What Are Those Black Streaks on a Shingled Roof?
Those unsightly black streaks are actually bacteria called Gloeocapsa magma (GM).
GM appears as a black stain and usually covers a majority of the roof surface area, more predominantly on the lower portion of the roof where moisture content is higher and taper as they reach the ridge caps.

How Does a Roof Get Stained with Black Streaks?
GM can spread from one infected roof to another via airborne spores. These spores land randomly on a roof and take root. A Shingle is the perfect breeding ground for bacteria due to its porosity and constant moisture content. A protective sheath creates the dark to black color the bacteria forms in an effort to protect itself from the sun’s UV rays.

How Does GM Grow?
Bacteria require moisture and proper temperatures to grow. Dew is the primary moisture source. The bacteria generally grow on the northern exposures of a roof since this exposure generally receives less sunlight. Bacteria are very well adapted to extreme conditions, meaning they can survive both extreme heat and extreme cold weather conditions.

What Is The Solution?
It is recommended to have your roof cleaned with a special roof cleaning mixture. While this job can be done by a homeowner it is best left to a professional roof cleaning company.

What You SHOULD NOT do!
It is recommended by the leading roofing manufacturers to not power wash/pressure wash your asphalt shingle roof. Power washing shingle roofs can dislodge the granules, which can lead to premature shingle failure.

Where Can I get More Information?
Visit our freinds at the Roof Cleaning Contractors to find a roof cleaning company in your area that will help you to rid your shingles on those black streaks..