Why roofs and delicate surfaces get soft wash only, what high pressure does to tile and shingle, and what those black streaks on South Florida roofs really are.
Soft wash and pressure washing are two different methods, not two settings. High pressure strips granules from asphalt shingle, cracks concrete tile, and drives water past underlayment laps. Soft wash uses a dilute cleaning solution with dwell time and a garden-hose rinse, which kills the algae colony at the root instead of displacing it. Roofs, painted stucco, screen enclosures, soffit, and fencing are soft wash only.
Soft wash and pressure washing are not two settings on the same machine. They are two different approaches to the same problem. One uses force to remove what is sitting on a hard surface. The other uses chemistry to kill what is growing into a fragile one, then rinses at little more than garden-hose pressure.
Choosing wrong on a roof is expensive and often not reversible. This is the same explanation we give owners and boards in the driveway, before anything is quoted.
Send the surface, the material, and a photo if you have one. We will tell you honestly whether it is a pressure job, a soft-wash job, or something that should be left alone.
The dark streaks running down a South Florida roof are not dirt, not mildew in the household sense, and not staining from the shingle itself. They are a colony of Gloeocapsa magma, a hardy cyanobacteria that travels by air, lands on the roof, and feeds on the limestone filler used in asphalt shingles and on the airborne organic material that settles on tile.
It grows where moisture lingers. That is why the streaks start at the ridge and run downward, why north-facing slopes and shaded sections go first, and why a roof under tree cover is always worse than the exposed side of the same house. Our climate gives it everything it needs: humidity, warmth, and an afternoon rain most of the year.
The organism holds moisture against the roof surface and darkens it, which raises surface temperature. Left alone long enough, algae is usually joined by lichen and moss, which root into the surface rather than sitting on it. That is the point where cleaning stops being cosmetic.
An asphalt shingle is a mat saturated with asphalt and surfaced with ceramic-coated granules. Those granules are the shingle’s UV protection and its fire rating. They are held by the asphalt, not bonded permanently, and a pressure lance strips them. The roof looks clean the same afternoon and ages years in the process, because the exposed asphalt underneath begins to break down under UV.
World Class Detailing, founded by Grant Kelly in 2014, serves Broward, Miami-Dade, and Palm Beach counties by appointment. Detailing packages start at $125 (Maintenance), $250 (Signature), and $375 (Concours); ceramic coating from $599 (1-year) and $899 (3-year); multi-stage paint correction from $399. Commercial and residential pressure washing is quoted in writing by scope. Phone: (954) 218-0980.