Have you ever pulled into your driveway, looked up, and seen ugly black streaks on your roof? Most people have, and many people hate how it looks. But to get this out of the way, no, the dark streaks are not hurting your roof. So what is that stuff?


How Does Algae Get on My Roof?

Algae is airborne, meaning spores can get pretty much anywhere. It’s especially easy for them to spread across roofs in many neighborhoods. If you have black streaks, your neighbors probably have some too, especially if they have asphalt shingles. Asphalt shingles get more algae growth because of the material they’re made of. Traditionally, asphalt shingles main material was asphalt, but they contain many more fillers now. In fact, one of these fillers is limestone, which is the algae’s main food source.

Additionally, where you live plays a big role in whether the algae can grow. If it ever gets hot and humid, like in Florida or Georgia, there’s a big chance there are some algae growing on your roof. States like Colorado have less to worry about because it’s cooler and dryer there. Milwaukee, Wisconsin is kind of in the middle.

How Do I Get Black Streaks Off My Roof?

Easy, just clean your roof. It’s simple. But, like so much else, it’s also complicated. Although cleaning your roof the right way won’t damage it, you may be breaking contracts for warranties and insurance policies. You need to check to make sure you do not void anything. However, let’s consider a simple clean as okay.

Google will give you tons of results for homemade formulas and even some brand name products. Do not forget that whatever you put on your roof to kill these algae can also hurt your skin. Check to see where the water runs off as well, as this cleaner could kill vegetation and landscaping around the house.

Note: Never power wash your roof.

Apparently a lot of people are doing this. It’s almost a sure fire way to void any warranty on your roof because it can really mess up your shingles.

Overall, don’t stress too much about algae growth on your roof. Although black streaks can be ugly, they are not harmful. Cleaning your roof can be a complicated endeavor, and sometimes it can be dangerous. Never hesitate to call folks like us, local Milwaukee experts, with any roofing questions you have. We’re always happy to help.