Algae Streaking
The one nearly everybody has
The dark vertical streaking on asphalt shingles is Gloeocapsa magma, a blue-green algae. It is cosmetic rather than structural, it spreads, and it is worst on the slope that gets least sun.
Soft Wash Roof Cleaning in Central Kentucky
The black streaks on a Central Kentucky roof are not dirt and they are not stains. They are a living organism, and the way most people assume you remove it is the way you destroy a roof.
- Crown’s published range: $250 to $600+, before anyone visits
- The streaks are algae, a specific organism, not dirt
- ARMA: never pressure wash an asphalt roof. We do not.
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Never pressure wash an asphalt roof, and that is not our opinion
This is the single most useful thing on this page, it is free, and it holds whether you hire us or anyone else. It comes from the association of the companies that manufacture the shingles, which makes it about as disinterested as advice gets.
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Pounds of pressure the asphalt roofing industry says belongs on a shingle roof
Asphalt Roofing Manufacturers Association, Algae & Moss Prevention and Cleaning for Asphalt Roofing Systems, the trade body for the companies that make the shingles
First, what the streaks actually are. ARMA states that “the black discoloration and streaks visible on many roofs across the United States and Canada are actually algae”, specifically “gloeocapsa magma or blue green algae.” Not dirt, not soot, not age. A living organism, which is why it comes back and why scrubbing is the wrong instinct.
Then the part that matters most. ARMA’s wording is not hedged: “Never use a pressure washer to clean an asphalt shingle roof as this will cause granule loss and very likely premature failure of the roof system.” The granules are the shingle’s UV protection. Strip them and you have not cleaned the roof, you have shortened its life, and the roof will look excellent on the day it happens.
What they recommend instead. ARMA describes “a 50:50 mix of laundry strength liquid chlorine bleach and water,” applied with a sprayer, left “to dwell on the roof surface for 15 to 20 minutes, and then rinse thoroughly with low pressure water.” That is soft washing. The chemistry does the work and the water only carries it off.
Why this is worth knowing before you shop on price. A pressure wash is faster, so it is cheaper to sell. The damage is invisible from the ground and shows up years later as a roof that fails early. If a quote for your roof does not use the words soft wash or low pressure, ask what pressure they intend to use, and compare the answer against the sentence above.
ARMA also notes that zinc or copper strips, a common prevention suggestion, require “applying the strips with exposed nails (which can cause leaks over time) or breaking the sealant bond (which may eventually result in wind damage).” This is a plain-English summary of published material, not roofing advice, and your shingle manufacturer’s own guidance governs your warranty.
What soft wash roof cleaning costs
Published ranges, because almost nobody in this market will give you a number before a site visit. You get a firm figure before anything starts and only pay for work completed.
A typical roof soft wash
$250 to $600+
Crown’s published range for this service. Pitch and access move this one more than roof area does.
🔶 PLACEHOLDER: steep, very high, or lichen needing a second treatment
Crown to supply
The site publishes one band and nothing above it. The axis here is access and whether the growth needs revisiting, so that is what any figure past the band should be built on.
- Pitch
- A walkable pitch and a steep one are different jobs. Steep roofs are treated from ladders and poles, which is slower and needs more setup.
- Access
- Two-story, tight side access, conservatories, or beds and hardscape under the eaves all change how long the setup takes before anything is applied.
- Which growth it is
- Algae is the quickest. Moss is slower. Lichen is the one that occasionally needs a second visit, and we say so at quote rather than after.
- What is underneath
- Gutters, planting and anything living below the eaves gets pre-wetted and rinsed. That protection is part of the job, not an extra.
The $250 to $600+ figure is Crown’s own published roof soft wash range, carried from the pressure washing hub unchanged. It is the highest-value surface on that page, and it is also the one where the cheapest quote is most likely to be the one that costs you a roof; see the section above before you compare on price alone.
What comes off a roof
Different things grow on a Central Kentucky roof, and they do not all come off the same way. Only one of them is more than cosmetic.
