What Is Marine Grade Plywood? | Everything You Need to Know

Marine-grade plywood is made from multiple veneer sheets of Western Larch or Douglas-fir wood. All these layers are glued perpendicular to each other. It is more durable and stable compared to ordinary plywood and MDF. 

Marine-grade plywood is an excellent choice for building boats, docks, and waterproof doors. We can use It for all applications where they are exposed to moisture and weather.

Dutch door manufacturer Cornelius Bruinzel first introduced marine plywood in the 1930s. During World War II, many boats were built using marine-grade plywood. These boats are much lighter and stronger than wooden boats. And it was also very easy for the army to move from one place to another.

Uses of Marine Plywood

1. Boats


Marine Plywood is an excellent choice for making a boat and boat parts. You have to seal the boat from the outside and inside to make it extremely durable. Liquid latex, waterproof paint, or varnish are good options for sealing plywood, giving great results.

The reason we choose marine plywood for boat building is that it is more durable and is also easier to work with than solid wood. A boat made of marine plywood can save you a lot of money.

2. Lake Platform

Lake Platform
Lake Platform

The lake platform is a good place to spend time with family, relax, and for yoga. The lake platform is always in contact with water. Marine Plywood is the best material for the lake platform project.

3. Docks

A dock is a wooden structure that is always in contact with the water. Many decades ago, docks were made of lumber. Which needed to be repaired every year. Marine plywood is more durable and cheaper. It does not require regular maintenance.

5. Bathroom door and kitchen platform

The bathroom and the kitchen both are places where water and moisture are present. In such a situation, the door of the bathroom should be such that it can withstand daily moisture and Marine Plywood is a very good choice for the kitchen platform and bathroom door.

Marine plywood is not chemically treated. So that it is not harmful, we can use it in the kitchen without any risk. Mainly used to make a kitchen platform.

5. Deck

Using lumber to build a deck can be expensive and requires regular maintenance. Whereas marine plywood is cheaper and lasts longer. It’s easy to make a deck out of plywood at a very reasonable cost.

Types of Marine Plywood

There are many types of marine-grade plywood available. The type of plywood can be described by the grading system. Each grade represents the quality of the front and back sides of the plywood.

1. A-A Marine-Grade Plywood: A-A grade is the highest quality grade of marine plywood. A-A Grade Plywood is made from the best quality Veneer (Piles) sheet which is knot-free and defect-free. It is mostly used for marine applications such as boats and docks. It is more expensive than all grades.

2. B-B Marine-Grade Plywood: B-B  grade marine plywood also known as face-back Marine plywood. Knots may be present in the B-B grade. 

3. A-B Marine-Grade Plywood: Knots may be present somewhere in A-B marine. It is mainly used for making bathroom doors and kitchen platforms.

4. Medium-density overlay (MDO): Medium-density overlay (MDO) plywood made with exterior-grade plywood core laminated on one or both surfaces with weather-resistant resin under high heat and pressure.

MDO is ideal for exterior and interior applications, but it was designed for commercial sign painters. After finishing it gives an excellent smooth surface. 

MDO plywood is pressure treated and heat treated to prevent insect damage and to protect against rot. It is available in many sizes and thicknesses. You can choose them as per your requirement.

5. High-density overlay (HDO):  The method of making HDO is similar to the MDO, but the outer layer of HDO is considerably higher than for MDO. HDO is more durable and expensive than MDO. It is widely used for signboards, concrete forming, exterior siding, and industrial containers.

How to Identify Marine Grade Plywood?

How to identify marine plywood?
How to identify marine plywood?

There are many types of marine-grade plywood. Each grade has its own properties and uses. It is important to choose the right grade for your job. 

But it is very difficult for a common person (who does not know about plywood) to identify marine-grade plywood. There are some tips that will help in identifying marine-grade plywood.

  1. There are no voids and gaps at the edges of real marine-grade plywood. There are no knots on the surface of marine plywood.
  2. Marine plywood is made with quality western larch or douglas-fir layers and has a smoother surface than regular plywood.
  3. Real marine plywood should not bend more than 18mm.
  4. Estimate the weight by lifting the plywood. Quality plywood carries the most weight.
  5. Every quality plywood is ISI certified. So you can check the labels on the plywood to identify the plywood. Marine or Waterproof Plywood is IS: 710.

Is marine-grade plywood waterproof?

Is marine grade plywood waterproof?

No, marine plywood is not waterproof. It has excellent water and weather-resistant properties. It does not absorb moisture like ordinary plywood.

Many people believe that marine plywood is completely waterproof, but it is not true. But marine plywood is more durable to moisture and weather conditions than other wood products.

Marine-grade and hardwood plywood is made with Resorcinol glue, also known as resorcinol-formaldehyde. Resorcinol glue has excellent water-resistant properties. It has a combination of resin and hardener which makes plywood capable of withstanding moisture.

Marine-Grade Plywood vs Pressure Treated.

Marine-grade plywood is usually stronger, durable, stable, and expensive than pressure-treated plywood for exterior use. Both plywoods are made for different purposes.

#Marine-grade PlywoodPressure Treated Plywood
1Marine-grade plywood is not chemically treated.Pressure-treated plywood is chemically treated.
2There are no voids between the layers of plywood. So that moisture and water cannot penetrate into the plywood.There may be gaps between the layers. Water can enter these voids and cause the plywood to rot and damage.
3Made with waterproof adhesive.Made with water-resistant adhesive. 
4It is not easily warped.It can deform due to constant exposure to water.
5It is more expensive than pressure-treated plywood.It is cheaper than marine-grade plywood.
6Marine-grade plywood is designed for marine applications such as boats and docks.Pressure-treated plywood is used for projects that are exposed to moisture, such as fences and decks. 

Read also the advantages and disadvantages of Marine plywood.

Marine Plywood Alternative

Plywood is an expensive product, but it justifies its cost. For some applications, we require an alternative to marine plywood. So the good news is that there are many alternatives to marine plywood available on the market.

The best marine plywood alternatives are as follows:

1. Fiberboard

Fiberboard is the best alternative to marine plywood. Fibreboard has a medium density which is strong and long-lasting. It is an engineered wood product made from small fibers of wood mixed with wax resin. It is available in the market at a lower cost than marine plywood. 

2. Ribbon Grain Plywood

Ribbon grain plywood is made by gluing multiple thin sheets of wood. The interesting thing is that the wood grain runs along the plywood’s length. So it looks like natural wood.

3. Fiber Cement Board

Fiber Cement Board is made with wood fiber (small pieces of wood) and cement. Due to cement, there is better moisture resistance.

Fiber cement board is a well-known material as an alternative to marine plywood. It is a product that can be used in almost any type of construction application, such as exterior walls and ceilings.

4. 3M Reinforced Polyurethane Foam

It is an excellent lightweight, rot-resistant, and water-resistant material. It is easy to install and work with. The 3M Reinforced Polyurethane Foam board is widely used for boat construction.

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