Asphalt Roof Shingles

If you are situated in a moist or humid area in your state, you definitely have seen unpleasing dark spots and streaks on your asphalt roof shingles. These are often due to the accumulation of mold, dirt and blue algae that can be spread via airborne spores. If you think that a little algae does not cause so much damage to your roof, you may be wrong as this can badly affect the overall appearance of your home.

Chimneys and roof vents are free from algae because they are made up of pure copper and zinc. These kinds of compound material are very toxic to the algae. Thus, whenever it rains, the water that flushes off from the roof (with metal and copper) inhibits algae formation.

Recently, roofing manufacturers have started mixing copper grains to roofs like 3M Scotchgard that makes them highly resistant to algae growth. If you think that you are in an area with high susceptibility to algae growth, make sure to replace your roof with this type of shingle.

Thorough chemical cleaning can remove algae but it eventually returns in time. But be careful not to overdo this as it may shorten or damage the life of asphalt roof shingles.

Products that are designed to facilitate removal of stains and algae from roof like Moss Out and Spray and Forget can be used. A simple mixture also of bleach and water can be helpful in the removal of stains. Oxy-bleach has the power to lighten stains on the roof without harming the environment.

Here are the things you need in cleaning your roof:

  • Pump sprayer
  • Cleaner
  • Hose with nozzle
  • Rubber gloves
  • Safety rope
  • Rubber shoes
  • Ladder
  • Old clothes

Safety First

Working on the roof is dangerous and even becomes more hazardous while it is wet, so just be sure that you know enough safety precautions before doing the chore. Never work on a steep roof, the use of safety rope is also highly needed. If you plan to use chemicals, see to it that your eyes and skin are protected all times.


It is best for you to clean on a cloudy day as this would prevent easy evaporation of your solution or might as well check the manufacturer’s instruction for cleaning recommendations.

If you plan to use Oxygen bleach follow this formula:

  • 1 gallon water
  • 1 quart of bleach
  • ¼ cup (trisodium phosphate) or other cleaning solutions

Mix them well in a garden sprayer (pump type) and spray. Let the solution stay in the roof’s surface for 10 minutes before rinsing off with water using a garden hose.

Finally, to prevent algae from thriving back to your roof, it would be best to install a copper strip or zinc coated metal along the sides of the roof.

The procedure above may also be effective in the removal of moss.

VIDEO: Asphalt Roof Shingles

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