Those black streaks are Gloeocapsa magma. Also referred to as "Roof Algae".
YES! Over time, Gloeocapsa magma begins to break down the contents of your shingles by feeding off of the limestone granules embedded in the shingles and this decreases your roof’s life. That can cause the quality of your shingles to slowly diminish. They have been found to curl up at the corners as well as form raised humps on the surface. This ultimately can result in damage and broken shingles.
Only a low pressure roof cleaning method should be used to clean your roof. Never should a pressure washer be used. High pressure cleaning will cause damage and remove the granules of your roof. That is why we only use our low pressure equipment to clean your roof safely and effectively.
The average price to replace your roof could be upwards of $12,000. We are just a fraction of the price to replace your roof. Visual inspection will done to see your roofs quality and determine if its cleanable. If its beyond cleaning you will be notified right away and recommended for replacement.