Spraying a mixture of one part bleach and one part water on a roof kills moss. Plants around the perimeter of the house should be sprayed with water before spraying the mixture. This helps protect them from bleach that runs off the roof.
Moss thrives in moist, shaded environments but does not grow near copper. Strips of copper can be inserted under the shingles to prevent the moss from growing again. Moss can damage the shingles on the roof and lead to water damage. A power washer should not be used to remove moss from roofs, as the pressure of the water can damage the shingles.