Why Does Mildew Grow on Vinyl Siding?

Vinyl siding is a popular addition to the exterior of homes because it’s known for being durable and affordable. But there is a downside to this material, and it’s that mold and mildew tend to grow on vinyl siding. Whether homeowners are considering adding vinyl siding to their home or are concerned about the siding they currently have, it’s a good idea to find out more about mildew and mold on vinyl siding. More specifically, it’s helpful to learn the factors that can lead to this issue.

Prevent mold and mildew on vinyl siding by performing regular cleaning & maintenance on your houses siding.

Buildup of Dirt

One of the main reasons someone might see mildew or mold on vinyl siding is that dirt has accumulated on the surface. Not only does that make the siding look unclean, but it can also lead to mildew because fungus often feeds on dirt and dust. In addition, if the home is near trees, some sugary sap from those trees could end up on the siding, and that’s appealing food for fungus.

Excess Moisture

Another reason someone might find mildew and mold on vinyl siding is that there’s moisture somewhere on or beneath the surface. It could be that rainwater got trapped behind the siding or even within the material. It’s also possible that there’s a broken drain pipe or gutter constantly dripping water on the siding, causing it to stay wet. That’s basically an invitation for mold or mildew to start growing on a house.

Lack of Sunlight

Moisture and dirt aren’t the only culprits when it comes to mildew and mold growing on vinyl. Mold and other fungi thrive in dark places, so if part of the house is constantly shaded, it’s more likely to develop a fungus problem. In some cases, there’s a tree, shed or porch roof that keeps one side of the house from receiving sunlight. Getting rid of this source of shade can help prevent mildew or mold from growing on vinyl siding.

Preventing Mildew and Mold on Vinyl Siding

If moisture, lack of sunlight and dirt are all common causes of fungus growth on siding, preventing this problem should involve getting rid of these potential causes. Of course, it’s not always that simple. It can be hard to prevent a house from ever getting wet or dirty, and removing trees and shade structures isn’t always desirable. Fortunately, there are other ways to keep mold and mildew from growing on siding.

Cleaning siding with effective cleaning products is an easy way to prevent fungus growth without making any major changes to the property. For example, Gold Eagle carries 303® Mold & Mildew Cleaner + Blocker, a spray that can prevent mold and mildew stains when used according to the instructions. This cleaner’s formula is strong enough to battle mold and mildew growth, but it’s not too harsh on any water-safe surface because it does not contain bleach. This means it’s safe to use on everything from vinyl siding to fabric, such as seat cushions, so it’s ideal for homes, cars and boats.

Clean your vinyl siding regularly to prevent mold and mildew stains.

Gold Eagle features a range of products that can help prevent or treat mold and mildew on vinyl siding. Browse our selection today to find out more about which cleaning products can help keep mold and mildew growth under control.

Leave a Reply

  • How is this product used? Does it clean existing mold?

    • Hi, Kathleen. This will help to quickly remove mold & mildew stains on contact!

      • The North side of my house gets mold from lack of sun. I just spray on 50% Bleach/Water mix. Let stand a few minutes and wash off with the garden hose. The mold comes right off in minutes. Nothing to it. I have a two gal garden sprayer made for bleach. Amazon has them in stock.


  • How long will this last before mold comes back?

    • It is rather difficult to predict when mold/mildew may appear due to the season, temperatures, location, storage conditions, and exposure. To ensure that it does not come back, we recommend regular use of the 303® Mold/Mildew Cleaner + Blocker -about 4-6 weeks or as needed. Hope this helps. If there are any questions, please feel free to contact us at producttechsupport@goldeagle.com. Thanks for the question!

      • We used to have cedar shake wood shingles for the siding until we decided to have vinyl siding over 10 years ago. We never got mold on the cedar siding. Wish we hadn’t changed to vinyl now!