Tile, shingle and metal roofs cleaned by soft wash at low pressure - so the algae dies at the root instead of being blasted off and coming straight back.
The dark streaks running down a Central Florida roof are not dirt and they will not wash off in the rain. They are a blue-green algae called gloeocapsa magma, and it feeds on the limestone filler in asphalt shingles. It thrives in exactly the climate we have here - hot, wet and humid most of the year.
It spreads by spores, which is why it takes hold on the shaded north side first and why once a neighbour's roof has it, yours is next. Left alone it holds moisture against the roof surface, which shortens the life of the covering and adds to what your air conditioning fights in July.
Get a Free Roof Cleaning QuoteConcrete and clay tile cleaned at low pressure, including the growth that sits in the pan of every barrel and makes a rushed job look streaky from the street.
No-pressure chemical wash, which is what shingle manufacturers ask for and what keeps the granules where they belong.
Mildew and oxidation rather than heavy algae, with the solution matched to the finish so a painted standing-seam roof is not left dulled.
The gloeocapsa magma stain everyone recognises - killed at the root, not rinsed off. More on black streaks on your roof.
Rooted growth that holds water like a sponge and grips hard enough to mark the surface. Needs dwell time and sometimes a second visit - see moss and lichen.
Roof runoff is what stains gutter faces and puts mildew on a pool cage, so most roof jobs go out with gutters or a house wash attached.
Not the way we do it. Low pressure and the right solution is what roofing manufacturers ask for - most shingle warranties are written around low-pressure cleaning, and using a pressure washer on shingles can void them. The damage people worry about comes from pressure stripping the granules, which is precisely what soft washing avoids.
A properly soft washed roof normally holds two to four years before growth is visible again. Shade and tree cover move that number more than anything else - a roof under oaks will spot sooner than one in full sun. Houses under heavy canopy are usually better off on a maintenance plan than paying for a big reset every few years.
Not if the crew wets down and covers the landscaping before anything is applied, which is standard on our jobs. Most plant damage from roof cleaning is not the chemistry - it is somebody skipping that step.
Yes. Panels change how the runoff has to be managed so it does not sheet across the array, and they are worth cleaning on their own schedule since output drops as they haze over. See dirty solar panels.
Staining on its own is not a reason to replace a roof - algae is cosmetic damage that turns into real damage over years. If tiles are cracked or shingles are curling and bald, that is a roofer's call rather than ours, and we would rather tell you than clean a roof that needs replacing.
The coloured granules on an asphalt shingle are its sunscreen. Blast them off with a pressure washer and you have taken years off the roof while making it look clean for a single season. If you find granules in the gutters after somebody cleans your roof, that is exactly what happened - see granule loss.
Tile is no safer. Concrete and clay tile look tough but crack under foot traffic and under pressure, and a cracked tile leaks long before anyone notices. Tile also holds growth in the pan of every barrel, which is why a rushed job looks fine from the driveway and streaky from the street.
Soft washing solves both. A professional solution goes on at roughly garden-hose pressure, is left to break the growth down at the root, then rinsed away. It is slower on the day and it lasts years rather than months, because regrowth starts from zero instead of from a head start.
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