Those stains on your roof are eating your shingles!
People are often surprised to learn that the black staining on their roof is almost always algae and mold. More often than not, it appears on the North side of the roof where there is less exposure to the sun and moisture hangs around longer.
It survives by feeding off the limestone fillers in the shingles. As it feeds, it grows and spreads across the roof. Over a period of years, this algae will eat enough of the shingles to begin to loosen up the protective surface granules. As the shingles lose these protective granules, their protective qualities degrade. These granules help protect the shingles and reflect the sun’s rays to keep your home cooler.
People are often surprised to learn that the black staining on their roof is almost always algae and mold. More often than not, it appears on the North side of the roof where there is less exposure to the sun and moisture hangs around longer.
It survives by feeding off the limestone fillers in the shingles. As it feeds, it grows and spreads across the roof. Over a period of years, this algae will eat enough of the shingles to begin to loosen up the protective surface granules. As the shingles lose these protective granules, their protective qualities degrade. These granules help protect the shingles and reflect the sun’s rays to keep your home cooler.