Metal Roof Wash Questions!

Hello everyone, I’ve been following this forum for the past couple of years and have gotten great info from the posts here. This is my first post. I’ve been in the residential house washing business for a number of years now and have just recently been washing roofs here and there. This will be my biggest job, I added a couple of pics for reference. What would be my best chemical to use for this roof? X-Jet application and low pressure for the rinse? I have a 4GPM/4000PSI belt driven machine. Customer does want to use SH for the job. Most of the “black stuff” on the roof is from the nearby oak trees. Thanks for the help, guys!

Do you guys think a 10-12.5% SH with roof snot through the X-Jet would take this off? The roof has never been cleaned. Anyone with experience or input on this would be greatly appreciated!

How old is the roof?

Roof is about 10 years old. Never been cleaned.

How have you done the other roofs you’ve cleaned? Metal roofs can be cleaned in a similar manner to asphalt roofs. Whether you xjet it or use a 12v pump or whatever. The black should come off with any of the common methods.

I’ve used my normal house washing solution…8.25% SH, Jomax, elemonator mix downstreamed. I had to apply some pressure on the metal to get the black mildew and mold off on the last two metal roofs I washed… I’m thinking my chem mixture just wasn’t strong enough. I’m hoping I don’t have to get on this roof. The others were not steep and were overhangs that were close to being flat w/o any pitch. I have an Xjet on the way.

1 Like

And thanks for your input and help. Suggestion on solution mix?

Definitely need a stronger mix. Downstreaming won’t cut it. Even downstreaming 12% won’t do it efficiently. Xjet will get a stronger mix on the roof. Ideally, you want a system to deliver the chemicals that’s independent from the pressure washer, such as a 12v pump or a diaphragm setup. Is downstreaming or xjet your only current options for chemical application?

1 Like

Actually, someone on this site said something about removing a piece from the inside of the xjet and getting close to a 50/50 mix, which is ideal for roofs. @squidskc, was that you that mentioned that?

Yep. Just rinse and rinse and rinse some more on a metal roof. If it’s blazing hot out I wouldn’t do it. I’d schedule it for the mildest day of the week at the coolest part of the day. Even still, I’d probably presoak the heck out of the roof and watch how fast it dries to get an idea of what kind of timeline I’m working with.

1 Like

Good call. How did you suggest modifying the xjet to get a stronger mix?

Thanks guys. And yes, right now I’m using downstream and xjet.

Any recommendations on the roof surfactant additive?

@Clean1 told me to remove the proportioner for stucco/dryvit and it worked beautifully. I wouldn’t try 50/50 on metal though. SH is metal corrosive. I’d probably start at 10/1 with the x-jet and go up maybe to 6/1, but two passes are better than destroying a surface.

Roger that, Thanks!

Look at the card that came with your xjet. You want the one that gives you about 3-1. that would equate to about a 2.5-3% mix. I’d start there and see what happens. If you don’t see results in about 5-7 mins, go a little stronger. Don’t let it dry.


Ok, thanks! Will do.

These guys know what their talking about so I recommend their advice over my own, lol.


All advice is much appreciated!

On a metal roof, Elemonator will work just fine. I can’t wrap my brain around “roof surfactant” anyway. The effect of gravity on a sloped roof is no more powerful on a vertical surface like siding. I’d avoid Dawn or other soap like the plague. Super tough to rinse and suspends the SH. Another guy posted a pic of some ruined siding recently and he was running dawn.

Take a pic of that dang card and laminate it. Lol mine came like it was printed on a business card and once wet pretty much worthless.