Power Washing and Roof Cleaning Forum

Art O · Approved Exterior Cleaner

Black on Vinyl Siding

Doug Rucker · Vender

Looks like mold. Strong house wash mix

Fred W · Guru

Yep....what Doug said.

waxman18324 · Founding Member Rest in Peace

Art,

I also agree with Doug Rucker. We see this quite often up here in the sticks on vinyl siding and dryvit. Most times we find it in densely shaded areas behind plant material that is situated too close to the footprint of the home. Last week we had to spray some dryvit with 4% to get it clean.

Hank

ginty · Aprovered Exterior Cleaner

reverse osmosis ,pure water works on some molds and algi

Brian C Jackson · Approved Exterior Cleaner

Art
I had some of that on a house was last week. I did 2 rounds of house wash mix with 2nd mixa little stronger. Finally i hit it with roof mix and rinsed it quick. Then followed up with a coat of house wash mix and let it dwell. Seemed the roof mix needed to get the ball moving and the house wash finished the job.

Capital Roof Wash · Approved Exterior Cleaner

Art, what would concern me the most is why it is so predominant on the first 3 courses of siding and the 4th is minimal than the 5th is non existent. A sprinkler head below the siding would have an arcing pattern from a sprinkler head. I wonder what you would find behind the siding?

RIP Rapid HotClean · Eternal Member

We see that around here everyday. It's almost always easy to get off.

Capital Roof Wash · Approved Exterior Cleaner

If it's organic I'm sure a strong house Soft Wash mix will remove it but I have never seen such a drastic change from one course to the next on vinyl siding.

SprayWash · Approved Exterior Cleaner

I'm wondering if that's having some kind of moisture/heat reaction with the block foundation. Like maybe the house is very cold and the block is very warm or vice versa and there's some condensation under those first couple of runs.

Either way it doesn't matter strong house mix will clean it up. Might even take a couple of doses. I'm just speculating on the cause of it.