The dirt isn’t just dust – It’s alive. Some of the black or very dark roof stains are caused by a resilient type of algae, Gloeocapsa magma (a type of blue-green algae commonly found in climates with warm, humid summers). The algae grow in standing water, as well as in our lakes and ponds. The algal spores are carried to our roofs from the water sources by the wind and birds, and then from roof to roof where it grows and feeds on the limestone filler in asphalt shingles. Worse still, as the algae grow, they retain water and foster the growth of other roof inhabitants.
The black stains are also very likely to harbor a number of molds or fungi. Unlike algae the fungi on our roofs lacks chlorophyll. They are unable to manufacture food from raw materials. So, it must get nutrition from some form of organic matter. To thrive, these heterotrophs, who used to be called saprophytes, also require a warm, humid environment.
Fungi normally begin their life cycle as an airborne spore that settles on roofs, especially the asphalt-shingle ones. The spores on the northern exposure of the roof stand a better chance of survival because that portion of the roof is the last part to dry after a rain or morning dew. This raises the humidity on the surface of the shingle, thus creating a perfect feeding and breeding ground.
The tar used in roofing is fossilized, dead organic matter -- and an important food source for fungi. Asphalt, at the granule base, is normally consumed first. Once these granules dislodge, accelerated deterioration will occur. Ceramic granules represent the outer hard shell that protects against hail and other falling debris. Ceramic granules protect against damaging UV radiation and insulate the roof against extreme heat. So you can understand that their dislodgement by the growing fungal colonies can be detrimental to our roofs’ longevity. Surprisingly, the blue-green algae are also food for the fungi.
While not all mold (fungi) and algae pose a health danger, some are harmful, especially for us older folks, younger children and people who suffer from asthma and respiratory problems. Their spores, which are on your roof, can get inside your home because they end up on the driveway and walkways from rain, and are easily tracked inside. They can even be drawn into our air conditioning systems and eventually populate our ducts.
Different mold species can have varying health effects, but it is important to remember that any excessive mold growth needs to be taken care of, regardless of the species. Any excessive mold growth can lead to increased allergies, toxicity, and house/building structural problems.
If you have a roof that is showing signs of infestation, give us a call. We would be glad to come out and talk with you about your options, and explain why we are the best