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HomeExclusiveWhat Are The Black Stains On My Roof

What Are The Black Stains On My Roof

How To Remove Black Roof Stains

Roof Cleaning – Remove Black Stains on Roof

Our home is 10 years old and the asphalt roof shingles are starting to stain badly on the north exposure. Is there something that we can use to clean off the staining and treat the shingles to prevent further staining?-Tim

Hi Tim,

Your stains are probably caused by the airborne spores of a blue-green algae known as Gloeocapsa Magma, which is often mistaken for mold or mildew. While doing little harm to your shingles, the black streaks caused by the algae are unsightly.

Algae can be killed and the stains removed using chemical cleaners, though they usually return over time. Use a cleaner specially made for killing algae, or by spraying a mixture of one part bleach to four parts water with TSP or other detergent added in a garden pump-up sprayer. Allow the bleach to remain on for 15 to 20 minutes, then rinse it off with a hose.

Note that bleach may kill or damage plants, so wet down or cover any shrubs or flowers that will come in contact before starting. Repeated use of harsh chemicals or pressure washing can damage or shorten the life of your shingles.

Once the roof is clean, consider installing strips of zinc or copperwhich are toxic to algaealong your roof below the ridge. Molecules of the metal will then wash down the roof each time it rains to keep new algae from forming. A better solution is to specify algae resistant shingles, which have copper granules embedded in them, the next time you have your roof replaced.

Good luck with your project,

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Make Your Shingles Last Longer

Roof stains are a common roof problem. Black streaks on the north- and west-facing and shaded areas of your asphalt-shingled roof can really wreck the appearance of your home. The roof streaks look like mold, but theyre actually algae colonies that form in your shingles and feed on moisture and the limestone filler agents in the shingles.

Using shingles that have been treated with algicide keeps the growth at bay for about 10 years . But once the algicide wears off, your roof hosts an all-you-can-eat buffet for the neighborhood algae spores. So it pays to clean your shingles as soon as you spot algae growth.

How Can Algae Affect Your Familys Health

Besides algae being slippery, it produces elevated toxins. These toxins take the form of airborne droplets that you can inhale and become sick from. Algae can cause symptoms such as vomiting, diarrhea, eye irritation, sore throat or headaches. Symptoms generally begin hours to a couple of days after exposure.

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Are Certain Roofing Materials More Prone To Algae

Algae are most likely to grow in certain environments. They prefer shaded, moist, humid areas, and they prefer to grow somewhere they can get nourishment. You are more likely to find algae growth on wood shingles and asphalt shingles, which is one reason many homeowners opt to go with metal roofs for their homes.

Black streaks on asphalt shingle roofs are the most common, perhaps due to how common this type of roofing is and also how great a place it is for algae to thrive.

If you have an asphalt shingle roof on your home, be sure you check it regularly for any signs of algae growth to help prevent premature aging.

Black Soot Stains On Roof Surfaces Around & Below Chimneys

Why Does My Roof Have Black Streaky Looking Stains?

Soot from fireplace flues washing down onto the roof – characterized by staining appearing below and in line with the chimney, as Roger Hankey is demonstrating above.

See CHMNEY-CAUSED ROOF STAINS for the full article on this topic as well as some important fire and flue gas safety warnings.

The photograph of a soot-stained roof top was provided courtesy of Roger Hankey a Minnesota home inspector. Thanks again Roger.

Continue reading at BLACK or GREEN ALGAE STAINS on ROOFS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

  • TEST LABS – ROOF SHINGLE
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    BLACK ROOF STAIN CAUSES at InspectApedia.com – online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

    Or see this

    INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ROOFING

    Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

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    What Causes Black Streaks On My Roof

    Taking care of your roof and keeping it clean are all necessary parts to roof maintenance. The best way to go about this is to fully understand what dirties your roof and what presents a threat. There are several possibilities for why you could have black streaks on your roof, though one of these is by far the most common.

    Concerned That Your Roof Has Been Damaged

    If you are concerned about your roofs shingles being damaged or dried out by moss or age? Give our friend, Nick Roberge, a call at RoofMaxx.

    Asphalt shingles contain small, sand-like pebbles that stick together when shingles natural oils are intact. Once those oils start to dry out with age, you may see the granules flaking off in your gutters or downspouts. You might also notice black stains and streaks or shingles cracking, breaking, and curling. Since each roof is different, your local dealer will perform a free inspection to tell if Roof Maxx can help you.

