Black Streaks on Your Roof: What Causes Them and Do They Cause Damage?
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 […]
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