Yes It Can! Algae can cause black streaks, an ugly roof stains.
Will algae cause roof damage to your home, in short YES, it can and will harm in many way but the primary way is by damaging your shingles. Algae is a living organism that thrives on dust, pollen, and the organic materials that make up the roof. Dampness triggers its growth. Stains are usually more prominent on northern and western exposures and in heavily shaded areas. Algae grows on, under, and behind the tiny granules that cover the shingles. This results in unsightly stains and streaks on the roof. Heavy algae on roofs can super heat the attic resulting in higher home cooling costs as well as reducing the natural life span of the shingles.
Roof Shampoo® is the GREEN, eco-friendly roof cleaning method to clean dirty roof stains from asphalt and fiberglass shingles.