Can You Use Exterior Paint Indoors? Pros & Cons Explained

It's a common question, especially when you have leftover paint, but the short answer is: no, you shouldn't use exterior paint for interior walls. While they both serve the purpose of adding color and protection, interior and exterior paints are fundamentally different. Using the wrong type can lead to a host of problems, from health risks to a poor-looking finish.

Key Differences Between Interior and Exterior Paint

The main differences lie in their chemical composition, which is designed for two very different environments.

Durability and additives

Exterior paint is formulated to withstand the elements. It contains additives that help it resist cracking, peeling, and fading from harsh UV rays, rain, and temperature changes. It's built to be tough and flexible. Interior paint, on the other hand, is designed for different challenges. It is formulated to be more washable and resist scuffs from daily wear and tear.

VOC levels and safety

One of the most significant differences is the level of Volatile Organic Compounds (VOCs). VOCs are chemicals released into the air as the paint dries. Exterior paints have a much higher concentration of these chemicals because they are meant to be used outdoors, where there is a constant flow of fresh air. Interior paints are specifically engineered to have low or zero VOCs to ensure they are safe for people and pets inside an enclosed space.

Risks of Using Exterior Paint Indoors

Using exterior paint indoors is not only a bad idea for the quality of your paint job but can also be a health hazard.

Strong odors and off-gassing

The high VOC content in exterior paint leads to a strong, lingering chemical smell. This "off-gassing" can continue for months after the paint has dried and can cause headaches, dizziness, and nausea. Prolonged exposure to these fumes can be harmful to your health.

Poor indoor finish and texture

Because exterior paint is so thick and filled with additives for durability, it often results in a chalky or gritty texture. It's not designed to provide the smooth, clean finish that interior paints are known for. Additionally, interior paints are formulated to be scrubbable, which exterior paints are not. Trying to clean an exterior painted wall can damage the finish.

When Exterior Paint Might Be Used

There are very few exceptions where using exterior paint inside might be considered, and they are typically in spaces that mimic outdoor conditions and are not living areas.

Rare cases like basements or garages

In some rare cases, exterior paint is used in unfinished basements or garages. These areas often have higher moisture and temperature fluctuations, making them more suitable for exterior paint's durable qualities. However, even in these instances, you must ensure the area is extremely well-ventilated to avoid the risks of off-gassing.

Only with proper ventilation

If you absolutely must use exterior paint indoors for a special project, it is critical to have maximum airflow. This means opening all windows and doors and using powerful fans to create a cross-breeze. This is not a substitute for using a paint designed for interior use, but it is the only way to mitigate some of the health risks.

Best Practices for Interior Painting

To ensure a safe and successful painting project, always use products that are designed for your specific needs.

Choosing the right paint type

Always purchase paint labeled "interior" for your indoor projects. It's formulated for a smooth finish and a safe indoor environment. You should also consider the finish (matte, satin, or semi-gloss) based on the room's function and the look you want to achieve.

Using low-VOC or zero-VOC options

For added safety, especially in bedrooms, nurseries, or high-traffic areas, opt for low-VOC or zero-VOC interior paints. These paints provide the same great coverage and finish without the harmful fumes, making your home a safer place.

FAQs

Can exterior paint be toxic indoors?

Yes, exterior paint can be toxic indoors. The high levels of VOCs and other chemicals can be harmful, causing a range of symptoms from mild headaches to more severe health issues with prolonged exposure.

Does it last longer inside the home?

No, using exterior paint indoors will not make your paint job last longer. It's designed to withstand outdoor elements like sun and rain, which interior walls don't face. Interior paint, on the other hand, is designed to withstand scuffs, marks, and frequent cleaning, making it more durable for indoor use.

Planning a painting project? For the safest and best results, choose a professional who uses the right paint for your home. Contact us today for a free quote!