    • Before

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    How Do I Get Rid Of The Algae And Moss On My Roof

    Any damage to your roof can be costly but we have great news! There is a simple and cost effective way you can remove that algae and moss growth. Roof Soft Washes are a great way to get your roof clean and reduce your concern of roof damage. Roof Cleaning from a Soft Wash company keeps your roof safe with little to no pressure and long lasting results. Those black streaks will be gone in a blink of a eye and the moss/lichen will be gone in 4-6 months. If your roof has grown the moss, the tiny root systems take a little bit longer to fall off. The roof soft wash will kill the roots but they often take months before they lift and release. You do not want to scrape the moss of your roof as that can cause more serious damage. Allow them some time to fall off. Contact Red Door Pro Wash to book your roof wash today! We offer a 7 year warranty to ensure that your roof is protected now and in the years to come. If youre planning to sell your house, you can let your buyers know that they are covered by the Red Door Pro Wash roof warranty.

    Proximate Cause Roof Shingle Stains: Tree Debris

    How to remove those ugly black stains on a roof with Roof Sparkle

    If you see a roof stain that develops only in limited areas of a single roof slope look for a relation between the stained area and a proximate cause such as a sooty chimney top or a tree that shades that section of the roof or drops organic debris onto it.

    These include tree shade caused moss, tree-shade caused lichens growth on a roof, or dark stains on roof coverings caused by organic debris such as leaves and sticks that fall onto and collect on the roof surface .

    See details at DEBRIS STAINING on ROOFS.

    Our photo below shows brown stains below a metal roof chimney.

    Probably more important than the stains is that this chimney has lost its cap, risking damage to the flue, possibly damage to heating equipment, risking heater malfunction that could be unsafe.

    See details at SOOT STAINING and also see

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    Why Are My Roof Shingles Turning Black

    Blackasphalt roofshinglesthe

    . Consequently, why do some roofs have black streaks?

    Roof experts say black streaks are caused by an algae known as gloeocapsa magma. Airborne spores deposit it on your roof, where it soaks up plenty of sunlight for photosynthesis and munches on the limestone filler in your shingles.

    what is the best cleaner for roof shingles? The most effective method of cleaning algae and moss from a roof is with a 50:50 mix of laundry strength liquid chlorine bleach and water. Apply with a sprayer and allow the solution to dwell on the roof surface for 15 to 20 minutes, and then rinse thoroughly with low pressure water.

    Regarding this, will bleach damage asphalt shingles?

    Chlorine bleach / TSP chemical combination can kill plants, and the phosphates hurt the environment. Chlorine bleach also dries out a shingle roof causing curling, and ultimately shortening asphalt roof shingles life. Roof Cleaner QSE does NOT CONTAIN bleach or chlorine chemicals.

    Can you pressure wash a shingle roof?

    It’s generally not necessary to pressurewash a shingle roof for the purpose of removing ordinary dirt and leaves, and pressurewashing can potentially damage the shingles‘ coating of protective grit. A light sweeping or a rinse with the garden hose is usually sufficient, and most roofs don’t even need that.

    Black Algae Stains On Asphalt Shingles Roll Roofing & Many Other Kinds Of Roof Surfaces

    Black algae stains on roofs is in many areas the most common explanation for black blotches, streaks, or discoloration on asphalt roofing products as well as on some other roofing materials.

    Misnamed as “mildew” or “fungus” by some writers, algae staining on asphalt shingles usually in shaded areas or on the more-shaded roof slopes characterized by black staining fairly uniform over shingles, but appearing specifically in areas of the roof shaded by nearby trees.

    See BLACK or GREEN ALGAE on ROOFS for our full discussion of this topic.

    The black stains on the roof at above left are probably an algal growth.

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    Blog Why Is My Roof Appearing Discolored

    Staining is a common problem on roofs that are not properly cleaned and maintained. If you notice staining on your roof, its important to have a professional roofing company take a look to identify the source, and formulate a plan to prevent further staining.

    Distinguishing why roof stains occur and how to treat them is important for the value and safety of your home.

    A clean home exterior, including roof and shingles, is a determining factor in curb appeal. Regular maintenance, like cleaning and sealing, is recommended to preserve the appearance and health of a roof. Staining is a common problem on roofs that are not properly cleaned and maintained. If you notice staining on your roof, its important to have a professional roofing company take a look to identify the source, and formulate a plan to prevent further staining.

    Black or dark green streaking on shingles is most likely caused by algae that prefer warm, humid environments. This type of algae in particular thrives on the moisture and shade provided by certain roof pitches. These unsightly streaks are oftentimes located on north-facing roof slopes due to lack of direct sunlight. A chemical can be applied to rid shingles of stains, but its only a temporary solution and staining may reappear.

    Catalog Of Types Of Stains On Building Roofs Surfaces Walls

    Roof Cleaning: Are Those Black Streaks on My Roof?

    In the following guide we list types of stains by stain color & appearance, by building location or material, and by stain cause. We distinguish among the following stuff that may stain or be found growing building roofs, walls, or other surfaces, with extra focus on asphalt shingle roofs as well as other roofing materials such as wood shingles, wood shakes, roll roofing, and even slate or tile roofs.

