Atlanta Roofing-What Are The Black Stains On My Roof?
If you see black stains on your roof, especially on the north side of the house, the Atlanta roofing experts will tell you, it is most likely a form of algae known as Gloeocapsa magma. This is a particularly hardy variety and it is hard to get out of tiles, shakes and asphalt shingles because their surfaces are porous. It may start out as almost undetectable spots, but before long, the algae plants can grow and spread over your roof.
This algae likes moisture and humid climates, but it can grow anywhere in the USA. People call Atlanta roofing contractors all the time asking what the dark streaks and stains are on their roof. Many think their shingles are discoloring because they are not made well. Few are excited to hear it is algae.
If left untreated, algae can seep down into the insulation, the under deck wood and into your home. If you have a recently built home with fiberglass shingles, or have just replaced your older asphalt roof shingles with the newer, lighter ones, they most likely have limestone in them. Limestone is especially susceptible to algae formation. The algae spores could have been lying dormant on the old roof, waiting until they had a substance onto which they could thrive.
But there are ways to kill off algae. Zinc and copper are poisonous to it.
An Atlanta roofing contractor can install copper strips along the peaks of your roof.
Then, when it rains, a bit of it will cascade down and deter the algae from spreading. A professional Atlanta roofing contractor can lay a row or two of copper stripping under the shingles at the cap of the roof. The trick is to slide the copper sheet about five inches under the shingle, leaving about two inches exposed to the elements. Another way is to buy new fiberglass shingles with copper granules built right into them.
Finally, if you do see dark streaks, clean the roof with the use of a deck cleanser. Just be sure to choose one with oxidizing bleach in it – but not chlorine bleach. The fumes from chlorine bleach can be hazardous to your lungs. On a cloudy but dry day, mix the cleanser with water, following the instructions on the label. Spray the roof down with it. Try not to let it dry, but allow it to soak for about thirty minutes. Then scrub it with a brush in the direction of the slope and rinse the roof thoroughly. Never spray up under the shingles where water can accumulate and seep into the attic. Always rinse down the slope to the eaves and make sure none of the water pools in the valleys of the roof.
One word of caution – be very careful. Wet roofs are slippery roofs. Please wear a safety harness at all times.