You’ve seen them.  Those unsightly black streaks on the roof of an otherwise-beautiful home.  They are not caused by soot from the chimney, as some may believe, but are actually algae that form on the shingles.

Algae grows most often on a roof that is shaded by trees, or on the North side of the home, which receives less sunlight.

Does this black algae shorten the life of a roof? Some say it really has no affect. Others disagree, arguing that the algae actually feeds off of the limestone filler that’s an ingredient in many asphalt shingles.

According to Dr. Victor H. Morgenroth, a semi-retired, adjunct professor of neurology at UM, this roof algae can be a health hazzard. “While not all mold (fungi) and algae pose a health danger, some are harmful, especially for us older folks, younger children and people who suffer from asthma and respiratory problems. Their spores, which are on your roof, can get inside your home because they end up on the driveway and walkways from rain, and are easily tracked inside. They can even be drawn into our air conditioning systems and eventually populate our ducts.”

So what do you do if you have this algae growing on your roof?  While not an easy task, it can be cleaned.  Some recommend an oxygen bleach to remove the stains.  Others say chlorine bleach is fine, but watch out: you might kill any plants or shrubs around your house if you don’t contain the bleach.  It’s best to hire a professional who cleans roofs for a living, rather than attempt to do it yourself.

If you need a new roof, then the best route is to pick a roofing material that’s resistent to algae growth.   Pinnacle® HP featuring Scotchgard™ Protector shingles now come optional with the power of  Scotchgard™ to defend against algae streaks and help retain original color.  If you’ve gone to the trouble of picking a nice color for your shingles, you really don’t want that color to change, darken or streak.

Give us a call if you’d like an expert opinion on whether your roof needs replacement, and if so, what are the best products for your home.