Soft-Wash Roof Cleaning & Black-Streak Removal
Those black streaks aren't dirt — they're a living organism eating your shingles. We remove them with a low-pressure soft wash that kills the growth without stripping the granules that protect your roof. Text a photo for a flat-rate quote.
What causes the black streaks on your roof
The dark streaks on an asphalt roof are caused by Gloeocapsa magma, a cyanobacterium that feeds on the limestone filler in the shingles. It forms dark, melanin-pigmented colonies that protect it from UV — which is exactly what you see as the black staining. It spreads by airborne spores, which is why entire neighborhoods often streak the same way, and in West Michigan's humid climate it's active from spring through early fall.
Because the streaks run with rainwater, they trail downward from the ridge. Older roofs streak first — more of the limestone filler is exposed as shingles age. It's not cosmetic-only, either: the dark growth holds moisture against the shingle and absorbs heat, both of which work against the roof. We cover the full biology in what causes black streaks on a roof.
Why you never pressure wash a roof
Asphalt shingles are protected by a layer of mineral granules — that granule layer is the roof's UV shield and weather barrier. High-pressure water blasts those granules off (you'll see them collect in the gutters), and every pass shortens the roof's life. The Asphalt Roofing Manufacturers Association (ARMA) specifically recommends low-pressure cleaning methods for asphalt shingles, not pressure washing.
This is the situation behind the homeowner who's told they "need a new roof" because of the streaks — when in reality the shingles are fine and the staining just needs to be killed and rinsed. Pressure washing a roof can turn a cosmetic problem into an actual replacement.
How soft-wash roof cleaning works
We apply a cleaning solution at very low pressure (under ~100 PSI), let it dwell so it kills the organism at the cellular level, then rinse gently. The streaks fade as the growth dies. Some residual discoloration can take a few days and a rain or two to fully wash clear — that's normal, and it means the organism was killed rather than just scrubbed.
Landscaping safety matters more on roof jobs because the solution is stronger than a siding wash: we pre-wet and rinse all plants and grass below the roofline as standard practice on every visit.
How long results last
A soft-washed roof typically stays streak-free for three to five years, depending on tree cover, humidity, and whether neighboring roofs are seeding spores onto yours. Zinc or copper strips at the ridge can slow regrowth; we don't install them but we're happy to point you in the right direction.
Soft-Wash Roof Cleaning questions
Is soft washing safe for asphalt shingles?
Yes. Soft washing is the low-pressure method recommended by the Asphalt Roofing Manufacturers Association (ARMA) for asphalt shingles. It kills the algae without stripping the protective granules. High-pressure washing is what damages shingles.
Will the black streaks come back?
Eventually — Gloeocapsa magma spreads by airborne spores, so regrowth depends on your tree cover and neighbors' roofs. A proper soft wash usually keeps a roof streak-free for three to five years.
Do I really need my roof cleaned, or do I need a new roof?
Most streaked roofs don't need replacing — they need the organism killed and rinsed. Send us a photo and we'll tell you honestly whether a soft wash will fix it.
House Washing
Full siding soft-wash. Removes algae, mildew, dirt, and the black gunk in the corners — plant-safe, no high pressure.
Gutter Cleaning & Brightening
Hand-clean the troughs plus an exterior gutter-face wash. Don't find out they're clogged when it pours.
Full Property Exterior Cleaning
House + roof + drive + walkways + deck in one visit. One crew, one flat-rate number — the highest-ROI option.
See it for yourself. Text a photo.
Get a flat-rate quote for soft-wash roof cleaning — most come back the same afternoon, no site visit required.