If you've noticed dark black or gray streaks running down your roof, you're not imagining it and it's not just dirt. Those streaks are a living organism, and they're slowly doing real damage to your home.
What Are They Actually?
The black streaks are caused by a type of algae called Gloeocapsa Magma. It's airborne, spreads from roof to roof, and thrives in the moisture and humidity of the Ozarks climate. The dark color you see is actually the algae's protective outer shell — it darkens to shield itself from UV rays.
Once it takes hold on a roof, it spreads. It feeds on the limestone filler that manufacturers add to asphalt shingles to make them heavier and more durable. Over time, it eats away at the shingle material itself.
Why It's a Problem
- It shortens the lifespan of your shingles significantly
- It can void manufacturer warranties if left untreated
- It causes your roof to absorb more heat, raising energy bills
- It spreads — left alone it will cover your entire roof
- It makes your home look neglected and hurts curb appeal
How to Remove It Safely
The correct method is soft washing — low-pressure application of a professional cleaning solution that kills the algae at the root and rinses away. This is the method recommended by the ARMA (Asphalt Roofing Manufacturers Association) and most shingle manufacturers.
What NOT to do: Do not pressure wash your roof. High pressure strips the granules off your shingles — those granules are what protect the shingle from UV damage and weathering. Pressure washing your roof causes more damage than the algae itself and will void most warranties.
How Often Should You Clean Your Roof?
In Missouri's climate, most roofs benefit from a soft wash treatment every 2–3 years. If you have a lot of tree cover or north-facing sections that stay damp, you may need it more often. The earlier you catch it, the easier and cheaper it is to treat.
Diamond Edge Power Wash uses a safe, low-pressure soft wash process to remove algae and black streaks from roofs throughout West Plains and the Ozarks. Free estimates, same-day response.
Call for a Free Roof Cleaning QuoteIf you can see black streaks from the street, the algae has been there a while. The sooner you treat it, the more shingle life you save. A roof cleaning costs a fraction of what early replacement would run — it's one of the best maintenance investments you can make.