We have a rental unit that is having a paint problem. We didn't paint the trim, but it is oil over oil. All of a sudden, it's started bubbling. We suspected water but used a moisture meter after a recent rain and the trim reads the same of as the rest of the house - pretty low. No moisture issues anywhere in the house.

We plan to go in, scrape, sand, prime & repaint - but any ideas on what is causing it? When we bought the house, there was one small patch of this on another doorway that we fixed. The same thing is happening on this whole frame. The rest of the trim in the house is fine. So far.....

how do you know it's oil over oil? could it be it was oil then they used a waterbased paint on top, or vice versa?

I am confident they are both oil. I used some lacquer thinner to test that underneath layer. I would guess that the top coat that is bubbling was painted in the last couple of years. I have the can of touch up paint - SW Pro Classic oil.

I guess I'm just wondering what could be the trigger for this to happen.

I just talked to the people at SW and they say either poor prep, the house vacancy for a year caused dramatic temp shifts that lifted it (?) or possibly water wicking up from under the house (pier & beam construction - but I've been under there & there are no leaks or drainage issues).

Hmmmm....

schwack schwack said:

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I just talked to the people at SW and they say either poor prep, the house vacancy for a year caused dramatic temp shifts that lifted it (?) or possibly water wicking up from under the house (pier & beam construction - but I've been under there & there are no leaks or drainage issues).

Hmmmm....

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Looks water related... maybe it was the house vacancy for a year. Could be the house got hot and humid.

If the paint is peeling off another layer of paint it's poor prep. If moisture, the paint would peel all the way down to bare wood.

^^ Good point.

From that picture, I would say they probably sanded before repainting but didn't get all of the dust off. Water based over oil will peel not crack.

SAAG93 said:

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If the paint is peeling off another layer of paint it's poor prep. If moisture, the paint would peel all the way down to bare wood.

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This - identify where the actual problem is (check). Between the 2 coats, which would be due to lack of adhesion. look at the back of the chips for dust and look at the coatings underneath to see if it was sanded or dulled down.

It is very important to clean trim/baseboards before sanding because it gets so dirty from hands, pest spray, dirt,etc.... sanding it alone does not clean it.

Hard to tell from the picture, but if the peeling paint is one coat of oil-based paint, that looks very thick which would cause the coating to be more brittle than usual. It only takes one spot to start cracking then it can spread and get worse form there, especially with improper adhesion.