Can You Use Interior Paint Outside? – Complete Guide

House painting is an important task for any homeowner, but it can be tricky to know when to use interior paint and exterior paint. In some cases, you may be able to get away with using interior paint outside.

Yes, it is possible to use interior paint outside of your home. As with all painting projects, it’s important not to rush or skimp on priming and preparation. You will get more than one season out of your new paint job if you follow these steps.

In this article, you will learn how to use interior paint outside and some tips for applying it in the best way possible. Keep reading to learn more! There are a few things you need to keep in mind.

What Is Interior Paint?

Before we learn how to use interior paint outside, we should know what it is and why it’s different from exterior paint. Interior paint is designed with three main formulations: 

water-based latex, low VOC solvent-based enamel, and 100% acrylic latex.

Low VOC

The water-based formula of interior paint is advertised as a low VOC product. VOC stands for volatile organic compounds, chemicals released from certain products. They can hurt air quality and contribute to smog.

Odorless

The paint will not give off strong odors or fumes while you work. It will dry quickly, and it is simple to clean up with soap and water once you are done painting.

Lightweight Pigments

Interior paint also has lightweight pigments, which allow it to dry quickly and easily cover surfaces with just one coat. It is designed for walls, ceilings, doors, woodwork, cabinets, and trim.

Exterior paint is quite different from interior paint. It has a high viscosity, which makes it the perfect paint for the exterior of your home. The base of exterior paint is alkyd or oil-based. Exterior paint can be used on siding, shingles, and soffits.

It has a shiny finish, whereas interior paints have a matte or flat finish. It is also typically formulated with oil, which contributes to air pollution. Interior paint is formulated from organic materials that will not contribute to smog.

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Should You Use Interior Paint Outside?

Exterior Paint Is Best for Exteriors

It’s not always best to use interior paint outside. It is an especially bad idea on siding and shingles, which the oil-based exterior paint will damage. If you have a wooden porch or trim that needs a new coat of paint, interior paint will work well.

Exterior paint is best for the exterior woodwork of your home. It is also good to use exterior paint on metal trim, gutters, and downspouts. If these items are in good shape when you start painting them, they should make it through at least one season with little or no problems.

You can use interior paint on these items, but you will need to add a topcoat of exterior paint over the interior paint to last through rain and humidity.

Interior Paints Are Better for Interior Uses

It is a good idea to use interior paint on all other surfaces. An exterior water-based product can be used inside as well, but you will experience shrinking and peeling due to all those volatile organic compounds.

Interior paints dry quickly, and they cover in just one coat. Many have a low odor that dissipates once they are dry, ideal for painting indoors where air quality is a concern. Interior paint does not contain oil or VOCs, which is good when working inside.

Choosing the Right Interior Paint

To use interior paint outside, you will need to choose an exterior grade of paint. You can find this type of paint at the hardware store or home improvement center.

However, not all interior paints are appropriate for use outside. To use interior paint outside, you must choose an exterior grade of paint. Ensure that the label on the can states that it is made for outside applications.

Here are some other things to keep in mind when you are choosing your paint:

  • The best time to apply exterior paint is during warm weather, which means May through September. This will give it plenty of time to cure before winter arrives. You will need at least three hours of dry time before applying a second coat if you live in a humid climate or six hours in a less humid area.
  • Only buy as much interior/exterior paint as you need for this particular project since it may not be usable next year or after being opened.
  • Remove all oil and grease from the surface before painting it with your interior paint. If you want extra protection, apply a coat of exterior-grade primer first to ensure that the paint lasts as long as possible.
  • Ideally, you should apply two coats of interior-grade exterior paint to get optimal coverage and performance.
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When Is Interior Paint Not Appropriate?

Interior paints are not recommended for use on the following surfaces:

  1. Wood with a moisture content of over 20 percent
  2. Masonry or concrete block
  3. Metal or aluminum siding, which will require an exterior grade product even for indoor applications
  4. Fiberglass products

What Happens If You Accidentally Used Interior Paint Outside??

You should remove the paint as soon as possible to prevent damage. The oil-based interior paints will begin to yellow, dry out, and peel within just a couple of months if used on exterior surfaces. Failure to remove the paint can result in further peeling, flaking, and chipping that may necessitate repairs by a professional.

The exterior paint you used inside will not harm the wall or other surface, but it is still best to remove it before repainting the room.

This way, you can be sure that you are using an interior grade product on the interior surfaces of the area and an exterior product for all exterior surfaces, including window sills, door trims, and any other areas where you may have used the exterior paint.

Use a Paint Stripper on Oil-Based Interior Paints    

Removing oil-based interior paint with a paint stripper is possible, but you must be careful to protect your skin and adjacent surfaces such as walls or flooring.

Never use a brush or roller when you are applying the paint stripper.

Choose a time of day when it is unlikely that rain will occur to prevent unintentional damage from occurring. The next step is to clean everything thoroughly before you repaint.

Allow the paint to bubble up and then scrape off with a plastic putty knife or another scraper.

Use a Paint Thinner to Remove Interior Paint from a Brush or Roller

Interior paints are water-based and contain no solvents, but they can still be difficult to remove once they have dried. You can use paint thinner to remove the paint from either a brush or roller.

Can I Paint Over Exterior Paint With Interior Paint?

Yes, you can use interior paint on the surface, painted with exterior paint. But make sure to choose an exterior grade of paint. Ensure that the label on the can states that it is made for outside applications. The best time to apply exterior paint is during warm weather, which means May through September.

This will give it plenty of time to cure before winter arrives. You will need at least three hours of dry time before applying a second coat if you live in a humid climate or six hours in a less humid area.

What do you mean by exterior grade paint?

Exterior grade paints are available in both oil-based and latex formulations. Both products contain more solids than interior paint, which causes them to cover better with fewer coats, but they also contain resins that give them additional protective qualities.

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Latex paints are made with a water-based binder which means they will dry faster and may not have as much protection against moisture or ultraviolet light exposure.

Oil-based paints take longer to dry, but they contain solvents that give them the ability to help remove dirt and grease from surfaces. This can be very beneficial if you are painting a deck or fence that has been exposed to the elements.

Frequently Asked Questions

Do you need to use special paint for concrete? 

 Yes. For interior applications, use an enamel-based paint. If you are painting the inside of a garage where it is likely that gasoline or other flammables will be stored, then choose an oil-based enamel instead of latex because these products will not emit vapors which could cause safety problems for your family.

What is VOC in paints?

VO stands for volatile organic compounds. These organic components have a high vapor pressure at room temperature, and these will evaporate quickly when exposed to air. If you paint a surface with a product that contains VO, the fumes could cause dizziness if inhaled, so it is best to use an exterior grade paint on any kind of exterior surface, including siding, fences, decks, and stucco.

Can you use water-based paint outside?

Yes, you can use interior-grade water-based paint on any surface painted with exterior paint. This may be beneficial if you want to change the color of a deck, for example. However, be aware that water-based paints often take longer to dry, which could cause problems in humid areas during certain times of the year.

Can you use emulsion paint outside?

Yes, you can use interior-grade emulsion paint on any surface painted with exterior paint. Just as water-based paints, oil-based paints also need to dry thoroughly before a second coat can be applied, but this is especially true if you live in a humid environment.

Conclusion

When painting an exterior surface with interior paint, it is very important to use the proper products to ensure durability. However, if you choose to ignore this advice and decide to use an interior product instead, you will find that most of these paints are water-based and, therefore, very easy to clean up.

Thanks for reading!

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