What Is Marine Grade Plywood?

Plywood is one of the inventions that actually have a place in our daily lives. Marine grade plywood is a type of plywood that is good for certain specific uses.

So, what exactly is the marine grade plywood and how is it different from the regular stuff? The key component here is that the glue which holds the veneers together is waterproof. In addition, this plywood is always smoothed out and it is made of a type of wood that doesn’t easily allow fungus growth, even in moist environments.

So, where can you use this, and what else is there to know about it? Here you can find more detailed information about marine grade plywood, where to use it, and the common differences between marine grade plywood and the regular type.

What is the Difference between Marine Grade Plywood And Others?

This is the type that handles contact with water better than any other type. This plywood is sturdier and is always made of high-quality wood of certain tree types.

During the production, the thin sheets of veneer are put on top of each other perpendicularly and they go through a process called cross-lamination. Cross-lamination makes this type sturdier. Heat and pressure play a critical role in the production process.

There are three key points for plywood to be certified as marine-grade. The first is that the glue must be waterproof. The second is that there should be no air left between the glued veneers. The third is that both the face and the inside veneers should be made of good quality wood.

These are critical components since they all ensure that the wood in contact with water will keep up with the harsh environments for a long time. For example, the waterproof glue which is used for marine-grade water production should endure a “Weather and Boil Test” which is a stringency test. The most used glue type for marine grade plywood is phenol-formaldehyde.

The use of waterproof glue is important so that the plywood won’t delaminate, or won’t divide into individual layers under harsh conditions, like high temperatures or moist environments.

Voids in marine grade plywood is an important aspect since the wood can absorb the water. If there are any gaps between glued veneers, the water can pass through the exterior veneers to inner veneer layers. This makes the plywood brittle or very open to possible fungus infection and rot.

The last most important aspect is that it isn’t treated with any chemicals beforehand. This is about maintaining the quality of the wood.

Another important aspect is the overall quality of the veneers. The knot size and frequency is controlled. There are rules for repairing inner veneers. The thickness and number of plies is also controlled.

There are certain types of trees preferred for the production: fir, Okoume, and meranti. Let’s take a better look at them.

Douglas Fir

This type of wood is used as it’s very strong. The other reason why Douglas fir is chosen is that it bends well and it isn’t too heavy. This makes it a good choice for boat hulls or anywhere the wood should be bent.

In addition, it is very weather-resistant. It is generally cheaper than the other options as well.


These types of trees are native to Africa and they are good quality materials for marine grade plywood. This type of wood has a similar look to mahogany. The best thing about Okoume is that it is quite light. This makes it excellent for boat interiors and exterior design since it doesn’t add to much weight to the boat.

It also looks good after it is laminated. It has a finish like glass. The Bruynzeel option is the best example of this.


This is another type of tropical tree that is used for high-quality production. The main advantage of meranti is that it’s much sturdier than Okoume, especially against bending, however, it’s also heavier.

It was first developed by Cornelis Kees Bruynzeel who studied woodworking and he was an avid sailor. Bruynzeel developed the water-resistant glue and made the first marine grade plywood.

Let’s take a closer look at the grades.


First of all, there are different thicknesses of this type of plywood. The thickness comes in increments of 1/8”. It is usually ¼,3/8, ½, 5/8, and ¾ inches thick. The general width and height is 4”x 8”. The price changes according to thickness and size.

When you’re planning your construction, you should take the thickness and grade into consideration. These are the grades:

·        A-A: This grade is usually 1/2” thick and comes in 4” x 8”.

·        A-B: The size stays the same as A-A but the thickness is 3/4”. It has no knots and it’s stronger.

·        B-B: You can also find these under the name of face-back marine plywood.

·        Medium-density overlay (MDO): This comes in the regular dimensions but the thickness varies. You can find it with thicknesses of 3/8”, 5/8”, ½”, and even 1”. This has a high-quality thermosetting and it is impregnated with resin fiber overlay.

·        High-density overlay (HDO): This grade is shinier than MDO because it is impregnated with more resin. The dimensions are the same and the thickness varies from ½” to 3/4”.

·        D: The least expensive type.

Just like this guide about how to choose marine plywood, you can check similar ones about engine driven welders or fuel transfer tanks.

Best Uses

So far, we’ve introduced you to what it is made of and which properties make it different from the regular stuff. Here, you can learn more about where to use this type of wood for your next construction project.


Because boats are always in contact with water and moisture, this is the most common place that this type of wood is used. Note that this is why Bruynzeel developed it in the first place.

This type of wood, given the fact that it is high quality, is 100% waterproof. It is also quite pliable, therefore you can even use it in hulls or other curved parts of a boat. To properly use it in boats, you should make sure to seal it properly.


