Understanding Marine Plywood Grades: How to Choose the Best Grade Plywood 

marine plywood grades

Marine plywood is a versatile and durable building material commonly used to construct boats, docks, and other marine structures. However, not all marine plywood is created equal, as different grades offer varying levels of quality and performance. Understanding the different grades of marine plywood is essential in choosing the best option for your project.

In this article, we will explore the various grades of marine plywood and provide insights on selecting the most suitable one for your needs. Whether you are a professional builder or a DIY enthusiast, having a comprehensive understanding of marine plywood grades will ensure that your project stands the test of time in even the harshest marine environments. 

What is Marine Plywood? 

Marine plywood is a specialized type of ply or plywood distinct from standard plywood. It is made from high-quality hardwood veneers glued together with a waterproof adhesive. This adhesive ensures that the plywood remains strong and durable even when exposed to moisture. Plus, the veneers are typically made from Douglas fir or western larch, both known for their strength and resistance to decay.

In addition, marine plywood is specifically designed for use in environments where it will be exposed to moisture, humidity, and even submersion in water. It is different from standard plywood because it is made to withstand these harsh conditions. The key factor that sets marine plywood apart from standard plywood is the use of waterproof glue in its construction.

Uses of Marine Grade Plywood 

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Marine plywood is a versatile material with a wide range of applications due to its exceptional waterproof properties and durability. Here are some additional areas where marine plywood is commonly used:

Docks and Piers: Marine plywood is frequently used to construct docks, piers, and other waterfront structures. Its ability to withstand constant exposure to water and resist decay makes it an excellent choice for these applications.

Marine Transport: Apart from boat construction, marine plywood can be found in various marine transport applications, including the interior fittings of ships, ferries, and yachts. It is used for cabinetry, wall paneling, and flooring to ensure longevity and resistance to the corrosive effects of saltwater.

Aquariums and Fish Tanks: The moisture-resistant properties of marine plywood make it suitable for constructing aquariums and fish tanks. It can provide the necessary structural support while maintaining a watertight seal to contain the water.

RV and Camper Construction: Marine plywood is used to manufacture recreational vehicles (RVs) and campers. It is employed for subflooring, cabinetry, and other interior components to ensure durability and resistance to moisture, which is crucial for vehicles that may encounter various weather conditions.

Exterior Signage: In outdoor signage and billboards, marine plywood is a favored choice due to its ability to endure exposure to rain, wind, and sunlight. It can be used as a substrate for graphics and signage materials.

Marine-Grade Furniture: Beyond outdoor furniture, marine plywood is also used to craft high-quality indoor furniture. Its durability and resistance to humidity make it suitable for kitchen cabinets, bathroom vanities, and other furniture pieces that may be exposed to moisture.

Architectural Millwork: Marine plywood finds its place in architectural millwork, where it is used for decorative paneling, molding, and other interior and exterior architectural elements that require both aesthetic appeal and moisture resistance.

Industrial Applications: Certain industrial settings may require marine plywood for platforms, workbenches, and storage cabinets, especially when these structures are exposed to moisture, chemicals, or high humidity.

Soundproofing and Acoustic Panels: In applications where soundproofing is necessary, marine plywood may be utilized as a substrate for acoustic panels. Its rigidity and moisture resistance make it a suitable choice for maintaining the structural integrity of soundproofing systems.

Art and Craft Projects: Marine plywood is sometimes used by artists and craftsmen for specific projects that involve exposure to moisture or require a robust and stable base for their work.

Characteristics of Marine-Grade Plywood

Waterproof Adhesive and Glue

Marine plywood is known for its exceptional waterproof adhesive and glue. This vital feature ensures its resilience and durability, even when subjected to moisture. The waterproof glue creates a robust bond between the veneers, making the plywood highly resistant to delamination. This starkly contrasts standard plywood, which typically uses non-waterproof adhesives and is susceptible to damage when exposed to water.

High-Quality Veneer and Overlay

The quality of the veneer and overlay used in marine plywood is highly significant to its strength and longevity. Veneers, thin sheets of wood comprising the plywood, are typically crafted from superior hardwood species like Douglas fir or western larch. These hardwood veneers offer exceptional strength and resistance to decay. Additionally, marine-grade plywood often features an overlay, a thin layer applied to its surface, enhancing its durability and moisture resistance.

