Skip to Content

Can I Use Polyurethane Outside? (All You Need to Know)

Polyurethane is one of the most common and effective coatings for different surfaces. We can even use polyurethane on paints and other finishes too. Generally, we use polyurethane in different furniture, cars, or other interior elements. But the environmental and weather effects are different from the inside.

So, you might be confused about whether you can use polyurethane outside or not. Well, you have to know about the safety of the outside wall after using polyurethane. Moreover, knowledge of the durability of polyurethane outside is pretty essential.

Can I use polyurethane outside?

You can use polyurethane outside, but the polyurethane should be exterior polyurethane. Exterior polyurethane is specially made with resin, a flatting agent, a UV ray absorber, etc. These elements of exterior polyurethane will protect the outside. But don’t use interior polyurethane outside.

However, polyurethane can be of different types. For example, interior and exterior polyurethanes are different. For some important reasons, you should use exterior polyurethane. Let’s see why you can use polyurethane outside.


When we apply an exterior coating, we expect the coating will be oil-based. Because oil-based finishes are suitable for use outside. So, the exterior polyurethane is made with oil-based materials. If you use exterior polyurethane outside, the polyurethane will stick to the outside surfaces well. Moreover, it will be durable and long-lasting.

So, if you want a durable coating that will not chip off, you can apply exterior polyurethane. The overall finish will be suitable outside.


Exterior polyurethane is protective for use outside. It will keep the outside wall safe from environmental effects. For example, it will protect the walls from humidity, moisture, temperature, etc.

Moreover, one of the most essential features of exterior polyurethane is its UV protection. If you use exterior polyurethane outside, this coating will protect the walls from ultraviolet rays.


Exterior polyurethane is a balanced coating with suitable ingredients. So, the coating is flexible for use. Sometimes, we plan on applying paint and a coating over the paint. The good news is that polyurethane is also compatible with paint.

So, you can paint the outside first, and then you can apply a coating over it. Even the application process is easy. So, polyurethane has flexible features that make it suitable for use outside.

Easy to clean:

Cleaning the polyurethane is pretty easy. You can clean the outside with less effort. Even cleaning the dirt, dust, and grease from polyurethane is easy. Moreover, polyurethane will protect the surface from weather effects. That’s why the surface will not get dirty easily.

How does polyurethane hold up outside?

Generally, polyurethane is made of materials that are suitable for sticking on the outside surface. We use polyurethane for interior and indoor furniture. But when we want to use it outside, we think that polyurethane might not hold up outside.

But we use exterior polyurethane outside. This polyurethane has all the features that help hold it up outside. For example, polyurethane contains resin that helps bond with a surface. Moreover, it has other additives that help it stick to the surface.

So, if you use interior polyurethane outside, it might not hold up well outside and chip off quickly. But if you use exterior polyurethane outside, it will hold up well.

Can you use polyurethane for outdoor furniture?

Whether you can use polyurethane for outdoor furniture or not depends on the type of polyurethane. Polyurethane can be different for use inside and outside. Generally, interior polyurethane doesn’t have additives suitable for use on outdoor furniture.

But most exterior polyurethanes are suitable for use for outdoor furniture. Because exterior polyurethane has some additives that can protect the outside furniture. So, if you want to use polyurethane for outdoor furniture, you have to use the exterior one.

Generally, the exterior polyurethane has protective materials that will protect the outside surface from weather effects, UV rays, and other effects.

How long will polyurethane last outside?

How long polyurethane will last outside depends on the type of polyurethane. Generally, if you use conventional or interior polyurethane outside, it can last up to one year. Even sometimes, the coating might peel off before one year.

But if you use exterior polys outside, it can last up to 2 to 3 years. Even if you care for the outside coating regularly, it can last longer. If you want to keep the polyurethane lasting for a long time, you can re-coat the exterior polyurethane after one year.

Moreover, if you use multiple coats of exterior polyurethane outside, it will become more durable.

