Blotching on siding?


I was at my parents shore house in NJ this weekend and noticed they had some blotching on their siding. In person its more noticeable from a side angle rather than straight on.

Anyway, they had someone powerwash it last year and they believe it was straight pressure, i.e. no chemicals. Just curious if anyone can tell from the pics if this is definitely oxidation or if maybe something else is going on…


looks like a hot sh mix and it dried on it. I would try washing it with a hot mix as well as see if it goes away.


Not necessarily a hot mix but definitely not enough rinsing. House wash mix, dwell, rinse, rinse and then rinse! GL!

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