Algae Growth

Algae Growth


  • Airborne algae is deposited and grows on roof, resulting in a dark discoloration, usually brown to black, and a streaked, dirty-looking rooftop.
  • Occurs mostly in warm, humid climates such as the Southeast (where algae resistant shingles are available), but doesn’t affect long-term performance.


  • Discoloration of roofs caused by fungus or algae is difficult to remove, but may be lightened by spraying a diluted solution of chlorine bleach, trisodium phosphate and water onto the roof. This solution can be rinsed from the roof in 10 to 15 minutes. Do not scrub because scrubbing will loosen and remove shingle granules.
  • After spraying, be sure to thoroughly flush the roof and the greenery around the home (grass, bushes and shrubs) with water. The effectiveness of this type of cleaning may only be temporary, and the discoloration may recur.
  • High-pressure washing is not recommended because of the possibility of removing granules, which can shorten the life of the roofing system.
  • For a more permanent solution, reroof with Owens Corning™ algae-resistant shingles. They are specifically designed to inhibit most algae growth for extended periods of time and are backed by our product warranty and Algae Resistance Warranty.*

* See actual algae-resistant shingle warranty for details. Algae-resistant products are not available in all areas. Contact Exterior Energy Solutions for more information or FREE ROOF INSPECTION.

Leave a Reply