The dark streaks running down your roof are algae colonies feeding on the limestone in your shingles — ugly now, corrosive over years. Soft-wash removal clears them without harming a granule.
Before we price Algae Removal Black Streaks Erased, we look at the decking, the valleys and the ridge vent — the details that decide how long the work holds. You get a photographed assessment and a written scope with no obligation, and if the cause traces to a storm we document it for your carrier. Licensed and insured in Ohio, Pennsylvania and New York.
Water damage gets worse every hour — call nowRoof Algae Removal — priced in writing before we start, no obligation.
Those streaks are Gleocapsa magma, a blue-green algae that feeds on limestone filler in asphalt shingles. It spreads downslope with rainwater, which is why the staining runs vertically, and appears first on north-facing slopes that stay damp longest. It is primarily cosmetic, but it darkens the roof surface and holds heat. Related: roof moss removal and roof cleaning – soft-wash.
Gloeocapsa magma is an airborne algae that colonizes shingles and feeds on the crushed limestone filler inside them — the black streaking is millions of organisms with UV-protective dark sheaths, always worst on north slopes and shaded runs. Beyond curb appeal, mature colonies hold moisture and slowly degrade the surface. Soft-wash treatment kills the colony and the streaks fade with the weather — no pressure washing, which strips granules and voids warranties.
Algae re-seeds from the air, so bare shingles in shade will streak again in years. Modern shingles fight back with copper-infused granules — algae-resistant lines carry long stain warranties — and zinc or copper strips at the ridge wash trace metal down the slope with every rain. If your roof is due for replacement anyway, choosing an algae-resistant shingle makes this a solved problem.
Both, slowly — the colonies hold moisture and consume filler minerals. Ugly arrives years before damage, which is why treatment now is cheap insurance.
Algae favors slopes with less direct sun and slower drying — typically north-facing and tree-shaded runs. The streak-free south slope is getting free UV treatment daily.
Homebrew mixes at wrong strengths kill lawns, corrode gutters and streak siding — and ladders plus wet roofs end badly. Soft washing exists because the chemistry and the safety both matter.
Gloeocapsa magma algae feeding on the limestone filler in shingles — an organism, not dirt, which is why washing never fixes it.
Copper-infused granule lines carry long stain warranties and genuinely resist recolonization — the permanent fix if a replacement is in your future anyway.
Correct soft-wash dilutions are shingle-safe; homebrew strengths kill lawns, corrode metal and void warranties. The chemistry ratios are the whole job.
Typically several years before recolonization shows — shaded north slopes recolonize fastest, and ridge metals stretch the interval.
The algae lives outside and isn’t a health hazard indoors — the cost is curb appeal now and slow shingle degradation over years.
The exterior works as one assembly — these are the pieces that connect to this one.
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Learn more →Algae Removal is available across our licensed service territory in Ohio, Pennsylvania and New York. Find your city below, or call (330) 918-1018.
Free photo quote — most streak jobs treated in one visit.
Takes about 20 seconds.
