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What Causes Black Streaks on Roof Shingles?

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  • If you’re seeing black streaks running along your roof, chances are you’ve mistaken them for dirt or even mold. They’re actually algae, otherwise known as gloeoapsa magma, and they are as nasty as they are resilient.

    Algae arrive on the rooftop through the air in the form of spores or clumps of cells. Once they’ve landed on the roof, it takes a while before they become visible. They start out as small spots and evolve into ugly black streaks over a span of two to three months. Since they’re transmit

    If your roof is infested with unsightly algae, chances are you’ll see most of them on the north side. This is because this side of the roof is the least exposed to the sun. Algae thrive in a wet environment. Without the sun’s rays to dry out the moisture, the roof becomes a breeding ground for these little critters. Zinc, copper, and galvanized steel are also toxic to algae, which is why they’re likely to grow around your roof’s metal flashing, chimneys, or roof vents. In fact, many roofing manufacturers now offer shingles fortified with copper granules to keep algae away.

    Algae, if left untreated, can also cause your shingles to deteriorate over time. After all, asphalt shingles contain limestone, which happens to be one of algae’s major food sources. Algae grow and reproduce as they continue to feed on the limestone, turning your roof shingles into loose husk over time.

    Why are algae colored black?

    It’s not the algae that are colored black. Rather, it’s the protective pigmented outer coating they produce to protect themselves from the sun’s harmful UV rays. As algae continue to proliferate, so does this black substance, causing black streaks to appear all over your roof.

    Algae are not harmful to your health, but they are so unsightly that it’s always better to be rid of them. If left to thrive, these algae can also attract fungus, resulting in lichen growth. Once lichen has taken root, getting rid of algae becomes more difficult. This is why it’s recommended to clean the roof immediately at the earliest sign of moss. Remember, the longer the algae stay on your roof, the harder it will be to remove them.

    Besides, black streaks don’t exactly look good on your roof. If you want to maintain your property’s curb appeal, you need to get rid of all that algae.

    How to clean roof algae

    roof being cleaned

    The ideal way to clean roof algae is by using a bleach solution. This simple bleach and water mixture not only kills the algae, but it also promotes the health of your shingles. Experts also warn against using pressure washers since they tend to cause physical damage to asphalt shingles.

    That said, you’ll need a stronger cleaning solution if algae growth has progressed to a point where a simple bleach solution won’t be enough.

    The market is teeming with products designed to get rid of algae. Most are a mixture of trisodium phosphate, bleach, and water.

    Trisodium Phosphate Cleaner

    Trisodium phosphate, otherwise known as TSP, had been a staple cleaning solution in many households for decades. In fact, it was often used as a detergent for laundry and dishwashing jobs, at least until its harmful effects on the environment were revealed in the early 1970s. The right dose, however, should not cause much harm. If a regular bleach solution isn’t enough to remove algae from your roof, using a TSP cleaner should do the job.

    The recommended TSP mixing ratio depends on the strength of the material that needs cleaning, but the most commonly used is ½ cup of TSP and 2 gallons of water.

    William Woodring, Director of Technical Services at GAF, recommends the following mixture:

    • One cup of trisodium phosphate
    • One gallon of bleach
    • Five gallons of water

    Oxygen Bleach Cleaning Solution

    What’s great about oxygen bleach is that it works like a non-toxic version of chlorine bleach. It’s the preferred cleaning solution for the home because it’s been proven safe for humans, pets, and plants. On that note, make sure to read our article on dog proofing your home.

    The ideal mix for your oxygen bleach cleaning solution depends on the concentration of the oxygen bleach you’re using. Follow the directions on the label to ensure you’re using the right amount. For better results, put the entire solution inside a spray bottle and spray away.

    Cleaning the Roof Yourself

    roof before and after cleaning

    So, you’ve decided to get rid of those ugly black streaks from your roof yourself? That’s great. But before you do, make sure to make some preparations first. After all, cleaning roofs is not only difficult, it’s also a dangerous job.

    1. Make sure that the skies are clear and that the weather is calm and cool before you even take one step up that ladder. Cleaning your roof in hot weather is not ideal because the sun’s harsh light will cause your cleaning solution to dry up quickly, minimizing its effects. Check the weather forecast to see if the weather will stay friendly the entire day.
    2. Protect the and any furniture directly below your roof’s edges as well as the areas surrounding it from spray runoff by or any covering that’s just as strong.
    3. Don’t forget to wear rubber gloves, protective clothing, non-slip shoes, and safety goggles. Having a friend nearby would be great as well just to be on the safe side.
    4. Use a ladder and be extra careful while using it.
    5. Remove any debris — leaves, branches, etc. — that might obstruct your way around the roof.
    6. When spraying, start at the top of the roof and work your way down. This is because spraying up might cause your shingles to come loose.
    7. Take care not to step on any wet surfaces.
    8. After spraying the affected area with a cleaning solution, allow it to dry for at least 20 minutes before rinsing it with a regular garden hose. (again, don’t use power washers because they tend to cause your shingles to come loose).

