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HomeExclusiveHow Do You Remove Mold From Roof Shingles

How Do You Remove Mold From Roof Shingles

Removing Moss Mildew Fungus And Associatedstains On Roofs

How to Remove Moss & Mold from your Roof Shingles with Wet & Forget Roof Shingle Demo Video

Roof cleaning is a topic that draws yawns in New England but causes shudders andscreams of agony from Florida and points south, where vegetable life seeksworld domination! How do we keep that “fungus among us” under control.

Since starting on a quest for the ideal method of cleaning fungus and algaefrom roofs, I have contacted dozens of individuals and companies. Some of my readers came forwardwith suggestions and a few companies also supplied information helpful to thisresearch.

For the purposes of this article, the terms “mildew”, “fungus”, “algae” and”moss” are interchangeable… even though their mothers’ might object!

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.

How To Get Rid Of Algae On The Roof

You could replace all the roofing with new shingles dark enough to disguise the staining, or with shingles laced with copper granules, which are lethal to algae. But that would only make sense if the shingles were worn out.

The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. Just be sure to wet your foundation plantings first, and rinse everything in clean water when youre done. Plants dont like bleach, and wetting them with plain water first protects them.

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Would You Believe Fungus

Yessiree… the 3M Companyhas developed an additive for asphalt roofingshingles using copper granules. This unique advance in shingle technologygives long-term fungus protection for the entire roof. Theycall it the AlgaeBlock system. You can find more information onthese special roofing shingles HERE.

3M is not a manufacturer of asphalt shingles, just the granules. However, at the time of this writing they do list anumber of companies that are producing shingles meeting their specifications.

How To Identify Youve Got A Mold Problem On Your Roof

What is the Process of Removing Moss from a Roof ...

Microbial overgrowth from algae, moss, mildew, and mold are common in homes located where there is high humidity, or insufficient roof drainage.

Unfortunately most homeowners mistakenly characterize the signs of a mold problem as a cosmetic issue or one of old age.

Heres what you should look for when looking for mold on roof:

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Why Are My Asphalt Shingles Turning All Black

It is most common on asphalt shingles and can be the spore-based algae that lives in the limestone of your shingles. If eaten, it will corrode the limestone, and if left untreated, it will permeate the entire roof, giving it a “completely black” appearance, even if it is not the color of shingles. In fact, it is algae growing on the coating.

Preventing Reinfestation Zinc Strips Are One Option

If you wish to prevent reoccurrence of fungus, think zinc! Zinc strips have been used for many years as an algae preventative. offers sets of 3′ zinc strips, which areattached near the peak of the roof. When it rains, a slight amount of zincdissolves from the strips and coats the roof, inhibiting algae and fungusgrowth.

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Apply A Moisture And/or Microbial Barrier

Roofing materials and technology has advanced greatly within the last few decades.

One of those advances is the ability to apply chemicals to your existing roof that repels water, or prevents algae and mold from developing. New roofs are often constructed of materials that have these properties impregnated into them.

Why Shouldnt I Add A New Roof Over Moss

How To Remove Roof Moss – And Keep It Away

When you need a new roof, it may be tempting to add a second layer of shingles over your existing shingles. Doubling up your shingles can save time and expense on your roof replacement as your roofer doesnt need to remove and dispose of the old shingles. This strategy is convenient for homeowners because the replacement wont take as long or make as much of a mess. However, there are some circumstances where merely adding a new layer of shingles isnt a good idea.

For example, when you have significant moss growth on your roof, simply covering it up with new shingles isnt wise. Several potential problems may occur if your roofer simply adds a new roof over your existing, moss-covered roof. These potential problems include:

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Dos And Donts: The Best And Worst Ways To Clean A Roof

If youre reading this, chances are youre looking for roof-cleaning tips because your shingles are no longer looking new and attractive. If your roof appears dark and discolored in some areas, you may think that mold has developed on the surfaces of the shingles. However, the black streaks youre seeing are really colonies of blue-green algae. If youre noticing thick, green patches on your roof instead, then youve got a moss problem, The north, west, and shady areas of your roof are most susceptible to these moisture-loving nuisances.

Moss and algae spores are carried by the wind or animals from rooftop to rooftop, which is why entire neighborhoods are often affected. Moss can seriously impact asphalt shingle performance by causing them to curl up and blow off, eventually resulting in leaks. While algae doesnt actually harm your roof, it can impact its aesthetic appeal. Further, climbing on your roof frequently to clean off growth CAN damage your roof and shorten its lifespan by loosening the granules on your shingles. So, its best to know how to clean your roof properly so that you ensure you dont have to do it too often.

