Interior and exterior painting projects can be stressful, especially when it comes to choosing your paint type.
Today’s market has so many options that it can easily lead to a frustrating rabbit hole of research.
In this handy guide, we dive into the differences between interior and exterior paint to help you decide which is right for your next DIY painting project.
1. Types Of Binding Resins
External paint is made of acrylic, which is softer and more flexible. Having these qualities ensures that the paint on exterior surfaces or outdoor surfaces can adapt to big changes and remain intact for years to come.
Internal paint, on the other hand, is often made of epoxy or silicone, making it less prone to scuffing but more susceptible to cracking. These differences are subtle but have a major impact on the paint’s durability and serve different purposes.
Interior and exterior paint both come in a wide range of colors, but external paint does not typically come in as many finishes.
This is because people tend to have more variety of interior painting their homes regarding colors, taste, and design than exterior surfaces of the home. This difference between interior and exterior paint is a subtle one but still important to bear in mind.
External paint has more additives to add resistance and durability; these additives are non-organic in nature to increase the paint job’s lifespan. As we briefly dove into, additives are what give the paint features such as mildew or moisture resistance.
Exterior paint has more to contend with and thus has more additives. Interior paints does not experience such extremes and can therefore have fewer additives in its formula.
Both paint types are tough, but flat sheen exterior paint has the edge in terms of lifespan. The outside world has many things that can damage paint to consider, including wide temperature changes, rain, hail, and animals.
Exterior paint must be tough to last for years to come against such dangers. Interior paint is tough in a different way; it must stand up to scuffing, washing, scrubbing, and resist staining, among other things.
The flat paint enables water to exit without creating bubbles in the paint.
5. Level Of VOCs
In terms of VOC level, the exterior paint vs. interior paint debate is short. Exterior paint has more non-organic additives and more rigid resins, meaning that it has a naturally higher VOC level than interior paint does.
During the curing process, these compounds evaporate and would be harmful to breathe in an enclosed space. Interior paints have little to no VOCs to preserve your home's air quality.
Both paint styles have good adhesion but, once again, the exterior paint has the edge. It is typically much harder to damage or chip external paint due to its strong, flexible resin.
This strong adhesion, along with other elements, is a big factor in the long lifespan of an exterior paint job. As durability is an incredibly vital part of external paint, it only makes sense that there is a focus on strong adhesion.
7. Dry Time
Many elements go into how quickly something paint dries; from the air circulation to the paint thickness to the formula to the temperature, it is often hard to say how long it will take.
Both paints can vary in their dry time, but exterior paint dries faster due to open-air circulation and direct sunlight and uv rays. Water-based paint dries faster than oil-based, which is often the edge in favor of interior paint.
8. Weather & Temperature Resistance
Exterior paint is without question the standout in this area as it is specifically designed to withstand extreme weather and temperature changes. Your garden and home’s external walls need to withstand the elements as well as animals, sunlight, and garden games.
Interior paint is typically only kept between 60- and 90-degrees Fahrenheit and does not experience constant sunlight or elements, meaning it is less durable overall.
9. Fade & Moisture Resistance
External paint is, once again, the winner in this category due to its constant brushes with direct sunlight and rain. Additives in exterior paint are designed to resist mildew and not hold onto moisture as easily.
Interior paint is resistant to things like cleaning and stains but does not have to contend with those as often as external paint does.
10. Scuffing and Scratches Resistance
Both internal and external paints are hardy when it comes to scuffing and scratch resistance. Exterior paint is typically harder to damage as it is softer and more flexible; it takes a lot to chip it, but scuffs can happen.
On the other hand, interior paint is created with harder resins such as epoxy or silicone, making it more scuff-resistant but more susceptible to chips.
A lot goes into the price of paint – from the brand to the amount to the color and finish, there is more than meets the eye with the price tag. The cost of interior paint vs exterior paint is often similar.
To split hairs, exterior paint can be more expensive as there are more additives, but you may end up buying more interior paint from local paint manufacturers as it is less durable, and you may need to touch it up in the future.
There's no good reason to use interior paint outside or use exterior paint inside or exterior paint indoors. If you already used exterior paint inside, it's a much more problematic situation, given the health hazards.
Exterior Paint Overview: The Basic Characteristics
Typically made from water based paints or oil based paint formulas (like latex paint), exterior paint products is often used when redecorating outside walls, fences, sheds, and other garden projects. In latex paint, the solvent is water. Unlike latex paints, oil based paints have solvent of choice is mineral spirits.
This type of paint is a hardy, durable sort that must stand up to the seasons, constant sunlight, large temperature changes, excess moisture, and other potential damage of exterior surface. Because of this, it is made with acrylic paint resin, which binds the paint to the wall in a way that promotes flexibility, durability, and strong bonds.
Non-organic pigments that color the paint are also added with increased durability and fade-resistance in mind. However, the many additives and resins needed to formulate exterior paints release more volatile organic compounds. These volatile organic compounds are potentially harmful to breathe in enclosed spaces.
Interior Paint Overview: The Basic Characteristics
Typically used for decoration and aesthetic purposes, interior paints comes in a wide range of colors and finishes to suit your tastes. You might find this paint used on ceilings, interior walls or brick walls, interior surfaces and furniture.
Interior paints does not have to stand up to such extreme wear and tear as most exterior paints does, but it is still tough; these paints work to prevent and resist dampness, washing or scrubbing, maintenance, and stains.
Interior paint is made from harder resin, making it more susceptible to cracking and fading. Organic pigments are used to create the colors, and interior painting has little to no VOCs as it needs to preserve the indoor air quality in your home.
Frequently Asked Interior Vs Exterior Paint Questions
Are interior and exterior paints interchangeable?
Interchanging the interior and exterior paints are not recommended, especially when trying to use exterior paint indoors. These paint types are suggested for specific situations for a reason and interior paint should not be used outdoors.
Is it OK to mix interior and exterior paint?
Yes, it is possible to purchase hybrid paints that have both interior and exterior paint mixed in. However, we do not recommend mixing them yourself as it may not be as effective. Hybrid paint could be suitable for some smaller projects.
Can I use interior paint outside as a primer?
We do not recommend using interior paint outside as a primer as it could interfere with the adhesion of the exterior paint to the surface; this could make it less effective in the long term.
Knowing the difference between interior vs exterior paints should now save you both time and money on your project.
With these facts, it is possible to make a more informed decision while decorating your home.