The answer to 'fascia algae growth' is that it is a common problem caused by excess moisture, poor air circulation, and lack of sunlight. Symptoms include green, black, or brown discoloration on the fascia boards, which are the horizontal boards that run along the edge of the roof. This can lead to rotting and structural damage if left untreated.
The best solution is to address the underlying causes. This may involve improving ventilation, trimming back overhanging trees or vegetation, and regularly cleaning the fascia boards. In some cases, replacing the affected boards may be necessary. While minor fascia algae can often be treated with a DIY cleaning solution, more extensive growth or damage may require the expertise of a professional roofing contractor.