Skywalker Roofing Company
May 14
By Luke Wilson | Roofing

Algae and Your Roof – What’s the Story?

You’ve surely seen it in your neighborhood – ugly dark streaks on a home’s shingle roof. What causes these black marks to appear and then spread? It’s not because something is leaching out of the shingles. What’s happening is there’s actually a living organism growing on the roof!

What Is Algae?

What’s causing these unattractive dark streaks is a tiny organism called Gloeocapsa Magma. This alga is blue-green, but as it builds up it starts to take on a black tone on your roof. Algae can occur on any shaded roof, but it grows best in warm, humid conditions. If you think that North Carolina and Virginia sound like ideal environments for algae, you’d be right! Algae on roofs are especially common in the Southeastern U.S. It’s also easy for the algae to become airborne and spread to other places around the home, too. If your roof is warm, damp, shaded, or any combination of these factors – this algae can most likely thrive there!

What Is Algae

Algae Affects Your Home’s Appearance

Regardless of the color of your roof, algae will appear black on your shingles. An algae infestation usually starts at the top of the roof, and then works its way down towards the bottom edge. Naturally, the black streaks trailing down your roof will detract from your home’s overall appearance. In fact, algae on the roof can lower the value of a home and property; this certainly won’t help if you intend to put your home on the market. In many ways, houses with algae-streaked roofs can devalue the whole neighborhood’s reputation.


Algae Increases Your Energy Costs

It’s bad enough that algae streaks mar your home’s appearance, but they can have a negative impact on your energy bills, too. The algae color is likely to be darker than your original shingle colors. Algae build-up also serves to block some of the reflective properties of your shingles. Both of these situations will lead your roof to start absorbing more heat. On a sunny summer day in NC or VA, an algae-streaked roof ultimately produces more heat for your air conditioning system to have to deal with! The result, of course, is a higher energy bill thanks to the fact that your A/C is working overtime to try and disperse that extra sun-induced warmth.

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The Effect of Algae on Roof Shingles

Algae are able to grow on the limestone granules in asphalt shingles. As the algae slowly consumes the limestone, the shingle itself becomes weakened. As time goes on, algae can combine with fungus on your roof to produce a more advanced life form, a lichen. Lichen is much sturdier, more destructive, and harder to remove from a roof than algae alone. Furthermore, lichen is a gateway to the growth of moss on your roof.

Effect of Algae on Roof Shingles

Moss – The Next Step in Roof Damage

Lichen growth can lead to moss taking root on your roof shingles. Since moss is a plant, it will put literal roots into your roof. Moss roots can grow in between and even underneath your shingles, affecting the integrity of your entire roofing system. Moss and its roots also absorb water, which means increased moisture in and around your roof shingles. The extra dampness can encourage even more kinds of growth, including bacteria, mold, and mildew. In the winter, the moisture in moss roots expands as it freezes, which can then result in cracks in and around your shingles. Eventually, moss will produce a layer of soil which can allow other plant seeds to sprout. And another negative impact of moss? It’s slippery, so it increases the danger and difficulty of working on your roof. Once moss takes hold, your roof has reached an urgent state that will need some real, professional attention.


What NOT To Do About Algae

If you see those dark streaks that indicate algae on your shingles, your first instinct might be to have your roof cleaned. Many homeowners think that power washing is the best way to remove those algae stains. This could not be further from the truth! While power washing may remove the algae, it will also remove the protective granules from your shingles. These granules are critically important – they help reflect light from the shingles, reduce heat absorption, protect the shingles from the elements, and add weight and strength to the shingles. Stripping the granules from your shingles by power washing will significantly shorten the lifespan of the shingles. Additionally, roofing systems are not designed to handle the level of direct pressure that results from power washing. Power washing can dislodge shingles from the roof, ruin the bond between shingles, and damage sealants around openings in your roof (e.g., a skylight), resulting to leaks. Power washing can even help spread algae to other parts of the roof, which may ultimately make your algae problem even worse! While the immediate result of power washing may look nice in the short term, your roof will pay the price afterwards. The negative effects of power washing a roof simply aren’t worth it.

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A Better Option: Algae Resistant Roof Shingles

Of course, the most effective method for dealing with algae on your roof shingles is to avoid the situation entirely! While roofing experts have designed methods to safely remove algae and its stains from your roof, these treatments can be costly and time-consuming. And if you live in an algae-prone area like North Carolina or Virginia, you’re likely to find that you’ll need to repeat the cleaning process every few years. Algae-resistant roofs are simply the best way to keep your home safe from this threat. Skywalker Roofing offers some great, algae-resistant roof shingles from Owens Corning for the best protection for your home. Owens Corning has developed these algae resistant roof shingles with a special, non-toxic formula that inhibits the growth of algae, without damaging the environment around your home.

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Benefits of Algae Resistant Roofs

It’s easy to see why installing algae-resistant shingles is the most cost-effective way to deal with your potential algae problem. As the saying goes, an ounce of prevention is worth a pound of cure. You can stop algae before it even starts by installing algae-resistant shingles in the first place. With an algae-resistant roof, you won’t have to worry about any of these problem issues:

  • Unsightly Stains – Keep your roof free from those black streaks caused by algae growing on your roof shingles. You don’t want to be the homeowner whose roof detracts from the look and value of the whole neighborhood!
  • High Energy Bills – Your cooling costs can creep up slowly at first, but as the algae continues to spread, your bill will keep rising. Algae-resistant roof shingles help keep your energy bills lower.
  • Damage Prevention – While simple algae isn’t extremely destructive to shingles, its presence does lead to other things which can reduce the lifespan of your roof. The presence of algae is just the first step in a process that results in serious roof damage. Algae growing on your shingles is a sure sign of more roof problems down the road.
  • Lower Cleaning and Maintenance Costs – Algae can be cleaned from roof shingles, but that’s really a job for a professional. While roof cleaning and maintenance is essential to maximizing the life of your roof, you can reduce the amount of professional cleaning required by going with algae-resistant roof shingles!

If you want to avoid the appearance of dark streaks on your shingles, the hassle of repeated roof cleanings, and the worries about algae-induced damage to your roofing system– algae-resistant roof shingles are the answer. Skywalker Roofing is proud to offer Owens Corning shingles with Streak Guard Algae Resistance Protection to inhibit algae growth. Contact us for more information about installing an algae-resistant roof for you anywhere in the NC Piedmont Triad, Triangle, Charlotte Metro, and Roanoke, VA areas!

Luke Wilson

Luke Wilson

Owner - Skywalker Roofing

Luke Wilson started working on roofs with his dad when he was a teenager, and eventually launched Skywalker Roofing in 2003. Skywalker operates in 5 locations across NC & VA, and now includes windows, siding, and other exterior services. Luke also hosts the popular Roofing Mythbusters series on YouTube.

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