Spread across your shingles are black streaks that seem to be crawling down the roof. Black mold stains on roof shingles have become common on houses in every price range and neighborhood. What causes roof shingles to streak?

What can I do to get rid of roof stains? Is Power washing roof shingles smart or is the pressure from the wash going to damage the granules on the shingles?

We’ll explore the answers to these questions as we explore how to remove dark stains from roofs.

What are the black streaks on my roof?

Many home owners are surprised to discover that the once clean asphalt roof shingles have been slowly covered with a form of roof mold or mildew that appears as a light discoloration and spreads down the roof toward the gutters. The black roof stains are caused by a form of algae that has been around for years, typically found in the woods on the north side of trees, or on exposed rocks; but now this black algae is termed a roof shingle algae because of the annoying discoloration on a asphalt shingle roof.

The roof algae (sometimes called a roof mildew or shingle mold) actually feeds on the crushed limestone that is present in shingles from most asphalt shingle roof manufacturers. The roof algae is spread by wind and animals from roof to roof and is almost impossible to prevent.

How an black roof stains be removed from shingles?

The good news is: Yes, Roof Stain removal is possible!
Choose between two common roof cleaning solutions used to :
do it yourself roof cleaning using a roof cleaning product, or using roof cleaning services from a professional roof cleaning business.

The difference between the roof cleaning company and DIY roof cleaning is cost, and results.

Hire a Roof Cleaning Business

A roof cleaning business has experience at the shingle cleaning techniques and appropriate pressure to use with roof wash products. Pro roof cleaner’s years of experience will typically result in more complete removal of roof stains.

Do It Yourself Roof Stain Removal

Search for “Roof Cleaning Products” to find roof cleaner suppliers who offer roof cleaning chemicals, but be careful to know the company and what products they offer.   Trust roof cleaner supply companies that offer multiple formulas, and preventive solutions as well. Over the years we have found Roof Cleaner QSE and Roof Shingle Cleaner OX to be quality products with thousands of customers every year.

When you clean your own roof shingles be prepared to set aside an afternoon, and get your ladder out. There is no magic bullet when it comes to Roof Cleaning, and you will at least need a ladder to get up to the level of the gutter. The closer you are to the roof stains, the better your Roof Stain Removal Products will work.

So black stains on roofs can be removed, just choose a quality roof cleaner product or your local roof cleaning professional and make your roof look better!

12 thoughts on “How to remove black streaks from shingles?”

  1. fred coutts says:

    thanks for the info. i have those new 3-d (layerd) SHINGLES 3years old and they are starting to show green and black stains. i will search further to see what i can find

  2. Tom Breen says:

    The streaks are mold forming on the roof, the safest way to remove is with an Roof Cleaner that is safe to use and will not harm plants or animals. Bleach and chlorine are way to dangerous.

  3. steve says:

    Would this work on algae stains on swimming pool? I’ve emptied pool, used chlorine products and power washed, all to no avail. HELP!

  4. @steve – Cleaning the pool once drained should work. Admittedly, I have not heard of anyone trying this but algae is algae, so give it a try!

  5. Dan Cronauer says:

    Hey Dan here from Apex Roof Cleaning in Pennsylvania. This is a very informative blog, I would like to share a few things. Shingle manufacturers are now making an Algae Resistant shingle, they resist algae from growing but are not fool proof. We have had several calls about these AR shingles showing black and green streaks. Also zinc strips have been thought to release Zinc Oxide, killing any algae on the roof, this is true, but the strips would have to be placed every 3 feet in order to be effective. Costing much more than hiring a professional.


    1. Dan,
      We have also heard that the Algae Resistant shingle warranty is fairly complex to file a claim and is prorated.
      Making us think it is more marketing and less functionality.
      Thanks for sharing.

  6. Gary Montgomery says:

    how long will a cleaning last? will i ie have to redo yearly?

  7. Gary Montgomery says:

    are there mold/algae resistinat shingles…

    1. Yes, Dan from Apex mentions them above.
      They are an option, but don’t rely on algae resistance alone.
      We have found many homeowners are now considering Roof Stain Prevention to be just a part of annual household maintenance (just like gutter cleanings and house washing).

  8. Jonathan K says:

    I saw that the OX is very environmentally safe .
    Also, do these product eliminate the algea or just bleach out the black color?


    1. The OX products go after the algae, mold and mildew at the organic cells that are causing the discoloration. There is no bleach, so there are no color games, just getting rid of the culprit causing the color.