The black and green staining on Florida stucco and sidewalks is not dirt. It is a living growth, and the wrong cleaning method can make it come back faster than before you started.
Boards and CAMs often assume more pressure means a better clean. For painted and coated surfaces, the opposite is true. Choosing the right method for each surface is the difference between a wash that lasts and a wash that needs redoing within a season.
Algae and mildew grow fastest in Florida during July and August, when summer heat combines with an afternoon thunderstorm most days. That combination of warmth and moisture is exactly what the growth needs to spread across stucco, privacy walls, and walkways.
Left alone, the staining does not fade on its own. It spreads into the surface over time, which is why communities that wait until it looks bad usually find it has already gone further than it appears from ground level.
Blasting a painted or coated surface at high pressure removes the visible staining, but it also strips the paint or coating itself. That drives water behind the finish and leaves the organism that caused the staining alive at the root.
The result shows up within months: the same streaks return, often faster than the first time, because the surface is now more porous and the growth was never actually killed. Pressure washing did not clean the building. It gave the stain a haircut.
Soft washing uses low pressure combined with the right detergent mix and enough dwell time for the solution to do the work the pressure would otherwise be doing. Instead of stripping the surface, the growth dies at the root.
Because the surface itself is not damaged in the process, a soft wash typically lasts two to three times longer than a high-pressure clean on the same coated surface. The building stays clean through budget season and into the winter board meetings, which is when a property tends to get looked at hardest by residents and board members alike.
Boards do not need a chemistry background to understand what a soft wash is actually doing, but it helps to know the mix is not random. A typical soft-wash solution combines three things: a mild bleach-based agent to kill the algae, mold, and mildew at the root, a surfactant that helps the solution cling to a vertical wall instead of running straight off, and a rinse step at low pressure to carry the dead growth away without touching the coating underneath.
The surfactant is the detail most people miss. Water alone runs off a stucco wall in seconds. A properly mixed soft-wash solution is closer to a light foam, which is why it can sit on a vertical surface long enough to actually kill the organism instead of just wetting it. Dwell time, not pressure, is what does the cleaning.
This is also why soft washing needs a trained applicator rather than a pressure washer with the tip swapped out. Mix ratios matter, dwell time matters, and rinsing at the right moment matters. Too weak a mix or too short a dwell time leaves growth alive under a clean-looking surface, and it reappears within weeks instead of years.
Pressure washing equipment is typically discussed in terms of two numbers: PSI, which measures the force of the water, and GPM, which measures the volume moving through the wand. Both numbers matter more than most quotes make clear.
As a general framing, uncoated concrete flatwork can generally tolerate the higher end of residential-to-commercial pressure ranges without damage, since it was built to handle traffic and weather abuse. Painted, coated, or textured vertical surfaces cannot. The same PSI that clears years of grime off a driveway can etch soft stucco, blow out old caulk lines, or strip a thin coating in a single pass.
Rather than asking a vendor to quote a specific PSI number, which varies by equipment and nozzle tip anyway, ask what pressure range they use on flatwork versus vertical coated surfaces, and whether that range changes based on the surface's age and condition. A vendor who cannot answer that distinction is likely running one setting on everything, which is the exact mistake this article is about.
Use this table to sort your property into the two categories before any vendor picks up a wand.
| Surface | Method | Why |
|---|---|---|
| Sidewalks, driveways, pool decks | Pressure wash | Uncoated concrete built to take abuse; pressure is faster and does no harm |
| Painted stucco walls | Soft wash | Pressure strips the paint and leaves the growth alive at the root |
| Coated breezeway ceilings | Soft wash | Coating is thin and easily stripped by direct pressure |
| Under-building parking garage flatwork | Pressure wash | Uncoated concrete, same rule as open flatwork |
| Pavers | Pressure wash, then reseal if coated | Bare pavers take pressure well; sealed pavers need soft wash or the sealer strips with the stain |
| Roofs (tile, shingle, metal) | Soft wash only | Direct pressure lifts granules off shingles, cracks tile glazing, and voids most manufacturer warranties |
| Pool cage and lanai screens | Soft wash only, low pressure hand rinse | Screen mesh and its frame seals tear or blow out under direct pressure |
| Any surface with a visible painted or sealed finish | Soft wash | Default to soft wash whenever a finish is present, not just walls |
The test is simple, and it is the one our crews apply on every wash: concrete flatwork can take pressure. Painted and coated surfaces get soft washed.
Sidewalks, driveways, and pool decks are uncoated concrete built to take abuse, so pressure is the right, faster tool there. Painted stucco walls, coated breezeway ceilings, roofs, screens, and any surface with a finish on it need the soft wash approach instead. Mixing the two up in either direction either wastes time on flatwork or damages a coated surface that needed the gentler method.
Boards rarely see the damage happen. They see it weeks or months later and often do not connect it back to the wash. A few patterns are worth knowing so a board can recognize them and ask questions.
Etched or striped stucco. High pressure on a painted wall can leave faint parallel lines or a blotchy texture where the wand passed closer or slower in some spots than others. This is the coating itself being unevenly stripped, not dirt being unevenly removed.
Faster-returning stains. If the same streaks reappear in a shorter time than the last wash cycle, the growth was not killed, only knocked loose from the surface. A surface that is now more porous from stripping also holds new growth more readily than before.
