Roof cleaning in Sarasota should always be done by soft wash, never high pressure. The black streaks on Florida roofs are Gloeocapsa magma, a hardy algae, not dirt. A sodium hypochlorite based solution with surfactant is applied at low pressure, allowed to dwell so it kills the algae at the root, then rinsed. Call 941-266-5284.
If your roof has dark streaks running down from the ridge, you are not looking at dirt and you are not looking at a stain that will rinse off. You are looking at a living colony. It grows, it spreads, and every year it covers a little more of the roof than it did the year before.
Sarasota Paver Sealing Pros cleans tile and shingle roofs across Sarasota, Bradenton, Venice and Lakewood Ranch using soft wash only. No high pressure touches your roof. This page explains what is actually growing up there, what kills it, and why the method matters more on a roof than on any other surface at your property.
What are the black streaks on my Florida roof?
They are almost always Gloeocapsa magma, a cyanobacteria that behaves like algae and thrives in warm, humid climates. It feeds on moisture and on the limestone filler used in asphalt shingles, which is why it is so common on shingle roofs and why it tends to run downward in streaks. It spreads by airborne spores, which is why one house on a street getting it is often followed by the neighbors.
The organism protects itself with a dark pigmented sheath, and that sheath is what you see as black staining. It is a survival adaptation against UV. It also means the discoloration is structural to the organism, not a film sitting on top, which is why scrubbing and rinsing does not resolve it.
You may also have lichen and moss, particularly on the shaded north face and under tree cover. Lichen is the more stubborn of the two because it anchors into the surface with root like structures. Moss holds moisture against the roof, which is the real problem, not just the appearance.
| Growth | How to recognize it | Where it starts | Response to soft wash |
|---|---|---|---|
| Gloeocapsa magma (black algae) | Dark streaks running downslope from the ridge | Anywhere, worst on shingle and shaded slopes | Lifts during the wash, results visible same day |
| Lichen | Crusty gray or green patches, often circular | North slopes and under tree canopy | Killed during the wash, releases over several weeks |
| Moss | Raised green cushions, holds water | Valleys, north slopes, under overhanging limbs | Dies and weathers off, valleys may need a second look |
| Mildew and general mold | Diffuse gray or black film, no clear pattern | Damp shaded areas and low slope sections | Removed during the wash |
| Organic debris (leaves, palm litter) | Loose accumulation in valleys and gutters | Under trees, in valleys and roof gutters | Cleared before washing, not a chemical issue |
Why should a roof never be pressure washed?
On an asphalt shingle roof, high pressure strips the ceramic granules off the surface. Those granules are the shingle's UV protection and its wear layer. Once they are gone the asphalt underneath is exposed to Florida sun and the shingle ages quickly. You often cannot see the damage from the ground on the day it happens. You see it two or three years later as premature failure.
On barrel tile and flat concrete tile, high pressure cracks and chips tile, and worse, it drives water sideways under the tile and into the underlayment. The underlayment is what actually keeps water out of your house. Tile is a shell over it. Forcing water under that shell is how a cleaning turns into a leak.
There is also the simple matter of a person walking a wet roof with a pressure wand. Tile roofs are walked in specific places for a reason. The less time and force applied up there, the better the outcome.
How does soft washing actually work?
Soft washing is a chemical process delivered at low pressure, roughly the force of a garden hose. The cleaning solution is sodium hypochlorite based, mixed to a strength appropriate to the roof and the severity of growth, with a surfactant added.
The surfactant matters more than most homeowners realize. It reduces surface tension so the solution clings to a sloped roof instead of running straight off, and it lets the mix penetrate the algae's protective sheath rather than beading on top of it. Without surfactant you are mostly rinsing chemical into the gutters.
Then comes dwell time. The solution has to sit long enough to kill the organism at the root. Rushing this step is the most common mistake, because a roof will often look better before the algae is actually dead, and it comes back within months. After dwell, the roof is rinsed at low pressure and the dead material continues to weather off over the following weeks.
What we do before, during and after a soft wash roof cleaning
- Walk the property and identify plants, pool, screens and anything needing protection
- Clear loose debris from valleys and gutters so solution reaches the surface
- Pre-wet all landscaping and keep it wet for the duration of the job
- Mix solution strength to the roof type and the severity of the growth
- Apply at low pressure with surfactant so the mix clings and penetrates
- Allow full dwell time rather than rinsing early for a fast visual result
- Rinse at low pressure and flush gutters and downspouts
- Rinse landscaping again and walk the property with you before we leave
Will my roof look clean immediately?
Mostly, yes. Black algae staining generally lifts during the wash and the difference is dramatic the same day. What does not always finish immediately is lichen. Lichen anchors into the surface and often needs the treatment plus several weeks of sun and rain to fully release and wash away.
We tell homeowners this before we start so nobody is surprised. A roof that still shows faint lichen shadows a week after cleaning is behaving normally. The organism is dead. What is left is the residue working loose.
Is soft washing safe for my landscaping, gutters and pool?
Landscaping is the main thing to manage, and it is entirely manageable. Plants are pre-wet before any solution goes up, kept wet through the job, and rinsed thoroughly afterward. Diluted solution on wet foliage that gets rinsed is very different from concentrated solution landing on dry leaves.
Gutters and downspouts are rinsed as part of the process, since runoff naturally travels there. Pools and lanais near the work get covered or protected depending on layout. Windows and doors on the work side should stay closed. We walk the property before starting and identify anything that needs protection rather than discovering it partway through.
How often does a Sarasota roof need cleaning?
Exposure decides it. A roof in full sun with airflow on all sides resists growth far longer than a roof shaded by live oaks with limbs hanging over the ridge. North facing slopes always grow first because they dry slowest, which is the same reason the shaded side of a lanai is always the worst side.
The honest guidance is to watch the roof rather than the calendar. When faint streaking starts to reappear on the shaded slope, that is the time. Cleaning at that point is a lighter job than waiting until the growth has covered the field. Trimming back overhanging limbs buys you real time between cleanings, more than any product will.
Does roof cleaning need to happen before roof sealing?
Always. Sealing a roof that still has living algae in it locks the growth under the coating. A sealer is not a disinfectant and it will not kill what is underneath it. You end up with dead and living material sealed against the tile, and removing it later means removing the coating too.
If sealing is the goal, cleaning is step one and it is included in the work rather than sold as an extra. The roof also has to be fully dry before sealer is applied, so the two steps are usually separate visits.
