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Thread: Roof Algae

  1. #1
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    Roof Algae

    Yesterday I noticed black streaks on the third of my roof that has not been replaced in 20+ years. I am reading this is an algae caused by the type of hot humid weather we had this year and can removed with a sprayer and bleach/ water or similar solution. Has anyone else done this?

  2. #2
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    I have never used bleach/water but I have used Wet and Forget on roof lichen and black algae on concrete. The information on the label states that Wet and Forget will remove algae, mold, moss, mildew. Wet and Forget works.

  3. #3
    Senior Member SteveinMN's Avatar
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    Consider how much effort you want to put into (onto?) a roof that is close to/at the end of its useful life (asphalt shingle, right?).

    Newer asphalt shingles are made with granules which are coated to resist algae and similar contaminants.
    If Americans expended even a fraction of the energy on civic engagement that we spend on consumer ideology, our democracy would be much healthier. Can you imagine people camping out to vote? -- Charles Roberts, Amherst, Mass., Nov. 25, 2006

  4. #4
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    We have these streaks and our roof is only 7 years old. We never had them on the old roof, but we have used wet and forget on siding, cement and it does work! Only problem is it cannot be used on a hose end sprayer only a garden sprayer and I have yet to find one that sprays up to the roof....So we will need to be on the roof...so it won't be done. I'm looking for a relatively inexpensive garden sprayer that will at least reach the siding on the steep sides of our little rancher.

  5. #5
    Senior Member Williamsmith's Avatar
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    Our condo association uses an algicide to kill the unsightly algae. We can’t have our community looking shabby now, can we?

  6. #6
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    Wet and Forget sounds good. There are no shingles buckling from heat so I think the roof still has some life in it. And the roof is relatively flat and close to the ground (from a 3 season porch that was later completely enclosed).

  7. #7
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    I had my roof professionally cleaned a two years ago,way to high for us to do ourselves. Yes SteveinMN was correct about the new shingles. IDK, I kinda felt it was a waste of time washing the roof.

  8. #8
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    A note about shingles. We replaced our shingles that had been on the roof for over 60 years. The shingles were still fine but we wanted a different color. I don't know anything about the shingles (brand) other than they were really thick. We have a very steep roof and never had algae or mold on the old shingles. I am sure our new shingles will definitely not last that long but then I won't be alive to see. Roofers tell me that steepness helps prolong the life of shingles.

  9. #9
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    Interesting about the slope goldensmom.

  10. #10
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    Quote Originally Posted by Yppej View Post
    Interesting about the slope goldensmom.
    There must be some advantage to a steep sloped roof. The disadvantage, however, is that one company that gave us a bid on the roof job then declined to do the job because the roof was too steep, they did not want their men working on such a steep roof! It is a 2 -1/2 story house with lots of angles.

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