Really bad algae on dryvit- pics attached

Hi guys, here’s another situation i could use some input on. I’m finding that dryvit is a drag to clean. Too many nooks a crannies for algae and other gunk to hold on to. I soft washed most of a house today and it went pretty good. My mix was 4 gallons of 10% sh, 10 oz. simple cherry and 1/4 cup of dawn.

There were a few spots where the algae was really heavy and the initial application didn’t seem to cut it. So i used a soft bristle brush and applied the mix undiluted to those areas, let it sit for a few minutes and then rinsed. That seemed to do the trick.

I have one more area to clean that is in worse condition than anything i’ve yet dealt with. see the pics below. my question is, should I just apply undiluted mix with a brush to this stuff, since the algae is so heavy? should i try a different product? any methods i don’t know about? how would you restore these columns if you had to clean them?

dont have enough posts to add links or photos, so just copy and paste the links below please. thanks!

I would try using a product like Fresh Wash. Fresh Wash will augment the cleaning power of the SH, which may allow the mixture that you stated to work. On it’s own tho, that ratio is probably too weak for cleaning this job, assuming you have a normal injector.

You’re going to need almost roof cleaning mix to clean this. I would do a direct application method. You could use a roof cleaning pump, or even a pump up sprayer for stuff this easy to get to. Using a brush to apply would be too messy and you would waste a lot of chemicals. I would try using a 50/50 mix of your 10% and surfactant. This, of course, would give you a 5% ratio. This high of a mix can kill plants. Keep everything wet and rinsed.

Just so you know, be careful when setting expectations for these kind of jobs. You may be able to clean it, but it may not look brand spanking new when you’re done. Sometimes they turn out perfect, but not every time. Algae buildup of that caliber can hide a lot. If the surface needed painting before the algae started growing - your not going to fix that simply by washing it. On jobs like these, I guarantee the surface will be clean, but it may not look perfectly new.

I have a pump sprayer. do you think i should apply an undiluted shot of my current mix via sprayer ( to maximize use of chemical) and then rinse with moderate pressure? i’m shooting for monday as my last day on this project and i’m basically working with a blank check. wasting chemical isn’t a big deal on this one…

Your pics below, sir.

I am a simple cherry fan myself and so I would approach it with a 50/50 blend of hypo and water with 16 ounces of SC per five. Apply with a roof pump or pump sprayer as Micah suggested. Either would work fine here. We used to use dawn for house wash surfactant but it can kill the bleach in short order so make sure to use it soon after mixing.

Spray, dwell, gently agitate with an acid brush, spray, dwell, agitate, rinse. Be amazed. Repeat as needed. I do agree with Micah that you will likely find some surface deterioration under all that funk but chances are that the customer will be impressed non the less.

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got this job done today. followed most of the advice you guys gave me. 1/2 12% sh, 1/2 water, 10 oz. simple cherry. Went through about 6 gallons total. i did apply with a brush, mainly because my pump sprayer sucks and the time i saved paid for the mix i wasted. pretty pleased with the results. Tim, you were right- some significant surface damage. But from 5 feet away the columns look like new.

I’m guessing the nba basketball wife of the house will be more than impressed with the results. doesn’t take much to blow these kinds of people away.

thanks for the advice.

Nice work, Caleb.