Docks are another place where the wood is constantly in contact with water. Since you can use marine grade plywood for boats it makes sense that you can use it to build your own dock as well.

The biggest reason that you should choose this over other types of wood when you’re building a dock is that it doesn’t require sanding. This saves you the work of sanding every year. Also, because the type of wood that is used for the plywood is weather-resistant, you won’t have rot, decay, or warping problems.


When we say interiors, we mean the moistest and wettest parts of the house: The kitchen and bathroom.

If your bathroom is floods or you like to take steamy showers, you may consider having bathroom furniture made out of marine grade plywood, or you can try it as a replacement for flooring or siding. This choice will also reduce the mold and rot in the bathroom.

As for kitchens, it is also a good choice for your next remodeling project. Given the fact that Bruynzeel developed marine grade plywood for kitchen use, it makes a lot of sense to use it there! You can use this wood to replace your cupboards or as a replacement for flooring or siding.


In addition to the interior use, you can use it in exterior areas of your house such as decks, patios, and porches.

Because it comes in various sizes, it’s rather cheap to cover all your exterior parts of the house with these boards. It will be very weather-resistant if you choose to do so; the boards don’t rot easily!

In addition to flooring or siding, you can always make yourself a nice fishing dock out of this material. If you have a pond or body of water where you can regularly go for fishing, it’d be a nice addition.

To be able to do renovations on your house or build your boat you may require some additional equipment. You can read about wide belt sanders,plasma cutters,oxy-acetylene cutting torches to learn more about how to choose the best tools and use them correctly if you’re considering building yourself a dock!

Now, let’s take a closer look at the differences between pressure-treated plywood and marine grade plywood.

Pressure Treated vs Marine-Grade

For the untrained eye, it may seem like a good idea that you can repair your boat with pressure-treated plywood. However, unfortunately, the pressure-treated option and marine plywood are not interchangeable. These two have very different places where each type should be used.

To begin with, the biggest difference between these types are the ways they’re chemical treated. Marine-grade is almost never chemically treated during production, whereas pressure-treated plywood is. This changes the overall quality and water-resistance of the wood. Contact with water on a constant basis will wear out the chemicals on pressure treated wood.

Another important difference is the overall water resistance capacities of each individual. For marine grade plywood, water-resistant glue is used which gives it very distinctive features; however, pressure-treated wood isn’t necessarily produced with water-resistance in mind.

Pressure-treated plywood is generally made out of softwood as this easily allows chemical treatment but also means water penetration between the different veneers is a consideration. In contrast, marine-grade uses harder types of wood and this alleviates the water penetration problem.

In addition to the hardness of the wood, marine plywood generally has a higher numbers of thinner veneers than the regular pressure-treated wood. This is another reason why it is sturdier than other options.

Another critical difference is the number of plies. During the production of marine grade plywood, the number of plies is controlled to increase the sturdiness. However, this isn’t the case for pressure-treated wood.

A thing that the two do have in common is rot-resistance. The main reason pressure treated plywood is rot and insect-resistant is the chemicals used in the production. Given the fact that constant water contact will wash away the chemicals, it’s expected that the pressure grade plywood will lose this ability over time.

Overall, marine-grade plywood is developed and used for places that have a lot of exposure to water, why it has the name that it has.

Exterior Grade vs Marine-Grade

At first glance, you may not recognize the key differences between exterior grade plywood and marine plywood. However, when you start taking a closer look, it becomes evident that there are a range of differences.

Let’s start with the reason why these types are sometimes considered interchangeable by untrained eyes. The reason that they are often compared is due to the nature of their general weather-resistant features. Exterior grade plywood is also made of A-bond glue, which makes it water-resistant in the first place. Why it is designed to withstand the unpredictable forces it gets exposed to outside.

Unfortunately, the similarities end there. To begin with, for plywood to be labeled as marine it has to meet some strict standards. Exterior-grade doesn’t need to satisfy these criteria.

The criteria here for marine grade plywood is first and foremost that there must be no void between the veneers. The second is that the veneers must be of the highest quality. The last is that the glue needs to be waterproof. Most of the time, exterior grade won’t make the cut because of the quality of the wood.

In addition to the quality of the wood, exterior grade plywood may have some gaps that are created during the lamination process. This is absolutely bad if you use them for a boat as the water can reach the inner veneers. Using marine grade plywood ensures that the water will never reach the core of the ply, hence no rot.

Another important fact here is that marine plywood will never have aesthetic problems. By aesthetic problems, we usually think of the finish, the plies, and the knots. You can use exterior grade plywood for some outdoor purposes, though, although, you would never use them for the interior of a boat.

