Can I use exterior paint inside? What you need to know

Interior paint is used for indoor areas like walls and ceilings, while exterior paint is used on surfaces like siding and fences on the outside of the house. If you have leftover exterior paint from an outdoor project, you may be wondering, “Can I use exterior paint inside?”

In general, exterior paint should not be used indoors.mainly due to health concerns and because its properties make it unsuitable for indoor spaces.

VOC

Exterior paints contain more VOCs (volatile organic compounds) than interior paints.

VOCs are chemicals found in paint and other household materials such as cabinets, furniture, carpets and flooring. VOCs produce toxic gases and have the potential to harm residents and the environment if concentrations are high enough.

Although VOCs will eventually dissipate, this can take days or weeks. Some VOC-containing substances off-gas for years.

If you use exterior paint indoors, you will emit up to 17 times more VOCs than if you use interior paint.

Want more tips and inspiration for your home improvement project? Sign up for our free daily newsletter for the latest home improvement tips, tutorials, and more!

Compatibility

While exterior paint is somewhat compatible with indoor spaces, it is not the best paint to use here. Interior paint is formulated for indoor areas.

• Exterior paint:Due to harsh outdoor conditions such as temperature spikes, exterior paint is designed to expand and contract. But it is quite soft and does not withstand scratches well.
• Interior paint:Interior paint is harder than exterior paint. Its hardness helps it withstand wear from scratches, damage, and cleaning.

Spread Rate

Exterior paint has a lower spread than interior paint, so you will need to use more exterior paint than interior paint to cover the same area.

On average, one gallon of water-based exterior paint can cover 300 square feet, while one gallon of interior paint can cover 375 square feet.

So four gallons of interior paint will cover 1,500 square feet. But if you use exterior paint, you’ll need to add another gallon to cover the same space.

Drying time

Exterior paint takes longer to dry and coat than interior paint.

Both exterior and interior paints are dry to the touch in about an hour. However, recoat time for exterior paint can be up to four hours, and recoat time for interior paint can be one to two hours.

Adequate ventilation helps speed up drying and recoating times. When you factor in the limited ventilation of the interior space, exterior paint applied here will take four hours or more before another coat can be applied.

Use exterior paint inside

Although exterior paint should not be used indoors, it is acceptable in certain interior spaces.

You can use exterior paint inside garages, sheds, workshops or other outbuildings that are not used as living spaces.

Only if you want to use more paint. If possible, buy interior paint for indoor spaces.

Use interior paint outside

Interior paints used outdoors do not pose the same health risks as exterior paints used indoors. There are fewer VOCs and there is no chance of them being retained outdoors.

Using interior paint on the exterior is a bad idea because:

• It will crack because it is not designed to expand and contract with external factors.
• The product does not contain fungicides and other additives found in exterior paints.
• Interior paint will fade faster than exterior paint.

Paint for interior use

In general, interiors should be painted with 100% water-based acrylic-latex paint (sometimes called latex paint or acrylic paint).

The base coat will be clearly labeled as interior paint. When ordering paint from the paint counter, specify that you want interior paint.

Within the acrylic-latex family, choose the gloss that best suits each room in your home. Satin, eggshell, and semi-gloss are durable and easy to clean, making them ideal for kitchens. Bedrooms can use a gloss on the flatter end, such as eggshell or gloss/matte.

Paint for exterior use

Use 100% water-based acrylic-latex paint on the exterior of your home. This paint, labeled as exterior paint, is suitable for most siding and trim.

Consider using an oil-based enamel paint on exterior doors, trim, and metal for added protection. Oil-based exterior paint takes a long time to dry and must be cleaned with solvents, not water. But it provides extremely strong, long-lasting protection against scratches, rust, and harsh weather conditions.