Medium-Density Overlay (MDO) and High-Density Overlay (HDO)

Some marine-grade plywood incorporates a Medium-Density Overlay (MDO) or High-Density Overlay (HDO) on one or both sides. MDO and HDO overlays consist of resin-impregnated paper that provides an extra layer of protection against water and adds strength to the plywood. This added protection makes marine plywood particularly suitable for applications where exposure to moisture is a concern. It’s worth noting that these overlays are not found in standard exterior-grade plywood, further highlighting the superior performance of marine-grade plywood in wet conditions.

Various Marine Plywood Grades

Marine plywood comes in different grades, each tailored to specific applications and performance requirements. These grades feature variations in the quality of veneers, overlays, and overall construction. The highest-grade marine plywood is engineered to withstand the harshest marine environments, while lower grades are suitable for less demanding applications. It’s crucial to select the appropriate grade of marine plywood based on the specific needs of your project to ensure optimal performance and longevity.

Superior Moisture Resistance

Marine plywood is made and is renowned for its ability to withstand prolonged exposure to moisture and harsh environmental conditions. Its waterproof adhesive, high-quality veneers, and optional overlays make it ideal for boat building, marine installations, and other outdoor applications where standard plywood would quickly deteriorate. The enhanced moisture resistance ensures that marine plywood remains structurally sound and functional even when immersed in water or exposed to high humidity.

Durability and Longevity

Marine plywood is significantly more durable and long-lasting than standard plywood, thanks to its waterproof features and quality construction. Its ability to maintain its structural integrity in wet and humid conditions sets it apart, making it a preferred choice for projects that demand exceptional performance and longevity. While marine plywood may be more expensive than regular plywood, its extended lifespan and superior performance justify the investment in many applications.

Different Grades of Marine Plywood

Different types of marine plywood are available in the market, each designed for specific applications and environments where moisture, humidity, and water exposure are a concern. The most common types include:

a. A-A Grade Marine Plywood: This is the highest quality marine plywood available. It is made from high-quality hardwood veneers on both sides and features a solid, smooth, and defect-free surface. A-A grade marine plywood is often used in applications requiring aesthetics and superior strength.

b. A-B Grade Marine Plywood: A-B grade marine plywood is a versatile option with excellent strength and durability. It has a smooth surface on one side (A grade) and a slightly less smooth surface on the other (B grade). This type of marine plywood is widely used in marine and exterior applications.

c. B-B Grade Marine Plywood: B-B grade marine plywood is suitable for applications where the appearance of the plywood is less critical. Its name implies lower-grade veneers on both sides (B-B grade). Still, it offers good durability and performance, making it a cost-effective choice for many projects.

How are Marine Plywood Grades Determined?

The grading system of marine plywood is based on various factors that assess the wood’s quality, strength, and ability to withstand harsh marine environments. Understanding these grades helps individuals and professionals select the best marine plywood for their specific needs, ensuring that their projects meet the challenges of marine environments and outdoor applications. Here are the most common ways to determine the grades of marine plywood:

  1. Plywood Type and “Marine Grade”: Marine plywood is a type of plywood that is fundamentally different from standard plywood. Its ability to withstand exposure to water and moisture sets it apart, making it suitable for marine and outdoor applications. Marine plywood is often called “marine grade,” indicating superior quality and performance.
  2. Plywood Composition: Marine plywood is different from regular plywood in its construction. It is made from high-quality wood veneers, typically from hardwoods like mahogany, meranti, western larch, or Douglas fir. These veneers are bonded using waterproof glue, which is critical in determining the plywood’s resistance to water damage.
  3. Grades of Marine Plywood: Marine plywood comes in different grades, each indicating its quality, durability, and intended use. The primary grades for marine plywood are “A” and “B.”

    a. A Grade: This is the highest quality marine plywood available. It is often called “First Grade” or “AA Grade.” A-grade marine plywood features a smooth, sanded surface on both sides and is virtually free from knots or defects. It is well-suited for visible applications where aesthetics and quality are paramount, such as boat interiors or high-end outdoor furniture.

    b. B Grade: B-grade marine plywood is slightly lower quality than A-grade but is still highly durable and water-resistant. It may have some minor surface defects and knots but is structurally sound. B-grade marine plywood is commonly used in boat construction, decks, and other outdoor applications where appearance is less critical than performance.
  4. Performance Factors: Marine plywood is rated based on its ability to withstand moisture, decay, and delamination. The waterproof glue in its construction ensures it remains stable and strong even when exposed to wet conditions. Additionally, marine plywood can withstand bending and stress, making it suitable for structural integrity applications.
  5. Variations in Grades: Some marine plywood products may have variations within the exact grade, denoted by numbers like “A-A” or “B-B.” These indicate that both sides of the plywood meet the respective grade’s criteria. For example, “A-A” means that both sides of the plywood are of A-grade quality, while “B-B” means that both sides are of B-grade quality.
  6. Cost and Availability: Marine plywood is generally more expensive than regular exterior plywood due to its higher quality and waterproof characteristics. It is essential to consider your project’s specific needs and budget when choosing the grade of marine plywood.
  7. Applications: Marine plywood is used in various applications, including boat building, marine construction, outdoor furniture, and exterior siding. Its ability to withstand water and moisture makes it invaluable in any project requiring long-term durability.

