shingle roof cleaning; any experience with commercial sprays???

jaansuAugust 18, 2013

I note there are a number of products for cleaning roofs of black streaks (Spray and Forget, Defy, Zinsser Jomax). I have some minor streaking I'd like to clean by spraying something without needing to use any brushing. Anyone have any experiences, good or bad, with such products?

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It's usually an algae. Bleach and water mixed 1:2 (ie 1 gal bleach, 2 gal water) will make it go away, pretty much instantly. Apply with a garden sprayer. No need for anything fancier or more expensive. I've heard that copper, lead or zinc strips mounted at the peak will prevent regrowth, but have no experience with this.

    Bookmark   August 19, 2013 at 1:15PM
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Thanks, I've mixed reviews to strong base on shingles. The commercial mixes seem to make use of other oxidants and are less likely to impact my plants.

I put up zinc strips but they haven't entirely protected the roof. Trouble is that relatively little rain washes down the zinc ions since they are near the top of the roof.

    Bookmark   August 19, 2013 at 8:04PM
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If you are worried about plants, paint some of the perspective cleaners on a sample and see what happens. Be reasonable. Wet them before and rinse them promptly. If you are worried about shingles, soak some shingles in a solution for an extended period and see if there are any effects. I think that in both cases, you will see that there is no impact.

    Bookmark   August 19, 2013 at 8:56PM
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that's a great idea, do a stability test before starting. Thank you.

    Bookmark   August 20, 2013 at 6:46PM
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Been there, done that...hopefully I won't have to do it again.

Had a company come out and do a "test drive" on part of the roof. Same thing, a slight change but nothing significant. I then tried a couple of commercial solutions that had little effect on my roof.

I ended up using 1:2 bleach to water with a squirt of Dawn dishwashing liquid in a garden spray bottle.

I sprayed a section, and let it sit, then rinsed. Some improvement, but not a what I was looking for.

I ended up having to lightly scrub the shingles with a very soft bristle brush, just to agitate the liquid against the granules. I really didn't loosen any granules. Just a soft scrubbing.

I thoroughly watered the foundation plants (mostly holly) and the grass near the house both before and after treating the roof. Didn't lose any plants or grass. I do have gutters and downspouts, I gave the gutters a good hosing afterwards.

    Bookmark   August 26, 2013 at 7:35PM
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Alkalinizing the solution with TSP or a substitute can increase the effectiveness of the bleach considerably. TSP is not available in some areas due to its impact on water quality. Substitutes, sodium meta silicate, borax and sodium carbonate, have varying effectiveness.

You might not need the higher effectiveness so much for removing the black or algae (most common and will not harm the shingles). For moss and lichen (that will damage shingles), you might find it useful. You will probably want it for black mold too,

Wetting the surface of the plants is likely more important that watering the soil. Use caution when using strong bleach solutions, especially if alkalinized further. Use eye protection, and don't breathe the dust. The solution may cloud glass and is corrosive to metals so rinse metals and glass promptly.

    Bookmark   August 26, 2013 at 8:42PM
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Depending on condition of stains, different cleaning agents are being used for cleaning roof shingles. We have used Roof Cleaner OX which is Oxygen Powered, environmentally green eco-cleaner that works well with roof algae stain removing power.

    Bookmark   September 3, 2013 at 5:11AM
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thank you all. I decided to use a product I found at HD that claims it is safe but required 6-9 months after spraying to remove the algae stains. As my roof has barely noticeable problems, I shall wait and see the results next spring or so. Otherwise it is the TSP/bleach route.

    Bookmark   September 3, 2013 at 8:15PM
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What was the product? Algae would be expected to bleach out and slough off if it is all dead, but it would take time. Bleach will decolorize and kill in one swoop. I expect that your product is an algicide or algistat. I wonder if it has some residual effect.

    Bookmark   September 3, 2013 at 8:37PM
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I don't know if I am supposed to mention product names but they sell Spray & Forget. The reviews seem to look good and my reading the MSDS (I'm a chemist) suggests it isn't too toxic or corrosive. Must admit, very easy if it works. Just spray it on and you are done. I'll try to post back by next spring to give a report.

    Bookmark   September 6, 2013 at 6:37PM
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"Cationic surfactants" I think it will not work very well with hard water.

    Bookmark   September 6, 2013 at 7:32PM
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There are several different reasons why someone may decide to clean their roof. The most common reason is to restore the appearance of the roof as well as the overall curb appeal of the home.

Roof Cleaning Company

    Bookmark   August 22, 2014 at 7:18AM
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The Spray and Forget stuff I put on last year seems to have helped on the minor discolorment but it is still not good for one section where I still clearly see the darker areas. This area remains in shadow and is a particular problem. These shingles are at least 15 yr old and may have lost the anti-algae properties. I will spray again this fall and see if the troubled areas fade to any degree.

    Bookmark   September 1, 2014 at 10:05AM
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I tried using this Bayer Algae and Moss Killer stuff, and it did nothing. It is basically soap (potassium salts of fatty acids).

I am tempted to use bleach, but is that safe for the roof? Some Googling reveals this is bad for roof tiles... but that is from people trying to sell a professional roof cleaning I think. My roof still has plenty of life left and I don't want it to wear early from all the moss and lichens etc., I have a section of roof in full shade.

    Bookmark   October 1, 2014 at 11:06AM
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Soap (potassium salts of fatty acids) will not work well with hard water. If you want to know if bleach (or any other agent for that matter) will hurt something, soak the material in a container at the working concentration for a few hours to a few days and see what happens.

    Bookmark   October 1, 2014 at 8:30PM
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