Depending on the the type of roof, different roof cleaning methods can be used.
Roofs consisting of Composite Shingles should NEVER be pressure washed. Doing so will take years of longevity from a roof. When cleaning moss from a composite shingle roof, we use a brush to loosen all moss, then a blower to remove it from the roof. All moss is then cleaned out of gutters and off of ground level surfaces.
Tile and Aluminum roofs are cleaned with a pressure washer. Gutters and surround areas are also cleaned of any roof debris.