What is the black stain on your roof?

Do you have black stains or streaks on your roof? This is caused by a bacteria called gloeocapsa magma. These bacteria are feeding on the moisture and limestone granules embedded in your shingles. As the bacteria colony grows, gravity pulls it downward resulting in the black streaks you see on your roof.

If the bacteria growth is left untreated it could lead to premature aging, rotting and/or granule loss as the bacteria feeds on the limestone and retains moisture. This bacteria is airborne and can even spread to nearby roofs.

The buildup of gloeocapsa magma on shingle roofing has led to earlier roof replacements, lowered property resale values, insurance companies canceling policies and increased utility costs as the black stained roofing decreases a roof’s ability to reflect ultra-violet rays from the sun.