Remove black algae streaks, lichen, and biological growth from tile, shingle, and metal roofs — using the low-pressure soft wash method recommended by roofing manufacturers.
The dark streaks running across rooftops throughout Southwest Florida are one of the most visible and misunderstood exterior maintenance problems in the region. Most homeowners assume the streaks are dirt, pollution, or simply age. They are not. The black and dark grey streaks on Florida roofs are Gloeocapsa magma — a cyanobacteria that feeds on the limestone filler in concrete roof tiles and asphalt shingles. It thrives in Florida's warm, humid climate and spreads through the air from roof to roof across neighborhoods. Once established, it grows steadily, darkening the roof surface and consuming the roofing material itself.
The consequences of untreated biological growth on a roof go beyond aesthetics. Gloeocapsa magma and other biological organisms actively shorten roof lifespan. Lichen, which often follows algae colonization, attaches to the roof surface with root-like structures that penetrate tile coatings and shingle granules. Moss holds moisture against the roofing material, accelerating deterioration. Several roofing manufacturers explicitly void warranties if biological growth is present and untreated. A $15,000 to $30,000 roof replacement is a cost-avoidance argument for regular professional cleaning that writes itself.
Rain Exterior Home Service provides soft wash roof cleaning throughout Fort Myers, Cape Coral, Naples, Bonita Springs, Estero, Marco Island, and surrounding Lee and Collier County communities. Soft washing uses low-pressure application — under 500 PSI — of a professional biodegradable cleaning solution that kills biological growth at the cellular level. Unlike pressure washing, which removes the visible surface of the growth while leaving spores behind, soft washing kills the organism completely. Regrowth is significantly slower after a proper soft wash treatment.
We clean tile, concrete tile, asphalt shingle, and metal roofs. Each material requires a different formulation and approach — tile and metal roofs can use slightly higher-concentration solutions than asphalt shingles, which require careful product selection to avoid granule damage. We assess your specific roof before applying any treatment and will not proceed if the roof has damage that could be worsened by cleaning.
Results
How It Works
We walk the perimeter and assess the roofing material — tile, concrete tile, shingle, or metal — and identify the type and extent of biological growth before applying any cleaning solution.
A professional-grade, biodegradable soft wash solution is applied at low pressure (under 500 PSI). The solution kills Gloeocapsa magma, algae, lichen, and moss at the cellular level — not just at the surface.
The solution is allowed to work for 15 to 30 minutes. This step is essential — killing the organism completely rather than just removing visible growth prevents rapid regrowth.
A low-pressure rinse washes all residue off the roof and into the gutters. We inspect every section of the roof and address any areas where growth remains before leaving the site.
Common Questions
No — soft washing is specifically designed to clean roofing materials safely. The Asphalt Roofing Manufacturers Association (ARMA) explicitly recommends soft washing for asphalt shingles and warns against pressure washing, which strips protective granules and voids warranties. For tile roofs, soft washing removes biological growth without cracking tiles or dislodging mortar at ridge caps. For metal roofs, we use solutions formulated for metal that do not cause discoloration or surface damage.
The black streaks you see on roofs across Southwest Florida are caused by Gloeocapsa magma, a cyanobacteria that feeds on the limestone filler in roofing materials — particularly asphalt shingles and concrete roof tiles. The bacteria is airborne and spreads from roof to roof in humid climates. Left untreated, it gradually consumes roofing material and shortens roof lifespan. Some roofing manufacturer warranties are voided if biological growth is present and untreated.
Most roofs in Fort Myers, Naples, and Cape Coral need professional cleaning every 2 to 3 years. Florida's heat and humidity dramatically accelerate biological growth compared to drier climates. Metal roofs in coastal areas near the Gulf may need cleaning every 18 to 24 months due to salt air accelerating corrosion and oxidation. The visible sign of a roof that needs cleaning: black streaks, green or brown patches, or general darkening that has not been present since the last cleaning.
Yes. We use biodegradable soft wash solutions formulated to be safe for gutters, aluminum fascia, and established landscaping when applied by a trained technician. We wet down plants and shrubs in the fall zone before applying solution and rinse them thoroughly after the roof rinse. Runoff from soft wash solution dilutes significantly as it moves through the gutters and onto the ground, and biodegrades within days of application.
Yes. The biological organisms that cause roof staining — cyanobacteria, algae, lichen, and moss — actively degrade roofing materials. Lichen is particularly damaging because it attaches to the surface with root-like structures that penetrate tile coatings and shingle granules. Regular cleaning prevents this biological degradation and can add years to the useful life of a roof. For a home requiring a $15,000 to $30,000 roof replacement, a $300 to $600 cleaning every two to three years is a straightforward investment.
What Homeowners Say
"Our tile roof had black streaks all the way across it — looked terrible for years. After soft washing it looks like a different house. The streaks are completely gone. Wish I had done this years ago."
"I was worried about my shingles but they explained the soft wash process before starting. No pressure — just solution and a gentle rinse. The roof looks brand new and everything is still intact."
Serving Fort Myers, Cape Coral, Naples, Bonita Springs, and all of Southwest Florida. Most jobs quoted within 24 hours.
Rain Exterior Home Service
We Regularly Serve Homeowners in Southwest Florida: