Understanding Marine Plywood Grades : A Comprehensive Guide

Marine Plywood Grades

Marine plywood is a type of manufactured wood product that’s considered ideal for water-based environments. It’s incredibly strong and durable and can withstand moisture without getting damaged.

This makes it perfect for a wide range of water-based wood applications such as boat building, yachts, outdoor furniture, dock, aquarium, and use in bathrooms and kitchens.

Marine plywood is nowadays easily available in retail stores. They have high demand but good availability.

Also, you must know that marine plywood comes in many grades or types varying in terms of strength, durability, and price. It is generally more expensive than regular plywood.

Here’s everything you need to know about the different grades of Marine Plywood.

What is Marine Plywood?

It is a type of engineered wood specifically designed for use in marine or water-based environments.

It is made using high-quality wood veneers that are bonded together with waterproof glue or other adhesive to form a very strong board.

Marine plywood is different from regular plywood due to its enhanced resistance to moisture, decay, and fungal growth.

The use of waterproof glues or resins and high-quality wood species, preferably hardwoods, provide incredible strength and durability to this plywood.

Hardwood veneers, such as meranti or Douglas fir, are commonly used for making marine plywood.

Uses of this plywood range from boat and shipbuilding to many other marine applications like docks, decks, flooring, and outdoor furniture, especially ones intended for use near water bodies.

Its ability to withstand water exposure provides longevity to the projects where this plywood is used.

Different Types of Marine Plywood Grades

There are multiple types of marine plywood grades available in the market, each with its own characteristics and intended uses. Here are some of the top grades of marine plywood:

1. A-A Marine Grade Plywood

This is the highest quality marine plywood. It has a smooth and perfect surface on both sides without any patches, knots or holes.

It is constructed using high-quality, durable hardwood veneers and waterproof adhesives or glue. Both sides are A-grade, i.e. the highest quality veneer.

A-A marine grade plywood is nearly waterproof, which makes it suitable for building boats, yachts, and other marine construction where both aesthetics and excellent strength are required.

A-A grade is also called exterior grade plywood because of its high quality and decay resistance. It is commonly used in high-end applications and for making nearly waterproof objects.

Examples of the uses of A-A grade marine plywood include boat building, decks, docks, outdoor furniture, and siding.

Pros of A-A grade Marine Plywood

  • Superior quality plywood. Both sides are made of high-quality A-A grade, water-resistant veneer.
  • Very durable and stable
  • Extremely strong
  • ersatile applications. Suitable for use in both indoor and outdoor woodworking projects.
  • Needs low maintenance and is prone to daily wear and tear.


  • It can be quite expensive because it uses high-quality and sometimes rare solid wood species such as Ipe. It is the most expensive type of plywood.

2. A-B Marine Grade Plywood

This type of marine plywood is strong but not as strong as the A-A grade plywood.

This is high-quality and durable plywood with good resistance to moisture. This plywood has A-grade veneers on one side (smooth and void-free) while the other side has B-grade veneers (having minor patches or repairs).

It is still resistant to moisture to some extent and is considered suitable for various marine applications, especially ones where one side will be in contact with the water while the other can be hidden or covered.

The B-grade veneer is of slightly lower quality than the A-grade and may have defects and knots on its surface.

Some common uses of the A-B marine plywood include boatbuilding, construction, subfloors, and exterior applications.

It can be used in applications where the front face (A-grade) is exposed while the other face is hidden or covered.

Pros of A-B grade plywood

  • High-quality plywood made from durable hardwood species
  • Defect-free one side
  • Durable in terms of resistance to moisture, decay, warping, and cracking
  • Less expensive than A-A grade plywood


  • Still very expensive, especially when compared to regular plywood
  • The back side panel (B-grade) is not very attractive and might require additional finishing

3. B-B Marine Grade Plywood

This type of marine plywood has B-grade veneer on both sides, i.e. both sides of this grade plywood may have defects, repairs, or holes.

B-B marine-grade plywood is moderately strong and durable and not extremely resistant to weather.

It is commonly used for structural applications in exterior projects such as boats or docks where appearance is not a concern. It can provide good strength and moderate moisture resistance to any project.

