Those Black Streaks Are Alive
No Pressure, Ever
Pressure washing a shingle roof strips the granules that are the shingle's actual protection. It looks clean for a season and takes years off the roof. We never do it. Instead we apply a soft wash treatment that kills the organism at low pressure, then let rain rinse it. Results appear within days and keep improving for a couple of weeks. Tile and metal roofs are treated with methods appropriate to those surfaces. Before you book anyone, ask three questions: will you be walking my roof, are you insured for it, and do you use pressure. A roof cleaning done wrong is expensive in a way a driveway never is.
What the Staining Actually Is
The dark staining running down Florida roofs is Gloeocapsa magma, a cyanobacteria that feeds on the limestone filler in asphalt shingles. It is not dirt, it will not wash off with water, and it does not stop spreading on its own. Left alone it holds moisture against the roof surface, which shortens shingle life. Insurers notice it and so do buyers. Under the heavy oak canopy common across Plant City and Lakeland it shows up earlier and darker than in newer, more open subdivisions.