Moss
The one that is not just cosmetic
Moss holds water against the shingle and lifts the edges as it grows under them. Left long enough it stops being an appearance problem. It also comes off more slowly than algae, because it has to die first.
Lichen
The stubborn one, and honestly the hardest
Lichen bonds to the granule surface rather than sitting on it. It is the one growth that can need a second treatment, and we would rather say that up front than surprise you with it.
What It Is Not
What you are actually buying
This is not a repair and it is not a coating. Cleaning removes what is growing on the roof. If a shingle is already failing, cleaning will reveal that rather than fix it, and we will tell you if that is what we can see.
How soft wash roof cleaning works
Four steps, no obligation, and you only pay for work completed.
Free quote from photos
Send photos of the worst of it and the whole elevation. A number is guaranteed within two hours during business hours, no site visit needed for most of these.
Everything below the eaves is protected
Gutters, downspouts, planting and hardscape are pre-wetted and covered before any solution is mixed. This is the longest part of the setup and it is where corners get cut.
Solution applied at low pressure, then left to work
The solution is applied with a sprayer and given time to dwell. Nothing is scrubbed and nothing is forced. On moss and lichen the result keeps developing for days after we leave.
Low-pressure rinse and a walk-round
Rinsed at low pressure, gutters flushed, and everything below the eaves rinsed again. If a second treatment is going to be needed we tell you that day rather than waiting for you to ring.
What Our Customers Say
Very quick from contact to in home to remove some flooring. Once on site they got straight to work and did an outstanding job! Very reasonable price for the work done. Will continue to use them for all future needs.
Very hard workers that cleaned out a whole house that was trashed and filthy. Very polite and considered. Would definitely recommend this company!
Extremely helpful and nice, was hired for land clearing and site preparation they removed pesky honey suckle. Definitely going to hire them in the future.
Soft Wash Roof Cleaning across Central Kentucky
Based in Lexington, working the counties around it. Send the address rather than the town: access decides more than distance on most of these jobs.
The questions we get asked
Answered properly rather than deflected to a phone call.
Not sure it’s this job?
Send two or three photos. If it is really a different service we will say so and point you at the right page. It costs you nothing either way.
Send photos insteadCan you pressure wash a roof?
You can, and you should not. The Asphalt Roofing Manufacturers Association states plainly: “Never use a pressure washer to clean an asphalt shingle roof as this will cause granule loss and very likely premature failure of the roof system.” The granules are the shingle’s UV protection. This is why the service is called soft washing and why we will not quote a roof any other way.
What are the black streaks on my roof?
Algae. ARMA identifies it as “gloeocapsa magma or blue green algae” and notes that what looks like discoloration is actually a living growth. It is cosmetic rather than structural, it spreads across the slope over time, and it is always worst on the side that gets the least sun, which in Central Kentucky is usually the north face.
Will cleaning void my roof warranty?
Soft washing is the method the manufacturers’ own association describes, so it is the conservative choice rather than the risky one. That said, your warranty is a contract with your shingle manufacturer and not with us, and its terms govern. If your roof is under an active manufacturer warranty, it is worth five minutes reading what it says about cleaning before you book anyone.
How long does it stay clean?
🔶 PLACEHOLDER: Crown to supply from its own completed jobs. We are not going to publish a number we cannot stand behind. Algae is airborne and re-establishes at a rate that depends on shade, tree cover and which way the slope faces, and a national average would not describe your roof.
Is moss worse than the black streaking?
Yes, in the sense that it is the one that stops being cosmetic. Moss holds water against the shingle and grows under the edges, lifting them. Algae streaking is an appearance problem. Moss left long enough is not.
Do you do the gutters while you are up there?
The gutters get flushed as part of the rinse, because everything we take off the roof ends up in them. Clearing packed debris out of gutters is a separate job: say so when you send photos and we will price both.
Get a price on your roof
Send a photo from the street and one from the worst slope, and say how many stories. A firm number comes back within two hours, guaranteed, and whatever you decide, do not let anyone pressure wash it.
- Quotes guaranteed within 2 hours, 8am to 6pm, Monday to Saturday
- Free and no obligation. You only pay for completed work
- View all pressure washing services