The answer to 'how to clean flat roof' is to regularly clean and maintain the roof to prevent buildup of debris, moss, and other contaminants. This helps extend the life of the roof and ensures proper drainage. Start by sweeping or blowing off any loose debris and leaves. Then, use a soft-bristle brush and mild detergent solution to scrub the roof surface, taking care not to damage the roofing material. Rinse thoroughly with a garden hose. For tougher stains or buildup, you may need to use a specialized roof cleaning solution, but be sure to follow the manufacturer's instructions carefully.
It's recommended to clean a flat roof at least once a year, or more frequently if you live in an area with a lot of trees or other debris. If you notice any significant damage, leaks, or issues that require repair, it's best to call in a professional roofing contractor to assess and address the problem.