Ask A Roofer: Why Is My Roof Turning Black?

Roofing Tips


Ever wondered what those black streaks on your roof might be? Here, a roofer discusses the question asked by many people living in South Florida.

Why Is My Roof Turning Black?

What might be mistaken as dirt or mildew is actually a type of blue-green algae, known as gloeocapsa magma.

Like most types of algae, this one thrives in humid hot environments like South Florida. Most people know algae to be bright green in color, but this type contains a dark pigment to protect the algae from UV ray damage, making it easier to thrive in hot climates. Because algae spread by airborne spores, they can easily travel via the wind, attaching themselves onto rooftops around the neighborhood.

How Can I Prevent Algae Growth On My Roof?

Although it may seem harmless, the moisture retained in the algae can cause damage to the roof over time.

If you notice any dark spots or streaks forming on your roof, especially in the shady areas, then it’s time to get your roof professionally cleaned. Unfortunately, one cleaning will not prevent algae from forming, so regular maintenance is one of the most important parts of keeping your roof in check.

Aside from regular maintenance cleans, you could also check that your gutters are draining correctly. Any areas that tend to collect water should be monitored closely and tended to, as the more moisture there is, the more chance there is of algae growth to occur.

For example, gutters draining directly onto the roof can prevent the roof from drying, and overhanging trees can also contribute to an increase in shade and dew. A shady or damp surface will also prevent the sun from drying the roof quickly, in turn encouraging algae growth, so keeping your trees trimmed can help to prevent the problem.

Don’t DIY

Cleaning a roof requires a whole set of specialized tools such as cleaning devices, approved chemicals, specialized skills, and even certain types of ladders. Save your time and give your roof the right attention by consulting a professional roofing contractor to take care of it for you.

Safety is just one of the many reasons to avoid DIY, and many homeowners make the mistake of using high-pressure hoses to try and clean the algae off. This can cause damage to roof shingles, as well as put yourself at risk of falling. What’s more, certain chemicals used to clean can be harmful to the roof materials. Not only can chemicals damage your roof, but it can be unsafe safe for humans and vegetation.

Is There An Alternative To Constant Cleaning?

If you don’t want to repeat the cleaning process every year, you could hire a contractor to install strips of zinc and copper under the shingles near the ridge, as metal ions released by the zinc or copper can prevent algae from growing. Every time it rains, water runs over the metal strips, causing them to release microscopic quantities of metal ions that flow down the roof. This will kill off any algae before it has a chance to spread to other areas.

If you want to find out more information, on a good pressure cleaning company, contact Aabco Roofing, where we provide high-quality, cost-effective solutions for all your roofing maintenance needs.

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