Back streaks are a common occurrence on many asphalt roofs.
Many people think that it’s just affecting their curb appeal but it actually can do more damage than that. These black streaks are a collection of blue-green algae, cyanobacteria called gloeocapsa magma. Gloeocapsa magma collects on your roof and as it spreads, it is pulled down by gravity. Gravity causes these vertical black streaks on your roofs.
But of course, it does more than just affect your curb appeal. This bacteria is actually eating your roof. Gloeocapsa magma feeds on the limestone that is in the asphalt shingle. This results in granular loss in the shingle, lessening the lifespan of your roofs, and also gets rid of the reflective properties of the roof. This can lead to more energy loss and more energy usage because you may be turning on your AC longer because your house is soaking in all those UV rays.
Gloeocapsa magma, to get it to go away, it really needs to be treated otherwise it is going to get worse and worse each year, thus, doing more damage to your roof. The best way to treat it is to hire a reputable roof cleaning company. You want to make sure that you hire a company that will soft wash your roof because pressure washing your roof will certainly damage your shingles and definitely would void your warranty.
So in short, the black streaks on your roof is a bacteria called Gloeocapsa magma. It is eating your roof. It needs to be addressed. Reach out to your local roof cleaning company. You should have to do this about every 5 or 6 years. Have professionals treat your roof and stop bacteria from deteriorating your roof.