The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them. You can also cover them with tarps or plastic sheeting, which will protect the soil around your plants as well. Make sure that you create a wide radius around your home to be safe.
Allow the solution to soak into the shingles for at least 15 minutes. If they are severely molded, you may want to give it a little longer. Next, rinse the shingles thoroughly with a garden hose at low pressure. Start from the top shingle and rinse downward to prevent water seepage.
To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.
The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above.
On Whidbey Island in Washington state, moss on the roof is a common and it is treated with a water/vinegar mix. The acidity of vinegar prevents further growth of the moss. The addition of water to the mix keeps the vinegar from harming the roofing material. Spray it on and you should see an end to moss growth. By the way, there are options for commercial products that will do the same as the vinegar/water mix.
I would just power wash the roof. Then make sure that the roof gets sun since moss grows when it doesn't get sun to keep it from growing. I had this issue with half of my she'd the south side received sunshine the north didn't and to top it off the neighbors tree limbs come over the shed. I don't want to pay for someone to cut his tree limbs it's a beautiful old tree that is scary but healthy. I know my rights and I can have them cut but I don't want to harm nature. Power washing is quick. If you don't own one you may want to rent one if you feel comfortable handling this on your own and only you can decide, otherwise hire someone to do it.
This week I noticed that my 12 year old roof has bright green moss on the shingles. This roof faces north/east and we have had two very wet summers in SW Michigan. I ...
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Use a product called Wet-N-Forget which is a safe non-toxic product s for all surfaces.
The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them. You can also cover them with tarps or plastic sheeting, which will protect the soil around your plants as well. Make sure that you create a wide radius around your home to be safe.
Allow the solution to soak into the shingles for at least 15 minutes. If they are severely molded, you may want to give it a little longer. Next, rinse the shingles thoroughly with a garden hose at low pressure. Start from the top shingle and rinse downward to prevent water seepage.
To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.
The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above.
On Whidbey Island in Washington state, moss on the roof is a common and it is treated with a water/vinegar mix. The acidity of vinegar prevents further growth of the moss. The addition of water to the mix keeps the vinegar from harming the roofing material. Spray it on and you should see an end to moss growth. By the way, there are options for commercial products that will do the same as the vinegar/water mix.
I would just power wash the roof. Then make sure that the roof gets sun since moss grows when it doesn't get sun to keep it from growing. I had this issue with half of my she'd the south side received sunshine the north didn't and to top it off the neighbors tree limbs come over the shed. I don't want to pay for someone to cut his tree limbs it's a beautiful old tree that is scary but healthy. I know my rights and I can have them cut but I don't want to harm nature. Power washing is quick. If you don't own one you may want to rent one if you feel comfortable handling this on your own and only you can decide, otherwise hire someone to do it.
Get a box of tide and sprinkle on the roof, along the top then when it rains it washes it down and off. Works great here in WA. state.
Clean the roof, then put down Moss Out by sprinkling it all over the peaked part of the roof.