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Asphalt Shingle Roofs: Removal And Prevention Of Black Algae Stains

Published on September 8th, 2020

Removal & Prevention Of Black Algae Stains

People who live in humid areas are likely to experience the problem of algae growing on their asphalt shingle roofs. These people know that it is not a pleasant sight. The dark streaks covering the roof are really bad for aesthetics – it just doesn’t look attractive at all – it just makes your roof look dirty, dull and uncared for. Those aren’t the signals you want to portray to your neighbors or to prospective buyers of your house.

Gloeocapsa Magma is the blue-green algae which is spread by airborne spores and is usually the cause of those dark streaks. It doesn’t do much to your actual roofing, except make it look unattractive, so we’ll show you how to clean it and keep it clean.

You can do some occasional chemical cleaning – you should only do it occasionally, because overuse of the harsh chemicals can damage your roof and shorten your shingles’ lifespan. You can use various products such as “A mixture of trisodium phosphate (TSP), bleach, and water”. There are some things that you’ll need to do your cleaning. They are:

  • Cleaner
  • Pump sprayer
  • Garden hose with spray nozzle
  • Safety glasses or goggles
  • Rubber gloves
  • Safety rope
  • Old clothes
  • Slip resistant shoes
  • Ladder

You should know that bleach is not only dangerous to algae, but it is dangerous to other plants and to the human body as well. That’s why you need to wet down any surrounding plants and cover them with alcohol. Also, wear protective gear to keep yourself safe from the effects of the chemicals.

The best kind of day for cleaning the roof is a cloudy day, because that helps to keep the cleaning product from evaporating too quickly. Contact the shingle manufacturers or their website for directions and recommendations on cleaning. Check out the cleaning products you will be using for your roof and follower their directions carefully.

The basic formula for cleaning a roof with bleach is:

  • 1 quart bleach (6% sodium hypochlorite)
  • 1 gallon water
  • 1/4 cup TSP (trisodium phosphate) or other heavy duty cleaner (not one made with ammonia)

Cleaning: Wet the roof with the solution and leave it there for approximately 15 minutes and then rinse it off with a hose.

Preventing: Install a strip sheet metal, coated with copper or zinc along each side of the roof, just under the ridge. “While copper is more toxic to algae, galvanized sheet metal is much less expensive. You can also use these methods to get rid of moss on the roof as well.

Discuss it with us. We know the ups and the downs and we can help you choose what’s right for you. If you’re in Nashville, you can contact us for all of your roofing needs. We are certified roofers in Nashville and we start with an inspection and a FREE estimate for your roof installation, repair, or replacement. Even when storms do their damage, we’re there for you to fix leaky roofs and more. Pick up the phone and call – we’re waiting!

Asphalt Shingle Roofs

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Showalter Roofing Services, Inc.

2183 Hillsboro Road, Suite 206, Franklin, TN 37069

(615) 266-2625

Fax: 865-381-1533