Top 5 Best Exterior Polyurethanes (2024)

Looking for a great exterior polyurethane for your next project? I’ve used many different polyurethanes over the years and have some strong opinions. That’s why I put together this list of the best exterior polyurethane you can buy!

In a hurry? Minwax Helmsman Spar Urethane is the best exterior polyurethane overall because it’s a durable, long-lasting, easy-to-use polyurethane that can make wood surfaces look truly stunning.

Best Exterior Polyurethane

• #1 Best Overall – Minwax Helmsman Spar Urethane
• Highest Quality – TotalBoat Gleam Exterior Polyurethane
• Best Value – Varathane Oil Based Spar Urethane
• Best UV Protection – Varathane Ultimate Water Based Spar Urethane
• Best Color – ZAR High Performance Exterior Polyurethane

1. Minwax Helmsman Spar Urethane – #1 Best Overall

When it comes to exterior polyurethane, it’s hard to do better than Minwax Helmsman Spar Urethane. It’s a strong, visually appealing, and easy-to-apply product that can be used indoors as well, mainly because it’s less toxic.

A water-based, glossy polyurethane, it can be applied to hardwoods, softwoods, and other materials, but it’s best to refrain from using it on lighter woods, since it does yellow over time.

And since it has UV-blockers, even prolonged exposure to direct sunlight won’t wear it down.

Plus, it’ll hold up year round, as it’s formulated to resist temperature fluctuations. This is big, in my book, since temperature fluctuations wreak havoc on wood finishes and are impossible to predict.

But its ability to seal wood is what distinguishes it as the best of the best; it can rain for days and this poly will stay sound the whole time.

Typically, it’s used on exterior furniture, like deck chairs, tables, and benches. Minwax advises against using this on decks and larger wood surfaces, as it’ll be hard to maintain.

Also, refrain from applying it to the surfaces you walk on routinely, i.e. hardwood floors and stairs, as its glossy sheen will make them slippery and dangerous.

A full can provides 125 sq ft of coverage, and a synthetic-bristle brush is the recommended applicator. However, I’ve found that spraying this poly generally achieves better results—but it’s up to you!

Usually, only three coats are needed, but if you live in an area that gets battered by the elements routinely, 4-5 are recommended.

It takes 2 hours for a coat to dry. The final coat should dry for 24 hours, unless the surface is a countertop, in which case 72 hours of drying time is necessary.

This poly, once fully cured, can be easily cleaned with warm, soapy water.

Finally, this product is backed by a warranty. So if you receive a defective product, let them know and they’ll replace it or refund you.

What I Liked:

• It’s a versatile water-based polyurethane, as it can be used both indoors and outdoors.
• Your chances of getting harmed during application are lower since there are less VOC.
• The glossy sheen accentuates wood grain and other natural features without being overpowering.
• You don’t need to spend as much time prepping since there’s no mixing required.

What I Didn’t Like:

• Can’t be used on light-colored woods since it ambers over time.
• The finish will have to be touched up 2-4 times a year to ensure it’s strong and visually appealing.

2. TotalBoat Gleam Exterior Polyurethane – Highest Quality

When it comes to durability, few exterior polys can compete with TotalBoat Gleam Exterior Polyurethane. But its impressive strength isn’t the only thing it’s got going for it—it’s visually appealing, versatile, and relatively easy to apply too.

This is an oil-based exterior polyurethane, and it’s made with my favorite natural wood oil: tung oil.

Because it’s oily, it has a glossy sheen, but it’ll display more of a satin sheen if you add more resins before applying.

It’s also prone to yellowing over time, but this is only a problem if you apply it to light-colored woods. On the other hand, this yellowing can actually enhance darker woods.

Though it’s designed for outdoor use, particularly marine applications, it can be used indoors.

A full can will cover up to 250 sq ft, and it can be applied with a brush, roller, or sprayer.

The manufacturer recommends putting down 4-6 coats for interior and exterior surfaces, and I’ve found that six can withstand prolonged moisture quite well.

It takes about an hour for a coat of this poly to dry on outdoor wood surfaces, and it’s best to apply it when the temp is around 72° and there’s not much humidity.

Once dry, all you’ll need to clean it is warm, soapy water, but mineral spirits should be used to clean your applicator after you’re finished.

