SH alternative? Additives?

Hey everyone, have a question regarding roof washes. Warm from most roofs seem to be different forms of concrete tile. My typical SH mix does help clean and brighten it up, especially if I give the entire roof a scrub with a push broom. Although it does yield good results it is not realistic long term and for big jobs.

I have no issue killing the moss and it does remove some of the dark color. As shown in the pictures, but it seems that this yellow/dark green stuck on algae seems to stay.

I’ve hit this roof multiple times with a 6% mix, adding more surfactant as well. I’ve seen people say to add rubbing alcohol? Sodium per carbonate ? ( bleach neutralizer)

Looking for something to give it that extra kick and kill the stubborn algae that doesn’t seem to die.(if anyone knows the name of the type of algae too that’d be great)

Rubbing alcohol lol. Please name and shame them.


I don’t live where you live, but you might want to do some reading on here. There have been numerous discussion about cleaning concrete tile, the problems cleaning it in warm climates, and tools that people have used in this country and other coutries to clean concrete roofs. SH still works, you just might need to do some other things as well.

First of all, understand that concrete is porous, once you fully understand that, it will help.


Also, a roof wash is not like a housewash in that the job is not “done” the day you walk away. Granted things may vary on concrete roofs (I’ve seen people promote surface cleaning those, among other things). But on asphalt roofs time is always your friend, but set expectations accordingly.

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I might get some criticism on here for this, but the thing with tile roofs like that is just treating it (even with 6%) doesn’t ultimately make it go away like asphalt shingle. What you’re dealing with is lichen, and that is much harder to remove than Gleocapsamagma (typical green growth found on roofs). Not even after two months. The surface of tile roofs has a different porosity and lends itself to the growth of Lichen which sticks like crazy, (whether it’s dead or alive). The only way I found to make those types of roofs look good is to pressure wash it with a turbo nozzle afterwards. Now it’s very important for everybody reading this to understand that this is ok to do on most concrete tile roofs, but NOT for asphalt shingle. You never want to use pressure on asphalt shingle. One thing you need to be careful with though is that some of these concrete tile roofs, possibly the one shown in the picture, have added color to them and it is possible to takeoff some of the color using pressure. I explain to the clients that the benefit of a tile roof is longevity and ability to withstand cleaning with pressure, but the downside is that unlike asphalt shingle roofs, you cannot just treat it and have it look amazing in a month or two. It needs to be pressure washed to remove the Lichen. It is a very time-consuming process. One other thing to be really careful of is some of the older roofs lack a waterproofing underlayment. If you find a tile roof that does not have this just pass on the job. (I know that sounds silly, but those roofs hold up to regular rain without it in some parts of the country but they do not hold up to using pressure to clean.

If anybody else has a better way to do this, please let me know! But I would like to see some before and after photos with first-hand experience, not speculation based off of experience doing asphalt shingle and what they think should happen. I have a lot of tile roofs out here. Another thing is, some parts of the country might have different kinds of growth on tile roofs than I have. If it’s just Moss or standard growth found on asphalt shingle then you might not have to use pressure. But Lichen, that stuff is your enemy!

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Could you imagine buying a 53 gallon drum of rubbing alcohol? All your neighbors would be like what the heck are they cooking meth in there lmao. I don’t know anything about cooking meth, or if rubbing alcohol would even be an ingredient with that, but it seems sus lol.


Haha for real! I had seen the rubbing alcohol recommendation on a thread somewhere on this site. Wont end up using that.

I’ve thought about using the turbo nozzle or a low pressure JROD tip. The owner was still happy with the results though.

sometimes you have to treat it, dont rinse, then let it actually dry, so you can see whats still needing treatment, then re-treat it again. At least thats what Ive encountered. I’ve never done a roof, but theres a method and time expectation to wait for it to clean itself. This treat and wait method I’d the most beneficial to the roof, whether tile or shingles.

Chloroform does not clean a roof effectively