What polyurethane can be used outdoors?

Polyurethane is not just one type. It has some other types too. So, some polyurethanes are suitable for outdoor use. Most of them are exterior polyurethanes. Moreover, oil-based exterior polyurethanes are suitable outdoors. So, let’s see what polyurethane you can use outdoors.

  • RUST-OLEUM Ultimate Oil-Based Spar Urethane
  • General Finishes High performance
  • Minwax Helmsman Outdoor Spar Urethane
  • RUST-OLEUM Ultimate Water-Based Spar Urethane
  • Deft Interior Exterior Water-Based Polyurethane Finish Gloss, Quart
  • ZAR Exterior Oil-Based Polyurethane

Can you use interior polyurethane outdoors?

You should not use interior polyurethane outside. Because interior polyurethane doesn’t have the characteristics of saving outside surfaces.

For example, interior polyurethane might not protect the outside walls from ultraviolet rays. Moreover, the coating will not be durable and hard. As a result, the interior polyurethane will degrade quickly.

On the other hand, you can use exterior polyurethane on the outside wall. Because exterior polyurethane has the maximum qualities you want for an outside finish. For example, the exterior polyurethane can protect the outside wall from ultraviolet rays.

So you must use exterior polyurethane outside. Because the interior or other polyurethane may chip off easily. So, if you want a durable and flexible finish on polyurethane outside, you should not use interior polyurethane.

What happens if you accidentally use interior polyurethane outside?

If you use interior polyurethane outside, it might not be problematic instantly. But it can affect the coating and the surface in the long run.

Less durable:

Interior polyurethane doesn’t have the additives necessary for the outside surface. Outside surfaces need a coating that has enough durability. So, if you use interior polyurethane outside, the coating will not be durable. It might last only one year. Sometimes, the polyurethane might not last even a year.


Interior polyurethane doesn’t provide enough protection. It will not give protection from ultraviolet rays outside. Moreover, interior polyurethane might get damaged by weather effects.

Peel off:

Interior polyurethane is not enough for exterior polyurethane. It will start to peel off soon. After a couple of months, the interior polyurethane will chip off from the surface and make the surface unsafe from different effects.

Will not hold on:

Interior polyurethane will not hold on the outside. Because interior polyurethane doesn’t have all the additives that the outside surfaces require.

What is the difference between interior and exterior polyurethane?

Interior and exterior polyurethanes are not the same. So, let’s see what the differences are between interior and exterior polyurethane.

UV protection:

One of the important differences between interior and exterior polyurethane is UV protection. Generally, the interior polyurethane doesn’t contain UV protective resin. But exterior polyurethane has UV protective resins.


The durability of interior and exterior polyurethane is different. Interior polyurethane doesn’t have much durability. It might last a year if you use it outside. But exterior polys have such durability that they will last up to 2 to 3 years outside.


Generally, interior polyurethane has fewer additives since it doesn’t provide much protection. But exterior polyurethane has more additives. Otherwise, the exterior one will not provide much protection.

Can you use polyurethane on decks?

No, you should not use polyurethane on decks. A deck is an outdoor thing. If you use polyurethane on decks, it will deteriorate soon. The polyurethane will peel off and the outlook of the decks will no longer be smooth.

Moreover, polyurethane might hamper the deck’s longevity. The outside elements, like decks, are not suitable for using polyurethane. The deck’s surface will be too harsh for polyurethane.

Moreover, the surface of the deck comes close to moisture all the time. So, the polyurethane will quickly deteriorate. But if you still want to use polyurethane on your deck, you can try exterior polyurethane. Because exterior polyurethane is more protective than interior polyurethane. But considering the overall situation, you should avoid using polyurethane on decks.

Final Thoughts

You can use the exterior polyurethane outside. Interior polyurethane doesn’t have the features the outside surfaces require. But exterior polyurethane will protect the outside surface from ultraviolet rays and other weather effects. So, exterior polyurethane will be suitable for the outside.