Marine plywood will never have any, or at least only very few of them. On the contrary, exterior grade may have knots as big as 1”. This entirely changes the look of the plywood when that is the case.

In conclusion, exterior grade plywood may replace cheap marine grade plywood in cases of an outdoor structure yet it will never fully replace it for all uses. Especially if you are planning to build your own boat you shouldn’t replace marine grade plywood with something that doesn’t have the same level of water-resistance.

So, let’s say you’re on a tight budget. What other types of materials can you look for instead?


Although marine grade plywood is the best when it comes to a range of jobs, sometimes you may not easily procure them or you are on the hunt for a cheaper alternatives. These alternatives may not fill the shoes of marine plywood easily, but they may still serve as reasonable alternatives.

The first alternative that you can look for is polyurethane foam made by 3M. This is a lighter and rot-resistant alternative. These boards have fiberglass reinforcement and they are suitable or high strength applications including marine purposes. You can especially choose this if you have weight concerns you need to take into account.

These foam boards also come in the same sizes that marine grade plywood does, 4” x 8”. They are perfectly straight and easy to shape with tools. You should use marine grade screws to secure them.

Another alternative is fiberboard. These have a lot of similar characteristics; however, they are not 100% wood! Fiberboards contain wax resin to increase their strength. This is a special kind of wood. It’s broken down into fibers from softwood, and these fragments are mixed with a wax resin to make up the boards.

Fiberboards can give you the feeling of wood while being an alternative to marine grade plywood. You can also find them as sheets and they are heat-resistant just like marine grade plywood. You can use these sheets under waste oil heaters or hot water recirculation pumps for better insulation.

Ribbon grain plywood is also another alternative. This type gets its name from the appearance as the grain is shaped like ribbons and the vertical stripes run along with the wood. This is also a very smooth type and the appearance is alluring! They don’t have all the same characteristics; however, they are much cheaper.

Fiber cement boards aren’t technically plywood but they contain a good amount of wood material. They are good for exterior use such as walls or ceiling. This is a special type of board since it’s actually cement mixed with wood fibers. These are quite sturdy.

In short, you can sometimes replace marine grade plywood with other types of material while still getting the features that you are looking for. You should, however, always keep the project you have in mind and make your choice accordingly.

The next and last question that remains is where can you find them?

Where to Buy Marine Grade Plywood

There are several ways you can buy plywood. You can either look for the sellers on Amazon or you can go online and find the nearest distributor. Now you know what to look for when you’re buying it, it should be easy to see if the seller’s descriptions match your needs!

We have a couple of suggestions for you. When you are looking for your distributors, first ask them if they supply Bruynzeel marine plywood. This is a reputable brand; therefore, you can buy those while knowing you are getting the quality you are looking for.

If you don’t have any local suppliers, you can always check out big distributors like Amazon and Home Depot. Unfortunately, for higher-end stuff like Okoume marine grade plywood, you may have to check for a local supplier as we weren’t able to find any reliable sources online. Here, we have provided you an option you can choose.

3/4” Marine Grade Plywood 2’ x 4’

This certain product is made by Capitol City Lumber. It’s ¾” thick and the sheet’s dimensions are 2’x4’. This product has a clear and smooth finish; however, it’s not knot-free and has patches of blemishes. Nevertheless, it’s marine grade because of the exterior phenolic glue and the fact that there aren’t any voids between the plies.

In Conclusion

Marine-grade plywood is a good choice if you want to redecorate the parts of your house that get exposed to a lot of moisture, like your home’s exterior, and it’s the perfect material if you are dreaming of building a boat or kayak to take out on a lake near where you live. We hope that this article helped answer a lot of the questions you may have had.

Additionally, we would like to tell you a little bit about the mission that we are on here at Atlantic Aspiration, because we have a bunch of other features that we would love for you to explore while we have your attention!

Our mission is clear: We wan’t to revolutionize how pros complete their work, how they pick their tools, and how we all make sure that we are changing the built world for the better.

What that includes is that we are trying to create transparency where we believe that there has previously been very little, and we are doing so by creating a range of different resources that we are offering on this website, including informative guides like the one that you have been reading.

However, we are also working on changing the way that pros are buying the tools that they are needing for their work, which has previously involved scouring the internet for reviewsand scattered resources on the tools that they are researching. Instead, we are trying to make the process a lot easier by both gathering all the relevant resources that they might be needing throughout their search, while also combining it with showing what we believe are some of the best manufacturers in the business! We are doing this in order to cut down on the time they are spending finding the right tools.

However, we are also creating a bunch of resources for homeowners, like this one on hydroponic farming.

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