Those black stripes running down your roof are not dirt and they are not shingle wear. They are a living organism, and it is eating the roof.
📞 Call or Text (804) 571-7226 — most quotes go out the same day.
What the black stripes actually are
Gloeocapsa magma is a cyanobacteria that feeds on the limestone filler manufacturers mix into asphalt shingles. It starts at the ridge, where moisture lingers longest, and runs downward in the streaks everyone recognises. It hits north slopes and shaded rooflines first — and Richmond’s tree canopy makes this close to universal on any roof past year eight.
Never pressure wash a roof
Granule loss takes years off a roof and voids most shingle warranties outright. A pressure washer strips the protective granules that shield the asphalt from UV; the roof may look clean for a season and then age at double speed.
Our method follows the ARMA (Asphalt Roofing Manufacturers Association) recommendation: a sodium hypochlorite solution applied at roughly garden-hose pressure, with no unnecessary foot traffic on the shingles. The solution kills the organism; rain and time carry the residue away.
Streaks vs. moss vs. lichen
Three different organisms, three different treatments, three different timelines. Algae streaking generally disappears within hours. Moss dies and releases over a few weeks. Lichen is the stubborn one — it roots into the granule surface, dies on contact but sheds over several weeks of weather. We say that before we quote, not after.
Does cleaning actually extend shingle life?
Yes, and the reason is mechanical: the algae mat holds moisture against the shingle and consumes the limestone filler that gives the shingle body. Removing it stops both. Also worth knowing — insurers in Virginia have become noticeably more interested in roof condition at renewal, and a heavily streaked roof photographs badly.
What we protect
Landscaping below the working slope is soaked and covered. Downspout runoff is managed and diluted. Driveways and walkways below get rinsed. Gutters are flushed of solution before we leave.
Common questions
Is it safe on architectural shingles?
Yes. Soft washing is the method the shingle manufacturers themselves recommend.
Do you clean metal and standing-seam roofs?
Yes, with an adjusted solution — metal has different sensitivities, particularly around fasteners and coated finishes.
How long do results last?
Typically three to five years in this climate. Heavily shaded roofs return sooner.
Will my landscaping survive?
Yes, with proper pre-soaking, covering and post-rinsing — which is standard on every roof we do, not an upsell.
Are zinc strips enough on their own?
They slow regrowth on the area directly below them, which is useful after a clean. They will not remove existing growth, and coverage below the first few feet is inconsistent.
📞 Call or Text (804) 571-7226 — most quotes go out the same day.