Why are Black Streaks on my Roof?

Have you ever stepped outside, looked at your roof, and noticed it was covered in unsightly black streaks? When you got over the initial annoyance that those stains exist in the first place, you may start to wonder what exactly is causing them to appear.

Why are Black Streaks on my Roof?

While the dark streaks on your roof may look like dirt or mold, the more common cause of those black streaks is blue/green algae. When it first forms, the algae can appear as small spots on your roof, but after time, they can become longer streaks.

The algae spores that can end up staining your roof can come from a number of different things — carried by animals, the wind, or even you. The spores have a dark, outer coating that keeps them safe from the sun’s UV rays, which is why they form dark streaks on your roof.

Do They Grow on Every Roof?

These algae spores grow most typically on shingle roofs, since many shingle materials contain limestone that acts as a food source for the algae spores.

The chance that your roof will fall victim to these spores, and the black streaks that follow, partially depends on where you live. Pennsylvania homes are moderately susceptible to algae spores. Excess moisture, due to clogged gutters and nearby plants, can also make you more susceptible to the streaks.

How Do I Get Rid of Roof Streaks?

More often than not, you can get rid of those black streaks with a professional roof cleaning.

Keystone Gutter Helmet technicians are professionally trained and equipped for roof cleaning and stain prevention. We can safely restore your roof to its original color — and keep it that way without harsh chemicals or pressure cleaning.