What are the black stains on my roof?

Asphalt shingles are made with limestone as a filler. These shingles hold moisture and organic "bacteria food" material longer than the paper/asphalt/ceramic shingles of the 1980s. This cyanobacteria causes substantial destruction to roofs causing shingle decay and loss of reflective power. Over time, Gloeocapsa magma breaks down the shingles by feeding off of the limestone granules embedded in the shingles. This decreases a roof's ability to reflect ultra-violet rays of light and shortens the life of the roof.

Once the bacteria have become noticeable, the stains will continue to worsen year to year. As the bacterial colony grows, gravity pulls it downward, resulting in the smear-like stain down roofs. Most "experts" within the subject area conclude the bacteria to be harmful, if left untreated, as the growth holds moisture within shingles causing premature aging, rotting, and/or granule loss.

The buildup of Gloeocaspa magma on residential properties has led to earlier roof replacements, lowered property resale values, insurance companies canceling policies and increased utility costs as the black stained roofing draws in more heat.