You may notice that your roof has dark streaks and wonder what they are. Read more through this article to find out.
Algae Growth on Asphalt Shingles
The algae growth can cause roof discoloration, resulting in black streaks or brown spots.
It is possible to mistake algae for soot or dirt, but most produce minimal discoloration.
In the United States, dark streaks or roof discoloration due to algae can occur in various degrees, particularly in areas exposed to hot, humid conditions. It is more common in the east, often found on roofs with northern exposure.
The cyanobacteria Gloeocapsa magma algae is the primary species that grow on roofs. It is contained in the air and can be transported through it.
It is possible to find green algae (typically green) or moss on roofs with northern exposure or overhangs.
Is it possible to remove dark spots or algae discoloration from an asphalt roof?
It can be hard to get rid of algae discoloration, but you can lighten it by spraying a solution of chlorine bleach with water on the roof.
Disclaimer: When cleaning your roof, we recommend that you hire a licensed/certified roofing contractor. Remember that a roof can be slippery if wet, so be careful. While cleaning the roof, wear appropriate fall protection and proper PPE such as slip-resistant boots/shoes and eye protection.
How to lighten dark spots or Algae Discoloration on an Asphalt Roof
- Before applying the solution, covering all ground vegetation under the roof is essential.
- A mixture of 1-gallon bleach with 1 gallon of water (1:1).
- Spray the solution on the roof for around 10 to 20 minutes.
- Avoid using high-pressure pressure power washers or scrubbers to clean the roof. This action can cause damage and shorten the life span of your roof covering.
- You should spray the roof with water after approximately 10 to 20 minutes. Be sure to flush all greenery (grass, shrubs, and bushes) around the roof.
- If algae growth becomes extensive, the cleaning process might need to be repeated. The discoloration can recur, but this is a temporary procedure.
What Does Algae Do to Asphalt Shingles Performance?
Algae deposits do not affect asphalt shingles’ performance. Instead, algae or streaking is more an aesthetic issue and can impact your home’s curb appeal or look.
What are Algae Resistant (AR-) Shingles?
For reducing the cyanobacteria Gloeocapsa magma algae growth, asphalt shingles with algae-resistant minerals granules are still the best option. These products contain metals such as copper-lined minerals granules to reduce algae growth.
After observing that the shingles reduced algae staining under metal flashing or vents on roofs, experts realized that copper and other metals have anti-algae properties.
Some roofing companies have a full line of algae-resistant asphalt shingles with anti-algae technology that helps reduce algae growth. But unfortunately, these products don’t address green algae (typically green in appearance), or moss often found on roofs with northern exposure or overhangs.
Contact your Roofer
If you see that your roofs have dark streaks and want to get cleaned or replaced, contact a trusted roofing company around your area, such as Roofing Repair Milford MA, to estimate the costs and services offered.
