Noticing dark stains or green patches on your siding? That’s often a sign of mold or mildew.
St. Louis, the humid climate creates ideal conditions for mold and mildew to grow—especially on areas of your home that stay shaded and don’t dry quickly. Vinyl siding is particularly vulnerable because it can trap moisture behind the panels. While fiber cement siding, like James Hardie, is more resistant, it still needs occasional maintenance. Understanding how and why mold develops is the first step in preventing it.
Why Does Mold & Mildew Grow on Siding?
Mold and mildew thrive in damp, shaded areas where moisture doesn’t dry out quickly. In St. Louis, the biggest culprits are north-facing walls that receive little to no direct sunlight.
One of the most common siding materials affected by mold and mildew is vinyl. Because vinyl siding is made from plastic and installed loosely, it allows air and moisture to move behind the surface. This creates an environment where mold and mildew can grow quickly, especially in humid climates. The trapped moisture behind vinyl siding makes it particularly prone to mold buildup, requiring regular cleaning to maintain its appearance.
While fiber cement siding, like James Hardie, is far less likely to develop mold and mildew, it’s still a good idea to perform routine maintenance to keep your home’s exterior in top condition.
How to Prevent Mold & Mildew on Siding
Taking proactive steps to prevent mold and mildew can save you time and money in the long run. Here are some simple but effective ways to keep your siding clean and looking new for years to come.
1. Keep Your Siding Clean
Regular cleaning is one of the easiest ways to prevent mold and mildew from forming. Here’s what we recommend:
- Use a Garden Hose: Twice a year, rinse down your siding with a garden hose to remove dirt and prevent buildup. A high-pressure washer isn’t necessary for routine cleaning.
- Apply a Mild Cleaning Solution: A mixture of water and a small amount of household cleaner can help break down grime and prevent mildew.
- Avoid Harsh Chemicals: Some commercial cleaners contain bleach or harsh ingredients that can damage your siding. Stick with solutions specifically designed for siding maintenance.
- Use a Residential Pressure Washer If Needed: If you notice significant buildup, a low-pressure residential power washer can be used with caution.
2. Ensure Proper Drainage Around Your Home
Excess moisture is a primary cause of mold and mildew on siding. To minimize water exposure:
- Keep Gutters and Downspouts Clear: When gutters overflow, water can run down your siding, creating the perfect breeding ground for mold.
- Redirect Sprinklers: Avoid aiming sprinklers directly at your home’s exterior.
- Improve Landscaping Drainage: Ensure that water flows away from your foundation instead of pooling near your siding.
3. Trim Trees & Shrubs
Overgrown trees and shrubs can block sunlight and trap moisture against your home. Trimming back vegetation allows more airflow and sunlight to reach your siding, which helps prevent mold and mildew from taking hold.
4. Schedule Routine Inspections
Even if your siding looks fine at a glance, mold and mildew can develop in hidden areas. Walk around your home a few times a year to check for signs of buildup. If you notice dark streaks or green patches, take action immediately to clean the affected areas before the problem spreads.
5. Consider Upgrading Your Siding
If you’re constantly battling mold and mildew on your siding, it may be time for an upgrade. While vinyl siding is prone to mildew growth, fiber cement siding is far more resistant and requires less maintenance. At Hawthorn Home Exteriors, we offer high-quality siding solutions that are built to withstand St. Louis’ humid climate.
The Best Way to Remove Mold & Mildew from Siding
If mold and mildew have already appeared, don’t worry—cleaning it off is easier than you might think. Here’s how to do it safely:
Step-by-Step Cleaning Guide:
- Rinse the Area with a Hose: Use a garden hose to wet the siding before applying any cleaner.
- Apply a Cleaning Solution: Mix water with a mild detergent or a specialized siding cleaner.
- Scrub with a Soft Brush: Gently scrub the affected areas to loosen mildew.
- Rinse Thoroughly: Once the mildew is gone, rinse your siding with clean water to remove any residue.
- Let It Dry Completely: Avoid excessive moisture buildup by ensuring your siding dries fully after cleaning.
If the mildew is stubborn, a low-pressure residential power washer can be used, but be careful not to damage the siding with high-pressure settings.
In Summary
Mold and mildew on siding are common issues in humid climates like St. Louis, but with regular maintenance and a few preventative steps, you can keep your home’s exterior looking fresh. Simple measures like rinsing your siding, keeping gutters clean, trimming back vegetation, and inspecting your home regularly can make all the difference. If you’re looking for a more permanent solution, upgrading to fiber cement siding can significantly reduce mold and mildew growth.
If you would like more information or need expert siding solutions, contact us today. At Hawthorn Home Exteriors, we’re here to help you protect your home and keep it looking beautiful for years to come.
