Stain & Growth Identifier in Island Park, NY

What it is: Usually roof algae, most often a type called Gloeocapsa magma. It looks like dirt or soot but is a living growth.

Why it happens: The algae spreads by wind and feeds on the limestone filler in many asphalt shingles. It grows fastest on shaded, slow-drying slopes, and the streaks follow the path rain takes down the roof.

Safe steps you can take:

• Trim branches that shade the roof so it dries faster after rain
• Keep gutters clear so water drains off the roof edge
• Look from the ground or a ladder at the eaves rather than walking on the roof

What not to do:

• Don't pressure wash shingles: it strips the protective granules and shortens the roof's life
• Don't walk on a wet or treated roof; it is extremely slippery
• Don't let strong cleaning mixes run onto plants without pre-wetting and rinsing them

How a pro removes it: A soft wash: a diluted cleaning solution applied at very low pressure that kills the algae, followed by a gentle rinse. Plants and the area below are protected and rinsed. See the service

What it is: Algae, often mixed with mildew and dirt. It is most common on north-facing and shaded walls.

Why it happens: Walls that stay damp from shade, sprinklers, nearby plants or overflowing gutters give algae the moisture it needs. Pollen and dust give it something to hold on to.

Safe steps you can take:

• Spot-clean small areas with a soft brush and a mild detergent, then rinse with a garden hose
• Point sprinklers away from the house
• Trim shrubs back so walls can dry

What not to do:

• Don't aim a pressure washer up under siding laps; it drives water behind the panels
• Don't mix cleaning products, especially bleach with ammonia or acids
• Don't scrub hard enough to dull the finish

How a pro removes it: A house wash (soft wash): a low-pressure cleaning solution that kills the growth at the root, given time to work, then rinsed from the top down. See the service

What it is: Often artillery fungus, a fungus that grows in mulch and shoots sticky black spore masses up to several feet onto nearby surfaces. Larger, fuzzy black patches are more likely mildew.

Why it happens: Artillery fungus thrives in damp wood mulch near the house, usually on the shaded side. Mildew grows where walls stay damp.

Safe steps you can take:

• Check the mulch bed below: fine, wet wood mulch is the usual source
• Refresh or replace old mulch, or use stone or another material near the walls
• Try removing a few spots gently with a plastic scraper and mild detergent

What not to do:

• Don't blast spots with high pressure; on vinyl and painted surfaces it damages the finish before the spots come off
• Don't use abrasive pads on vinyl or car paint

How a pro removes it: Mildew comes off with a soft wash. Artillery fungus spots are stuck on very firmly and may not come off completely; a pro can test what works on your surface and tell you honestly what to expect. See the service

What it is: Iron stains. On walls and walks near sprinklers they usually come from iron in well or irrigation water; scattered spots on driveways and walks often come from fertilizer granules; rings come from metal furniture and planters.

Why it happens: Iron in water or fertilizer oxidizes when it dries on the surface. The stains keep coming back as long as the source is there.

Safe steps you can take:

• Find the source first: adjust sprinkler heads, sweep fertilizer granules off hard surfaces right after spreading, put pads under metal furniture
• Try a rust remover made for your surface, following the label and testing a small area

What not to do:

• Don't use bleach on rust; it doesn't remove it
• Don't use muriatic or other strong acids yourself; they etch concrete and can burn skin and plants
• Don't expect pressure alone to lift rust

How a pro removes it: A dedicated rust treatment matched to the surface, applied and rinsed carefully. If a well or irrigation system is the source, an iron filter or sprinkler changes keep it from returning. See the service

What it is: Efflorescence: water-soluble mineral salts left on the surface when moisture moves through masonry and evaporates.

Why it happens: Water from rain, the ground, sprinklers or a leak carries salts from inside the brick, mortar or concrete to the surface. It is common on new masonry and after wet seasons.

Safe steps you can take:

• Brush it off with a stiff dry brush when the surface is completely dry
• Look for the moisture source: downspouts, sprinklers, poor drainage or leaks
• Give new masonry time; efflorescence often fades as it cures

What not to do:

• Don't pressure wash it with plain water; that can dissolve the salts and bring more to the surface
• Don't use strong acid without knowing the surface, pre-wetting it and neutralizing afterward

How a pro removes it: A masonry-safe efflorescence cleaner applied to a pre-wet surface and rinsed, plus advice on the moisture source. A breathable sealer may be suggested once the surface is clean and dry. See the service

What it is: Weathering: the surface wood fibers have been broken down by sunlight and water and turned silver-gray, often with mildew mixed in.

