Roof Moss

Hey everyone,

First posting here, loving the interchange of knowledge and experience.

I have a window and gutter cleaning business on Vancouver Island and during winter I’ve been pushing roof Moss treatment.

One issue I’ve run into is moss REMOVAL. For the majority of clients it’s not an issue as I’ve explained the process of killing moss first through treatment and then removing it with a brush after 3 months. However some of my clients have steeper roofs, and some have have thick tiles which don’t easily brush off.

With me having back issues I don’t want to spend 8-10 hours on my hands and knees or with my harness on scraping moss off individual tiles… so after all of that preamble my basic question is: have any of you ever used a power brush to remove moss from a roof, and would this be a safe / time efficient way to do it?


You have to look into a roof cleaning set up. It requires a dedicated pump to apply your roof cleaning solution. For moss you would need a 3-4 % mix . You need tanks to hold your solution, An some knowledge of how to do it. For moss it’s not a instant thing. Moss has roots , so you’ll need a few applications, meaning multiple times back ,an after a while the moss will die , roots will loosen , An the rain will wash it away.

you can not listen to a single person outside of the PNW. They do not get it.

You got choices. Full on soft wash a roof with pre brooming and gutter cleaning or come up with your own “moss” kinda thing.

If you do moss treatments you are in the bottom barrell of roof care and get all the assfucks.

Thanks for the input guys, appreciate it - however this doesn’t really address my core question - is it safe to use a power brush on shingle roofs to remove the moss?

Could you post a link to what you’re thinking of using? Not sure if everyone is on the same page as to what a power broom is.

Lol indeed. In a way it’s like taking concrete off bad tempered. No matter how you do it the surface runs the chance of being damaged.

If you use power brushes on it you will most likely be removing a lot of the grit from the surface of the asphalt shingle/composite. That’s like scratching the heck out of glass, seeing as the grit is actually providing protection to the underlying waterproof felt. Without protection from the sun the felt deteriorates and the roof loses years off its effective life. Why you don’t want to power wash them either.

What Majestic66 said is probably the best solution, but most customers don’t want to hear that. Depends on what shape their roof is in and how they feel about it. Explain the risks in removing the most using whatever method you decide on. If a roof has so much moss on it that it’s covering the whole roof then removing it all will expose the potentially damaged roof. Probably be good to have it in writing as part of the service agreement.

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After rereading the original post I’m not sure the ‘tiles’ being referred to are comp… Actual tile roofs would be different - but still what Majestic66 said.

Btw - if you’re walking on most tile make sure you step on them properly. They can break - usually in the PNW they’re over felted sheeting so it’s not as critical, but unless it’s changed from when I did it many years ago, in some areas they are the only thing keeping water out of a house. A cracked tile can be a pita.

Also curious to know what your process is during the winter months . Don’t things freeze up ?

Before undertaking roof cleaning, imo you should know how the roof is constructed, what cleaning techniques can be used on the particular surface.

For example I use surface cleaners on most roofs here. 90% of USA roof cleaners would assume I am some type of hack. But they have no idea or care factor how the houses are constructed here and will argue til they are blue in the face that i am doing it wrong. However it is how the manufactures say to clean their product. here 50% of roofs are colourbond which is a powder coated steel sheet, it is a stand alone product there is no plywood under it, as a matter of fact there is virtually no plywood in Australian home construction the other 50% of roofs are concrete tiles, which are held to the roof via roof battens not some felt sheeting, I have cleaned over 1500 roofs using pressure, nev er had any issues, I have cleaned about 15 roof with just soft wash, out of those 15 I had 6 complaints due to oxidization on the powder coated roofs which the surface cleaner removes. but soft washing makes stick out where the oxidization was walked on to where it wasn’t.

I have no idea if Canadian construction differs from the rest of North America, look into it.

Hopefully this link works…

Yeah it’s majority asphalt shingles here where I am so power washing isn’t an option unfortunately

My window/gutter business keeps me going March-December so I was looking for something in Jan - Feb to keep the revenue flowing. We only get about 2-3 weeks of snow in that period so snow removal isn’t much of an option.
With an already dedicated customer base I emailed them all about Moss treatment and used Kirkland detergent. It worked - all the moss died but it hasn’t all fallen away, just went chalky but mostly sat there.
So there was nothing to freeze up in my setup, to answer your question

Looks like it take the moss off for sure, and then some. I wouldn’t use it on comp myself - unless they are planning on re-roofing. But that’s me. Hate to have a job like that become a source of liability just to make a few bucks. In a way, seems leaving the moss there, so long as it’s dead and not still breaking down the roofing material, might help protect the damaged comp from sunlight like the gravel does. Another reason not to aggressively remove it all imho.

The main question is if in the process of removing all the moss you damage the roof or expose underlying issues previously unseen in the roof are you going to be liable? Is it worth taking the job if so? Does your liability policy cover workmanship?

You could always take some pictures and use them as a sales tool. Then pass on the job and pursue other jobs using the pictures to find customers interested in proper maintenance. Hard to pass up a job when you need work though. On the other hand, you could do a number of roofs that just required a basic treatment- without the liability.

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Have you seen the Airpoles?

If you have a compressor you can run the tube up a WFP. I haven’t done it myself but in the videos it looks very effective.

I hadn’t before you mentioned it, looks interesting…that might actually work!!!

Our situation is similar to PNW so I’m interested in the Airpole company’s offerings - but I think it would be possible to set up a test case with a homemade system.

The pneumatic fittings should be similar.

A lance has to fit the wfp top.

I am not sure I like petrol compressors if I could get away with plugging in an electric one.

Don’t like the idea of scaffolding but if I paired an Airpole with the Waspak coming in the post I could fly around houses.

That airpole looks pretty cool. Like it’d work good for tile or slate, metal even, but still looks like it’d blow a lot of the protective gravel off comp, possibly voiding any warrantees. Just saw a video the other day of someone using a zero degree tip with a pressure washer to blast moss off a composite roof. Had to laugh.