    We recommend that you don’t try doing this yourself, since you could easily either get hurt or cause damage to the structure, which could lead to roof leaks.

    Prevent Black Streaks from Growing on Your Roof

    You already know why black streaks are appearing on your roof. It makes you wonder: What could I have done to prevent them from growing and spreading? After all, prevention is better than cure, right?

    But before we dig deeper into the answer, let’s get one thing straight: you can’t get rid of algae completely. Algae are like the common cold. They are always out there. But just like with the common cold, you can take precautions to prevent your roof from catching them. It’s equivalent to washing your hands regularly or putting on a face mask in public places.

    Keep debris away

    Make sure that your roof is always cleared of debris. By allowing debris to accumulate on the roof, it creates an environment where algae can thrive. Are there any overhanging branches above your roof? Then take the time to trim those branches every few months or so, or get a professional tree cutter to do it for you. This way the sunlight can come in contact with the roof, preventing the proliferation of algae.

    Also, you need to ensure that the gutters and downspouts are free of clogs. A working drainage system, after all, prevents debris from collecting debris. If your gutters are redirecting water into your roof, it collects standing water. Standing water promotes the growth of algae and slowly destroys the structural integrity of your shingles. Leave it there long enough and it might even find its way into your cellar and your home’s foundations.

    Install algae-resistant material along the roof

    You can install copper/zinc strips or galvanized roof flashing along your roof’s upper section to prevent algae build up. As mentioned in an earlier section, these materials create an environment that is toxic to algae. Place the material under the shingles, leaving just enough of the material (about 3 inches) exposed to the elements.

    When it rains, the water will cause the solution to run down the roof, making it an unfriendly environment for algae. The only drawback is that they don’t actually eliminate the algae, just prevent them from growing. Before installing the material, make sure that you get rid of the algae first.

    Copper strips, while very effective, can be expensive. If you’re on a tight budget, galvanized roof flashing should be the more affordable solution. You can buy copper/zinc strips or galvanized roof flashing at any local home improvement establishment — both online and offline.

    Buy new shingles

    If your shingles are teeming with black streaks, you can always replace them with copper-fortified shingles. Bear in mind, however, that replacing your old shingles might not be cost-effective especially if you can still eliminate the algae. Simply follow the instructions we provided on this article and you should be able to get rid of those black streaks in no time.

    However, if your shingles are already nearing the end of its lifespan, replacing them with algae-resistant shingles might be the way to go. While copper roofing is expensive, its long shelf-life, great curb appeal, and resistance to algae should more than make up for it. Just don’t forget to buy from a manufacturer that provides the best warranty to ensure that your investment is maximized and protected.

    The Importance of Regular Roof Maintenance

    There’s a reason why the phrase “putting a roof above your head” is a popular expression when referring to basic shelter or a place to live. The roof, after all, is the most important part of the home. Without a roof, you and the interior of your home are exposed to the elements. A roof not only provides you with protection, but it also makes you comfortable in your day-to-day.

    Since your roof is essential in your daily living, it stands to reason that you do everything necessary to keep it in good working order for as long as you’re able. Hiring a roofing contractor to fix roofing problems as they arise helps, but you must do regular maintenance as well if you want your roof to last longer.

    While maintaining and monitoring your roof sound like a lot of work, knowing the consequences of not doing both should be more than enough to spring you into action. Here are the reasons why regular roof maintenance can go a long way into maximizing your investment.

    Increases your roof’s shelf-life

    Regular roof maintenance can extend your roof’s shelf-life in more ways than one. It doesn’t just get rid of roof issues quickly as they occur, it also prevents them from happening in the first place. More importantly, it minimizes the risk of major damages. Remember, damages have a cumulative effect. They can lead to other, possibly more serious issues if you let them be.

    Minimizes costs

    Hiring a professional to do roof maintenance can save you more money in the long run. For one thing, roofing contractors charge more for emergency service calls. Emergency calls bill you for labor, time, and materials. They may even charge you for the amount of time it takes them to arrive at your location. All in all, these types of services will cost thousands of dollars.

    Hiring a roofing professional for roof inspection or a routine maintenance, however, is way cheaper. By addressing roofing issues before they even occur, you tend to spend less on materials, equipment, and labor over a long period of time, and you avoid suddenly find your roof leaking when it rains.

    Your roof will look better

    Your house’s roof is one of the first things that people see when they pay a visit. With the right design, it can spruce up your home’s landscape. Your home’s interior might look pristine and fashionable, but a sagging or algae-riddled roof tends to ruin the entire tableau.

