Cedar Roof Cleaning 101

I have a customer with a 10k sq ft cedar roof… HEAVILY infested with everything you could imagine that would grow on the roof. To the customer, cost isn’t the issue. First things first… let’s talk chemicals and cleaning methods.

I have done tons of research, seen what Sullivan does on his roofs (great work), watched videos, read articles about cedar. I don’t want to use SH on the roof since I don’t want to bleach the shingles and def do not want to put pressure on it. I want to clean the shingles with chemicals and water pressure. I can get industrial TSP (Trisodium phosphate), Sodium Percarb, and Sodium Hydroxide from my supplier. I totally agree with Sullivan on not putting pressure on the roof and instead, use your 12v to apply chem AND rinse with water. I will be using ladder stand off’s (dont’ know what they’re called) so I can lean to the roof and not walk on it. Shingles can compromise if you don’t lift your foot when you turn, cedar can snap or worse if you aren’t careful. My goal is to mix my powders at the proper ratios and wash with my mix. I know Percarb is good for roofs like this, but just want to make sure that someone out there may be able to guide me a bit more as far as ratios, chemicals, and methods. Also, I want to do a brightener with oxalic acid after cleaning. Using an oil seems to not be necessary since the oil may or may not soak in, and probably doesn’t extend the life of the roof any. I may be making this a bit harder than what it is, but I really want to do a good job for this customer. Especially if I’m charging around $.80 a sq ft because of the infestation. Thank you all for your knowledge and support. Look forward to hearing from you.


Who is Sullivan?

He’s a member here. Has a cedar roof cleaning business and YouTube videos. Bruce Sullivan.

Tag him. Just use the @ symbol before his name on here.



Thanks for the tip, had no idea how to do that.

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Got any pics?

I’ll have to look back through, but I don’t think that I got any. I never planned on posting this. It’s just heavy infestation with lychen, moss, and black mildew. The moss infestation is pretty bad since a good bit of the house has some tree cover. It def isn’t good. I am prepared for the roof to take two to three washes given the situation, but want to make sure I’m using the correct chemicals and charging correctly. Cedar is a bit hardier than pine (used on decks), so I imagine any deck washing methods would suffice for the cedar too, but not using pressure? I’ll post what I did and how I did it on this thread when/ if the bid get approved. I also plan on putting a YouTube video up if time allows.

I think that good hard workers avoid work in fear of messing something up or not knowing where to research stuff. The thing is that if you’re a good contractor, you’re the best chance the homeowner has at getting something done without messing stuff up. They could be dooped into someone stealing money or someone saying they know what they’re doing but don’t. So if the information found here can help both a contractor and their customers, I’m in.

Any suggestions? I’m meeting with the guy next week. He asked how necessary it was to have it washed so I’m bringing him pictures of before and after and what it’ll do to the shingles if it stays on there. I guess at the price, I aught to bring him a steak dinner too.

So Sullivan has a system with proprietory chemicals he uses. He charges (last time i inquiered about $3000 usd) to buy into his system and referral network. You wont know his sistem unless you buy i or someone that bought into it tells you.

You can always use sodium percarbonate, low pressure rinse (1000 psi or less) and add some oxalic acid to brighten if youd like. You can also replace percarbonate and use hypochlorite using same steps.

You can use pre made cedar roof cleaners but you still have to low pressure rinse and it costs way more than buying percarbonate in bulk

Also i forgot to mention… if you hve lots of pine needles, moss, etc youre going to have to remove it first (leaf blowing, brushing, even heard you can use air pumps to blow them out even better)… also you better be comfortable walking on cedar shake roofs and buying good anchor + korkers with the right cleats or else book a room at your nearest hospital or funeral home lol

Figure out how many squares it is, then call the largest reputable roofing company in your area and get a price for replacing cedar shake roof. Most will gladly give you a ballpark figure. Then price it at about 10-15% of that. Don’t be shy on the pricing. Once you get that quote from roofing company, you know he’ll be ecstatic with your price, because he’s probably already checked too.

Ahh! You guys are awesome. I gave him $0.90 a square foot, he said is it necessary. I said, well… yes… I’m meeting with him Wednesday of next week to show what it’ll look like after, vs how it looks now. Also I’ll show him how that mess eats his roof.

Thank you so much for your input about the products and methods. I will probably go percarb (55lb bag here is 75 bucks) and wash that way, given he says yes. I have cougar paws and a ridge pro. Are there better options than those for walking cedar? I just called and booked a room at the hospital :joy::rofl:

I do roofing contracting as well, but know only shingle, and have guys that do metal and metal shake, but don’t know any cedar or slate roofers. I was going through Buckhead one day and almost stopped to get the roofers number. Lol. That’s a really great idea though, get a percentage of replacement. That’s going to be for the next job. I’ll keep y’all updated!