The answer to 'flat roof algae growth' is that algae growth on flat roofs is a common problem caused by moisture, shade, and lack of sunlight exposure. Symptoms include green, black, or reddish-brown discoloration and slippery surfaces. To solve this issue, you'll need to clean the roof, improve drainage, and consider preventative measures like applying an algaecide or reflective coating.
In many cases, flat roof algae can be treated with a DIY approach, but severe infestations or ongoing issues may require the expertise of a professional roofing contractor. They can properly diagnose the root cause, recommend the best solution, and ensure the work is done safely and effectively.