If you look up and see dark streaks running down your shingles, you are not alone. Across Atlanta, GA those marks are most often caused by Gloeocapsa magma, a common blue-green organism that leaves a black residue. Left in place, it spreads from roof to roof, hurts curb appeal, and can shorten the service life of your shingles.
Here’s the good news: RoofClean LLC removes those stains the right way with a gentle soft wash designed for asphalt shingles, metal, tile, and other common roof materials. If you want a clear, lasting result, our roof cleaning service is tailored to Atlanta’s humid climate and tree cover.
Gloeocapsa magma is a type of cyanobacteria. On your roof it looks like soot or mold, but it is a living colony that thrives in warmth and moisture. It clings to the limestone fillers found in many asphalt shingles and slowly creeps downward, which is why you see that streaked pattern.
Atlanta’s weather helps it grow. Hot summers, spring pollen, and late-afternoon thunderstorms create a damp film on shaded slopes in areas like Buckhead, Decatur, Sandy Springs, and East Atlanta. North-facing planes and areas beneath tree limbs show it first. Over time the colonies darken the roof, increase heat absorption, and can hold moisture against the surface.
Many homeowners first notice the streaks from the street in places like Virginia-Highland or Brookhaven after a heavy rain. Addressing them early is simpler than waiting until the entire slope darkens.
Pressure washers are great for concrete. They are not right for shingles. High pressure can dislodge protective granules and force water under the tabs. Soft washing, by contrast, uses low pressure with a roof-safe cleaning blend that breaks up the organic growth at the root level and then rinses gently.
Our process is purpose-built for roofing materials. We apply a controlled, low-pressure treatment that targets Gloeocapsa magma and similar growths, then allow the solution to dwell for proper contact time before a final rinse. On heavier growth, some light shadowing can remain for a short time and then fade as the sun and rain finish the work.
Never allow high-pressure washing on asphalt shingles. The right method is a professional soft wash designed for roofing materials. It cleans the stains without stripping granules or voiding manufacturer guidance.
Every roof and neighborhood is a little different, from Midtown townhomes to Dunwoody ranches. That is why we start with a careful inspection. We look for shingle condition, flashing, valleys, and areas shaded by pines and oaks. Based on the slope, material, and severity, we select the correct soft-wash mix and application pattern.
Next, we protect the property. Gutters are checked, downspouts are directed, and sensitive plants are rinsed before, during, and after treatment. We use low-pressure application only. The cleaning blend targets the organic growth and loosens dark streaks without abrasion. Rinsing is gentle and thorough to reveala uniform color again.
You will see a dramatic change on most roofs the same day. Heavier colonies can lighten immediately and then continue to brighten over the next week as any remaining residue breaks down. That is normal and expected with a proper soft wash.
In our area, spring through early fall are popular times to clean because pollen and humidity peak from March through September. If trees hang over your roof or you are near a wooded lot in places like Morningside or Smyrna, you may need to clean your gutters more often.
If you are preparing to list your home or you received a note from an HOA about roof appearance, timing the service a few weeks before photos helps the results look their best.
Done the wrong way, yes. Done the right way, no. The key is controlled application, correct chemistry for organic growth, and low-pressure rinsing. We follow a method designed for modern roofing materials, and we never use high pressure on shingles.
If you hear a contractor say they will “blast it clean,” that is a red flag. Ask about their process, insurance, and how they protect landscaping and gutters. A professional soft wash is gentle on roofing but tough on stains.
Most homeowners notice the biggest change when they pull into the driveway. The roof looks newer, the siding and trim pop, and the whole home reads cleaner. Interiors can feel cooler in summer because the roof is not absorbing as much radiant heat from the sun.
On certain ceramic or metal roofs you may see a uniform sheen right away. Asphalt shingles respond quickly as well, but the darkest sections may continue to lighten in the days after service. Light tan shadowing around vents or valleys can be normal on first rinse and fade soon after.
To help your results last, keep limbs trimmed back so sunlight can reach the roof and airflow can dry the surface after storms. Avoid letting leaves pile in valleys in the fall. A simple seasonal check from the ground is enough to spot any new streaks early.
Wind, birds, and even rain splatter move tiny fragments of the organism from one roof to the next. In tight Atlanta neighborhoods, that means a dark roof across the street in West End or Kirkwood can “seed” your roof over time. Shade and moisture finish the recipe. The longer the colony sits, the faster it expands.
Cleaning removes the active growth and resets the surface. Some homeowners choose to coordinate service with next-door neighbors so the whole block looks fresh at the same time. It also helps slow re-growth in shared tree canopies.
Look for a company that specializes in soft washing and stands behind their work. Ask for proof of insurance, photos of similar roofs, and a clear description of the steps they will take on your property. Reputable pros tailor the mix to your roofing material and explain how they will safeguard plants and fixtures.
A trustworthy pro will tell you exactly what they will not do, too. That includes avoiding high pressure on shingles and keeping ladders and hoses off delicate areas. When you speak with us, we will outline a plan for your roof style and shaded areas so you know what will happen and when.
Our city’s charm comes with lots of trees. Pollen and shade from loblolly pines, oaks, and sweetgums are common across Chastain Park, Grant Park, and Old Fourth Ward. That shade is great for porches, but it also creates cool, damp roof sections where algae thrives after summer storms.
If you live near a creek or low spot where dew lingers, expect north slopes to show streaks first. Homes with light-colored shingles may notice the contrast sooner than those with dark roofs. Either way, a proper soft wash restores an even tone without wear.
From the first call to the final rinse, we keep it simple. We confirm the roof type, check surrounding landscaping, and schedule when the weather suits. Crews arrive with the right gear, protect your property, and walk you through the before-and-after. Your driveway stays open, pets stay safe, and we leave the site tidy.
Curious what your home might look like without the streaks? See how clean a roof can look after a professional soft wash by booking our professional roof cleaning. You will get a clear, written plan for your roof and an appointment that fits your week.
Your roof is one of the largest surfaces on your property. When it is clean, the entire home looks brighter. If you are searching for roof cleaning in Atlanta, you are in the right place. Call RoofClean LLC at 770-727-8899 and let’s put an end to those black streaks for good.
Ready when you are. We serve homeowners across the Atlanta area with expert roof cleaning and treat every roof with the same care we would use on our own homes.
Black streaks on your roof are more than just an eyesore. They are often caused by a type of algae called gloeocapsa magma, which thrives in warm, humid climates and feeds on the limestone filler in shingles. Left untreated, these streaks can darken and spread, leading […]
If you look up and see dark streaks running down your shingles, you are not alone. Across Atlanta, GA those marks are most often caused by Gloeocapsa magma, a common blue-green organism that leaves a black residue. Left in place, it spreads from roof to roof, […]
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