How to Paint Over a Water Stain

Find out how to paint over a water stain. Get tips on lightly sanding the surface and using an oil-based primer before adding the topcoat.

LESLIE: Maybe you’re redecorating and have run into a painting dilemma like Ted in Pennsylvania.

Ted, what’d you do?

TED: Originally there was a hot water tank upstairs and it leaked. And then we painted and when we painted, not knowing the difference between the two different types of paint at least I thought we had – we only did the area that was damaged but the paint slightly rolled up. So I believe what that leak – it’s right over the bathtub and it’s that area mainly and then there’s some paint peeling. But I just think it was just a bad choice. I was concerned about moisture, possibly, but I …

TOM: Well, I think the moisture concern is accurate, Ted, because generally if paint bubbles or peels, it’s because something is damp or wet. Water is the enemy of paint and it sounds to me like you’re talking about an area that’s connected to the bathroom or under the bathroom. Is that correct?

TED: Well, I guess if it’s behind that wall that means that wall would have to be taken out and that scares me. I thought that what I would do is just sand it down and put an oil-based paint.

TOM: Well, what you could do is sand it down but even if you put oil-based and you get water behind it, it’s still going to peel. If you want to try kind of bringing it down, what I would do is I would try to prep that surface as much as possible, lightly sand it, then I would use an oil-based primer. I would use KILZ, for example – K-I-L-Z.

TED: Oh, K-I-L-Z. OK, very good.

TOM: Paint that wall with that product and then put your topcoat on it. But just be sure that any source of moisture in and around it has been dealt with because, generally, if you get paint that peels, it has something to do with a leak somewhere.

TED: I should do the whole bathroom in this?

TOM: Well, that’s a good question. If you have a large area that this stain affects, you probably are going to want to prime the whole thing, prime that whole surface. Because you will find that when you put the topcoat on top of it, if one area is primed with this oil base and one is not, it will have a different finish look to it. So you should definitely prime the whole surface, then add the top coat of paint and take it from there. But again, Ted, I can’t remind you enough; make sure you check for water leaks because if you have them it will still come through.

Ted, thanks so much for calling us at 1-888-MONEY-PIT.