B-B grade plywood is made of veneer that is strong and durable but has knots and defects which might affect its appearance, which is why this plywood is not commonly used for projects such as furniture where the appearance of the wood matters.

It is commonly used for building the structure for boats and ships and for making subflooring, sheathing and similar construction projects.

It is generally easy to work with and is considered a good option for DIY projects.

Pros of B-B Marine Grade Plywood

  • Cost-effective compared to the other two options. If you’re looking for strong and water-resistant plywood at a low cost, this is the best option.
  • Easier to work with than higher grade plywood or solid wood. It is less dense and lighter and can be cut and shaped easily.
  • It is a versatile plywood type that can be used in a variety of applications ranging from interior millwork to outdoor furniture and subflooring.


  • Not as strong or durable as A-grade plywood options.
  • Moderately resistant to moisture. Cannot withstand extreme weather conditions.
  • Not very attractive. Knots and defects may be there on both sides of this plywood, which makes it not the best option for projects where appearance is a concern.

4. MDO (Medium-Density Overlay)

Medium-Density Overlay (MDO) is a type of marine-grade engineered wood product used in outdoor applications due to its water-resistant properties.

It is made by combining a medium-density fiberboard (MDF) or particle board core with a layer of resin-impregnated kraft paper to provide a durable and weather-resistant structure. Basically, it is a water-resistant MDF panel.

MDO is used in many applications, including as a substrate for outdoor signs, siding and cladding, as a forming material for concrete structures, and for making cabinets and furniture.

Pros of Medium-Density Overlay:

  • MDO is highly durable in terms of resistance to moisture, weathering, and UV radiation, making it perfect for outdoor use.
  • It has a smooth and uniform surface which makes an excellent base for painting, printing (graphics), and applying finishes.
  • It is a strong and stable plywood material which is less prone to warping, swelling, or shrinking.
  • MDO is easy to use and can be easily cut, shaped, and drilled for various applications.


  • As a building material, MDO can be expensive.
  • MDO is denser than regular plywood. It can be heavier and difficult to handle and transport.
  • MDO is only available in standard sizes.

5. HDO (High-Density Overlay)

High-Density Overlay (HDO) is a type of engineered wood product that is similar to plywood as it is constructed by combining different layers of veneer.

It is different from MDO in terms of its higher density and strength and better surface characteristics.

It is made by combining HDF or fibreboard with resin-impregnated fibre surface on one or both sides to form an extra strong plywood material ideal for construction and structural applications. It is durable and wear-resistant and can take heavy loads.

Common uses of High-Density Overlay (HDO) include as a formwork material in concrete construction, industrial applications such as industrial shelving, workbenches, etc., and in the transport industry for truck flooring, trailer linings, and container floors.

Pros of High-Density Overlay (HDO):

  • High density and excellent strength and durability 
  • It can withstand heavy loads, wear & tear, and rough handling
  • It has a smooth, consistent surface and achieves a high-quality finish for applications like concrete formwork.
  • Easy cleaning and maintenance.
  • It is resistant to moisture and chemicals and can be used in outdoor applications.


  • HDO can be more expensive compared to regular plywood and other building materials.
  • HDO is dense and heavy and can be challenging to handle and transport.
  • It may not be as easily or widely available as regular plywood products and it comes in limited options in terms of thicknesses and sizes.

Alternatives to Marine Plywood

Some solid wood species, particularly hardwoods, are extremely strong and durable in terms of resistance to decay and rot.

These include Ipe, redwood, cypress, and shorea. These woods are often the primary choice over engineered wood (plywood) for household applications.

However, their limited availability and expensive price have forced people to look for alternatives such as marine plywood, which is less expensive than many hardwoods.

One must also know that marine plywood is water resistant, but it’s not 100% waterproof.

It can withstand moisture to an extent but will eventually start rotting if left in the water for a very long time.

It is generally protected with an extra layer of high-quality finish to provide better resistance to water.

Pressure-treated lumber is also often used as a water-resistant option for marine applications.

Know More or Buy Wood Online?

Want to know more about the best marine plywood grade options or the best hardwood options for outdoor use? Contact Cameroon Timber Export SARL to discuss your timber requirements with our expert and buy the best quality premium, sustainable wood at the right price with worldwide shipping.