And since this poly is self-leveling, the application process doesn’t take as long, and achieving a smooth, balanced finish is easier.

Finally, like other exterior polys, it has UV blockers and comes with a satisfaction guarantee.

What I Liked:

• Its UV blockers ensure it won’t discolor over time.
• It’s thin enough to be sprayed effectively, which can’t be said of most oil-based polyurethanes.
• You don’t have to worry about irregular coats since this polyurethane is self-leveling.
• The 100% waterproof seal it forms will ensure mold and mildew don’t grow underneath.

What I Didn’t Like:

• Its price is relatively high when compared with similar products.
• Not the best for interior surfaces due to a higher concentration of VOC.

3. Varathane Oil Based Spar Urethane – Best Value

The exterior poly that’s going to be easiest on your wallet is Varathane Oil Based Spar Urethane, and it’s not just affordable but effective too.

This is another oil-based poly, and its clear satin finish highlights wood features in a subtle but distinct way.

And whereas other products on this list can be used as interior and exterior polyurethane, this one is solely for outdoor use, mainly because it contains more VOC.

Once completely cured, this oil-based polyurethane will seal the wood surface it’s been applied to, making it totally waterproof.

But it does yellow with age, so it’s best to keep it off light-colored exterior surfaces—I found this out the hard way.

Its maximum coverage is 190 sq feet, and you should apply at least three coats to ensure a durable, smooth surface.

I’ve found that a natural bristle brush is the best applicator, but I’m sure you can also use a roller.

It’ll be dry-to-touch in two hours and ready for another coat in eight. The final coat should get at least 72 hours of drying time before you resume using the surface as normal.

And like virtually all polys, it’s cleaned with soap and water and comes with a warranty or satisfaction guarantee.

What I Liked:

• The seal it forms won’t just keep out water but pests and microscopic debris as well.
• You only need to touch it up every 1-2 years because it’s very durable once fully cured.
• It’ll only take a minute to clean your brush because this poly comes right off with mineral spirits.
• It’s versatile and cost-effective since it can be applied to more materials than just wood.

What I Didn’t Like:

• This exterior poly will eventually yellow despite it having UV blockers.
• You can’t spray this poly because it’s too thick, and thinning it can be risky. 

4. Varathane Ultimate Water Based Spar Urethane – Best UV Protection

Many exterior polys claim to be “clear”, “non-yellowing”, etc., but Varathane Ultimate Water Based Spar Urethane is the only product I’ve come across that actually stays clear long after it’s fully cured.

Its ability to resist yellowing mainly comes from the UV blockers it’s made with. These blockers essentially reflect UV rays, and if they weren’t there the poly would eventually yellow as a result of prolonged sunlight exposure.

This is a water-based product with a glossy finish, so it can be used as exterior or interior polyurethane.

And like its sibling above, this poly will also keep a wood surface 100% waterproof, and that’s the main reason why I used it on my kitchen cabinets awhile back.

Exterior wood surfaces tend to need four coats, but more coats may be necessary if you live in an area that gets a lot of rain.

A can of this poly covers 87 sq ft, and it can be applied with a brush, roller, or sprayer.

After 30 minutes of drying it’ll be dry-to-touch, and after an hour you can add another coat. And after the final coat has been put down, wait at least 24 hours before you use it.

Finally, it’s less toxic, easy to clean, and comes with a pretty solid warranty.

What I Liked:

• It can be used on virtually all kinds of wood because it doesn’t yellow over time.
• You can complete the application process in under a day since this poly is quick-drying.
• Its ability to block out moisture means no mold growth, discoloration, or rotting.
• Brush strokes won’t be pronounced thanks to its consistency.

What I Didn’t Like:

• It’s too glossy for surfaces that get a lot of foot traffic.
• Shouldn’t be used on large surfaces because maintenance would be expensive.

5. ZAR High Performance Exterior Polyurethane – Best Color

When an amber poly is what you’re after, consider ZAR High Performance Exterior Polyurethane, as it’s not just gorgeous but strong too, particularly when it comes to blocking out moisture and UV rays.

This water-based polyurethane has a satin sheen, and it can be used on wood and metal to great effect. 

It can be used as an indoor polyurethane too, since it’s less toxic, and it can be applied with a brush, roller, or sprayer.

