What are those black streaks on your roof? Dirt? Mildew? Burnout marks from Santa Clause? It actually is algae, gloeocapsa magma to be exact- otherwise known as blue-green algae. So why is it black? This alga actually has a darkly pigmented outer layer that protects it from UV rays, causing those dark streaks on your roof. These little bacteria build up over time as they feed on moisture and calcium carbonate.
Gloeocapsa thrives in environments with high humidity and temperatures, which makes the south a perfect place. The spores are airborne, giving them the ability to be carried by the wind and animals and allowing them to spread throughout the neighborhood. It's also a growing problem! Asphalt shingles were originally made mostly of asphalt, which is an oil-based product also containing felt material. As a cheaper alternative, manufacturers began using fillers like fiberglass and crushed limestone in their shingles. Algae also love to munch on that limestone filler.
You'll usually see algae growth in the northern part of your roof, as this area will usually be the most shaded area as the sun makes its way through the sky. The shade allows for moisture to hang around, allowing the perfect spot for algae growth. Gutters draining (or overflowing) directly onto the roof or overhanging limbs can also contribute to algae growth, as this can dampen the ability for the roof to dry.
While there are some ways to remove and prevent algae streaks on your roof, one of the easiest ways to confirm its presence is by taking a look at the other homes around you. You're likely to notice buildup on their northern side of their roof as well since the air and wildlife passes over their homes too.
If your home is susceptible to humidity and high temperatures, changing roof material can be the most efficient way to say goodbye to roof streaks. Trotter Roofing offers a variety of roof types, ranging from shingles, to tile, to metal roofing. Whether you need a new roof with shingles to start managing you're algae properly, or want to change material all together, call Trotter Roofing today to speak with our professionals about upgrading your home's first line of defense from the elements.