Can I use exterior paint inside my house?

[Al Kondo]

I am in the process of painting my bathroom. It was recommended to me by the Home Depot people to use good quality semi-gloss latex to paint the walls. I want to make sure that moisture does not get to the sheetrock underneath the paint.

Is there any reason why I can't use exterior semi-gloss paint in my bathroom? It would seem that the exterior paint would be excellent in the bathroom as it was intended to handle the tough weather conditions outside. I happen to have a fair amount of exterior white that I would like to use up.

Thanks, Al Kondo

[Joe]

Someone told me that you shouldn't use exterior paint indoors because some ext paints release harmful gasses as it cures.

[Doug Miller]

Use a couple coats of a good oil-based primer, then top-coat with two coats of anything, and your sheetrock will be quite adequately protected.

There are several reasons why you should not use exterior paint indoors.

First, exterior paints contain mildew inhibitors. They used to use mercury; I'm not sure if they still do. But in any event, you DON'T want these chemicals outgassing into your house.

Second, exterior paints are designed to "chalk" as they weather. This is definitely undesirable inside your house.

Third, exterior paints are formulated to be more flexible than interior paints, because they are subjected to a much wider range of temperatures. This means that they don't dry as hard. IOW, indoors, they'll always be a bit soft or sticky.

It might seem so, but that's not the way it is. A good-quality interior latex paint is plenty good enough for your bathroom. (Hint: you won't find good paint, or brushes, at Home Depot. Try a Sherwin-Williams store.)

Then paint your garage white. What you propose is false economy. The cost of the paint is a tiny fraction of the true cost of a painting project. Forty bucks is more than enough to buy paint for a bathroom. The real expense is in the time and effort needed to do a proper job of preparation: cleaning the walls, patching cracks and holes, removing switch and receptacle covers and other hardware, and so on.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

[Alan]

Some interior bathroom paints contain mildew inhibitors too. (for example Perma-White made by Zinsser - guaranteed mildew proof)

I thought good ones were not supposed to do this.

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[jeffc]

Some interior paints also contain mildew inhibitors.

"Soft"? "sticky"? I wouldn't say that.

False. We can argue the religious argument about what type of paint is best, but if anything, a Home Depot store will carry *better* brushes and rollers than a Sherwin-Williams store. Try Purdy or top end Wooster brushes, and Purdy rollers - woven ones (not knitted) for less lint, with beveled edges, such as the Purdy White Dove.