Roof Cleaning Charleston, SC

Black streaks on Charleston roofs are caused by Gloeocapsa magma, a hardy blue-green algae that feeds on the limestone filler in asphalt shingles. Charleston's combination of high humidity (typically 70%+), warm temperatures, and frequent rainfall creates ideal conditions for it to spread, and the north- and shaded sides of the roof always streak first because algae prefers low UV exposure. The dark color is from a protective sheath the algae produces to shield itself from sunlight — it's not dirt, and it won't rinse off with rain.

Most Charleston roofs need professional cleaning every 2–3 years. Homes under heavy oak or pine canopy, on shaded lots, or near tidal marshes often need it every 18–24 months because the algae returns faster. Homes in sunnier, more exposed locations — typical of newer subdivisions in West Ashley, Daniel Island, and Mount Pleasant — can usually go 3–4 years between washes. A good rule of thumb: if streaks are visible from the street, the roof is overdue.

Soft wash roof cleaning uses a low-pressure spray (under 100 PSI — less than a garden hose) combined with a diluted sodium hypochlorite cleaning solution and a surfactant that helps the mix cling to the shingle. The chemistry kills the algae, lichen, and moss at the root rather than blasting it off with water, so asphalt granules, flashing, and roof sealants stay intact. Results brighten over the days following the wash as rain rinses the treatment through the shingles. This is the method recommended by the Asphalt Roofing Manufacturers Association — high-pressure washing voids most shingle warranties.

Most Charleston roof cleaning jobs run $400–$800 depending on roof size, pitch, height, and how much black streaking, lichen, and moss has built up. A single-story ranch with mild streaking is on the lower end; a two-story home with steep pitch and heavy north-side algae is on the higher end. Broad Street Pressure Wash provides a free walk-around quote before any work starts.

Yes — when it's soft washed, not pressure washed. Major shingle manufacturers — GAF, Owens Corning, and CertainTeed — explicitly recommend the soft-wash method using a diluted sodium-hypochlorite solution in their published roof-cleaning guidance. High-pressure washing, by contrast, strips the protective granules off the shingle surface, shortens roof life, and often voids the warranty. Broad Street Pressure Wash uses the manufacturer-approved soft-wash method on every Charleston roof.

Yes. Broad Street Pressure Wash also serves nearby areas including Mount Pleasant, North Charleston, James Island, Johns Island, Daniel Island, Summerville, Goose Creek, West Ashley, Folly Beach, Sullivan's Island, and Isle of Palms.