What Causes Black Stains On Roof Shingles

Algae dark stains on asphalt roof shingles.

What causes black stains on roof shingles.

The algae will worsen and become more noticeable each year trapping moisture and causing premature shingle aging and granule loss. Black streaking on roofs is a common problem. Mix the soap and water well first then add the bleach. Learn more about what causes dark streaks on a roof and how to address the issue.

The black spots discoloring your asphalt roof are more than likely the pervasive and prevalent algae known as gloecapsa magma. Algae growth may cause discoloration on roofs resulting in brown or black streaks on a rooftop. These roof invaders require a moisture rich environment usually. It is not uncommon for roof shingles to turn black over time.

The bleach degrades into salt which kills microbial growths and the sodium silicate does the same. Algae is more likely to grow on shaded roof sections probably the cause of black stains on the lower roof in the photo at above right while asphalt shingle bleed through stains more often appear to emanate from single points regardless of sun or shade exposure probably the cause of stains in the photo at above left. Roof experts tell our researchers that though other components are being added to shingles to hinder algae growth they still get calls to deal with black marks on relatively new roofs. The streaks are caused by a type of algae known as gloeocapsa magma.

While the streaks do not cause a great deal of damage they can cause the shingle to age prematurely. Roofing manufacturers have tackled the problem of roof algae by creating shingles containing copper which is deadly to algae. Roof shingles are exposed to a lot of wear and tear as extreme heat sun wind and precipitation come into contact with them. Black marks became a problem about 20 years ago when manufacturers began adding limestone granules to add weight to material used to coat shingles.

As the blue green algae accumulate they develop a dark hardened outer coating which results in the black stains you see. This will cover 200 sq. Here is a diagnostic guide to types of stains and staining materials found on roof surfaces black red green brown or other coloured stains on asphalt roof shingles or on other roofing materials need first an accurate diagnosis of the stain cause and then proper steps to remove the stain or to prevent future staining on roof shingles surfaces. Spray the black stains first then the entire roof so the stains get a second dose.

When that happens it is generally caused by mildew algae mold or dirt stains.