Bald patches on shingle roofs. Direct pressure on asphalt shingles strips the protective granules, leaving a lighter, rougher patch that accelerates wear on that section of roof long after the black streaking is gone.
Torn or bulged screens. A pool cage screen hit with a pressure wand can develop small tears at the frame or bulge outward, both of which usually mean a screen panel replacement rather than a repair.
Water intrusion after washing. If a wall develops a new interior stain or damp spot in the weeks after a wash, high pressure may have driven water behind stucco, siding, or a window seal. This is worth a prompt follow-up with whoever performed the work.
Different surfaces get dirty and grow algae at different rates, so a single property-wide wash schedule usually over-services some surfaces and under-services others. A cadence built by surface type is more useful for budgeting and planning than a single blanket frequency.
| Surface | Typical Central Florida cadence | Why this rate |
|---|---|---|
| Painted building exteriors (soft wash) | Roughly every 12 to 24 months | Soft wash kills growth at the root, so the clean interval is longer than a pressure clean |
| Open flatwork (sidewalks, driveways) | Roughly every 6 to 12 months | High foot traffic and ground-level dirt reaccumulate faster than wall staining |
| Pool decks and cages | Roughly every 6 to 12 months, screens as needed | Constant moisture and shade around pools accelerates algae regrowth |
| Roofs | Roughly every 2 to 4 years, condition-dependent | Roof algae is highly visible but slower-growing than wall or deck staining |
| Coated breezeways and stairwells | Roughly every 12 to 18 months | Shaded, low-airflow areas hold moisture longer, accelerating regrowth |
Scheduling before peak summer growth, covered in more detail below, generally moves every one of these intervals to the earlier end of its range rather than the later end.
One recent job for a Central Florida condo community made the point clearly. The property is a three-story building with an under-building parking garage, and the scope covered the building exterior plus the garage front rather than treating the whole structure as one surface.
That kind of property forces the same surface-by-surface thinking as the decision rule above. Painted exterior walls and covered breezeway areas call for soft washing. Open flatwork like the garage entrance and community walkways can take pressure. A wash plan that treats every surface on a multi-level building the same way is usually treating at least one of those surfaces wrong.
Jobs like this also come with practical scope details boards should ask about up front: whether the crew needs a hydrant meter or portable water source, how unprepped or inaccessible areas are handled, and how many crew-days the job realistically takes. A vendor who has an answer for all three has actually planned the job, not just quoted a square footage number.
Pressure washing open flatwork moves fast, typically covering a large area of sidewalk or driveway in a matter of hours per crew. Soft washing a building exterior takes longer per square foot, since the detergent needs dwell time to work before rinsing, but it is still typically a same-day to few-day job depending on building size and the number of coated surfaces involved. A multi-level building combining both methods, like the three-story example above, is realistically a multi-day crew job rather than a single-visit wash, since flatwork and building washing are usually sequenced separately.
Algae and mildew growth accelerates through Florida's summer rainy season, so scheduling a wash before peak summer (spring, or as early in summer as the schedule allows) gets ahead of the heaviest growth rather than chasing it once it is already established. Waiting until late summer or fall means starting from a worse baseline and often needing a longer dwell time or a repeat treatment sooner.
Florida's rainy season generally overlaps with the Atlantic hurricane season, which the National Hurricane Center tracks each year, and boards already walking the property for storm prep during that window can use the same visit to flag surfaces due for a wash.
A simple wash log, kept year over year, turns a one-time clean into a record that makes future decisions easier and protects the community if a dispute ever comes up.
Does soft washing use bleach? Most soft-wash solutions use a mild bleach-based agent as the active ingredient, diluted well below concentrated strength and combined with a surfactant, then rinsed at low pressure once dwell time is complete.
Will soft washing kill my landscaping? A trained crew pre-wets nearby plants, uses an appropriately diluted mix, and rinses afterward. Problems generally come from an untrained applicator overusing concentrate, not from soft washing itself.
Can pressure washing ever be used on a painted wall? Not safely at the pressure levels needed to remove staining. If a painted wall needs cleaning, soft washing is the method built for that surface.
How do I know if my roof was pressure washed instead of soft washed? Look for bald, lighter patches on shingles where granules were stripped, or cracked glaze on tile. A properly soft washed roof shows clean coloring without a rough or patchy texture.
Why did the stains come back faster after our last wash? This is the clearest sign the method stripped the surface instead of killing the growth at the root. A soft wash done correctly should outlast a pressure wash by roughly two to three times on the same coated surface.
Do pavers need soft washing? Bare, unsealed pavers generally tolerate pressure washing well. Sealed pavers should be soft washed or the sealer strips off along with the stain, leaving the pavers exposed and due for a full reseal.
Is there a best time of year to schedule a wash in Central Florida? Scheduling before peak summer rainy season gets ahead of the fastest algae growth. Waiting until late summer or fall usually means starting from a heavier growth baseline.
Before you approve a community-wide wash, ask your vendor to walk the property and identify which surfaces are flatwork and which are painted or coated. If the answer is "we pressure wash everything," that is worth a second opinion, especially on any building with painted stucco or coated breezeways.
We offer a complimentary on-site inspection and a clear, specific proposal for building and flatwork washing across Central Florida, including Orlando, Longwood, Sanford, Maitland, Casselberry, Winter Park, and Lake Mary, as part of our pressure washing services. Message us or call the office at (407) 744-9122 to get on the schedule before peak algae season.