Two to three years
Roof Cleaning
Those black streaks are a bacteria, not just dirt, and soft washing is the method that actually kills it without risking the shingle warranty.
What's actually causing those black streaks
The dark streaking that runs down a Michigan roof is Gloeocapsa Magma, a bacteria that feeds on the limestone filler mixed into asphalt shingles. It spreads down the slope as it grows, which is why the streaks always seem to start near the ridge and trail toward the gutter line. Scrubbing or blasting it off the surface does not solve much on its own, because the bacteria is still alive in whatever residue gets left behind. Soft washing kills it at the source with a solution rather than force, so a treated roof stays clear for two to three years instead of streaking again by the following summer.
Safe for the shingles, safe for the warranty
Most shingle manufacturers specify soft washing and warn against high pressure, because the force strips the granules that protect the shingle underneath and can void the warranty outright. Every roof job here covers algae and moss removal along with the black-streak treatment, using the soft-wash method on every roofing material rather than pressure on some and caution on others.
Shining Star backs the result for a full year. Call (517) 605-5020.
From the reviews
My roof, which was BAD, looks like new
That's K C, describing a roof Roger cleaned across two different homes. Both times the result held, which is the point of a bacteria treatment over a one-time scrub: it does not just clean the roof, it buys the roof two to three years before the streaking has a real chance to come back. The same soft-wash pass also lifts moss and general algae buildup without touching the granule layer the shingle depends on to last.