To ensure a durable finish, the manufacturer recommends 3-4 coats; I’ve found that five are necessary in most cases.

You only need to wait an hour before adding a new coat. The topcoat should get at least 24 hours of drying time before you start using the surface as normal.

And, of course, this product is backed by a warranty, which I like just for the peace-of-mind factor.

What I Liked:

• Its rich, amber color makes it a terrific poly for accentuating wood grain in darker woods.
• Great for marine applications since it keeps moisture at bay and blocks out harmful UV rays.
• It has the strength of an oil-based exterior polyurethane, but without the high concentration of VOC.
• A full can will coverage a substantial area because it’s thin and easy to spread.

What I Didn’t Like:

• Higher price due to all its benefits.
• Additional coats sometimes take two hours to dry.

What to Consider When Buying Exterior Polyurethane

Strength

Strength is one of the most important factors to consider when browsing outdoor polyurethanes. Generally, oil-based polyurethane forms a more durable coating, and it lasts longer.

A sound polyurethane finish will protect a wood surface from scratches, impact damage, moisture, mold and mildew, pests, and UV rays.

Appearance

But strength isn’t everything—exterior polyurethane should be attractive too. Or, at the very least, it shouldn’t diminish the visual appeal of the natural wood, stain, or paint underneath.

When thinking about polyurethane’s appearance, yellowing should be one of the first things you consider. Most polys yellow over time, and while this isn’t a problem for the majority of wood surfaces, it can be for light-colored woods.

Ease of Use

Polys that are easy to use often yield the best results. Generally, exterior water-based polyurethane is easier to apply, as it’s thin, less odorous, and quick-drying. Also, there’s no mixing involved.

Oil-based polyurethane isn’t hard to use, per se. It does, however, take longer to apply, mainly because it’s much more viscous.

Want to know how to use exterior polyurethane more effectively? Check out the video down below!

Water Resistance

Most exterior polyurethanes can waterproof outdoor wooden surfaces, but some only make them water-resistant.

When it comes to preventing moisture damage and all the things that come with it, namely mold and mildew, marine polyurethane does best.

UV Resistance

An outdoor polyurethane must be able to withstand direct exposure to UV light, even if it doesn’t get a lot of this throughout the day.

It only takes a few hours of direct sunlight to yellow a once-clear polyurethane, but that’s only if the poly doesn’t have any UV blockers. These additives not only prevent yellowing but sunlight-related damage as well.

Toxicity

All polyurethane contains volatile organic compounds, but some have more than others. Water-based exterior polyurethane, for example, has less VOC, whereas oil-based poly has more.

To know how much VOC a poly has, simply look on the label; this information has to be included.

And if you can’t do this, do the “smell test”. That is, apply a little bit and see how odorous it is. Strong odor means more VOC.

FAQs

What is the best polyurethane for sun exposure?

The best polyurethane for sun exposure is one that includes UV blockers. These additives block UV rays to prevent surface discoloration and damage.

How long does exterior polyurethane last?

Depending on its composition, the surface it was applied to, how it was applied, and how it’s been maintained, an exterior polyurethane can last 10-20 years. Oil-based polys tend to last longer since they’re stronger than water-based versions.

What’s the difference between spar urethane and polyurethane?

Spar urethane is an oil-based product, whereas polyurethane can be oil-based or water-based. Spar urethane forms a richer, more durable finish, but it contains more VOC and takes longer to dry.

What is the best outdoor polyurethane that won’t yellow?

The best non-yellowing polyurethanes are water-based products that have UV blockers. Since they’re water-based, they don’t have the components that cause oil-based polyurethane to yellow, and the UV blockers prevent yellowing caused by the sun.

Final Thoughts

Minwax Helmsman Spar Urethane is the best of the best because it’s reliable, less toxic, easy to use, and great at bringing out the natural features in wooden surfaces. Moreover, it’s more affordable when compared to products of similar quality.

TotalBoat Gleam Exterior Polyurethane is the strongest exterior polyurethane, and as such it withstands prolonged exposure to the elements, expands and contracts with temperature fluctuations, and requires less maintenance.

Varathane Oil Based Spar Urethane is the most affordable polyurethane, yet it still delivers in all the ways that matter to me. It offers solid moisture and UV protection, it highlights a wood surface’s natural wood grain, and it’s easy to maintain.