The dark stripes running down North Carolina shingles are a living organism, not dirt. Here is what it is doing to the roof, and why the fix is a chemical one rather than a strong one.
Gloeocapsa magma. It is a blue-green algae, it travels on the wind, and it lands on every roof in the Triangle and Johnston County. What lets it take hold is the shingle itself. Asphalt shingles are made with limestone filler, and that filler is food. Once a colony establishes on the north side or under a tree line, it spreads, and the dark pigment it produces is the streak you are looking at.
It starts at the top because that is where the water starts. Every rain carries spores down the slope, which is why the stripes run vertically from the ridge and why the shaded elevation always goes first.
Humidity is why this is a Southeast problem. A roof in Arizona does not do this. A roof in Clayton does, and a roof in Clayton under pines does it faster.
Both, in that order. The look goes first and it is not subtle. A streaked roof takes years off the apparent age of a house, and it is the first thing a buyer photographs and the first thing an appraiser notes.
The damage is slower. The colony holds moisture against the shingle, and it loosens the granules that shed UV and rain. Granule loss is how a shingle ages. There is also a heat cost, because dark streaks absorb what the reflective surface was supposed to send back, which your air conditioner then pays for through a Carolina August.
If moss is growing alongside the algae, treat it sooner. Moss lifts shingle edges and holds standing water underneath, which is a leak forming rather than a stain.
A shingle is asphalt with a layer of ceramic granules bonded to the top. Those granules are the roof. They take the UV, they take the rain, and when they are gone the mat underneath is exposed and the clock runs fast.
Pressure strips granules. It does it even at settings that feel gentle, and the evidence washes into the gutter where you never see it. Two other things happen at the same time: water gets driven up under the shingle courses, which is how a wash becomes a ceiling stain, and the shingle warranty ends. Every major manufacturer says the same thing, and so does the industry body they all follow. Low pressure chemical cleaning, nothing else.
Beds, shrubs, and anything downslope get soaked before a drop of solution goes on the roof, and rinsed again after. This step is not optional and it is where careless crews kill landscaping.
A cleaning solution goes on at roughly garden hose pressure. Nothing is blasted, nothing is scrubbed, and nobody drags equipment across the shingles.
The solution kills the organism where it sits. The color change starts while we are standing there. What it does not do is scrub, because scrubbing is the thing that costs you granules.
We rinse down. Some residue continues to lift over the following rains, which is normal and is the difference between a roof that stays clean for years and one that greens up again by fall.
We wash roofs across Clayton, Garner, Smithfield, and every town on our list. If you want to see the condition up close before you decide anything, our free drone inspection flies the roofline and shows you the footage on a screen.
“The black streaks on our roof were embarrassing. Gone in one afternoon and the shingles were not touched.”
“Did the roof and the gutters in one visit and showed me photos of everything I could not see from the ground.”
“Same-day service and the whole property looks better. Will use them every year.”
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Read the guide →CommercialWhat property managers and owners across Wake County should actually be budgeting for, how often each surface needs attention, and why the after-hours question decides the whole thing.
Read the guide →ConcreteRed clay is not dirt sitting on your driveway. It is iron oxide that has soaked into the pores, which is why rinsing does nothing and why the fix is chemical.
Read the guide →We fly the roofline and show you the footage on the spot. You see your own gutters, joints, and downspouts on the screen instead of taking our word for it. It costs nothing and you are not committing to the cleaning.
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