Thank you for visiting our blog page. These are some before and after photos of a roof cleaning. This roof has a lot of moss. Since roofs cannot be pressure washed, the moss needs to be treated then will die, dry out, and start to decompose. It will become brittle and wash off in a few rains. For this reason you may need 4-6 weeks for the rains to fully wash off the dead moss. This growth will never go away on its own. The darker staining is a single celled bacteria that feeds on the limestone in the roofing shingle. It feeds on the roof like an “all you can eat buffet”. This roof treatment costs less than $500. The benefits of a clean roof are the shingle lasting years longer. Black staining on the roof actually absorb heat as opposed to deflecting UV. Its been proven that a clean roof can lower cooling costs. It doesnt cost to clean a roof, it pays!!