How to Remove Mildew Before Painting Siding

Mildew is a common problem on Ocean County homes, especially on north-facing walls and shaded areas. Painting over mildew is a recipe for failure—the new paint will peel quickly. Here's how to properly eliminate mildew before painting.

Is It Mildew or Dirt?

Simple test: Apply a drop of household bleach to the discolored area. If it lightens within a minute or two, it's mildew. If not, it's likely dirt.

Safety First

Mildew removal requires precautions:

• Wear safety glasses to protect eyes from spray
• Use rubber gloves
• Protect landscaping from bleach solutions
• Work in well-ventilated areas
• Never mix bleach with ammonia or other cleaners

Removal Solutions

DIY Bleach Solution

• 1 quart household bleach
• 1/3 cup powdered laundry detergent (without ammonia)
• 3 quarts warm water

Commercial Mildewcides

Products like Jomax or Concrobium are effective and safer for landscaping.

Application Process

Step 1: Wet Surrounding Plants

Saturate landscaping with plain water before and after applying cleaning solution to minimize damage.

Step 2: Apply Solution

Using a pump sprayer or brush, apply mildew removal solution liberally to affected areas.

Step 3: Let It Work

Allow the solution to sit for 10-15 minutes. Don't let it dry on the surface.

Step 4: Scrub If Needed

For stubborn mildew, use a soft brush to agitate. Avoid stiff bristles that can damage siding.

Step 5: Rinse Thoroughly

Power wash or thoroughly rinse with a garden hose. Remove all cleaning solution residue.

Step 6: Allow to Dry

Wait at least 48 hours before painting. Moisture trapped under paint causes peeling.

Preventing Mildew Return

Choose Mildew-Resistant Paint

Most premium exterior paints contain mildewcides. Check the label.

Address Moisture Sources

• Repair gutter and downspout issues
• Improve drainage away from the foundation
• Trim vegetation back from siding
• Ensure proper attic ventilation

Regular Maintenance

Wash problem areas annually with a mild bleach solution to prevent buildup.

When to Call Professionals

Consider professional help if:

• Mildew covers large areas
• It keeps returning despite treatment
• Structural moisture issues are suspected
• Lead paint may be present (pre-1978 homes)