Roof Cleaning Help (pictures attached)

After attending the Huge Convention, we decided to get into roof cleaning as a lot of homes in the area are in need.

This is only my second roof. The first one turned out really nicely. I’m a little concerned about this one. It almost looks worse than before to me. I am using a SH 12.5 mix recommended on Spraying directly from a tank, no rinse.

Am I doing something wong? Does the mix need to be hotter? Would rinsing help?

Looks like you just need to hit it again

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12.5 no dilution? DS or 12v pump?


Mix probably isn’t strong enough. Brown means it worked if it’s still black like that it didn’t

What’s your mix ratio? Make sure your SH is good and you need to be at 3.5 - 4% net of a roof like that. It will clean up easily. Not even super dirty but that looks like a before pic. If that’s an after pic, then why did you leave it. You should see a significant difference in less than 10 min. If not respray and/or bump your mix up and respray. It’s not rocket science.


Are you saying you are down streaming and pulling straight 12% to the injector? Its clear you arent applying straight 12

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If so that’s probably around 1.2% hitting the shingles and would explain the lack of effect.

Use a foamer is you are using a pw instead of a pump

Using the right percentage of sh is more important than application method. Let’s start with the right amount of sh


Answer the questions so ppl can help you. How’d you apply ?


Sorry about that guys my account was brand new when I asked the question and it was on hold so I couldn’t reply.

I had my mix in a poly tank sprayed directly with a 12v pump.

Turns out my mix was only around 26% so must have been a little too weak, right?

8 gallons 12.5%SH, 20 gallons of water, and surfactant

To weak… that dirty of a roof you need to be 15 gallons sh to 20 galllons of water…(might need more mix). Spray…wait ten minutes…spray bad areas again. Leave, let rain take care of it.

I do net 30 invoices on all my roofs


Thanks for your input. So should I expect to see a major difference while I’m still there at the job?

You will see black streaks turn brownish and start to go away…but will not be 100%.

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Ok awesome thank you!

Within 10 mins the roof should look nearly 100% new but with a slight tinge to them. That tinge will rinse off. Any dark areas should be hit again. If you have doubts it will rinse off, hit it again. Don’t want to have to make another trip out


Thank you. Is it possible to apply too much bleach?

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100% yes. Main reason is the harm to plants with runoff and over spray. Secondary reason is wasted money.