The answer to 'how to clean metal roof' is to use a soft-bristle brush and a mild detergent solution to gently scrub the surface. This will remove dirt, debris, and any built-up grime without damaging the metal. Be sure to rinse the roof thoroughly with a garden hose to wash away all the cleaning solution.
It's recommended to clean your metal roof at least once a year, or more frequently if you live in an area with heavy pollution, tree coverage, or other environmental factors that can accelerate the buildup of contaminants. Proper cleaning will help maintain the roof's appearance and extend its lifespan.