How To Remove Mildew From Siding

Mildew on siding can be an unsightly and persistent problem for homeowners. This fungal growth detracts from your home’s appearance and can lead to long-term damage if left untreated. Fortunately, with the right approach and materials, you can effectively remove mildew from your siding and prevent its return.

What Causes Mildew Growth

Mildew thrives in damp, shaded areas with poor air circulation. These factors contribute to its growth on siding:

• High humidity levels
• Lack of direct sunlight
• Poor drainage around the home’s foundation
• Overhanging trees or shrubs that block airflow
• Sprinkler systems that frequently wet the siding

These conditions create the perfect environment for mildew spores to settle and multiply on your home’s exterior. Seasonal changes and local climate variations can also accelerate mildew growth.

Common Types of Siding Affected by Mildew

Knowing your siding type can help you choose the most effective cleaning method and preventive measures. While mildew can grow on various surfaces, these types of siding have characteristics that can make them vulnerable to mildew growth:

• Fiber cement siding
• Painted surfaces
• Stucco
• Vinyl siding
• Wood siding

Preparing to Remove Mildew from Siding

We recommend proper safety precautions before tackling the mildew problem and gathering the necessary tools and materials.

Safety Precautions

When working with cleaning solutions and removing mildew, prioritize these safety measures:

• If working indoors, create proper ventilation in the work area by opening windows and using fans.
• Inform family members of your cleaning activities to prevent accidental exposure.
• Use a face mask to avoid inhaling mildew spores or cleaning fumes.
• Wear old clothes that cover your skin.
• Wear protective gloves and eye goggles.

These precautions will help protect you from potential hazards associated with mildew removal, such as skin irritation and mold spore inhalation.

Gathering Necessary Tools and Materials

To effectively remove mildew from your siding, you’ll need the following tools and materials:

• Bucket
• Cleaning solution (discussed in the next section)
• Drop cloths to protect plants and landscaping
• Garden sprayer or pressure washer
• Ladder (if necessary)
• Soft-bristled brush or sponge
• Trash can to dispose of used cleaning materials and debris

Effective Cleaning Solutions for Mildew

While many homeowners turn to chlorine bleach, there are better alternatives that are both effective and safer for your siding and the environment.

Avoiding Chlorine Bleach

Chlorine bleach has significant drawbacks when used on siding. Chlorine evaporates too quickly to get to the fungi’s roots, leading to regrowth. Additionally, chlorine bleach can cause the following issues:

• Contribute to environmental pollution
• Corrode metal fasteners and flashing
• Discolor or damage certain types of siding
• Harm nearby plants and grass
• Stain clothing

For these reasons, it is best to avoid chlorine bleach and opt for safer, more effective alternatives.

Oxygen Bleach

Oxygen bleach, or hydrogen peroxide, is a highly effective and environmentally friendly method of removing mildew from siding. It breaks down into water and oxygen when applied, making it safe for use around plants and on most siding materials. It’s effective because it penetrates porous surfaces, attacking mildew at its roots and preventing regrowth.

Choose a liquid concentrate such as Scotts Outdoor Cleaner Multi Purpose Formula, which is easy to use in a garden sprayer or pressure washer.

Alternative Cleaning Solutions

While we highly recommend oxygen bleach, there are other effective cleaning solutions you can consider, such as the following:

• Commercial mildew removers designed for siding
• Trisodium phosphate (TSP) and water
• White vinegar and water solution (1:1 ratio)

These alternatives can be effective, but test them on a small, inconspicuous area first to make sure they won’t damage your siding.

Step-by-Step Mildew Removal Process

With your cleaning solution chosen and safety precautions in place, you’re ready to begin the mildew removal process.

Inspecting and Preparing the Area

Start by thoroughly inspecting your siding to identify all areas affected by mildew. Look for dark spots or discoloration, especially in shaded areas and near the ground. Before cleaning, we recommend removing loose debris from the siding and covering nearby plants and landscaping with drop cloths. In addition, close all windows and doors to prevent the cleaning solution from entering your home.

