This asphalt shingle roof was treated with our moss killer and left to weatherize over a period of time. Once the moss is treated and left to die the process of weatherization occurs. Dying moss exposed to various the weather patterns help the moss to release from the composition asphalt shingles. Once the moss has had sufficient time to loosen up, it can simply be blown away from the composition roof. This roof cleaning process may need to be repeated a couple of times, but will not create any wear on the asphalt shingles. Please give Portland Roof Cleaning a call (503) 844-6500. Or visit our website at portlandroofcleaning.com