Mildew is unsightly but easy to remove. 

As a homeowner, if you see mildew on your siding or exterior walls, you don’t need to panic.  Instead, follow these simple tips to get rid of the mildew and help prevent more mildew in the future.

At the bottom of this page, there is a downloadable infographic on cleaning and preventing midlew on wooden siding and walls.


How can I prevent mildew on my house?

Moisture is caused by humidity and moisture.  

Mildew can be controlled, therefore, by making sure your home’s exterior has plenty of airflow and can dry quickly when it becomes wet.

What can you do to help prevent mildew?

  • Arrange landscaping so that natural breezes can flow near the house and dry the siding if it becomes wet from rain or dew. 
  • Keep shrubs away from the walls. 
  • Install gutters and downspouts, as well as a moderate roof overhang.
  • Give special attention to air movement patterns on northern exposures where sunlight cannot assist in drying. 
  • On sidings which may have a tendency to absorb moisture from rain or dew, a semi-gloss, gloss latex, or oil paint with an appropriate primer is recommended.
  • When wood siding is stained or left to weather naturally, use a water-repellent (often combined with a wood preservative) finish. These products are available in hardware/paint stores. 

To remove mildew from wood siding, hardi-plan, or stucco, use the following solution:

  • 1/3 cup all-purpose laundry detergent
  • 1 quart household chlorine bleach (must be fresh)
  • 3 quarts warm water
  • An alkaline cleaner such as washing soda or a cleaner containing trisodium phosphate can be added for extra cleaning. Follow package directions or use ½ to 2/3 cup.

Begin by scrubbing the surface with a soft brush. Avoid splashing on shrubs and other plants. Rinse well when you are finished. 

Commercial mildew remover/cleaners are also available. 

Make sure you wear protective clothing — long sleeves, goggles, and rubber gloves. 


Repainting siding after removing mildew

If your siding needs to be repainted, choose a mildew-resistant paint. 

The most mildew susceptible paints are latex paints, especially when linseed oil base primer is used. Acrylic gloss and semi-gloss latex paints are less susceptible to mildew than flat latex. 

The least susceptible paints are exterior enamels. Special paints are also available that contain a mildewcide. 

Your local hardware store or paint supplier will be able to assist you in choosing the correct paint and primer to reduce mildew on your home and its effects.


To remove mildew from brick: 

Once a year, spray your brick off with a water hose and a spray nozzle. A solution of one cup of bleach mixed with a gallon of water can be used with a stiff brush to clean the brick. 

Don’t use wire brushes or synthetic brushes—they can discolor the brick.  Instead, use a natural fiber brush. Also, make sure you soak the brick before washing with the bleach solution. 


To remove mildew from stone:

To clean stone walls, fences or other structures, wash the walls with a mild soap solution. Rinse well with clean water.



Mildew is not a homeowner’s friend, but thankfully it can be removed and taken care of pretty easily!

You can read more homeowner tips and tricks here from Design Tech Homes, 

If you are looking for new home construction or a custom home in San Antonio, Houston, and the surrounding areas, then view some of our available floor plans or get a quote today!


Click our infographic below to download!

Cleaning and Removing Mildew from Exterior Walls and Siding 1