Introduction: | Let's jump to the exterior of the home, for a couple of questions...Have you ever noticed an asphalt shingle roof that is only a few years old, but has been discolored by dark streaks? If you have seen it, have you ever wondered what caused this condition? |
Answer: | FALSE - OK - I kind of gave you an easy one with that question (only one person answered incorrectly)...the dark streaks are not be caused by bird droppings. BUT the REAL question is - what causes the streaks? According to a recent article in "COMMUNICATOR" magazine, the streaks are most often caused by algae build-up. The article specifically cites the Gloeocapsa magma variety of algae as being airborne and after landing on the roof, it feeds off the limestone filler used in asphalt shingles. According the Owens Corning, a leading manufacturer of asphalt shingles, the algae doesn't effect the service life. But there is no doubt this eyesore is unattractive when showing homes. So, what can you do about the discoloration? Short of replacing the roof, Owens Corning recommends spraying the roof with a solution of diluted chlorine bleach (1 gallon), trisodium phosphate[aka TSP] (1 cup) and four gallons of water. Rise the roof after 10 to 15 minutes - but scrubbing the roof or pressure washing IS NOT RECOMMENDED, as it will loosen or remove the granules. |
