The black streaks on South Florida roofs are caused by Gloeocapsa magma, an airborne algae that feeds on the limestone filler in tile and shingle and spreads fastest on humid, shaded slopes. Left alone it keeps growing. Cleaned with high pressure, the roof can lose granules, glaze, or tile integrity along with the streaks. The appropriate method is a low-pressure soft wash that treats the growth at its source and allows it to rinse away.
How Gulfshine washes a roof
The process starts on the ground with an assessment of the roof material, its age and condition, and what sits below it, because a roof wash is also a landscaping and runoff job. Plants, pools, and painted surfaces beneath the roof line are protected and rinsed, gutters and downspouts are accounted for, and the cleaning solution is applied at pressures comparable to rainfall. Cracked tiles, exposed underlayment, or repairs that should come before cleaning are flagged first, not discovered later.
The application itself is methodical: the solution goes on slope by slope, dwells for 10–20 minutes while it kills the algae colonies, and either rinses off or is left to let the coming rain finish the job, depending on the roof and the staining. Heavily streaked slopes may need a 2nd application. Downspouts are diverted or flushed so treated runoff does not sit in beds, and everything green below the roof line gets pre-wetted before work starts and rinsed after. The reasoning behind treating rather than blasting is the same logic covered in the difference between pressure washing and soft washing.
Why can’t a roof just be pressure washed?
Because every common South Florida roof material fails under pressure in its own way. Asphalt shingle sheds its granule layer, which is the layer that protects it from UV, a pressure-washed shingle roof can lose years of life in an afternoon. Barrel and flat tile lose their surface glaze and slurry coat, and walking a tile roof carelessly cracks tiles outright, which is why work is staged from ridges, walk pads, or accessed edges. Metal roofs handle water better but high pressure finds every seam and fastener. Beyond the material, pressure drives water under laps and flashing into the underlayment. None of this is theoretical, it is the standard damage pattern behind can pressure washing damage a house, applied to the most expensive surface on the property.
How often do South Florida roofs need washing?
Streaks typically become visible 1–2 years after algae takes hold, and most roofs here stay presentable on a wash every 2–3 years. Shaded slopes, homes under tree canopy, and properties near water tend toward the shorter end, open, sun-baked roofs stretch longer. The summer storm cycle from roughly June through October accelerates growth on any slope that stays damp between rains, and north-facing slopes almost always streak first. Timing-wise, the dry season makes scheduling easier, but a soft wash works year-round, the solution needs a rain-free window of a few hours, not a dry week.
Preparing your home for a roof wash
Preparation is mostly about what is under the roof. Move vehicles out from under the drip line, take down wind chimes and hanging plants near the eaves, and cover or move koi ponds and rain barrels that catch roof runoff. Close windows, including any that open under the soffits. Turn off sprinklers for the day so beds are not re-wetting treated runoff. Pets stay inside during application. Access-wise, the crew needs a working spigot and clear paths around the house; attic fans and open ridge vents are noted during assessment so solution is not drawn inside.
What goes wrong when roof cleaning is done badly
The failure list is short but expensive: granule loss and stripped glaze from pressure, cracked tiles from careless foot traffic, dead landscaping from unrinsed runoff, streaked walls where solution dripped and dried, and water forced under flashing that shows up as a ceiling stain months later. A cheap roof cleaning that shortens the roof’s life is the most expensive service on the block. The safeguards are all in the setup: correct method for the material, pre-wetting and rinsing everything below, controlled runoff, and a flagged list of pre-existing damage before work begins.
What it typically costs
Across South Florida, most roof cleaning companies land somewhere between $250 and $600 for a typical single-family home, with large tile roofs and steep or complex layouts running past that range. These are market figures, not a quote; what a given roof actually costs depends on its square footage, material, pitch, how heavy the algae staining is, and how easily crews can stage safely around it. For a number tied to your actual roof rather than an average, request an estimate, and see how much pressure washing costs for the broader exterior-cleaning price landscape.
Why regular roof cleaning matters
A streaked roof affects the appearance of the whole property, and many HOA communities cite roof staining in appearance notices. Roof washing pairs naturally with house washing and gutter cleaning in a single visit, and communities can fold roof cleaning into a phased common-area plan with an association scope. There is a maintenance argument too: algae holds moisture against the roof surface and feeds on it, so removing it is not purely cosmetic. Gulfshine serves 61 published cities across Miami-Dade, Broward, and Palm Beach counties, Monday through Sunday, 8:00 AM to 8:00 PM.
Who this service is for
- Residential homeowners
- HOA communities
- Property managers
Surfaces and scope
- Barrel and flat tile roofs
- Shingle roofs
- Metal roofs
- Ridge caps and flashing
Related questions
- What is the difference between pressure washing and soft washing? ; Pressure washing relies more on mechanical force; soft washing uses lower pressure with a surface-appropriate treatment process.
- Is soft washing safe for painted surfaces? ; It can be appropriate, but paint age, adhesion, oxidation, chemistry, dwell time, and rinsing still require assessment.
- Can pressure washing damage a house? ; Yes. Excess pressure or the wrong angle, distance, tip, or treatment can damage finishes and force water where it should not go.
Roof Washing is available across our South Florida service areas where the property and surfaces are a fit, mention it when you request an estimate.
Last updated .