Applying the Cleaning Solution

Proper application allows the cleaning solution to penetrate and break down mildew effectively. Follow these steps to apply your chosen cleaning solution:

1. Mix the solution according to the manufacturer’s instructions if using a concentrate.
2. Pour the solution into a garden sprayer or pressure washer reservoir.
3. Starting from the bottom and working your way up, apply the solution generously to the affected areas.
4. Allow the solution to sit on the surface for 10–15 minutes, but don’t let it dry completely.

Scrubbing and Rinsing Techniques

After the solution has had time to work, scrub and rinse as follows:

1. Use a soft-bristled brush or sponge to scrub the mildewed areas gently.
2. For stubborn spots, reapply the solution and scrub again.
3. Rinse the siding thoroughly with clean water, starting from the top and working your way down.
4. Continue rinsing to remove all the cleaning solution. Inadequate rinsing can lead to a cleaning solution buildup, which may attract additional mildew and dirt.

Using Pressure Washers for Mildew Removal

Pressure washers can efficiently remove mildew from siding, but caution is necessary to avoid damage.

Pros and Cons of Pressure Washing

Consider the advantages and disadvantages of pressure washing before choosing that method. Pros include the following:

• Quickly covers large areas
• Can reach high spots without a ladder
• Effective at removing stubborn mildew

These are the cons:

• Can damage siding if used improperly
• May force water behind the siding, leading to moisture problems
• Not suitable for all types of siding

Proper Pressure Washer Techniques

If you choose to use a pressure washer, follow these steps:

1. Use the lowest pressure setting that effectively eliminates the mildew.
2. Keep the nozzle at least 12 inches away from the siding.
3. Test the pressure washer on a small, inconspicuous area first to confirm it won’t damage your siding.
4. Spray at a downward angle to prevent water from getting behind the siding.
5. Move the nozzle in a steady, sweeping motion to avoid concentrating on one spot.

Preventing Future Mildew Growth

Consistent maintenance and preventive measures are key to keeping mildew at bay and preserving your home’s appearance.

Regular Maintenance Tips

Regular inspections and cleanings help catch mildew early and prevent extensive growth. Follow these tips:

• Clean your siding annually with a mild detergent solution.
• Inspect your siding regularly for signs of mildew growth.
• Make sure your gutters are clean and functioning correctly to prevent water from splashing onto siding.
• Trim trees and shrubs away from your home to improve air circulation.

Improving Drainage and Ventilation

Reducing the conditions that promote mildew growth provides a dryer and healthier exterior environment. Here’s how to improve drainage and ventilation:

• Adjust sprinkler systems to avoid directly spraying siding.
• Consider adding soffit vents to improve air circulation in your attic and reduce moisture.
• Grade the soil around your foundation to direct water away from your home.
• Install or repair French drains if necessary.

Dealing with Stubborn Mildew Stains

Sometimes, even after thorough cleaning, mildew stains persist. In these cases, additional measures may be necessary to restore your siding’s appearance.

Additional Treatment Methods

These additional treatments may help remove mildew stains:

• For wood siding, sand the affected area lightly and apply a mildew-resistant primer and paint
• Use a specialized mildew stain remover designed for your siding type
• Apply a mildew-resistant sealant to porous surfaces after cleaning

Follow the manufacturer’s product guidelines for effective and safe application.

When To Seek Professional Help

If you’ve tried multiple cleaning methods without success, or if the mildew problem is extensive, you may need to call a professional. Experts have access to industrial-strength cleaners and equipment that can tackle even the most stubborn mildew problems. Additionally, they can identify and address underlying issues contributing to persistent mildew growth.

Our Conclusion

Removing mildew from siding is a manageable task for most homeowners when armed with the proper knowledge and tools. Effective cleaning solutions such as oxygen bleach can restore your siding’s appearance and protect it from future mildew growth.

Remember that prevention is key. Regular maintenance, improved drainage, and proper ventilation can go a long way in keeping your siding mildew-free. With these strategies, you can maintain a clean, attractive exterior that enhances your home’s curb appeal and protects its value.