Discoloration on Hardie Siding

I am a homeowner and I have noticed one section of our siding looks weird. It seems to have appeared out of nowhere. This is the only section on the entire house that looks like this. Any ideas what it might be, what might have caused it or how to clean/fix it?

Hi, you have found a forum for Professional Pressure/Power Washers here. So please don’t be surprised if you get some snarky and less than helpful answers. Also, please use the search bar as I’m sure this has been discussed before. Just search Hardy or Hardie Plank and I’m sure something will come up.

If you want some help on this from the pros here, please provide some additional information to include age of home/siding, amount of sunlight this area gets, does this discoloration come off easily on your hands or a rag, did someone try washing this before? Letting folks know where you’re located would be helpful as well.

Once we’re able to figure out what this is, the best advice is going to be to call a pro in your area. This could be something relatively easy for a pro to address or something you can really make a lot worse on your own. Hopefully the guys and gals here can get you the right information to contact a pro in your area.

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Have you cleaned it lately? Looks like it was oxidized and the oxidation was partially removed.

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Hi thank you, recently purchased the home this month. The siding did not look like this at that time and I have just noticed the change in the siding. The house was built in 2005. That side of the house faces west however the entire back of the house faces west and this is the only spot that looks this way. I have not tried cleaning it with anything. If you rub your hand on it there is white chalky residue which I have read is oxidation. With oxidation is it normal to only have a section look like this and not all of the siding? Again, thank you I was hoping to get a few opinions on what it might be but I can call a local siding company to see if they have any opinions as well.

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We have not cleaned it. We have had a few rains recently. This is the only section on the west side of the house that looks like this. Is it the darker spots where the oxidation may have been removed and would rain do this as we have not cleaned it?

I gave an estimate the other day for a house that was badly oxidized on one side, slightly oxidized on another, and the other two were fine. I also gave an estimate yesterday, the siding was not oxidized at all, but the vinyl windows on the southern side were.

Definitely an oxidation issue. Could be wind driven rain or a sprinkler hitting that area causing the oxidized finish to run off. No issue with the actual siding, just the factory finish or paint. Best bet is to call a painter. Don’t go back with a flat paint.

Take a rag and some soapy water and clean a few feet on a couple of boards and let sit for a week and see how it looks. Post the pic here. Normally we try not to disturb the oxidation because, well it’ll look like that. But you’ll have an idea what it’ll look like if you decide to clean it. Oxidation removal will cost about 3 times what a regular housewash would cost, but to do one wall shouldn’t too bad.