I’ve never cleaned a metal roof*, but i have researched and read many threads about them. The guys above have the right idea, from what i have read.
From what ive read, its not too hard to get the black stuff off, but ive seen a lot of people talk about issues with oxidation. If it’s oxidized and you use too much pressure, you can leave streaks just like on vinyl. So go easy on it and maybe do a test patch. To fix oxidation issues, and/or to get the best result, people have scrubbed the roofs, which has produced some really excellent results, but that takes time, and needs proper safety precautions.
F-13 is something i have seen recommended to use on a metal roof with oxidation issues, in combination with brushing. It really brings the shine back in the examples i have seen. I just ordered some, to practice on the roofs of a couple of sheds, and a horse barn at my place.
*I cleaned one metal roof when i was helping a guy with a pressure washing business, but he was a dingbat and didnt really know proper methods. First we filled up a couple of 4 gallon backpack sprayers, and tried to walk up the wet roof without falling over… which im sure was quite a show. Then when that didnt work we resorted to climbing to the top and pouring jugs of Big Lots bleach (3%) down it. He had years of experience, and at the time i thought that was just how it was done. WRONG.
I’ve read several threads on their forum where Brandon and others discuss metal roofs. Final Wash is a finishing soap that neutralizes bleach and has a waxing agent in it. In those threads, he has said he uses Final Wash at the end, but not to remove the oxidation.
I would guess he is using Oxi-Wash to get the oxidation off, which is also sold by Softwash Systems. Several other people on their forum have discussed doing the same thing with F-13.
You could ask him in the comments of the video to confirm, probably.
I had a lot of trouble with the black stuff on the last roof I did. I had to apply some pressure to get it off…on a side note, my chem mixture was not nearly strong enough and I did not use enough. Luckily, the customer is coming on top with a sealant type product and requested me to apply pressure. Pictures here from the last roof job I’m referring to. I’m hoping no oxidation issues on this roof I quoted but I’ll find out soon enough, granted he goes through with the job. I’ll check into the F-13. The last thing I want to do is use a brush, or get on the roof at all! Down in south-SOUTH-Louisiana, alot of homes are built up in the air after storm surge flooding the recent past. You’ll notice that in my pictures at the top of this post. Steep roof plus a 20+ foot drop to the ground! I had to laugh at your garden sprayer method…can’t say I’ve never done it before, for applying house wash…not on a roof! lol Thanks for the input, @tireshark
I’ve been using roof snot on the past three roofs I’ve done. It has worked great and is stable with the SH. I ordered two 5 gallon buckets originally they’ve lasted quite awhile
LanglinaisServiceCo, You are getting some fairly reasonable cleaning advice in the replies. You mentioned you were hoping to avoid getting on this roof. Here’s my two cents; DON’T GET ON THAT ROOF! The gravitational pull followed by the sudden stop is a game changer.
