Choosing the right paint is key to achieving a quality and long-lasting finish. Most have heard of interior and exterior paint before, but is there any real difference between the two? Can they be used in place of each other? These are good questions, and we will answer them in detail throughout this post.

Exterior paint explained

Exterior paint is specifically designed for use on outdoor surfaces. It is highly resistant to UV rays, rain, mould growth and other harsh conditions typical for an outdoor environment. Exterior paint should not fade, chip, peel, or bubble when exposed to such elements. To get it to this resilient state, additional additives, mildewides, and resins are added to the formula. As exterior paint dries, it releases gasses, this process is known as outgassing. These gases or paint fumes can cause health issues such as headaches, nausea, and dizziness. When exterior paint is used for its designed purpose – outdoors, the risk is minimised as the gasses aren’t contained in an enclosed space.

Interior Paint explained

Interior paint is designed for use on indoor surfaces. It is not as durable, but it isn’t exposed to the conditions that exterior paint is, so it doesn’t need to be. Interior paint contains much fewer harsh chemicals, and the outgassing process is significantly less. As the paint fumes are nowhere near as strong, the chances of experiencing health issues relating to this are reduced. While interior paint is not as durable as exterior paint, it can be cleaned easily without damaging the surface, and if it is applied correctly, it shouldn’t peel, crack, or flake off for a very long time.

A breakdown of the differences between the two

One thing exterior and interior paint have in common is that when they are applied to a surface, they change it’s colour although they are vastly different. Here’s how:


Exterior paint offers the ultimate weather and temperature resistance to outdoor surfaces whereas interior paint doesn’t. If interior paint is exposed to excessive moisture or sunlight, there’s a good chance it will deteriorate as a result.


Both interior and exterior paint contain pigments, it’s what makes up its colour. Interior paints are typically made with organic pigments to lower the outgassing and the symptoms associated with that. Exterior paint uses stronger and harsher pigments to maintain durability, anti-fade properties and resistance to the elements.

Susceptibility to damage

It is not uncommon for interior paint to scratch or chip off when it’s met with force. It doesn’t even have to be excessive, a tap from a door handle or brushing past an interior wall with a piece of furniture and scraping it can see your indoor paintwork get damaged. Exterior paint, on the other hand, needs to cope with hail, tree branches hitting and falling onto it, and more.

Drying time

In general, outside has more fresh air circulating, and this increases the rate that the paint dries. If the weather is warm, the paint will dry at an even faster rate. Exterior paint will almost always dry faster than interior paint for this reason.


As we’ve mentioned, exterior paints have additives in them to help them stand up to external factors such as water, extreme temperatures and more. One of the additives is mildewcide, and this is vital to protect your outdoor paint from contaminants such as algae, moss, mould, and mildew. This additive and many others aren’t in interior paint.

Temperature protection

As the season’s transition through the year, the outside temperature can vary drastically. Exterior paint can cope with extreme temperatures without the risk of it affecting the integrity of your finish. Interior paint isn’t designed for such conditions, and as the temperature inside a home doesn’t normally reach the levels that it does outside, it doesn’t need this additional protection.

How well they adhere

Exterior and interior paints both have binders in them to help them to adhere to the surface they are being painted on however, the binders used in exterior paint are normally acrylic, and interior paints have either silicone or epoxy in them. Both work well to adhere to a surface, but when it comes to longevity, exterior paint is the front runner.


There isn’t a massive difference in price between interior and exterior paint, but exterior paint tends to be slightly more expensive. This is because of the extra additives needed to be able to withstand the harsh environments mentioned above.

Can interior paint and exterior paint be used interchangeably?

While you can use them interchangeably, it is not recommended. If you use interior paint outside, it’s not going to last and can leave your paint job looking tacky and in poor condition in no time. If you use exterior paint indoors, you are exposing those inside to outgassing for an extended period. It can take several years for exterior paint fumes to diminish entirely.

The quality of your paint job can make a huge difference in how the overall space looks and feels. Getting it wrong can be a time-consuming and costly mistake. To ensure your paint is applied correctly and is going to last, you should hire professional painters such as ours here at MDC Specialists. We are an expert painting and decorating team and guarantee top-notch finish every time. Contact us today for more information.