What the Dark Streaks on Your Roof Actually Are

April 23, 2019 10:51 pm Published by Leave your thoughts

It’s a common problem for homeowners: black streaks on a shingled roof. While they’re not something that will immediately damage your home, they can prematurely age the shingles. Usually these dark streaks appear on the north-facing slope of the roof and begin to show around five years after the roof was installed. While not a major cause for concern, you’ll want to keep an eye on it, and may need to call for roof repair in Salt Lake City, UT if things get out of hand.

What exactly causes it?

The exact cause of the dark streaks is algae. Roof slopes that are shaded or receive little sunlight are especially at risk. That’s because they hold moisture for longer. Algae feeds on the moisture and begins to grow, resulting in the discoloration. The black streaks don’t immediately cause any structural problems, and at first are just aesthetic issues. However, it may be a sign that parts of your roof are holding too much moisture. This can lead to increased wear and tear on those parts of the roof, and may eventually lead to water damage. If the streaks are getting larger, you may want to call for roof repair in Salt Lake City, UT just to make sure there are no underlying structural concerns from water damage.


Roof algae can be easily removed with a simple roof cleaning. You can potentially do this yourself, although you’ll want to take a few precautions to remain safe. Falling from your roof can cause serious injury or even death. You’ll want to also be careful not to damage your roof. Harsh treatments or power washing can harm your roof system and lead to more damage, so don’t use a power washer. You’ll want to be fully prepared with eye protection, slip resistant shoes and protective clothing like rubber gloves. Another option is to get professionals to do the job. A company that specializes in roof repair in Salt Lake City, UT, like Stubbs Roofing, Inc., can also clean your roof.


Sometimes the best thing to do is to try and prevent the black streaks from happening in the first place. For starters, you can trim tree branches to provide sunlight to your roof to dry out the moisture. This allows less of a chance for the algae to grow. You’ll also want to keep gutters and downspouts clear. You can do this just by doing a little maintenance once in a while to make sure they’re working and keeping water away from your home. Copper or zinc strips along the side of the roof are also a good preventative measure. The copper and zinc will help to kill the algae, although they’re not 100 percent effective. No matter what you do, you’ll likely still need to clean your roof, and may eventually need to call for roof repair in Salt Lake City, UT.

For nearly 20 years, Stubbs Roofing, Inc. has been providing highly skilled service to homeowners and businesses alike. Our knowledgeable staff is more than happy to answer any questions about roof repair in Salt Lake City, UT. Our team of highly skilled roofers specializes in a variety of services, including cleaning and repair. Give us a call today to learn more or schedule a consultation.

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