I have a utility trailer with plywood sides added on. They were painted several years ago with a standard exterior paint...I didn't do it myself, but I am pretty sure it was a water-based latex paint.

So main question: assuming I wash and then scuff-sand surfaces with appropriate grit, am I OK to refresh surface with a polyurethane or epoxy paint like what someone might use on a boat (above water line) or whatever? I am trying to get as long-lasting and durable of a surface on, and am open to other options.

2 Answers 2


If you accept that your adhesion is only as good as the adhesion of the paint you don't remove, since you'll be painting over paint; yes, that will work.

If you want full benefit of (particularly) an epoxy paint, you might want to get to bare wood first. But if the old paint is well stuck and the new paint protects it, could be fine and less work than going to bare wood.

  • Yep...makes sense. It's not a whole lot of sq footage, and I have access to a drum sander with enough width, so I'll probably take most/all of the old paint off 1st.
    – AA040371
    Commented Mar 18, 2023 at 16:36

You can use a polyurethane over your water-based latex or acrylic paint but you will get flaking so you need to choose a specific polyurethane especially formulated to bond with water-based finishes. But your best bet would probably be to go ahead and buy a good quality exterior latex paint. And just prep your building caulking and just peel old paint or whatever you need to do scrape that down but to just repaint the building won't be that hard to do depending on how much prep work you have. But your best bet would be to go with exterior water-based latex good quality paint.

You may have trouble with the polyurethane down the road on that building and end up having to repaint and then you'll have to use polyurethane again because it's going to be not too good if you repaint with a latex water-based latex over that It's best to go with the same type of paints. Even an oil-based paint who won't be good to use over that water base you'll have to sand the walls very well scratch them up real good to be able to get the old base paint to stick. Dont know how big your trailer is cant be that big you shouldn't have to use more than two gallons of paint so 350 ft² coverage per gallon is just to let you know how I know this is I've been painting for like 27 years that's what I do I'm a painter. Stick to your polyurethane and all that kind of stuff for flooring and countertops and that kind of thing but you're trailer walls no.

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