Why it happens: UV light breaks down lignin, the natural glue in the wood's surface. Without a finish, the loose gray fibers wash away slowly and the wood gets rougher.

Safe steps you can take:

• Sweep off leaves and debris, especially between boards
• Test a small area with a wood cleaner made for decks and a soft brush
• Plan a finish: unprotected wood keeps graying

What not to do:

• Don't use a narrow tip or high pressure; it gouges boards and leaves fuzzy, raised grain
• Don't stain over gray, dirty wood; the stain won't soak in or last

How a pro removes it: A wood cleaner and low-pressure rinse to remove the gray fibers, a brightener to restore the color, time to dry, then a stain or sealer. See the service

What it is: Motor oil, transmission fluid or other vehicle fluids soaked into the concrete or asphalt.

Why it happens: Concrete is porous, so oil wicks below the surface. The longer it sits, the deeper it goes and the harder it is to lift.

Safe steps you can take:

• Cover fresh spills right away with cat litter or another absorbent, then sweep it up
• Scrub with a degreaser made for concrete and a stiff brush
• Fix the leak, or park over a drip pan until it's fixed

What not to do:

• Don't use gasoline or solvents to clean oil; they are a fire hazard and spread the stain
• Don't rinse oily water into the street or storm drain
• Don't use degreasers made for concrete on asphalt; they can soften it

How a pro removes it: A degreaser, hot water and a surface cleaner lift most fresh and moderate stains. Old, deep stains usually lighten a lot but may not disappear completely. See the service

What it is: Iron-rich soil splashed onto the bottom of walls, foundations and steps.

Why it happens: Rain and sprinklers hit bare soil and splash it onto nearby surfaces. Red clay contains iron oxides that stain like rust once they dry in.

Safe steps you can take:

• Rinse fresh mud off with a garden hose before it dries in
• Cover bare soil next to the house with mulch, stone or plants to cut down on splashback
• Make sure gutters aren't overflowing onto the soil below

What not to do:

• Don't scrub dried clay hard into the siding texture
• Don't try high pressure; it can push the stain deeper into textured surfaces

How a pro removes it: A house wash removes loose soil, and set-in clay staining needs a specialty cleaner made for iron-based stains, tested on a small area first. See the service

What it is: Hard-water spots: calcium, magnesium and other minerals left behind when sprinkler or well water evaporates.

Why it happens: Sprinklers that hit the same surface every day build up layer after layer of minerals. They are common with well water and in areas with hard municipal water.

Safe steps you can take:

• Adjust sprinkler heads so they don't spray windows, walls or fences
• Try a cleaner made for mineral deposits on a small area first, then rinse well

What not to do:

• Don't use abrasive pads or steel wool on glass; they scratch
• Don't use acidic cleaners on natural stone such as limestone or travertine

How a pro removes it: A mineral-deposit cleaner suited to the surface, then a thorough rinse. Old, heavy buildup on glass can etch the surface, and etching can't be cleaned away. See the service

What it is: Pollen, often mixed with dust. It shows up as a yellow-green film on siding, windows, cars, screens and outdoor furniture.

Why it happens: Trees release large amounts of pollen in spring. On damp surfaces it sticks and becomes food for mildew and algae later in the year.

Safe steps you can take:

• Rinse it off with a garden hose once the heaviest pollen has fallen
• Close windows and run screens through a gentle rinse

What not to do:

• Don't pay for a full house wash in the middle of peak pollen; it may be coated again within days
• Don't dry-wipe screens and glass; pollen and grit scratch

How a pro removes it: A house wash after the main pollen season, often combined with window and screen cleaning. See the service

What it is: Rubber and plasticizers from tires, sometimes called hot tire pickup on sealed or coated garage floors.

Why it happens: Warm tires leave rubber residue, and on some sealers and coatings the plasticizers soften and stain the finish.

