To start out I have always believed in not pressure washing roofs. I went to this clients house located in puyallup for the first time a few days ago. In the past I have cleaned his rentals. I went up in his roof and went to work. I noticed that the shingles were extremely tender for a seven year old roof. I asked him how he cleaned his roof in the past and it was pressure washing. Also part of his vent was leaking. I could tell that it was because right below the vent the wood was soft. So I would strongly recommend against that type of roof cleaning. I on the other hand scrub lightly with a thin bristled brush aund a broom.