8 Best Exterior Polyurethane- Reviews & Buyer’s Guide

Image of outdoor table that needs best exterior polyurethane for protection

If you are looking to protect and give a beautiful finish to your exterior wood surfaces, then a polyurethane presents one of the best formulas to use in a bid to beautify and protect them. It doesn’t take much to give your products the most exquisite finish possible, especially if you have the best exterior polyurethane.

Getting the best polyurethane formulas can be difficult for most people, that’s why we have reviewed among the best exterior polyurethanes for your woodwork projects. Our list of best exterior polyurethane formulas include:

1. Minwax Helmsman Indoor/Outdoor Spar Urethane – Best Overall Polyurethane for Exterior Wood Doors

The reason we consider this product as the overall best exterior polyurethane is because you can use it both indoors and outdoors woodworking projects. First, you need to know that this product comes in quantities such as a gallon and a quart-size container with the gallon one giving more value for your money.

Minwax Helmsman does so well when it comes to dealing with the severe external factors. It comes with the ability to resist UV light hence prevents the yellowing of the wood. Besides, the UV protection also helps prevent the wood from peeling in the process. 

This formula has a faster drying time curing into a durable and Vclear finish with a beautiful shine. Its faster drying time might not necessarily be advantageous, especially when you are working on projects that call for constant corrections here and there. Putting a brush on a finish that has started drying already would ruin the whole thing. And, it might require that you sand.

A point of concern lies with the consistency of this product as it is a little thinner and soaks into surfaces of soft and porous woods requiring more coats for a perfect finish. 

The Summary of Top Features

  • The formula has UV blockers which prevent the discoloration of your wooden surfaces
  • It’s water resistance
  • This formula contains a special oil that expands and contracts with the wood with the variation in temperatures.
  • You can use it on indoor projects like doors, bar tops, kitchen countertops, etc.
  • It cures into a bright crystal finish that is best for light-colored woods and stains. The formula dries faster especially when the temperatures are warm


  • It offers excellent value for your money
  • Has anti UV
  • The product expands and contracts with the changes in temperature
  • Gives a crystal clear finish
  • The formula dries faster.


  • It’s a little thinner formula.
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2. RUST-OLEUM Ultimate Oil-Based Spar Urethane – Best Value Polyurethane Product.

If you are working on a budget, then this is your product. Considering that this is a Rust-Oleum product and the price, it is an absolute bargain to buy this formula. 

As you would expect from any other outdoor wood polyurethane product, this formula comes with resistance against the dangerous UV lights from the sun. The sun rays do wood surface damage, especially by causing discoloration. Having this product ensures that your wooden surface does not suffer from the damaging sunlight. 

What’s more about this product is that it dries into a finish that can withstand rigorous activities in the outdoor environment. Besides, it comes with strong resistance to molds and mildew. 

Additionally, this formula resists water and any other elements of moisture thanks to its oil-based nature. Remember that all oils are hydrophobic. 

Amid its amazing features, this product does have some limitations as it might start yellowing with time hence loose it’s clear finish status. Also, it takes a little longer to dry compared to other similar products.

The Summary of Top Features

  • It’s suitable for protecting outdoor wood surfaces such as furniture, fences, etc.
  • The formula comes with a more extended durability 
  • It dries to touch in just about 2 hours 
  • The formula comes with a coverage area of 190 sq. Ft. per gallon, recoat after 8 hours
  • It is weather and UV resistant formula
  • Cures into a gloss finish with a and clean look
  • UV protection


  • Best value for your money
  • It can resist mold and mildew
  • Gives a gleaming finish
  • It’s both water and UV proof.


  • It yellows with time.
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3. RUST-OLEUM Ultimate Water-Based Spar Urethane 

This formula is more or less the same as RUST-OLEUM Ultimate Oil-Based Spar Urethane, with the underlying difference is that one is water-based and the other oil-based. 

Using this product guarantees you a long-lasting finish that dries into a rock hard, beautiful finish. It takes a lot to damage surfaces coated with this polyurethane. Contrary to its oil-based counterpart, this product is clear and with very slim chances of yellowing with time. The most fantastic aspect of this wood polyurethane is its fast drying time. It takes just about 30 minutes to dry to touch and be ready for recoating 2 hours later- a quality that makes it best for projects that have a timeline.

