What’s Up With Those Black Streaks On The Roof?

What’s Up With Those Black Streaks On The Roof?

The primary role of your residential roofing system is to protect your property and the people living in it from the elements outside. However, this is not the only purpose a roof serves. Another essential function of your roof is to improve the appearance of your house. This is why homeowners put so much time into selecting which roofing material would be best for their roof repair or roof replacement. Since your roof is exposed to sunlight, dirt, storm damage, and everything else, its appearance is bound to get grimy. One such source that can deter from the beauty of your roof is when black streaks appear.

If you are a homeowner living in New Jersey, you are bound to see this type of roof damage. We will show you what these are, and what you can do about these black streaks on the roof.

What Are These Black Streaks On The Roof?

Do you see some dark-colored stains on parts of your roof system? These are called black streaks. When you see black streaks on your roof, it can be really disconcerting. It can make you think that there’s something wrong with your roof, or it could just be a sign of normal wear and tear. In either case, black streaks are not good for your roof and typically require immediate attention.

Causes Of Black Streaks

Black stains are a common problem not only in New Jersey, but throughout North America. If you notice black streaks on your roof, it is important to know the cause of the problem. Below are two of the most common reasons that black streaks can appear on your roof.


When you see the black streaks on your roof, it may be hard to believe that they can be caused by something as mundane as algae. Scientifically called gloeocapsa magma, and more common known as blue-green algae, it is a type of fungus that lives in water. Typically, airborne algae thrive in moist, warm climates. Since there is direct sunlight (and therefore heat) on your roof during the day and shade at night, your roof can create an ideal condition for algae growth—particularly when there are leaks in your roof decking or flashing.

Even though it’s not dangerous for you or your family, the algae will continue growing until something stops it from getting enough sunlight and moisture. The longer algae continues to grow on your roof, the more it can damage your roof and lead to expensive repairs. This is why you need to remove/clean any algae growth as soon as possible.

Mold And Mildew

Another cause of these black streaks on the roof is mold and mildew growth. If you have a dark spot on your roof, you may think it’s just a stain or discoloration from rainwater runoff, but it could actually be mold/mildew that has grown on the materials of your roof or shingles.

While it isn’t dangerous, it’s not the prettiest thing to look at. Mildew is a fungus that grows naturally on certain materials. It can grow in many different colors and textures and will generally stick to surfaces where there’s moisture or humidity.

How To Remove These Stains?

As mentioned above, black streaks on a roof may not seem harmful at first, but it’s still an issue that needs to be taken care of. The black streak on your roof is more of a cosmetic problem than anything else, but it can lead to more significant issues like mold and water damage in the future.

Algae tends to grow in moisture, so even the slightest amount of moisture retained can lead to your roof shingles deteriorating. If you do not remove the black streaks from your roof quickly, they can lead to a reduced life expectancy for your shingle roof.

Proper cleaning and regular maintenance of your shingle roof are required to remove these stains. You can do this yourself by mixing certain chemicals. The black streaks on a roof are typically hard to get off—they’re not easy to wash off with standard cleaning products like water and detergent. That’s why you need to use substances like trisodium phosphate (TSP) and chlorine bleach. These are both powerful and effective.

Need Help With Roof Maintenance? Call Champion Exteriors

Cleaning on your own is never a good idea, and there are many reasons for it. First, it can be very risky. Climbing onto the roof and cleaning those ugly black stains by yourself is dangerous. There is always a chance of falling and injuring yourself during the process. Also, if you do not use the right equipment, you can cause more damage to the roof.

So we ask, why not let an expert roofing contractor care for your roof? Call Champion Exteriors instead. We are proudly one of the best roofing companies serving the homeowners of New Jersey since 1936.

Our experience of more than 87 years in the roofing industry makes us the local experts for any roof repair, or roof maintenance needs that homeowners have. We use high-quality roofing materials, and our roofing contractors are licensed and certified. Contact us today at (609) 845-3576 to know more about the services we offer.