Safe steps you can take:

• Scrub light marks with a degreaser or a cleaner made for tire marks and a stiff brush
• Ask your coating installer which cleaners are safe for the finish

What not to do:

• Don't use solvents on sealed or coated floors without checking the coating's instructions
• Don't use high pressure on epoxy or painted floors; it can lift weak coatings

How a pro removes it: A degreaser and hot-water wash for bare concrete; on coated floors, a cleaner the coating can handle. Stains that have discolored a sealer may need the sealer redone. See the service

What it is: Moss is soft and green; lichen is a crusty gray-green or orange growth that clings tightly to shingles, tile, stone and pavers.

Why it happens: Both grow in shade and on surfaces that stay damp. Moss holds water against the roof, which can lift shingles and speed up wear.

Safe steps you can take:

• Brush loose moss off gently from a ladder with a soft brush, working down the slope
• Trim back trees that shade the roof
• Zinc or copper strips near the ridge are a common way to slow regrowth on roofs

What not to do:

• Don't scrape or pressure wash moss off shingles; it tears off granules and can lift shingles
• Don't walk on a mossy roof; it's slick

How a pro removes it: A soft wash treatment that kills the growth. Dead lichen often takes weeks to loosen and wash away with rain, and heavy growth may need a second application. See the service

What it is: "Tiger stripes": dark streaks bonded to the gutter's painted face where water spills over the edge.

Why it happens: Runoff from the roof carries dirt and residue over the lip of the gutter. As it dries, the grime bonds to the paint and normal washing won't remove it.

Safe steps you can take:

• Keep gutters clean so water flows to the downspouts instead of spilling over
• Try a gutter cleaner and a soft cloth on a small section from a stable ladder

What not to do:

• Don't use abrasive pads or strong solvents; they remove the gutter paint along with the stripes
• Don't lean a ladder against the gutter itself

How a pro removes it: Gutter brightening: a specialty cleaner and hand detailing that removes the bonded stripes without harming the paint, usually done with a house wash. See the service

What it is: Flattened chewing gum that has been ground into the concrete and turned black with dirt.

Why it happens: Gum is sticky, and foot traffic presses it into the surface. Busy entrances, bus stops and storefronts collect it fastest.

Safe steps you can take:

• Harden fresh gum with ice and scrape it off with a plastic scraper
• Try a gum remover made for concrete on a few spots

What not to do:

• Don't hold a narrow pressure tip on a gum spot; it etches a mark into the concrete
• Don't use flammable solvents

How a pro removes it: Hot water or steam with a pressure washer softens and removes gum, often together with a full flatwork cleaning for busy entrances. See the service

What it is: Spray paint, marker or other paint on walls, fences, signs or pavement.

Why it happens: Fresh graffiti has not fully bonded to the surface, which is why it comes off more easily in the first days. Many cities encourage quick removal because it tends to discourage repeat tagging.

Safe steps you can take:

• Take photos first if you plan to report it to the police or your city
• Check whether your city has a graffiti removal program
• Test a graffiti remover made for your surface on a small, hidden spot

What not to do:

• Don't blast painted or soft surfaces with high pressure; it often leaves a 'ghost' outline worse than the paint
• Don't paint over it with a color that doesn't match unless that is the plan for the whole wall

How a pro removes it: A remover matched to the paint and the surface, low-to-moderate pressure, and hot water where it helps. Porous brick and stone may need more than one pass. See the service

What it is: Tannin stains from wet leaves, berries, acorns and seed pods left on concrete, pavers and pool decks.

Why it happens: Tannins and natural dyes leach out of wet plant debris and soak into the surface. They often fade in sun over time.

Safe steps you can take:

• Sweep or blow leaves off regularly, especially before rain
• Try an oxygen-based cleaner and a stiff brush, then rinse

What not to do:

• Don't use bleach on colored concrete or pavers without testing
• Don't leave wet leaf piles on the surface over winter

How a pro removes it: A pre-treatment and pressure wash with a surface cleaner, with stain-specific cleaners for stubborn spots. See the service

What it is: Mildew, mold or algae on the boards, usually worst on the shaded side and near the ground.

Why it happens: Fences in shade, near sprinklers or against plants stay damp. Bare or worn finishes let the growth into the wood grain.

Safe steps you can take:

• Trim plants away from the fence and adjust sprinklers
• Clean a small section with a wood cleaner and a soft brush

What not to do:

• Don't use high pressure or a narrow tip on wood; it splinters boards
• Don't stain over mildew; it grows back through the finish

How a pro removes it: A low-pressure wash with a wood cleaner, and a brightener if the fence will be stained or sealed. See the service