What are the Black Stains on my Roof?

black stains on roof

Although they may seem like dirt from afar, the black stains on your roof are actually algae – specifically, gloeocapsa magma (blue-green algae). Starting off as small spots, this algae typically grows and eventually becomes large, visible streaks on your roof. By the time most homeowners notice the algae, it’s usually been there for about 2 months.

Why Do Shingles Get Algae?

Algae spores can be carried by the wind, animals, or your clothing, making them airborne. Algae spores can easily be spread from your rooftop to rooftop across your neighborhood or complex.

Asphalt shingles are most prone to algae, but any type  of roofing can develop algae. Common materials that make up asphalt shingles typically include fiberglass and crushed limestone, which is provides sustenance for algae to thrive. This is why asphalt shingles provide the perfect home for algae to develop and spread.

Warmer and humid climates are the friendliest environments for algae to grow in, but can affect homes in every climate. While algae in itself is not harmful, it can eventually cause the UV granules that cover a roof to come off and dry out, leaving your roof exposed to direct sunlight.

How Do I Remove the Algae Streaks?

Algae can be removed through a simple professional roof cleaning. Don’t risk climbing on a slippery algae-covered roof. Schedule a cleaning for your roof as soon as possible.

Preventing Streaks in the Future

You can’t permanently prevent streaks, but you can take measures to lessen the risks of algae in the future. Your roof algae is similar to a cold —  airborne and unavoidable. Here’s a few simple ways to improve the health of your roof:

  • Trim tree branches to allow more sunlight, and limit the amount of debris that may fall on your roof. This will make your roof environment less inviting the growth of roof algae.
  • Keep your gutters and downspouts clean of clogs to ensure your home has proper water drainage.
  • Get new shingles. If your roof is severely damaged, it may be time to replace it. Consider switching from asphalt to a different material, and make sure you get shingles that have the best and longest warranty.

Contact A Professional Today!

At Landmarks Exteriors, our professionals are here for all your roofing needs! Large or small, we take care of everything from routine maintenance items to emergency roof repairs. Contact us today to see how we can help!

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