BACKDEC 27, 2025
Have you walked around your house lately and noticed some unsightly green, black, or fuzzy patches starting to creep up your siding? It's a common sight for many homeowners, but it’s one you shouldn't ignore. Those patches are likely mold or its close cousin, mildew, and they're feasting on the organic materials and moisture on your home's exterior.
Looking for more guidance? Take a look at our Maintenance overview.
While they might seem similar, mold is typically fuzzy or slimy and can be green or black, while mildew is often powdery and appears gray or white. Regardless of what you call it, this unwelcome guest not only hurts your home’s curb appeal but can also lead to long-term damage to your siding and even pose potential health risks if it finds its way inside.
The good news? In many cases, cleaning mold and mildew from your siding is a very manageable DIY project. You just need the right approach. Think of me as your friendly expert on the other end of the line, ready to walk you through it. Let's get your home looking clean and pristine again.
Before you mix up any cleaning solutions or grab a brush, the first and most important step is to assess the scope of the problem. This will tell you whether it's a job you can handle or one that's best left to the pros.
Safety First! Mold can release spores that may cause respiratory irritation, so personal protection is non-negotiable. Before you get close, put on:
The 10-Square-Foot Rule Now, let's figure out how big the issue is. Take a walk around your entire house and look for any discolored areas, dark streaks, or fuzzy patches. The U.S. Environmental Protection Agency (EPA) recommends that if the affected area is larger than 10 square feet (roughly the size of a 3-foot by 3-foot patch), you should call a licensed mold remediation professional.
Why? A large area of mold on your exterior could signal a significant, hidden moisture problem behind the siding. Professionals have the specialized equipment and training to contain the spores and address the root cause without risking further contamination or structural damage.
While you're inspecting, peek at the nearest interior walls and attic spaces. Do you see any matching stains, smell a musty odor, or notice any water damage? If you see any signs of mold inside your home, stop immediately and call a professional. This is no longer just a cosmetic issue.
If your mold problem is small and contained to the exterior, it's time for the next step: identifying your siding type. This is crucial because the material determines the best cleaning method.
Not sure what you have? Vinyl siding is a very common plastic material with interlocking panels. Wood siding has a natural grain, while brick and stucco have distinctly rough, textured surfaces. Once you’ve identified your siding, you can choose the right cleaning path.
Alright, you've done your assessment, you're geared up, and you know your siding type. Let's get to cleaning. We’re going to use an oxygen bleach-based cleaner, as it's effective and less harsh on plants and siding than chlorine bleach.
This is the more straightforward of the two processes. The mold is just sitting on the surface, so our goal is to kill it and wash it away.
What You'll Need:
Instructions:
With porous siding, we need to give the cleaner a little more time to penetrate and kill the mold that's taken root within the material.
What You'll Need:
Instructions:
Cleaning the mold off is great, but making sure it doesn't come back is even better. Mold only grows where there's moisture, so the final step is to eliminate its water source.
Inspect for Damage: Once the siding is completely dry, take a close look at the area you just cleaned.
Eliminate Moisture Sources: If the siding looks good, it's time to play detective and find out why the mold grew there in the first place.
One of the best parts about this project is how affordable it is to do yourself.
If the job is too big or you'd rather not handle it, you can hire a professional.
You did it! By following these steps, you’ve not only restored your home's appearance but also protected it from potential damage. A little bit of proactive maintenance goes a long way in keeping your home healthy and beautiful.
For more easy-to-follow DIY guides, personalized maintenance reminders, and instant access to vetted home service professionals when you need them, download the Casa app today! We’re here to help you tackle any project, big or small, and make homeownership easier.
