Roof stain removal?
#11
I have a 40 year asphalt shingle roof about 18 years old. We have a shaded lot.

The section that faces east is covered with a greenish stain which is annoying LOML. Can treat this myself by spraying on an algicide or similar, or is this a job for pros? Is there anything to avoid using that would shorten the roof life or cause premature shedding of the roof grit?

Thanks in advance.

Chuck O
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#12
(02-22-2018, 09:13 AM)ChcukO1234 Wrote: I have a 40 year asphalt shingle roof about 18 years old.  We have a shaded lot.

The section that faces east is covered with a greenish stain which is annoying LOML.  Can treat this myself by spraying on an algicide or similar, or is this a job for pros?  Is there anything to avoid using that would shorten the roof life or cause premature shedding of the roof grit?

Thanks in advance.

Chuck O



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#13
I've had good luck with This stuff on my siding.  I've also heard pool shock works well - which would be similar to the bleach recommended by TOH in the article linked by Cletus.
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#14
3 Houses ago we were living in the woods with the problems you get with a shaded roof. I used household bleach to kill, and found I had to retreat every other year or so. Small tip: do not let it drip down, like onto someone's clothes or something...don't ask.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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#15
I had a similar problem on the north side of our roof, although maybe not as bad as you describe.  I applied a product called "wet and forget" with great results.  You mix it w/ 5 parts of water and apply by spraying. I used a pump type garden sprayer which meant being on the roof, a process I no longer enjoy.  If I have to do it again, I'll try a super-soaker from the edge of the roof at gutter level.  It took a few weeks for the stain to go away, but it did work.  ronwhit
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#16
(02-22-2018, 10:26 AM)JosephP Wrote: I've had good luck with This stuff on my siding.  I've also heard pool shock works well - which would be similar to the bleach recommended by TOH in the article linked by Cletus.

Pool shock is bleach, but much, much stronger than the stuff you use for the laundry.  I have no doubt that it will kill moss.  But so would dousing the roof with gasoline and lighting it.  

I wonder what damage it might do to the roofing materials themselves.
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#17
(02-22-2018, 10:54 AM)fredhargis Wrote: 3 Houses ago we were living in the woods with the problems you get with a shaded roof. .....

This brings up another point...are there a few limbs that you could have pruned back to get more light/airflow to the roof?  I'm an arborist, so I see this a fair amount.  When that is the client's primary objective, we can often take off just a few limbs without deforming the tree and significantly change the conditions of the roof.  It is always a little give/take because a cooler roof will last longer and keep the rest of the house cooler, so we aren't aiming for full exposure, just a little more light on the bad spots, better airflow, branches away from the roof so they aren't causing physical damage.  Usually that means the lower limbs over the roof come off, but the higher ones are left in place. I'm biased, but I recommend you check out treesaregood.org/findanarborist and look for a Certified Arborist to find a tree care professional will have a higher probability of knowing what they are doing...
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#18
I too use Wet and Forget on my roof, vinyl siding, shadowed deck and other stuff that gets green. Using bleach is not good for your roof or your gutters. It is corrosive and does not last well. Can't use it on your siding either. I sprayed my roof three years ago and it's just now starting to need a another treatment. My neighbor uses bleach and does it every year I think.
Was living the good retired life on the Lake. Now just living retired.
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#19
There are zinc strips you can add to the shingles. Rain water spreads a tiny bit of zinc on the roof and inhibits the growth.
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#20
A few years ago I think Mags recommended a product called Spray and Forget.
It takes up to a month or two for the algae and stains to disappear, but then they stay gone for a long time. Every 2 years I spray again and none of it has returned. It's also non- corrosive to your roof, unlike bleach.
Following the directions is key. I highly recommend.
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