Very heavy mildew


Hey folks, how strong could I go on this mildew with SH? I used a pump sprayer and applied at 5% and it worked for the most part, but not completely. I’m only letting it dwell for about 10-12minutes. Would you leave it longer? Any concerns if I bump it up to 7%? Last picture shows why they shouldn’t let their employees use a pressure washer. These are all before pics, only after pic I have is of the entire back side of the building.


Did you do multiple applications?

Me personally, i think id make it stronger, do a few more passes, and maybe add degreaser if needed??? That is probably terrible advise, and im sure other will chime in.

But i mainly wanted to comment and say how much I LOVE that last pic.


The right side of the building I started just DSing my regular mix. Noticed it wasn’t touching it, so when it started raining I ran home and grabbed my pump sprayer. Left side is 5%, 2 applications. A definite difference but i think it will get a bit cleaner. I didn’t get a chance to use the pump sprayer on the right side, gonna hit it tomorrow. Started raining again so I called it a day. And I happened to talk to the employee that did it. He mentioned he was the only other person to pressure wash the building in the past 4 years…


May have to hit several times with about 10min dwell in between. Don’t rinse in between. Make sure you have a little surfactant in mix. Usually that split face block will clean up really nice with just one strong application and just medium pressure.