What Do The Black Streaks On Your Roof Mean

Make your shingles last longer by keeping them cleaned off and free from algae growth. Are you tired of black streaks on your roof? Black streaks on the shaded areas of your asphalt-shingle roof can really wreck the appearance of your home. The streaks look like mold, but they’re actually algae colonies that form in your shingles and feed on moisture and the limestone filler agents in the shingles.

Using shingles that have been treated with algaecide keeps the growth at bay for about 10 years. But once the algicide wears off, your roof hosts an all-you-can-eat buffet for the neighborhood algae spores. As the algae eat away at the limestone, they dig into the asphalt and dislodge the light-reflecting granules. That’s the beginning of the end of your roof. So it pays to clean your shingles as soon as you spot algae growth.

Doing it yourself can save you money but there is always a risk of damaging your shingles. If you feel don’t feel comfortable cleaning your roof on your own, give us a call. We can help you get rid of those ugly stains for good.

If you decide to do it yourself you will need a full-body harness, a garden sprayer, a garden hose and a nontoxic, non-corrosive roof-cleaning chemical. Some manufacturers sell a special tool applicator and rinsing tool, but if the staining isn’t severe, you may not need them.

Choose the right chemicals

If you search online, you’ll see tons of posts on roof-cleaning methods. You will be convinced that all you need is a few gallons of household bleach and a power washer set at its lowest setting. Power washers and your roof don’t mix. 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 here’s the kicker. Bleach may kill the top layer of algae and lighten the stains, but it doesn’t kill the underlying algae. So the algae colony gets right back to work. So look for a roof-cleaning product that’s non-corrosive and safe for the environment. There are several brands to choose from.

Check the weather forecast and choose a cool or overcast day with little to no wind so the spray hits your shingles, not the neighbors’. Those conditions allow the cleaning solution to soak deep into the algae colonies without evaporating too quickly.

Next, repair any loose shingles or flashings, and clean the gutters and downspouts so they can drain freely. Then prepare the area by moving lawn furniture and covering vegetation, because you’re going to have overspray. Even though the product we chose isn’t toxic, the runoff can be pretty ugly.

We wish you good luck if you try to clean your shingles on your own as it can be a pretty big and time consuming job. It is also important to make note of the dangers involved in getting up on your roof and trying to clean it. Hiring a professional is a great investment. Professionals are able to protect your investment and are trained in how to walk on and clean shingles.