Hi , I performed a warranty inspection over the weekend. There are circles that appear to be oil stains on walls in several rooms. They apparently appeared a few months after they moved in. The circles vary from 1" - 3" in diameter. They are in random places on the wall. The owner said that one circle was painted, but it bled through. There was no indication of moisture when the areas were tested with a moisture meter. I’d like to know the cause. has anyone seen anything like this?
Thanks John
I wont venture a guess as to the cause because that is all it will be, a guess. I will say that I got some oil based hardwood floor finish splattered on my wall and learned that you cannot just paint over it. It will, as described here, bleed back through the paint in a relatively short time. I had to use a product, such as TSP, to clean the surface and then prime/paint to solve the issue.
It’s cosmetic. What is on the other side of the wall? Do the line sets from the air conditioning run in this area?
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Maybe the termite treatment chemicals from inside the wall tubes? In AZ we have tubes running in the walls and they can put the chemical in the tubes from the exterior…
Hi, thanks for the suggestions. There are some circles in internal walls so I don’t think the termite chemical is a plausible cause. My best theory is that the sheetrock compound was contaminated or there was a defective sprayer that leaked an oil based lubricant into the paint or compound causing the circular shape. I’m hoping the convince the builder to cut out a defective piece to see if the problem if through the sheetrock, or limited to the surface. It would be good to know the real clause.
Looks just like a ceiling stain i saw when somebody spilled some kinda lamp oil in the attic. Paint and primer and shellac are useless, always bled thru. Had to be cut out.
In this case, on walls, not sure?
If the stains are random all over the interior and exterior walls in no particular pattern I would suspect that oil ended up on the wall surface either from the paint or the drywall compound. You would need to seal the oil stains with an enamel based sealer or another type of similar sealer (check with your local paint supply counter) to prevent rebleed through the new top coat of paint.
Someone spraying bugs with Raid…
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If someone was spraying with a pesticide there would be streaks. Most pesticides have emulsifiers in them to help break the product down in water. When sprayed on a wall it breaks down the atmospheric dirt and causes streaks down the wall.
Not always ! I sprayed a big flippin’ spider in my garage and after the bast*red died I had a perfect circle of spray.
why did you spray it 
It was flippin’ ugly ! Yep!
And it was in my garage… We have some very big, ugly and poisonous spiders down here…
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that’s what shot guns are made for…
When I was in my 20s I had a big spider Corner me in my bedroom. And the only way out was through the door and this big spider was just above the door. I shot it with a 22. That is a true story. I hate the flipping things. I know they’re good but not for me.
I have my wife kill the bastards. Mind you. I’m 6-1 240 lb. LOL
I understand…
gentle giant?
Me too! 
I didn’t realize they could stack it that high and heavy in Canada
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Well now you know! 
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Junior! Dang it. I haven’t talked to you in awhile. How’s it been going in the great white North?