The answer to 'roof algae growth' is that roof algae, also known as black streaks or roof stains, is a common problem caused by the growth of cyanobacteria or algae on roofing materials. These organisms thrive in warm, humid climates and can discolor and degrade asphalt shingles over time. Symptoms include unsightly dark streaks or patches on the roof that can worsen if left untreated.
The main causes of roof algae growth are exposure to moisture, lack of sunlight, and poor air circulation. Homeowners should address these underlying issues to prevent and treat roof algae. DIY solutions like roof cleaning with a bleach-based solution or installing zinc or copper strips can be effective, but for severe cases or hard-to-reach areas, it's best to call a professional roofing contractor to properly clean and treat the roof.