Can You Use Exterior Paint Inside? (Answered)

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As a homeowner, I understand the effort it takes to keep a home in tip-top shape, particularly the exterior.

Now, when it comes to that leftover exterior paint, it’s tempting not to let it go to waste. Like many, you may have wondered if it’s okay to use exterior paint inside. Let me delve into this topic and address the common questions.

Outside vs Inside Paint

Various paint types have different formulations, and there are distinct differences between exterior paint and interior paint. 

One difference involves the formulation where one can resist environmental conditions, whereas the other is formulated for living spaces. Here are other key points you need to know:

Exterior Paint

Most exterior paint options are designed to be more durable with better coverage. These kinds of paints adhere to the surfaces very well. Furthermore, these paints resist fading. These kinds of paints are usually waterproof acrylic latex. More of quality waterproof paint for wood here!

Exterior acrylic latex paint can effectively work on exterior surfaces, including fiber cement, wood, brick, and stucco. Make sure to contact a contractor you trust that can help you with this painting job. 

house exterior paint

However, these paints are formulated to contain harmful substances and emit strong odors. Once these odors are inhaled can cause irritations and dizzy spells. 

Exterior paint is resilient outdoors because it’s damage and weather resistant. They have a durable coating formulated with resins. These resins help the paint contract and expand.

Interior Paint

Most interior paints are formulated for interior walls found inside the house. Furthermore, most interior paint is washable and has low odor, splatter, and scratch resistance. 

They are formulated with organic pigments. Furthermore, they contain minimal concentrations of VOCs and other detrimental chemicals.

white couch in a living room

These kinds of paints will fade and become prone to flaking as time goes by, especially when continuously exposed to direct sunlight. They are also water-soluble and lack mildewcide, making them susceptible to snow, heat, and rain.   

See Also: How Many Coats of Paint Should You Apply on a Wall?

Is it Okay to Use Exterior Paint Indoors?

It is not advisable to use exterior paint indoors. The weather and physical resistance that exterior paints may have seemed an excellent choice for indoors, but there are crucial reasons why you should not use it on indoor surfaces:

  1. Exterior paints take a longer time to dry.
  2. They contain harmful chemicals dangerous to you and your family, who will inhale the paint daily. 
  3. Exterior paints perform differently when applied indoors

Drawbacks of Using Outside Paint Indoors

Now that you know that you can’t use exterior paint inside the house, you can choose an appropriate option from the supermarket or hardware store. If, however, you have accidentally painted it indoors, you should know the following risks: 

painting wall grey

Risk of Toxic Fumes

Most exterior paints have more pigment and chemicals added to them. While these pigments give the paint more vibrance and saturation, these paints also have volatile organic compounds, known as health hazards. Here are some of the VOCs[1] found in exterior paint.

  1. Benzene
  2. Ethylene glycol
  3. Formaldehyde
  4. Methyl chloride
  5. Tetrachloroethylene
  6. Toluene
  7. Xylene
  8. 1,3-butadiene
spray painting outside

Some health hazards with continuous exposure to VOCs include the following.  

  1. Headaches
  2. Nausea
  3. Irritation
  4. Loss of coordination
  5. Damage to internal organs

Undesirable Results

Exterior paints work best outdoors, especially since it needs sunlight to cure. If applied indoors, it might take a while for it to dry. Furthermore, it might result in smudged surfaces, thus undesirable results.

Cleaning Inconvenience

Most of the exterior paints are waterproof, which makes them difficult to clean up in the event of spills. 

Interesting Read

What Would Happen if You Use Interior Paint Outside?

Indoor paints can technically be applied outdoors. However, it’s not recommended. Here are some reasons why using interior paint outside can lead to problems:

spray painting
  1. Indoor paints are not formulated to withstand the elements
  2. Indoor paints will fade away with time and exposure to the sun
  3. Indoor paints will peel and crack away

Here are some advantages of using indoor paints outside.

  1. Readily available
  2. User friendly
  3. It comes in a variety of colors
  4. Looks nice under the sunlight

Here are some disadvantages of using indoor paints outside. 

    1. Not formulated for outside use
    2. Not heat resistant
    3. Not moisture resistant 

Mixing Exterior and Interior Paint: Is it Doable?

You can mix interior and exterior paints. However, as I previously discussed, exterior paints contain high concentrations of VOCs. Once applied inside confined spaces of the house can be risky to your family’s health. 

Is it Worth Risking?

It is not worth risking to mix exterior and interior paints. Additionally, using exterior paints indoors is not worth the potential risks involved.

painting wall blue

How are Indoor Air and Painting Related?

The fumes from paint can significantly impact indoor air quality. Therefore, it’s essential to use paint as per its intended purpose and application area to ensure safety and effectiveness.

Recommended Read:

FAQ

What should I do if I unintentionally used outdoor paint inside?

Do not worry if you unintentionally use outdoor paint inside. If this happens, you can apply a primer on the walls and paint them using interior paint.

Furthermore, it is best to  consult the paint manufacturer’s instructions or contact a professional for further guidance on how to safely and effectively remove or rectify the situation.

What should I add to my interior paint to make it suitable for exterior applications?

You don’t need to add anything to interior paints to make them suitable for exterior applications. Interior paints are formulated solely for indoor use. 

Next Read: Is Spray Paint Resistant to Water

Conclusion

I hope I’ve answered all your questions regarding the use of exterior paint inside. It’s important to understand that interior and exterior paints are distinctly formulated.

I can’t stress enough the importance of understanding the pros and cons of each paint type. Always use outdoor paint for exterior surfaces and indoor paint for your living spaces to get the best results.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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