White tile/terra-cotta roof

Hello everyone!

First, I want to introduce myself. My names Jordan and I’ve been in the Central FL pressure washing biz for a decade now.

Second, y’all have been sooo very helpful in my education. So thank YOU!

Third: I have done 9 roofs now, and without the info you all have provided, I would’ve never even begun. BUT, I’ve got a WHITE TILE roof booked for next Thursday and it’s SUPER dirty and I need advice.

I did a test spot using 3.5% SH and some Gain dish soap (the “New Apple sauce” mix based on Apple Roof cleaning of Tampa’s recommended roof mix). I’ve used this roof wash mix with much success. But for this roof, it came out okay, but there we’re still some brown spots and the edge of the tiles were still brown. I applied a second coat at 4% SH and it was still there.

After I let it sit there for 20 minutes or so, I rinse it off with the garden hose. Did it just need more dwelltime? Was my SH not hot enough? I’d be nervous using anything more than 5% SH because there are no gutters on this roof.

Any suggestions on how to clean it all off?

Thank you!!

What’s your original application percentage actually hitting the surface?