Can I use exterior paint indoors?

There are several different types of paints and each is designed with a specific use in mind. While some speciality paints work similarly to their non-specialised counterparts, a strong distinction is interior and exterior paints. You might be wondering if you can use exterior paint indoors.

While you can technically use exterior paint indoors, it might not be very effective. Interior and exterior paints have different properties that make them suitable for specific purposes.

Properties of interior paint

Interior paints are designed for use indoors. The emphasis is on characteristics like smudge resistance instead of heavy winds and rain. Some other characteristics of interior paint include:

More characteristics of interior paint

  • Stain resistance. Stains are more likely to be a problem indoors than weather. Resistance to stains includes hiding roller marks
  • Easier to cure. Ideally, you want to use exterior paint on sunny days as the sun helps it to cure and dry properly. Indoor paints cure much easier without needing sunlight.
  • Easy to clean. It’s unlikely to use interior paint and never have anything spill on it. Once the paint is dried it’s easier to clean than exterior paint since it’s designed with this in mind.

Properties of exterior paint

A lot can happen outdoors. Exterior paint needs to be versatile to deal with the intense New Zealand sun as well as storms that bring heavy wind and rain. Good exterior paint inhibits the growth of mould and mildew, often using additives with these properties mixed directly into the paint.

More characteristics of exterior paint

  • UV resistance. Ultraviolet rays can be damaging to paint so most exterior paints in NZ have protection against UV rays. This in turn can help reduce paint fading over time so the finish can stay vibrant for longer.
  • Doesn’t peel or crumble easily. The resin used in exterior paint is softer so that it doesn’t harden as easily which could cause it to crack, crumble or peel with all the changes in temperature.
  • Additives for specific environments. There are all sorts of additives can go into exterior paints. Fungicide, pesticides, and even perfumes can be added into the mix.

Why shouldn’t I use exterior paint indoors?

At first glance, it might seem like exterior paint is the best choice for anything. It’s resistant to mould, mildew, and harsh weather. However, that extra durability isn’t needed indoors. Instead, being easier to clean while resisting stains is more important.

In extreme cases, exterior paint indoors can even pose health risks. Some of the additives used in certain exterior paints have compounds that can be harmful if breathed in at high amounts. They can even leave a foul smell behind or cause an allergic reaction in sensitive individuals. Outside, there is plenty of space for these compounds to escape into the air instead of being trapped inside.

If you use exterior paint indoors by accident, you’ll most likely be fine. However, the paint will likely take longer to dry and won’t have the benefits of indoor perks. If you notice any serious effects, you may need to contact a professional to help. For any other questions or to get a quote for your next interior or exterior paint project, get in touch with our team.