San Francisco Roof Soft Washing Service
Dark streaks, black stains, and green patches on roofs in San Francisco are almost always caused by algae (Gloeocapsa magma), moss, or lichen — not dirt. These organisms feed on limestone filler in asphalt shingles, gradually degrading them and shortening roof life. Soft washing — low-pressure cleaning combined with specialized biocidal solutions — kills these organisms at the root and restores the roof's appearance without the granule loss and shingle damage caused by high-pressure washing.
Roof soft washing in San Francisco costs $250–$450 for a 1,500 sq ft roof and $350–$600 for a 2,500 sq ft roof. 29 of 29 verified providers in San Francisco offer roof soft washing as a standalone service or bundled with house exterior cleaning. Service covers the San Francisco metro area including San Francisco Bay Area, Oakland, San Jose. Never allow any provider to pressure wash an asphalt shingle roof — the Asphalt Roofing Manufacturers Association (ARMA) explicitly recommends against it. Only soft wash is appropriate.
After soft washing, treated algae and moss may not disappear immediately — biological material dies and washes away gradually over the next few weeks of rain. This is normal and expected. The roof will continue to lighten for 4–8 weeks following treatment. A second visit is rarely needed. Many San Francisco homeowners schedule roof soft washing every 3–5 years or as soon as dark streaks reappear.
San Francisco Providers Offering Roof soft washing
gutter debris removal · downspout cleaning · solar panel cleaning · pre-solar installation roof washing · holiday lighting installation +1 more
gutter cleaning · window cleaning · exterior brightening
window cleaning · gutter cleaning · graffiti removal · water runoff reclamation
gutter cleaning · gutter guard installation · window cleaning · solar panel cleaning · paver patio sealing +1 more
gutter debris removal · downspout cleaning · solar panel cleaning · pre-solar installation roof washing · holiday lighting installation +1 more
gutter cleaning · solar panel cleaning · sidewalk cleaning
gutter cleaning · window cleaning · roof cleaning · floor cleaning · hood cleaning
gutter cleaning · window cleaning · graffiti removal · drain/sewer cleaning · asphalt recoating
gutter cleaning · window cleaning · deck and fence staining · solar panel cleaning · shingle preservation +1 more
gutter cleaning · deck restoration · limestone restoration
wood restoration · metal cleaning and restoration · interior surface cleaning · sign cleaning
gum removal · oil stain removal · grease stain removal · window cleaning
gutter cleaning · screen repair · screen cleaning
window cleaning · gutter cleaning · solar panel cleaning · rust removal · deck and fence staining +1 more
gutter cleaning · graffiti removal · bird removal · bird nest removal
gutter cleaning · window cleaning · solar panel cleaning
gutter cleaning · window cleaning · sidewalk gum removal · gutter guards installation · bird abatement +1 more
graffiti removal · window cleaning · initial construction cleaning · final construction cleaning · preventive maintenance +1 more
gutter cleaning · solar panel cleaning · window cleaning
debris removal · hand detailing · night/weekend service
window cleaning · gutter cleaning · graffiti removal · cobweb removal · oil/grease removal
gutter cleaning · window cleaning · solar panel cleaning
gutter cleaning · window cleaning · solar panel cleaning · skylight cleaning · roof cleaning +2 more
graffiti removal · litter removal · debris removal · bin delivery and servicing · recycling stations +2 more
floor buffing and brushing · strip and wax sealing treatment · high dusting · window cleaning · commercial painting
window cleaning · gutter cleaning · trash and garbage collection · parking lot resurfacing and striping · disinfecting services
gutter cleaning · window cleaning · marble restoration · stone floor polishing and restoration · high-touch area sanitization +5 more
Roof Soft Washing FAQ — San Francisco
How much does roof soft washing cost in San Francisco?
Roof soft washing in San Francisco costs $250–$450 for a 1,500 sq ft roof and $350–$600 for a 2,500 sq ft roof. Larger or steeper roofs run higher. Bundling with house exterior washing usually saves $50–$100. Compare quotes from 29 providers in San Francisco for your specific roof size and pitch.
Is pressure washing safe for my roof in San Francisco?
No — high-pressure washing on asphalt shingles strips protective granules, voids manufacturer warranties, and can force water under shingles causing leaks. The Asphalt Roofing Manufacturers Association (ARMA) recommends against pressure washing shingle roofs. Soft washing is the only appropriate method. If a San Francisco company recommends pressure washing your shingle roof, it's a significant red flag.
What causes dark streaks on my roof in San Francisco?
Dark streaks on San Francisco roofs are almost always caused by Gloeocapsa magma — a blue-green algae that feeds on the limestone filler in asphalt shingles. Green patches are typically moss. Black or dark areas with texture are often lichen. All three are killed by soft washing solutions. Left untreated, they can significantly reduce shingle lifespan by degrading the granule layer.
How often should I have my roof soft washed in San Francisco?
Most San Francisco roofs benefit from soft washing every 3–5 years, or sooner if significant algae streaking appears. Homes in shaded, humid, or heavily treed areas may need cleaning every 2–3 years. After soft washing, results typically last 2–4 years before biological growth visibly returns. Some San Francisco companies apply preventive zinc or copper strips after washing to slow regrowth.