How to clean black mold off galvanized roof?

Hello there.

A fellow minister called wanting the black mold off his tin roof on top of the church. I looked at it, appeared as the usual black/green mold. Question is, Is it safe to use bleach with soap on the galvanized tin roof? Can I spray anything else such as tsp or borax to keep the mold from coming back?

Thank you.

Sh on galvanized metal is not a good idea. Those old roofs need to be cleaned with special cleaners and a soft brush

What type of special cleaners? Can borax be used or TSP?

I’m not sure I always walk away from galvanized roofs . Not worth the pita

1 Like

I am just starting out therefor I can not afford to walk away from the job lead.

If you damage that roof, you would have made money to walk away from it.

It is a bit foolish to ignore what an EXPERIENCED wash contractor suggests…but, knock yourself out.


Before I begin here on this job. Is this galvanized? This is the result of a pump up sprayer and maybe a 3% mix and rinsed down really well

has a “sheen” to it. It’s not directly what I recall being galvanized as like street lamp poles. I also have agent halt.

Looks like painted galvalume to me. 1-2 percent is all that’s needed . Rinse very well

1 Like

Got the job taken care of. Took me two days.
Got the church and a house cleaned. Used SH x-jetted on the roof.

Worked like a charm and turned out great! However I came to realize that I really would like a dedicated SH application. I am wanting to go 12v route since I don’t have very many calls at this time.
What would be the pump of choice for the soft wash?

P.S. I know that AODD pumps is what professionals use but I am not there yet.

LOTS of professionals use 12v for their dedicated SW system. Lots of brands. 5.5 gpm vs 7 gpm. 6 of one half a dozen of another. :+1: