Discolored white vinyl siding - cause/solution?

So this house cleaned up beautifully, except this corner.

Pretty much all the siding, on both sides of this corner, under the overhang are discolored. You can see one part that is not. The light was pretty harsh so you cannot tell the stains on the left side but it looks like the right side by w/o that white strip (that is actually the clean white siding).

As soon as you get away from the overhang, the siding cleaned up fine. I hit it several times with hw with no success. There are 2 ac units below this. Gets morning and early afternoon sun - Ohio.

It seems awfully consistently stained to be rust runs but I suppose it could be. Going to be down the street from them next week and would love to have a solution for them. This is highly visible from the street, so would like to fix it for them if I can.

Rust or something else?


Oxidation… we wash houses all the time with oxidation issues with no problems. Every house around here has oxidation if it’s ten years or older.

We had a house last week that looked good…we washed it and the next day it looked terrible. Similar to the pictures you posted.

I’m going back this afternoon to try and fix. I have a chemical manufacture close to me called hydro chem. They specialize in fleet 2 step soaps and surfactants. The guy there told me to use there 2 step approach to the siding and it should fix the issue.

A citric acid blend 5 gallons was only $40. Dilute to 2-1 then downstream 10-1.

Then apply their film fighter (a high ph blend with caustic soda being a main ingredient) same dilution as the citric.

I will let you know how it works.

The back of my house (personal house) had bad oxidation and I wiped my hand all over to make those visible bad areas. I 2 stepped it two days ago and rinse…in the area I washed it looks good and no chalk when u rub it. Two feet to the left where I didn’t wash it looks like I put my hand in chalk in preps for some deadlifts.

If 2 stepping doesn’t give good results I’ll be going back on Monday to 2 step and brush it.


Our issue was a little different then yours… end result was very blotchy and uneven

Good luck and let me know how it goes…

it was much more discolored before I washed it. When I washed it this is how it ended up… I really thought it would all come off.

The whole house was oxidized, but turned out great… she just called to tell me everyone at their 4th party said the house looked new… it is a 1908…lol… got lots of compliments… hopefully some jobs out of it too!


I’d like to see before and after pics if you can see the oxidation in pictures. I just had a house with one wall come out worse after I washed it. Light green siding I do every year but this time just looked worse.

Well I didn’t take any before and after…I always get in to much of yank and leave my phone in the truck. The oxidation I was trying to remove mostly was from where one of my guys got to close trying to pop off some green spores. Left wand marks…so we two stepped the entire wall tonight. Suprisingly all the oxidation came off…no more chalkyness on the siding. But the wand marks were still present…lightly…but no chalk. I’m stumped lol. Going back on Monday to brush the whole house. Hopefully
That will fix it.

I’m going to two step an entire house of a friends or families that has bad oxidation in the next week or so and I’ll take before and after to see the results.