-
A room prepped for paintExterior paint coats the outside of a building or structure. It must withstand sun, rain and snow. Exterior paint remains flexible after curing so that it won't crack or peel as the surface expands and contracts with changes in temperature and humidity. Additives for mildew, fungus and UV resistance are added to exterior paints. Exterior paints are often not as easy to scrub as good interior paints. They typically come in three sheens -- flat, semi gloss and high gloss. - Interior paints are often harder and more washable than exterior paints. They are available in a wider range of sheens, including flat, matte, eggshell, satin, semi gloss and high gloss. While some interior paints have mildew remover added for use in bathrooms, most do not. When dry, they withstand the same temperature extremes as exterior paints, but will not hold up well in wet or sunny conditions.
- Typically it's fine to mix both interior and exterior paints in any possible color. The exception will be some yellow and red pigments that will quickly fade in direct sunlight. If you look through the light yellow and peach colors on the paint store color cards, you'll notice some colors marked "interior use only." This is because they'll quickly fade if used outside.
- Using exterior paint inside may not be safe. Some of the additives in exterior paints have not been approved for use inside homes. All water based paints take up to a month to cure, and during this time they are emitting VOCs (volatile organic compounds.) This can be of particular concern for people with breathing difficulties, small children, and pregnant women. Additionally, exterior paints are often not as stain resistant or washable as interior paints. So while it is technically possible, it is not really advisable. It would be fine to use exterior paint inside any building where safety and washability are not concerns, like sheds and garages.
- Unless you want to see the paint job start to peel, crack and fade within a year, interior paint should never be used outside.
- Interior and exterior paints are formulated for different functions. Interior paint dries and is much harder, less flexible and more washable than exterior paint. Paint formulated for outside use withstands sunlight and weather extremes to a much greater degree and is generally more mildew resistant. For most applications, it is best to use it for the function intended.