Knowing this, what are the best ways to clean a roof of algae and moss growth? Read on for our best roof-cleaning tips!

By Step Guide For Cleaning Molds From Roof Shingles

  • Spray the vegetation around the house with clean water to protect them from the chemical run over. You can cover some plants with plastic bags to be more careful.
  • Use a hard brush to scrub areas with the thickest layers of mold and the hard to reach places with your gas mask on to protect yourself from the mold dust. Care must be taken during climbing to avoid accidents. Ensure to use a ladder.
  • Mix the chlorine bleach with water in a ratio of one to four. One measure of chlorine goes with four measures of water.
  • Add a small measure of Trisodium phosphate in the mixture to remove the mold stains on the roof shingles. 50ml of TSP could go with 20 liters of the mixture.
  • Using a hand spray, start spraying the molded shingles until they soak the solution in. Start spraying from the bottom line of shingles as you climb to the top row. This is to avoid the mold from running down to the unsprayed shingles. Ensure all parts of the roof are sprayed.
  • After spraying, wait for 15-20 minutes for the solution to soak into the shingles. Good weather conditions are important to let the bleach work on the mold and stains. Too much rain could wash away the chemicals and also too much sunshine could make the bleach evaporate before killing the mold.
  • After the bleach has diluted the mold, the next thing is to rinse the shingles. U can use the hand spray or a garden hose with clean water. Ensure to rinse the roof thoroughly to ensure all bleach has been cleaned off.
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    Getting Rid Of Mold And Algae

    The old standard method for cleaning algae and mold stains from asphalt shingles is to spray on a solution of chlorine bleach and water. You let the solution sit for about 5 minutes, or so, then you rinse it off with a hose. However, bleach is not an ideal solution for a few reasons: it is toxic to plants , and it can damage shingles if it’s left on too long or isn’t completely rinsed off. You can protect your plants from bleach spray, but then you have the rinse water pouring down your gutters into your yard, etc.

    How To Remove Mold & Algae On Your Roof

    How to Remove Mold From Your Roof

    A lot of the dark streaky stuff found on roofs in wet climates like ours in the Lower Mainland and the South coast of B.C. is in fact, algae and not mold. There is difference between mold and algae and how they affect your roof. Algae commonly feeds on the limestone powder in asphalt shingles, while mold often thrives on plant and other organic matter that’s fallen onto your roof.

    You can’t do anything to prevent algae and mold spores from flying through the air and landing on your roof, but you can help prevent mold growth by keeping the shingles free of organic matter.

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    How To Remove Mold And Moss From Your Roof Shingles

    While it may not actually cause harm to your home, moss, mold, and algae certainly dont improve a houses appearance. These growths can be a major pain, especially when it comes to trying to sell your house. If youre not in the market for a complete roof replacement, it can require hard work to get rid of. We at Brava Roof Tile offer a few helpful tips to fight off the encroaching flora and keep it from coming back.

    The first thing to identify is what species youre actually dealing with. The most common form of growth in the US is Gloeocapsa magma, which is a type of algae that thrives in particularly humid environments. It usually shows up as a black discoloration across your roof shingles.

    We will focus our combative techniques on this particular species, as its the most prevalent, but these tips will be transferable to most other growths as well.

    The Process For Removing The Mold

    When Orlando roofers like Janney Roofing remove mold, we start by protecting the lawn and landscaping. We first splash the plants with water to protect them from the bleaching solution. Next, they cover the area closest to the roof with plastic sheeting or tarps to protect the soil.

    The choice of roofers for removing mold, among roofing supplies, is a special bleaching agent formulated for roofs. The roofing contractors mix this bleaching agent with water and spray the roof down, paying close attention to areas that are stained. They will let the mixture stay on the roof for a bit to ensure it penetrates the stain. Finally, we will wash the roof down with water to remove the bleaching agent and the stains.

    After rinsing the roof, we will inspect the roof again for mold and stains. If needed, we can reapply the bleaching to specific areas to get the last of the mold and staining off. After the last of the mold is gone, they will remove the tarps and then spray the ground down to dilute any run-off from the cleaning process.

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    Choose The Right Chemicals

    If you search online, youll see hundreds of posts on roof-cleaning methods. In less than 10 minutes, youll sign off convinced that all you need is a few gallons of household bleach and a power washer set at its lowest setting.

