Is It Safe to Use Exterior Paint Inside Your Garage?


If you’re looking to brighten up the inside of your garage with a lick of paint and you have a tin of exterior paint lying around, you might wonder whether it’s suitable to be used inside. So what’s the deal?

The United States Environment Protection Agency states that you should never use exterior paint anywhere inside your home or garage. Exterior paint contains certain fungicides and UV protective additives that are not approved for interior use. Indoor paint contains chemicals that are deemed safe to breathe in.

Let’s look at the different indoor paints options available, along with my garage paint recommendations and how best to paint your garage to ensure a professional finish.

What happens if I use exterior paint inside?

Exterior paint usually contains products such as biocides to prevent the growth of mold. As these ingredients can be toxic if breathed in, they should not be used indoors.

Paint that is designed for outdoor use has to be able to withstand extremes of temperature (wind, rain, snow), UV light, be resistant to chips and scratches, and be able to repel mold and mildew.

As such, they contain a lot of additional chemicals to help it do the job, and these chemicals emit gases while the paint is drying, which is called outgassing.

Generally, outgassing occurs during the first 48 hours after the paint has been used on the wall, but it can continue to produce a small amount of gas for many years afterward.

Therefore, exterior paint should never be used in an enclosed space as the gases that it produces can be extremely harmful when breathed in.

Different types of interior paint

Although both interior and exterior paints are made up of pigment, solvents, additives, and resin, they have some major differences.

One of the main differences is the type of resin that they contain. The resin acts as a binding agent for the pigment and is what makes the paint stick to the wall.

Most resins are acrylic, epoxy, and alkyd (oil-based). Oil-based and acrylic resins are used most frequently in indoor paints, while epoxy is usually only used in sealants and flooring.

Acrylic or latex paint (acrylic resin)

This a water-based paint and is used frequently in both interior and exterior paint as it doesn’t give out many volatile organic compounds (VOCs) during the drying process.

Paint that contains acrylic resin dries much faster than paint that is oil-based, often taking only 20 minutes to dry. It’s also much easier to clean.

Paint that contains epoxy usually provides a tough coat wherever it is used, which makes it suitable for painting onto any type of surface. It is resistant to corrosion, easy to clean, and breathable.

It is possible to mix acrylic paint with an epoxy base to produce latex paint which is long-lasting and an excellent type of paint to use in garages.

Oil-based paint (alkyd resin)

Paint that contains an alkyd resin are oil-based paints and are suitable to be used both indoors and outdoors. It’s a much tougher type of paint that is often used on surfaces that are more exposed and receive more use, such as window sills or doors.

However, oil-based paint produces more VOCs than paint that is water-based. They are often more difficult to remove or clean up and so you would generally need to use a paint thinner or turpentine as well.

Which is the best paint to use in a garage?

The most suitable paint to use in a garage is latex paint as it has a fast drying time and doesn’t produce much odor. You can also thin with water rather than paint thinner as it is a water-based paint.

You can use oil-based paint inside; however, it will take much longer to dry and produces a strong smell. Also, you would have to use paint thinner rather than water to thin it.

I recommend this Glidden Interior Paint and PrimerOpens in a new tab., which comes in a wide variety of colors. Although it’s a two-in-one paint and primer, I would still advise you to apply at least one coat of primer before the topcoat as a way to ensure longevity and avoid having to repaint in the future.

A lot of paints claim that it only takes one coat to obtain full coverage and a smooth finish. However, prepare to have to use up to two coats of paint to cover up old stains and get even coverage.

If you’re on a budget, it’s well worth applying two coats of primer so that you only have to do one topcoat. Primer is often cheaper than paint, so this is a great way to save money.

Here are a few other important things that you should always remember when painting in a garage:

Walls

  • You can thin latex paint with water, rather than needing to use paint thinner. It also dries much quicker as it is water-based.
  • Oil-based paint produces a strong smell, takes much longer to dry, and requires paint thinner.

Floors

  • Generally already sealed with an epoxy coating.
  • You must use a paint that is suitable to paint over cement with.

Ceilings

  • You can use the same paint as you use on the walls.
  • Always ensure you have sufficient ventilation in the garage when you are painting.
  • Allow enough time for the paint to dry properly before applying the next coat.

How to paint a garage

Good preparation and painting technique are the best ways to get a professional-level result in fewer coats with your DIY paint job. Follow these steps for the best way to paint a garage:

  1. Gather your tools and tins of pain.
  2. Open all of the windows and doors to allow as much fresh air in as possible.
  3. Clean all dust and dirt off the walls and leave plenty of time for them to dry.
  4. Lay drop cloths on the floor near where you are painting. If you are painting the ceiling, it’s a good area to cover the entire floor.
  5. Place some tape over all light switches and power outlets so that you don’t get paint on them. You should also put some around the windows and the edge of the ceiling if you’re not painting it.
  6. Use a paintbrush to apply primer to the first six inches in from all of the edges, corners, and trims and make sure you don’t use too much paint. Once you’ve done this, you can paint the rest of the wall with a roller.
  7. Leave sufficient time for the primer to dry and then use the same method to apply the paint. It’s advisable to begin at the top of the wall and work your way down, using horizontal strokes so that you don’t get too many drips.
  8. Allow plenty of time for the paint to dry between coats. You should only need to apply two coats of paint, however.
  9. Wipe up any drips while the paint is still wet. You can use a spatula or something similar to remove them if the paint has already dried.
  10. Remove all of the tape from the edges and light switches etc. You should now have finished painting your garage and are able to admire your handy work.

Thanks for reading!

Graham Walsh

I want to share everything I know about home improvement in order to help you. Whether you're a home enthusiast or an industry professional, I have the information that you need.

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