The Summary of Top Features

  • It’s a durable product for outdoor wood surfaces like furniture, doors, windows, fences, etc.
  • This formula comes with a low odor with easy application and cleans up using soap and water
  • It has has a faster dry time of 30 minutes with a coverage of up to 87 sq. Ft. per quart
  • It gets ready for recoat in 2 hours
  • This formula resists both water, UV and does not yellow 
  • It gives a crystal clear and a gloss finish 


  • Cures into a tough finish
  • It produces less odor
  • Easier cleanup using soap and water
  • It does not yellow
  • Has a faster dry time


  • The can leave streaks on the surface of the wood.
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4. Deft Defthane Interior Exterior Clear Polyurethane Gloss

This product has some of the best and secure finishes for your wooden structures. It comes with a wide range of uses on both the interior and exterior environments. Following its application, this formula dries into a clear and robust finish with high resistance to water. 

It has one of the best consistency in the market with a smooth flow that helps in minimizing brush marks. You can apply this formula to surfaces such as the stained wood, lacquered and varnished surfaces. The product comes with a faster drying time of just about 30 minutes with the surface ready for recoat in 6 hours. 

Its coverage is an amazing one with a range of 500 to 600 sq—Ft. Per gallon. 

The Summary of Top Features

  • This product is oil-based and best suited for hard use areas
  • It performs amazingly for both the interior and exterior wood surfaces. You can use it on unfinished and stained wood, painted, varnished, lacquered surfaces, etc.
  • You can buy it in a gloss finish and 1-quart container.


  • Faster drying
  • Extensive coverage 
  • For both interior and exterior environment
  • Has a great consistency


  • It takes longer to cure
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5. Deft Interior Exterior Water-Based Polyurethane Finish Gloss, Quart

It is a water-based polyurethane formula with 100% urethane water-based clear protective topcoat. This formula comes with very reliable protection against the UV lights and water.

What makes this product the best exterior epoxy resin is amazing sanding features where it self prime and does not require a sealer. What’s more about this product is that it contains low levels of VOC, which makes it a perfect companion to the environment. Other than it’s low VOC contents, this formula does not discolor and has a low odor. 

Its versatility is just incredible as you can use the product on both interior and exterior wood surfaces. The application is an easy one as you can do it using a brush, pad, airless as well as High Volume Low Pressure (HVLP) spray application. Finally, this formula is easy to clean, dry in about 2 hours, and available in a gloss finish as well.

The Summary of Top Features

  • Used on both Interior/Exterior surfaces
  • It lasts longer than the water-based poly
  • This formula takes just about 2 hours for recoat
  • It contains low VOCs with low odor as well. 
  • The formula has protection against The UV rays from the sunlight


  • The formula is easy to clean
  • It takes a shorter time to dry
  • Contains low VOCs
  • You can use it on both interior and exterior surfaces


  • Some users reported yellowing of the formula
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6. RUST-OLEUM 207008 Spar Varnish, Clear, Polyurethane

Rust-Oleum Marine Spar Varnish deserves mention as the best exterior polyurethane product due to its reputation as a reliable product. It’s a formula that gives your outer wooden structures sufficient protection against damaging elements such as sunlight, water, as well as chemicals on wood surfaces above the waterline. 

It’s a flexible coating that expands and contracts with the variation in the weather conditions. Besides, this polyurethane formula has a durability that is two times that of a standard wood finish. It’s all that you need, especially for your marine projects.

The Summary of Top Features

  • This product is the best especially for exterior wood surfaces above the waterline, such as trim, railings and wood furniture
  • It is an oil-based formula that expands and contracts with the variation in weather conditions
  • The formula takes about 2 hours to dry to touch
  • It has a coverage of up to 150 sq ft
  • It’s a durable coating with excellent resistance to UV, salt, and mildew
  • It cures into a crystal-clear varnish that leaves a beautiful gloss finish with utmost 


  • It has a faster drying time
  • Relatively broad coverage
  • It’s flexible to weather change
  • The formula is affordable.


  • Some users complained of white residues while using this formula.
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7. ZAR Exterior Oil-Based Polyurethane

It’s a satin finish that gives some tint to the surface in which you apply it. This property enables the ZAR Exterior Oil Based Polyurethane to bring out the best of any natural colors of the wood surface. 

Using this formula guarantees you both beauty and protection. It gives one of the high shine finishes you can find in polyurethane in the market today and far much better than what you’d get in its water-based counterparts. If you are looking for a contemporary and classy finish in polyurethane, then this is your product.

Other than its amazing looks, this formula dries into a tough finish. It can withstand different exterior damaging elements such as the notorious UV rays. Besides, it has antioxidants which help to counter possible discoloration of your finish.

The Summary of Top Features

  • It comes with superior protection to the wood surfaces
  • This formula is twice as durable as its counterparts
  • Contains antioxidants
  • Has UV blockers
  • Brings out the best in wood’s natural colors


  • This formula gives a deep, luxurious shine
  • It is perfect for beauty and durability
  • The formula resists UV light
  • Comes with antioxidants that resist yellowing


  • It has a short shelf life.
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 8. ZAR Exterior Water-Based Polyurethane

It is a marine-grade formula with a very high level of water resistance. You’d argue that all best exterior polyurethane products are water-resistant, yes that true, but this one is just so good. 

