Algae Or A Lot Of Trouble? What To Do About Black Streaks On An Asphalt Roof

Posted on: 11 October 2017

Asphalt shingles are among the more common roof materials available. They're affordable, last a decently long time, and look presentable on most roofs. However, they are prone to two different problems that result in a similar appearance: Algae is one, and wear and tear is the other. Obviously, algae on a roof require vastly different action than worn shingles, so it's important to figure out which one you're dealing with:

The Look

Both algae and wear can make the asphalt shingles look like they have black streaks on them when you look at the roof from the ground, unaided. You may see groups of shingles that look similar in both cases. You might think that algae are supposed to be blue or green, but the type that grows on your roof is not.

Get a pair of binoculars and focus on the black shingles. If the shingles look smooth, chances are the black coloring is from wear. The shingles, when they're in good condition, have protective granules on them, and wear due to age and exposure to wind and rain can gradually carry away those granules. That leaves a smooth surface behind. Like road surfaces, roof asphalt shingles are usually black.

If you can still see granules or the if surfaces of the shingles look rough, then you may be dealing with algae. Technically, you don't have to do anything about algae because it's not going to do anything other than sit on the shingles. But the presence of algae indicates that part of your roof is not receiving a lot of fresh air. The algae need a dark, damp environment, and that could be a sign that other parts of the roof have developed moisture-related issues as well.

What to Do

If you think the coloring is from algae, have the roof inspected to ensure that no other components have been compromised by moisture, and then have the algae professionally cleaned off. If you can locate the source of the problem -- say, some trees that need to be trimmed back, forming a small cave around your roof -- do what you can to get rid of the problem, like having those branches trimmed back to let more light hit the roof.

If you think you have worn shingles, then you need to have them replaced. Worn shingles carry with them an increased risk of letting water through and creating actual roof leaks. Worn shingles also indicate that the roof as a whole is old enough to be replaced. Have the roof inspected and patched or replaced as advised.

Have a few roofing companies come out to check out the shingles and offer bids for either cleaning or repair/replacement. Don't wait; if you let the problem sit, the chances of procrastinating more and not getting the job done are very real.

Contact a company like Rainy Day Exteriors for more information and assistance.