The answer to 'why is my metal roof algae growth' is that metal roofs can be susceptible to algae growth due to the moist, humid conditions they are often exposed to. Algae thrive in these environments and can discolor and degrade the metal over time. Common causes include poor ventilation, shaded areas, and proximity to trees or other vegetation.
Symptoms of algae growth on a metal roof include dark green, black, or reddish-brown staining or discoloration. This can lead to premature rusting and corrosion of the metal if left untreated. While some light algae growth may be manageable with DIY cleaning, more severe cases often require professional roof cleaning and treatment to prevent long-term damage.