Therefore, it is perfect for areas that receive a lot of rainfall, or structures that are close to water bodies. As much as this formula works perfectly on coatings above the waterline, we do not recommend it for underwater usage.

It’s a little thinner compared to most similar products in the market. However, it has less odor. Cleaning of this polyurethane is quite easy as it does not call for the use of any special chemicals in the process. 

When you use this formula for your exterior wooden structures, it offers protection against damaging elements such as UV rays. Besides, it has antioxidants that play an essential role in preventing the discoloration of your surfaces. In general, this product holds up to the weather in the best possible way.

The Summary of Top Features

  • Gives a light amber finish
  • Leading door manufacturers recommend this product
  • It provides one of the best marine-grade finish
  • Cleaning is a simple one as you need only soap and water cleanup


  • It’s perfect for marine use
  • Comes with antioxidants to prevent discoloration
  • Has a good coverage
  • Comes with a long shelf life


  • It’s expensive
  • It is susceptible to bubbling.
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Best Exterior Polyurethane Buyer’s Guide

The wood you use in the construction of your exterior structures is expensive to buy and even to build. Therefore, you should always ensure that you protect them to avoid incurring extra costs in replacing them.

One such way of safeguarding your external wood surfaces is by use of polyurethane finish. There are so many poly formulas in the market, and not all will offer adequate protection to your structure. In an attempt to help you get the best product possible, we have highlighted some of the essential factors that you need to consider before shopping for the best exterior polyurethane. And they include:

Types of Polyurethane Formula

There are two main types of polyurethane formulas:

Water-Based Polyurethane: Mostly, these types of polyurethanes are clear and help to portray the natural beauty of the wood, making them a favorite of many. They provide sufficient hydration hence protecting the wood from drying out, therefore, improving the overall appearance of your structures.

Oil-Based Polyurethane: Mostly, they are expensive and provide more durability compared to their water-based counterparts. Usually, they are the best choice for exterior surfaces as they tend to offer excellent protection from different weather conditions. Furthermore, these products expand and contract depending on the variation of temperature, which further enhances protection.

Other Factors to Consider In Polyurethane

Finish And Appearance

Poly products come with different kinds of finishes, such as matte/clear, gloss, and satin. The finish that you choose will determine how the surface of your wooden projects would look like. Therefore, you should have in mind a clear idea of how you would love your final finish to appear. 

Drying Time

The drying time of your poly products is an essential aspect of woodworking. If you are working on projects with short timelines, we do recommend that you go for fast drying polyurethane products. 


It’s arguable the most important aspect that you should consider. Going for products that will offer lasting protection to your wooden surfaces is very important. Durable formulas save you the costs of constant repairs, as well as the time you take in refinishing your surfaces. 

Ease Of Use

The products that are easy to use are preferred by many. If you are a beginner, for example, going for poly products that are simple to apply will make it a lot easier for you as you won’t have to involve hiring an expert in the woodworking industry to help you with your projects. 

Frequently Asked Questions

Is Polyurethane Toxic?

Yes, polyurethane does contain isocyanatesa compound that scientists consider harmful to the lungs.

Can You Apply Water-based Polyurethane over Oil-based?

Yes, provided you prepare your surface well, it is okay to apply a water-based polyurethane over an oil-based one.

Watch the video below on how to apply polyurethane with no bubbles:

The Conclusion

Polyurethane is a perfect finish for all wooden surfaces because it offers protection as well as beauty. If you are in the look for the best exterior polyurethane, then you will find this review and buyer’s guide important for your course. We have discussed some of the best poly products for your external use with Minwax Helmsman Indoor/Outdoor Spar Urethane as our best overall product in the market. 

All the products in this article are tested and certified. We do not doubt that whichever that you will choose based on factors such as your budget, as well as personal preferences, will serve you right. Happy shopping as you look to improve your woodworking projects!

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Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

2 thoughts on “8 Best Exterior Polyurethane- Reviews & Buyer’s Guide”

  1. I need a protection for outdoor ash wood slabs that will stand up to walking on, uv protection and water protection and I don’t have to put another mortgage on my house do you have suggestions. Minwax said theres is not for floors.
    Advance thank you

    1. Hello Jim,

      Epoxy would work well but they normally don’t protect against UV, so you might have to add a sealer over the epoxy.
      The sealer should be water and UV Proof.
      Epoxies and Latex paints bond well, so you might want to finish the epoxy with an exterior latex paint.


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