5 Tips To Prevent Mildew Stains On Your Building's Exterior

9 May 2023
 Categories: , Blog


Mildew and algae can leave dark stains on the side of your building's exterior. The staining is a common problem on concrete-block business exteriors, in part because the porous nature of the concrete can hold onto the moisture that fuels mildew growth. It can also affect other building materials, including wood and vinyl exterior cladding. 

1. Landscape Remediation

Shrubbery, vines, trees, and other plants growing right up against your building's walls will trap moisture, increasing the chances of mildew and algae growth on the walls. Further, landscaping overgrowth makes it challenging for your painters to do a proper job when the time comes to repaint your business. Before beginning, have the plants trimmed back or even removed so that access and airflow to the walls can return. 

2. Surface Cleaning

The stains will simply bleed back through the fresh paint if steps aren't taken to remove the mildew and algae prior. Usually, multiple techniques are used to ensure a thorough cleaning. Typically, your painters will begin with a pressure wash. This removes mold, mildew, algae, and flaking paint that may have trapped mildew spores. A mildew-killing cleanser may also be used. Scrubbing and scraping parts of the exterior to remove loose paint may also be necessary.

3. Damage Repairs

Moisture, which leads to mildew growth, along with mildew spores can hide in any cracks or crevices in the wall. Your painters will repair the damages. This may include replacing wood siding or trim that is suffering from moisture damage, caulking cracks in concrete block walls, or using fillers and patches to repair small holes in a variety of building materials. 

4. Sealing Primer

The right primer can prevent mildew growth from beneath the paint. Anti-fungal primer covers up old stains so they don't bleed through the fresh paint, while also killing any remaining spores that are present on the building's surface. Usually, a single coat of primer is used, although sometimes a second coat may be applied if there are coverage concerns.

5. Mildew-Killing Paint

A mildew-killing paint, which also contains fungicides, can help prevent surface mildew and algae growth in the future. These paints may contain a natural mildew-killing compound, like zinc, or they may contain chemical fungicides. These paints are available in a range of colors. They can also be custom tinted in the color of your choice so that your business can have just the appearance that you desire. 

Contact a commercial exterior painting service like Protected Painting  for more help.