We’ve all seen them, those strange dark streaks traveling down roofs. So what is it?
Algae! Gloecapsa Magma
It’s a type of algae that commonly plagues asphalt shingles. The algae feeds of the calcium carbonate from the shingles. They won’t damage the roof, but they can be quite unsightly. Luckily, there are ways to treat and prevent this. Treatment Don’t high-pressure wash. Try cleaning the roof with a simple cleaning solution. William Woodring of Those beautiful copper roofing accents aren’t just for show. Algae doesn’t grow around copper or zinc. The metal leaves behind traces in the water runoff, which prevents the algae from growing. Metal strips of copper or zinc can be applied to the roof ridges and flashings to make your roof less algae friendly. Even better, install algae resistant roofing for an easy and long lasting clean roof. GAF manufactures roofing that is very algae resistant. All of GAF’s StainGuard® shingles such as Timberline include a Moss is common on densely shaded roofs in damp areas. Moss is much more concerning because it can cause severe damage to roofing shingles. It causes the granule coating to wear away. Lichen is less damaging to roofs because it doesn’t retain moisture the way moss does. The earlier you remedy these problems, the better. Treatment If the roof has heavy moss or lichen cover, then it’s probably too late and a new roof is likely needed. If the shingles are damaged, then the roof cannot be safely cleaned. Contact a roofing contractor for a roof replacement assessment. GAF has a factory certified contractor search on their If you are re-roofing then choose a resistant roofing product. Asphalt shingles that are resistant to algae are also likely to resist moss growth. Another option to consider is a 100% metal roof. Metal roofs are not just for commercial buildings. There are a wide variety of metal roofing styles, some can even mimic slate or terra-cotta. Explore your options and talk with a certified roofing professional to help you through the process.