The answer to 'flashing algae growth' is that algae growth on roof flashing is a common problem caused by moisture, lack of sunlight, and organic debris buildup. Symptoms include green, black, or brown discoloration on the metal flashing around chimneys, vents, and roof edges. The main solutions are to clean the flashing, improve ventilation, and prevent future growth by applying a sealant or algaecide.
While minor algae growth can sometimes be treated with DIY cleaning methods, more severe cases may require professional roof maintenance or replacement of damaged flashing. It's best to address the issue promptly before it leads to further roof deterioration or leaks.