    Some of these types of roof stains or discoloration are only cosmetic in nature, while others may indicate growths that are likely to reduce the roof covering life. A more detailed, illustrated version of the list below is given

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    Are Black Streaks Harmful On A Roof

    As mentioned above, most of the time there are black streaks on roofs because of Gloeocapsa magma growth. This type of algae likes shade and dampness, so their spores settle in on moist, shaded asphalt shingles fairly easily. They also thrive in humid environments and can be found around gutters and downspouts.

    The problem is that algae retain moisture. This means they dont allow the shingles to dry out, which quickly causes deterioration in your shingles, and can eventually cause rot, which leaves the door wide open to mold and mildew growth.

    While algae and black stains arent immediately a threat to your roof, they can cause huge problems down the road if left alone to thrive. Thats why you want to have the problem addressed as quickly as possible and keep your roof clean, all to help your roof stay strong and avoid any severe damages.

    What Are Those Ugly Black Streaks On My Roof

    Although these dark spots and ugly black streaks on your roof may look like dirt, mildew, soot or mold, what they really are is algae. The most common type is known as gloeocapsa magmaâalso known as blue green algae.

    This algae growth usually begins as small spots and then eventually becomes visible streaks. By the time this algae is noticed by the homeowner, it has usually been on the roof at least two or more months.

    Why does this algae appear to be black? Gloeocapsa has the ability to form a protective darkly pigmented outer coating that shields the algae from damaging UV rays. This is what makes those unattractive black streaks on your roof!

    Although algae can be found on all types of roofing, it tends to be most common on asphalt shingles.

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    How To Prevent Black Streaks On Roof

    If youve already removed the algae from your roof once and you want to make sure you dont get it again, or if youre building a new house and you want to make sure that your roof doesnt get those black streaks from algae, there are 2 things you can do to prevent the algae from forming:

    #1 Look for algae-resistant roof shingles which have either copper or zinc added to prevent the algae from forming.

    Heres how AR roof shingles work:

    If exposed to sunlight, the ultraviolet rays will readily break down asphalt shingles. Thats why the shingles you see are covered with the small colored ceramic granules. These create a powerful sunscreen and offer you different colors to match your exterior decorating scheme. Many shingle manufacturers make shingles that have special colored granules that contain copper. These help to prevent the ugly black roof-algae stains you might see on your existing roof or that of a neighbor.

    Black Streaks On Roof Shingles Heres What To Do

    How to safely remove black stains from your roof!

    Have you noticed black streaks on roof materials or patches along your rooftop, especially in the shade? Roof shingles often fade into lighter colors over time, but sometimes the opposite effect can occur thanks to subtle plant growth. Fortunately, there are ways of removing those black patches.

    Black streaks: Blame the algae

    Those black streaks on your shingles may look like problems with old age or damage, but they are really caused by algae specifically, gloeocaspa magma is usually to blame for those wavy, dark shades that grow as the algae bloom spreads.

    Many homeowners are surprised to find that algae is growing on their rooftop, because algae is usually associated with pools and seashores. However, given the right conditions it can also flourish on shingles: Those conditions include plenty of moisture or humidity , and the right kind of minerals for the algae to feed on.

    So, how do you know if those black streaks on roof shingles are indeed algae, or a different problem? One of the best signs is how the algae behaves around metal. If you have metal vents, chimneys, or metal flashing along your roof, take a look: Do the black streaks die out around and underneath those metal pieces? During rainfall, elemental traces of zinc and copper often leak down from metal through your shingles. These traces are poisonous to algae, which will avoid these sections of your roof.

    Getting rid of the algae

    Algae-resistant materials

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    Catalog Of Black Stains On Building Roof Surfaces

    • about the various causes of black staining on roof shingles, slates, roof tiles, etc.

    InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

    Black stains on roofs: here is our catalog listing the types of black stains that are found on roofs, using asphalt shingle roofs as the prime example. This article series tells readers how to identify & explain the most-common causes of black, brown, red, gray, green, or white stains appearing on roof shingles and on other building surfaces.

    Roof shingle stains are often caused by black algae, bleed-through or extractive bleeding of asphalt, dirt, soot, or organic debris.

    We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

    Trust My Guy Services To Clean Your Roof Properly

    As soon as you notice black streaks on your roof, you should have your roof professionally cleaned. At My Guy Services, we recommend a treatment called soft washing to clean dirty roof shingles. Soft washing is a cleaning process that combines a unique cleaning solution such as sodium hypochlorite and copper sulfate with low-pressure washing techniques.

    My Guy Services offers expert cleaning services from a team of educated and experienced workers that knows the best techniques to clean your homes exterior. Call us today at or fill out our contact form for a free quote.

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