    By regularly cleaning your roof, you can prevent the accumulation of unsightly algae and debris. This, of course, increases your home’s curb appeal, making it not only attractive to visitors but also to potential buyers (if you do decide to sell your house in the future).

    Your roof might have an issue without your knowledge

    The thing with roof leaks is that they might escape your notice until the problem becomes worse. Moisture might already be invading the cellar and the foundations of your home without your knowledge. And once it catches your attention, it might already be too late. By then, your house might already be suffering from structural damage, and you have no choice but to spend a hefty amount to have it fixed, including fixing the home’s framing.

    By conducting regular inspections, a roofer can detect any sign of roof leaks and be able to fix it immediately, preventing any further damages and minimizing your expenses.

    Gives you peace of mind

    A roof doesn’t only provide you with comfortable living conditions, it can also save your life and the lives of your loved ones. It’s no secret that harsh weather can have severe consequences and that a good shelter spells the difference between survival and death. The point? Knowing that your roof is in good working order gives you peace of mind. It helps you sleep better at night knowing that you and your family are well protected in the face of potential calamity.

    Why You Should Hire a Professional Roof Cleaner

    Going the DIY route may have some benefits.  If the problem with your roof is not too serious, doing it yourself might be more cost-effective. It might even save you time. But there are times when hiring a professional roof cleaner is the best solution. Here are the best reasons why.

    Protect yourself from injury

    As mentioned numerous times in this article, the rooftop is one of the home’s most dangerous places. You might think you’re sure-footed enough to do the job, but there’s always the risk of slipping and falling off.

    As a homeowner, those are risks you’re better off without. Professionals, meanwhile, were not only trained, but they also have the extensive experience to do the job more safely. Most important of all, they have the insurance coverage that ensures everyone is compensated should they get injured on the job.

    You get quality work

    Professional roofers have undergone specialized training and acquired enough experience to become experts at what they do. This translates to their work, ensuring that your roof is cleaned in the proper and most effective way. They don’t do quick fixes; they offer long-term solutions. And they just don’t solve your roofing problems, they also implement preventive measures.

    Not only do professional roofers have the equipment and tools to do the job, but they also know which ones are appropriate for each circumstance or scenario (such as knowing which cleaning solution should be used depending on roof type and potential damages). They don’t cut corners, giving you the assurance that everything’s been accounted for during the course of the project.

    It’s worth every penny

    In the long run, paying a professional roof cleaner for regular cleaning is worth the money. First off, roofs that are cleaned on a regular basis tend to have a longer lifespan. While paying a roof cleaner costs money, it’s much cheaper than going for a full roof replacement.

    Roof shingles aren’t exactly cheap, and considering the amount of work that goes into replacing a roof, paying a high amount for manual labor is also to be expected. If you want to spend less on your roof, you need to think of it as an investment. And the only way for you to maximize that investment is to spend money on it.

    It may void your roof warranty

    Depending on the terms of the warranty provided by your roofing provider or manufacturer, cleaning the roof yourself may cause that warranty to be voided. Roof manufacturers discourage pressure washing since it may damage the shingles, but even if you’re not using a pressure washer, there’s always the risk of causing damages that may lead them to think that you used one.

    Professionals will use eco-friendly materials

    Professional cleaners are more likely to use cleaning solutions that are proven safe for the environment, thus also ensuring that your health and the health of your loved ones are not compromised in any way. Besides, all of us should do our part for the planet. You can always ask the pro what products they use.

    Your roof may require cleaning even if there are no visible signs of algae

    Most homeowners make the mistake of not having their roof cleaned just because there are no visible signs of algae. This can cause problems down the line. For one thing, algae buildup is not apparent in its early stages. In other words, algae might already be growing on your roof even if you can’t see them yet. That’s why it’s recommended that roof cleaning is done at least every three years to prevent algae buildup.

    Save yourself the hassle and the time

    Doing something you’re not trained for is usually just a waste of time. Instead of cleaning your roof yourself and wasting time trying to learn the ropes, you can hire a professional roof cleaning company instead and use that time to focus on things you’re good at and things that really matter.

    Get Free Quotes from Competing Competitors By Using Form on Our Site

    So, you’ve finally decided to hire a roofing company to give your roof the cleaning it deserves? Great! But now you’re probably at a loss on what to do next. That’s understandable. After all, you may end up hiring someone who will end up doing a poor job. You don’t want that. And there’s also the budget issue to think about.

    At this point, the next order of business is for you to get quotes from competing companies or competitors. Admittedly, that can be time-consuming, not to mention costly. After all, most companies charge for quotes.

    But worry not. Because we’re offering you the chance to get quotes from competing competitors — absolutely free of charge. No obligations here. Just straight up service and gratitude for reading this article all the way through. Just fill out the form on our site and you should receive free quotes from screened competitors in no time! Now do yourself (and your roof) a favor and get those free quotes!

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