Every Composition Roof is Different
Because of this being a rain wash-down process there is no longevity warranty. The more rain the roof receives, the sooner the product goes away. On my own roof, it lasted for two or three years before we started seeing moss coming back. How long yours lasts will depend on the severity, pitch, shade, and the presence of debris.
Because we have treated so many comp roofs, we have learned that they are all different. So we have started charging them according to their size, pitch, and amount of debris on them. Included are debris and gutter cleaning, as needed, as well as clean-up. The majority of our straightforward roofs (2000 – 2500 sq. feet) start at $795 and can go as high as $3,000, depending on which method of cleaning you decide upon.