Moss can cause critical damage to a roof by lifting and impeding shingles, allowing water to penetrate the subsurface. It can also cause unsightly stains. Removing moss regularly can prevent these issues.
Sprinkle It On
Powdered dishwasher or laundry detergent kills moss with minimum work and damage to the environment. Sprinkle the soap on the moss, allow it to sit for a few days, and then sweep the dead moss off of the roof. You will find commercial detergents available which are formulated specifically for removing moss from your home’s exterior. These are generally sprayed and the moss scrubbed away. These detergents can damage the environment if they include zinc sulfate.
As a last resort, you can use a combination of bleach diluted with an equal quantity of water to kill roof moss. Spray the moss and wash it with a stiff brush. Wash the residue.