Rinsing Roof Wash versus Leaving it sitting

What is everyone’s method of doing roof washes? I just started them a couple weeks ago and have done about five roofs so far. I mixed 50/50 with slo mo (great product slo mo - thanks @Firefighter4hire for the good advice) soaked it up there. Did all proper safety; tying, water, protective gear. After the first rain non on them came up clean lol. I went back to the first house as of today 9/1 three times for applications. The owner needs to sell the house due to it being a flip. The second woman is losing her mind thinking I am scamming her (it has become my mission prove her to utterly wrong and give her a clean roof beyond her expectations, my pride and word are on the line here guys)…

  1. Is it normal to need to re treat 3 or even 4 times if the moss is super thick? Also how long between treatments… how many days needed between treatments?

  2. How do you guys deal with relatively flat roofs that won’t get a strong run off from the rain.

  3. What do you guys do about the inevitable window splatter that leaves the windows (for example skylight windows, if your response to this is to avoid window splatter.

  4. If you happen to be one of the few who rinses how do guys safely do it?

Thanks a million in advanced for helping me out in my early business stages…

How are you applying the roof mix?

What % is the SH?

What type of roofing material is it?

Are you using a proportioner or batch mixing?


@garry.cooper I am using fresh 12.5% cut in half with water and mixed in with proper amount of surfactant. Shingle roofs and I am using a 12v 7gpm softwash to apply.

I typically do not rinse. use the search bar for roof cleaning and read read read for hours. the rinse or don’t rinse is a never ending debate


The problem is you need to educate the customer…so when dealing with moss it can take up to 90-120 days for the roof to come 100% free of moss.

Most will look great after 30 days but be upfront.

I used to wait net 30 for invoice but changed that recently.

Explain it’s like fertilizing the lawn, your not going to see instant results.


@Patriotspwashing I like the fertilizer idea. Do you have any answers about the other questions? I believe I will collect half up front and half when the roof is completed.

The only roofs I clean are moss covered asphalt. I rinse them otherwise the dead White moss makes it look worse. I let them dry a couple days then swing by and give it a quick rinse, everything comes down. I also build in a gutter clean into the price, will need to empty it out anyways.


When i do roofs i tell the customer upfront about my process. I explain they will see results when im done but after a few giod rains it will fully clean up that the process us not instant. The longer my chemical sits the better. I also offer a 5 year spot free warranty.

The only time i have rinsed is for a man who was putting his house on the market 3 days after i did the roof. I came back that morning to rinsed for a additional charge.

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@Grizz ok thanks

From what I can tell you didn’t do anything wrong you just need more time. You can brush the roof off with push broom then you gotta clean gutters and re apply roof wash.

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You got any pics of before or after?

@Firefighter4hire okay
@Racer no I know I know, I’m just more focused on working and communicating with customers than taking photos - I will snag some next time. But nothing outrageous. Just browned moss.

Also for window streaked, what do you do?

Did you streak a window washing a roof? Dont let chem get on window if you do rinse before it dries. If you really mess up and let it dry rinse with warm water.

We are talking about moss on the roof not mold correct

If you get any solution on windows or skylights, just rinse them before it drys. End of story.
If you’ve got heavy moss brush it off before you treat.
Don’t come down off the ladder till everything is brown. ‘If it’s brown it’s coming down’

You need to work on your presentation to customers as far as expectations. What Grizz said. It took many years for the roof to get that bad, going to take a little while for it to clean. Use thee fertilizer or weed treatment analogy.

I send out a written form for each service I’m doing with quote as far as the process, and what they can expect. That way no drama.


@Firefighter4hire okay wow I had no idea before. Avoid and clean immediately. Thanks :pray:

Okay @Racer you summed it all up
Really well. I will brush it off when possible and not come down until all is brown. I will have a proper explanation of procedure and timings for my future customers. How long should I tell them in general that everything should look great 90-120 days?

Depends on what it is. Realize your solution going to kill everything in like 5-10 min in most cases. Algae stains usually just a few decent rains. Lichen may take six months and moss usually within a month or 2, especially if you brush off the heavy stuff prior to treating, then same, few good rains.


Here, this may help


@racer thanks for sharing. I’ll definitely go off this general idea when talking to customers. I may even write one up of my own having them sign up front as well.

I don’t have them sign, I just send with my quote

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