Marine Plywood: All You Need to Know

Plywood is engineered wood made from thin sheets of wood veneer bonded together to make a stronger panel. It is a strong and lightweight alternative to solid wood demanded by versatile applications.

Plywood is often used in the construction of exterior walls, roofing, floors, doors, furniture making, and packaging.

However, plywood is not a one size fits all product. Depending on its intended use, there are different types of plywood suited for different purposes. Choosing the right type of plywood will ensure your project is a success.

Most standard plywood products aren’t built to withstand the rigors of constant exposure to water.

Sunlight and moisture will damage plywood over time, causing it to warp, rot, and break down.

Although there is a type of plywood designed for outdoor use also known as “exterior grade plywood”, it still doesn’t assure full protection against the water.

marine plywood

This is where marine plywood or also known as marine grade plywood comes in. Marine plywood is designed for use in high moisture environments and/or in direct contact with water.

It offers superior protection against water damage and is intended to be used in applications where constant exposure to water is a possibility.

Marine plywood is built using waterproof glues and has no voids in its interior layers. It is also built with only A-grade or better veneers on the face and back, which results in fewer defects.

This makes it ideal for use in boat building and other watercraft construction. It also has more layers than standard plywood, making it stronger and more durable.

If you’re working on a project that will be exposed to moisture or water, where water damage can cause a significant problem, then you need to consider using marine plywood.

Other than that if you are just looking for strong and durable plywood that can stand an occasional splash of water then exterior grade plywood would suffice.

Just remember that marine plywood is the better choice when it comes to protection against water damage.

It’s a more expensive option than both regular plywood and exterior grade plywood for its increased durability and waterproofing, but it’s worth the investment if your project requires it.

Let’s take a closer look at marine plywood and see what sets it apart from other types of plywood.

What Is Marine Plywood?

Marine plywood is a type of plywood that has been designed for use in marine applications.

It is made with waterproof glue and has a void-free core and higher quality surface finish which makes it ideal for use in boats and other watercraft.

However, limiting its use to marine applications would be a mistake. Marine plywood can also be used in any application where regular plywood would be susceptible to moisture. This includes outdoor furniture, decks, and even sheds.

Here is a larger list of other common uses for marine plywood:

  • Decks
  • Storage shelving cabinets
  • Garage & carport shelving cabinets
  • Various home & commercial projects
  • Countertop underlayment
  • Wooden toys
  • Docks
  • Porches
  • Patios
  • Saunas
  • Hot tubs
  • Playhouses
  • As a platform for bed frames
  • Fish house
  • Boathouse
  • Outdoor signs
  • Overlay applications

What is the grade of marine plywood products?

Plywood products are graded from A-A to D-D, with A-A being the highest quality and D-D being the lowest.

Marine plywood is typically made with A-grade or better veneers on the face and back, which results in few defects and a high-quality surface finish. They can be used as-is without requiring sanding or painting before use.

What sizes does marine plywood come in?

Marine plywood is available in a variety of sizes. The most common size is 4′ x 8′. Other sizes include 5′ x 5′, 5′ x 10′, and 6′ x 12′. However, marine plywood can also be specially ordered in custom sizes.

What thicknesses does marine plywood come in?

Marine plywood is available in a variety of thicknesses. The most common thicknesses are 1/4″, 1/2″, and 3/4″. Again, it can be manufactured in custom thicknesses as well.

What types of veneers are used in marine plywood?

Marine plywood is typically made of higher quality veneers than regular plywood. While most regular plywood is made of softwoods, marine plywood is usually made of hardwoods.

The most common type of veneer used in marine plywood is mahogany. Other types of veneers used in marine plywood include teak, cherry, maple, oak, and birch.

These veneers are more resistant to rotting and have a closer grain, which makes them less likely to delaminate.

Advantages of Marine Plywood

Pre-sanded and paintable

Marine plywood is already sanded and can be used without needing to be sanded again. This saves time and effort in the project. In addition, marine plywood is paintable without the need for a primer.

In order to get the best results, it is important to use a good primer and paint or stain that is designed for marine applications.

Resistant to rot & decay

One of the biggest advantages of marine plywood is its resistance to rot and decay. This is due to the waterproof glue that is used to bond the layers of wood veneer together.

Marine plywood has a high water resistance threshold. As a result, marine-grade is employed outside as garden furniture or stairwells.

As its name suggests, marine plywood is utilized in the boat-building business where there is a lot of exposure to water. For the same reason, it is preferred for bathroom and kitchen applications.

Exceptional strength & durability

Marine plywood is also much stronger and more durable than regular plywood. This makes it an ideal choice for any project that will be exposed to high traffic or heavy use.

The adhesives used in the manufacture of marine plywood are synthetic plastic resins, namely a Phenol Formaldehyde resin with high adhesive qualities.

The use of high-quality resins aids in the blocking of all moisture and water. To ensure that the quality of the plywood is not affected, good brands employ undiluted resin.

Since marine plywood is made with waterproof glue, there is very little chance of the layers of wood veneer coming apart. This makes it an ideal choice for any project that requires a strong and durable bond.

Marine plywood is the strongest in the plywood business due to the use of high-quality resins and wood.

They are well-known for their toughness and durability. The waterproof nature of these ply keeps the integrity of your furniture intact.

Marine plywood uses typically the same or very similar glue as exterior-grade plywood, but not the same type of glue used in regular plywood (construction-grade plywood).

Disadvantages of Marine Plywood

There are a few disadvantages to using marine plywood:

More expensive

Marine plywood is more expensive than regular plywood. Marine-grade plywood is approximately 4 times more expensive than exterior-grade plywood.

The price of marine plywood varies from brand to brand, but the price of plywood sheets varies more due to the grade of resin and timber used to create them.

The utility of marine plywood is extensive, which may influence marine plywood prices in the plywood sector. They have an exceptional surface finish for both home and commercial applications.

Not easy to find

Marine plywood is not always easy to find. Not all hardware stores or lumber yards carry marine plywood. You may need to special order it from a lumberyard or online retailer.


Marine plywood also tends to be heavier than regular plywood. This is due to the higher density of the wood veneers. The weight of marine plywood can make it difficult to work with for some projects.

Is marine grade plywood the same as exterior grade plywood?

The common misconception is that both exterior grade and marine plywood use a similar type of glue so they can withstand exposure to water similarly.

The truth is that marine plywood is much superior when it comes to withstanding prolonged exposure to water than exterior grade plywood.

This is due to the fact that marine plywood is made with waterproof veneers that are placed crosswise, in addition to the type of glue used. When exposed to moisture, marine plywood is less likely to delaminate and break down.

Exterior grade plywood is typically finished with fiberglass or painted to help protect it from the elements.

However, marine plywood is meant to be used “as-is” since the materials used to make it are already intended to interact minimally with moisture.

Also, exterior grade plywood has typically 5 layers while marine plywood has 9 layers.

There are additional interior and exterior veneers on marine plywood which helps make it more structurally stable. So, if we count those extra layers, then marine plywood would technically have 11 layers.

A typical exterior 4′ x 8′ sheet of plywood weighs approximately 53 lbs and will cost about $40. While the same size marine plywood can weigh up to 80 lbs and will cost about $160 or higher.