Choosing the Right Waterproof Plywood Marine Grade

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Considerations for Thickness and Durability

When choosing marine plywood, it is important to consider the thickness and durability of the plywood. The thickness of marine plywood typically ranges from 4mm to 25mm, with thicker plywood being more durable and suitable for heavy-duty applications. Selecting plywood with the appropriate thickness for your specific project is crucial.

Hardwood vs. Softwood Marine Plywood

Another consideration when choosing marine plywood is whether to opt for hardwood or softwood plywood. Hardwood marine plywood, such as plywood made with Douglas fir, is generally more durable and resistant to decay. Softwood marine plywood, on the other hand, is more affordable and may be suitable for less demanding applications.

Checking for Knots and Voids

When selecting marine plywood, checking for knots and voids is essential. Knots and voids can weaken the plywood, making it less suitable for demanding applications. Scrutinize the plywood for visible defects and choose plywood with minimal knots and voids.

Typical Marine Plywood Price

The price of marine plywood can vary widely depending on several factors, including the quality, thickness, and brand, your location, and the current market conditions. Marine plywood is typically more expensive than regular plywood due to its superior durability and resistance to moisture. In the United States, the price range of marine plywood generally is as follows:

  • Low-Grade Marine Plywood: $50 to $70 per 4×8-foot sheet.
  • Mid-Grade Marine Plywood: $70 to $100 per 4×8-foot sheet.
  • High-Grade Marine Plywood: $100 to $200+ per 4×8-foot sheet.

Comparing prices and types from different suppliers is advisable when purchasing marine plywood. This will help you better understand marine plywood’s price range and availability in your area. Also, choosing a reputable supplier that offers high-quality marine plywood at a reasonable price is crucial.

Frequently Asked Questions

Q. What is the composition of marine plywood?

A. The composition of marine plywood involves using high-quality wood veneers that are bonded together with waterproof glue, enhancing its durability and resistance to moisture.

Q. How does marine plywood perform in aquatic environments?

A. Marine plywood is precisely engineered to excel in marine environments, exhibiting outstanding performance in the face of water exposure, high humidity, and protection against fungal attacks.

Q. Is Douglas Fir a common type of marine plywood?

A. Douglas Fir is a popular choice for marine plywood due to its inherent strength, durability, and resistance to decay, making it well-suited for marine applications.

Q. What is the recommended thickness for marine plywood?

A. The recommended thickness for marine plywood varies based on the specific use, with typical options ranging from 4mm to 25mm, which caters to different structural requirements.

Q. Does marine plywood use waterproof glue?

A. Marine plywood is manufactured using waterproof glue, ensuring a robust bond between the wood veneers and enhancing its resistance to water infiltration.

Q. How is marine plywood different from regular plywood?

A. Marine plywood differs from regular plywood in its construction and adhesive. It undergoes a higher manufacturing standard with waterproof glue, making it more resilient to water-related issues.

Q. Are there different ratings for marine plywood?

A. Yes, the grades of plywood often carry ratings such as “A-A,” “A-B,” and “B-B,” indicating its quality and performance, with higher grades generally preferred for critical marine applications.

Q. Can marine plywood be used for other purposes?

A. While primarily designed for marine applications, marine plywood is versatile and can be used for outdoor furniture, flooring, and various projects, preferably requiring water-resistant properties.


In conclusion, understanding the different grades of marine plywood is crucial to ensure optimal performance. Unlike standard plywood, marine plywood is made with exterior grade veneer and glue, known as “marine grade,” that enables it to withstand moisture and harsh marine environments. The variety of grades, including exterior grade plywood, offers a range of attributes for tailored selection based on specific project needs. 

While the marine plywood price may vary across grades, it is a worthwhile investment for projects requiring durability and longevity. The glue used in marine plywood and waterproof glue sets it apart from standard plywood, making it an ideal choice for constructions where resilience is significant. As consumers, understanding the characteristics and performance of marine plywood is crucial for making informed decisions, ensuring that the selected piece of plywood aligns seamlessly with the specific demands of the intended application.

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