What causes those black streaks on my roof?
The stains and streaks are a form of algae named Gloeocapsa Magma .
This mold feeds on the organic matter commonly known as limestone . It will start to break down the composition of your shingles. The granules protecting your roof are loosened and will start to fall off. This will deteriorate your roof .
Roof algae will reduce the life of your roof by about 3 to 4 years. This algae is very unsightly. The appearance of your house can affect your property value. Anyone selling a house should be concerned. There are three things this algae needs to thrive. Heat, moisture, and nutrients
The north side will start to show algae 1st do to moisture not dried by sun. Gloeocapsa magma is blue-green algae, which is cyanobacteria . It is a type of algae. Algae are polyphyletic, and major algal groups are not all closely related to each other. Algae is NOT a taxonomic category, it is just a common name for all things photosynthetic that are NOT plants. Cyanobacteria are an ancient line of photosynthesizing bacteria, responsible for Oxygen gas in the atmosphere. It can be said that Cyanobacteria are responsible for all advanced forms ( eukaryotic cells ) of life on earth. It has gained notoriety in the Southeastern U.S. which is quickly spreading throughout the Midwest. The reason is this particular type of blue-green algae is responsible for creating the unattractive black roof stains and/or streaks commonly noticed by many. The blue-green algae, unicellular, accumulate over time; this accumulation begins to show the problematic black stains as the cyanobacteria develop their dark and hard UV-protective outer coating.
The primary reasoning behind the rapid spread and noticeably of this algae is:
Rising humidity and temperatures combined with more and more bacteria spores promotes their spread with these favorable conditions.
Fiberglass shingles (the most commonly seen amongst today’s residential homes) have been being made with limestone as a filler (in the asphalt). These shingles hold moisture and organic “bacteria food” material longer (especially on the North-side in the Midwest) than the paper/asphalt/ceramic shingles of 20+ years ago. Additionally, these particular algae enjoy the limestone as a food source.
Once the blue-green algae have become noticeable, the stains will continue to worsen year to year. There is debate over the actual harmfulness of this particular blue-green algae to roofs, as there is little supportive scientific research. However, most “experts” within the subject area conclude the blue-green algae to be harmful, if left untreated, as the growth holds moisture within shingles causing premature aging, rotting, and/or granule loss.
Gloeocapsa magma is a species of cyanobacteria . Cyanobacteria are an ancient line of photosynthesizing bacteria, which photolyze water generating oxygen gas. Ancient cyanobacteria were ancestral to the chloroplasts of all plants on earth. Gloeocapsa magma has gained notoriety in the Southeastern U.S. which is quickly spreading throughout the Midwest. This particular type of cyanobacteria is responsible for creating unattractive black stains and/or streaks on roofs. The bacteria accumulate over time; this accumulation begins to show the black stains as the cyanobacteria develop their dark and hard UV-protective outer coating.
Gloeocapsa magma may resemble “algae” in that they are green, but in fact cyanobacteria are bacteria whereas algae are single-celled eukaryotes (cells with nuclei) that are closely related to plants.