Cleaning ServicesExpert Advice

Cleaning Asphalt Shingle Roof

Q: I have a 12 year old white asphalt shingle roof with a lot of dark staining from the leaves of the nearby oak trees. Is there anything I can do about it?

A: Your question about discoloration on your roof is a good one that we hear a lot. There is no recommended solution for “oak” stains. However, according to the MSA (Master Shingle Applicator) manual published by Certainteed Roofing Products, the following is suggested for fungus or algae and should lighten oak leaf discolorations.

  1. Mix a solution of 1 part chlorine bleach, 3 parts water, and a pinch of TSP (Tri-Sodium Phosphate.) TSP can be purchased at most home improvement stores. Before applying the mixture you may also want to cover any plants or shrubs around the perimeter of your home to avoid damaging the foliage.
  2. Apply this solution gently to the surface of the roofing, being careful to avoid damage to other parts of the building and its surroundings.
  3. Avoid scrubbing as well as other physical contact with the roof because the friction may loosen and remove granules that coat the surface of asphalt shingles. Work from a ladder whenever possible, or use “walkboards.”
  4. Finally, rinse the bleach solution from the roof by gently spraying the surface with water.
  5. Observe all possible safety precautions when working on or near the roof. Besides giving special attention to ladder safety, be advised that the solution application and rinsing process makes the surface of the roof slippery and therefore hazardous on which to walk.

The effectiveness of the cleaning and bleaching techniques is temporary, and discoloration is likely to recur.

CAUTION:High-pressure washing systems for algae removal should be used only by reliable professionals because incorrect application can result in removing granules and shortening the life of the roofing system. This information is brought to you by Will and Kathy Babin of Superior Roofing in San Antonio, TX.

Kathy Maynard

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