Those black streaks on your asphalt shingle roof are usually blue-green algae, commonly called Gloeocapsa magma. The streaks are mainly an appearance problem: the Asphalt Roofing Manufacturers Association says there is no scientific evidence that algae damages asphalt shingles, but moss, leaks, and worn-out shingles are separate concerns. [1, 2] That means a streaky roof […]