Can You Use Exterior Paint Inside Your Home?

Before exploring the distinctions between exterior and interior paint applications, let’s lay the groundwork by understanding interior and exterior paint composition. Paint consists of a few core ingredients, each playing a significant role. So, whether you’re working on the inside or outside, having this basic knowledge about paint can help you make informed decisions.

Interior Paint Composition

Interior paints are primarily water-based and according to Sherwin Williams primarily contain four essential ingredients: binders, pigments, liquids, and additives. Binders are the components that hold the pigment particles together, creating a durable film on the surface. They also provide adhesion to surfaces such as walls or ceilings. Pigments give paint its color and can either be natural or synthetic. The primary base, known as the liquid, can be oil or water. Typically, oil-based paints are preferred for exterior applications, while interior paints mostly utilize water-based options. Lastly, additives are used to enhance specific properties of the paint, such as durability or moisture resistance.

Exterior Paint Composition

Exterior paints are often oil-based and have a slightly different composition. They consist of similar components as interior paints but with some key differences. Binders in exterior paint are usually tougher and more durable to withstand harsh weather conditions. The pigments used in exterior paint also tend to be more fade-resistant to maintain the color for longer periods. Additionally, the solvents in exterior paint are slower to evaporate, allowing for more extended working time and better coverage on large surfaces. Since exterior paint is slower to dry it means that the exposure to the potentially harmful VOC’s is longer.

Can You Use Exterior Paint Inside?

Technically, there is nothing stopping someone from using exterior paint inside. However, it may not be the best decision. Exterior paints are formulated to withstand harsh weather conditions and have a higher level of volatile organic compounds (VOC)

It is easy to think that you absolutely can use exterior paint inside, after all, exterior paint is designed to withstand all the elements from severe heat to the coldest of winters. Just imagine how it would hold up inside. Plus, paint is expensive, and if you happen to have some leftover from an previous project or maybe you found some discounted exterior paint at a hardware store, why not use it indoors? But just because you can do something doesn’t mean you should. Here are all the reasons you should NOT use exterior paint indoors.

Volatile Organic Compounds (VOC’s) 

As mentioned earlier, exterior paints tend to have a higher level of VOC’s compared to interior paint. These compounds are released into the air as paint dries and can be harmful to human health. The prolonged exposure to these chemicals indoors can lead to a variety of health problems, including respiratory issues, headaches, and nausea.

Different Aesthetics

Exterior paint is made specifically to withstand the harsh elements of nature, so it tends to have a thicker consistency and glossier finish. This may not be desirable for interiors, where a smooth and matte finish is often preferred. Exterior paints can also have a different color and sheen compared to interior paint options.

Drying Time

As mentioned earlier, exterior paint has a slower drying time compared to interior paint. This can be an issue if you’re working on a time-sensitive project or need to apply multiple coats in one day. The extended drying time may also result in the paint being tacky for longer periods, making it prone to attracting dirt and dust.

Cost

Exterior paints are generally more expensive than interior paints due to their durable formulations. Using exterior paint indoors can result in unnecessary spending, especially if you have to purchase more paint for touch-ups or future projects.

Adhesion Issues

Exterior paint is made to adhere to stucco, bricks, and other durable outdoor materials. Exterior paint is not designed to adhere to drywall like interior paint is. This could lead to exterior paint having poor adhesion when used inside your home leading to having to do the job twice and increasing the overall cost 

Odors

Since exterior paint has a higher level of VOC’s and other chemicals, it also tends to have a stronger odor due to the paint fumes. This can be bothersome for people with sensitivities or allergies and may linger in the home for longer periods due to the slower drying time.

Finishes

Interior paints come in many different types of finishes not usually offered in outdoor paints. This will severely limit your choices when selecting a paint color.

Designed Differently

Interior paint is made to be scrubbed, resist common household staining, and allow for easy cleaning. Exterior paints are made to prevent fading and be mold and mildew-resistant.

Compliance Issues

Due to the different formulations using exterior paint inside may not comply with local regulations or building codes. It’s always best to check with your local authorities before using exterior paint indoors.

Using Exterior Paint Inside: Final Thoughts

To finally answer the question can you use exterior paint indoors? It is best to stick with interior paints for interior locations and exterior paints for exterior locations. It really just makes sense. Exterior paint products are specifically designed for use in their intended location and using them outside of the intended use could be potentially dangerous. This is especially true when indoor paint is relatively inexpensive and now comes in low odor and with a less toxic composition.

Using Indoor Paint Outdoors

You may also be wondering about the opposite. Can you use interior paints outdoors? The answer here is a resounding no. Indoor paints are not formulated to withstand the harsh outdoor conditions the exterior of your home often faces, such as intense sunlight and large amounts of moisture. Interior paints may quickly fade, crack, or peel if used outside. This could lead to huge maintenance bills from moisture intrusion into your home. As my kids like to say interior and exterior paints are just built differently.

Interior or Exterior Paint on a Covered Patio

Lastly, you may be wondering if you should use interior or exterior paint on a covered patio. The answer is that it depends on the conditions of your covered patio. If it is fully enclosed and protected from any outdoor elements, then interior paint would be just fine. However, if your covered patio is exposed to the elements at all then it would be best to use an exterior paint.

Conclusion

In conclusion, it is always best to use the right type of paint for its intended location. While exterior paint may seem like a viable option for indoor projects, there are many reasons why it is not recommended. From higher levels of VOC’s and different aesthetics to potential adhesion issues and compliance problems, using exterior paint indoors will likely end up costing you more in the long run.