    We dont recommend that approach. Even at low pressure, a power washer can seriously damage shingles. Plus, chlorine bleach is a corrosive agent that can damage metal roof flashings, gutters and downspouts. It can lighten the color of your roof and bleach anything the overspray contacts. And the runoff harms plants. But heres the kicker. Bleach may kill the top layer of algae and lighten the stains, but it doesnt kill the underlying algae. So the algae colony gets right back to work.

    Sodium hydroxide products, on the other hand, work better than bleach and are less harmful to vegetation. But theyre also corrosive, and using them requires you to don full protective gear.

    So look for a roof-cleaning product thats noncorrosive and safe for the environment. We chose Defy roof cleaner for this story , but there are other brands.

    Is It Too Cold To Install Asphalt Shingles

    Removing Algae Stains From Roof Shingles

    If you’re wondering what the temperature is too low to install shingles, here’s the answer: The ideal temperature for installing shingles is 40°F to 85°F . You can still successfully install shingles in temperatures below 40°F if you follow certain guidelines and guidelines for cold weather installations.

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    Choose A Safe And Effective Product To Clean Asphalt Shingles Without Damaging Them

    The first step in maintaining your roof is to roof it right. If youre not doing the work yourself, choose a qualified professional roofer to do the job. And choose your roofing material wisely. Some roofing will require less maintenance than others. Choices include metal and slate. Some roofings types last longer than others, as well. That said, data shows that you are probably going to choose asphalt shingles, which can last a lifetime, but likely not without some repairs and maybe replacing a few shingles here and there. And, you may need to clean the roof once in a while.

    Twenty years ago I bicycled about 500 miles along the Oregon / Northern California coast and marveled at the number of asphalt shingle roofs carpeted with lichens and moss. The roof growth gave character to many seaside and forest cottages. Though the roofs looked cool, I knew the shingles probably wouldnt last too much longer.

    Lichens and moss accelerate shingle deterioration by loosening shingle granules and exposing the asphalt and fiberglass base materials. The granules arent just there to color the shingles they protect the base materials from sunlight and weathering.

    About five years ago, I noticed a few patches of lichens growing on the north side of my roof. Like most lazy homeowners, I ignored the problem. Then about two years ago, when the roof looked like those out in the Pacific Northwest, I knew I couldnt put off treating the growth any longer.

    What Are The Dark Streaks On My Roof

    You may have noticed dark streaks across your roof. Given that moss grows upright on surfaces, and algae stays low and flush to the surfaces it grows on, its likely any dark streaks you see are algae.

    Algae staining on roofs all start out being spread by wind, birds, and varmints, affecting homes across much of the United States.

    This algae normally begins its lifecycle as airborne spores that will settle on your roof, especially those roofs that have asphalt shingles. The northern exposure of roofs has the most chance for algae to survive/thrive because that part of the roof is exposed to the least UV and dries last after morning dew and rain.

    As the algae grows and spreads, it begins to look like large black streaks on your shingles.

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    How To Remove Mold Mildew And Algae

    Again, while we dont encourage it, you can handle mold, mildew, and algae yourself. The biggest thing to keep in mind is to completely remove the stains and streaks, otherwise, they will just come back. If you have an asphalt shingle roof with mold, mildew or algae, there are several ways to effectively remove it.

    If you dont want to buy a product, you can also create a cleaning solution by mixing 1 part oxygen bleach cleaner with 1 part water. This can be sprayed or poured over the affected area of your roof, killing the algae. Let the solution sit for 30 minutes before cleaning with a hose. If you choose to use this method, please be careful. Algae, mold, and mildew can make your roof extremely slippery when wet. Better yet, spray your roof from a ladder or call the professionals!

    Last but not least: Do not pressure wash your roof. This can cause lasting damage to your shingles, reduce the lifespan of your roof, and cost you hundreds of dollars in repairs.

    Rinse The Bleach Solution

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    After spraying the shingles with the bleach solution, allow the bleach to sit for approximately 15 to 30 minutes, depending on the severity of the mold growth. Using a garden hose at low pressure, rinse the roof shingles thoroughly to remove the bleach solution. When rinsing, start at the top affected shingle and work downwards. While wearing gloves, run your fingers across the shingles. If you still feel slime on the shingles, apply the bleach solution a second time and let it sit for an extra 10 minutes. You can then rinse the roof again.

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