly toxic to breathe, ammonia is going to be your best bet against a fierce or widespread infestation, as it kills mold immediately and forces it to release from the surface.
Products like RMR-141 kill mold on contact without scrubbing. Spray the solution, let it work, and rinse it away. Use only in well-ventilated areas and follow all label directions.
- Ammonia-based mold cleaner requires no scrubbing to kill mold
- Ammonia-based cleaners can be scented and properly diluted for minimal respiratory discomfort
- Ammonia should not be used around children or pets; exposure to non-diluted solution can cause burns
- Kills mold on contact, but still requires a pressure washer or scrubber to remove mold debris
Ammonia solutions can range from $10 to $40 per gallon, depending on potency, brand name, and other added ingredients, and is usually diluted to around 1 cup per gallon of water. If you choose to use a scrubber or power washer to remove debris, that cost will be added as well.
6. Simple Green Solution
Simple Green is the best option for use on concrete patios near landscaping, sewn grass, or gardens. Because it’s all natural and safe for use near plants, pets, and children, Simple Green solution is a DIY mold removal favorite.
If your patio is near grass, plants, or pets, use a biodegradable option like Simple Green. It lifts mold from the surface for easy rinsing.
- Simple Green is non-toxic and safe for use around pets, plants, and children
- Doesn’t require scrubbing or power washing
- Not as powerful at removing visible mold stains as bleach
- May require more than one application on thick mold
Simple Green solution costs around $10 per gallon, which should remediate a small to mid-sized patch of mold growth.
How to Prevent Mold On Concrete Patio
If you’ve developed mold on your concrete patio or sidewalk, chances are it will re-develop if preventative measures aren’t taken. If mold developed once, unless the environment is substantially altered to make it uninhabitable by fungi they will find their way into the area once more. Once you’ve cleaned the mold, prevent it from returning with these tips:
- Increase airflow: Use fans or open space to keep the area dry.
- Improve drainage: Make sure water doesn’t pool on the patio.
- Reduce shade: Trim back bushes or overhanging branches.
- Clean regularly: Sweep and rinse the patio to prevent debris buildup.
What to Do If Mold Spreads Into Your Home?
f the mold reaches your foundation or interior walls, you’ll need stronger solutions—or a professional. Use the same cleaning methods (vinegar, bleach, ammonia), but always wear protective gear indoors and ensure good ventilation.
For persistent infestations, consider calling a mold remediation expert.
Final Thoughts
Mold on concrete isn’t just ugly—it can damage your patio and pose a health risk if ignored. Whether you use natural solutions or heavy-duty cleaners, the key is to act quickly and follow up with proper maintenance.
Tried any of these mold removal methods on your patio? Let us know what worked best for you!
