7th Dec 2022 -

Regular plywood sheets can become damaged when faced with water, warping and degrading beyond a usable state. A high-end solution is to use marine plywood, which is graded for excellent water performance. In this guide from Building Materials Nationwide, we’ll explain the key information on marine plywood, how it’s used within the UK, and the sizes and costs of marine plywood boards.

What is Plywood?

Plywood is one of the most popular engineered wood products in the UK. It is produced from veneers of wood, essentially thin sheets cut from a tree which are glued and bonded into a board with heat and pressure. Plywood is a very popular building material for several key reasons, its strength, the many varied looks it can have, and its lower costs compared to timber. Plywood is used for both building construction and furniture, with different varieties on sale such as softwood, hardwood, structural and marine plywood available.

A male construction worker wearing blue jeans, a striped t-shirt and blue trainers nailing plywood subfloor material with a nail gun.

What Is Marine Plywood?

While it performs better than some other engineered wood sheets, plywood will ultimately absorb moisture, causing damage to the veneers and the bonding agents between them. When looking to use plywood in environments with moisture or water, you’ll need to opt for a graded choice. Here are the different moisture performance classes.

Class IDesigned for dry interior uses
Class IIDesigned for interior environments with some humidity such as kitchens and bathrooms, and for minor contact with water.
Class IIIDesigned for high humidity, exterior environments, and frequent water contact.

Marine plywood will be a class III plywood that is specifically optimised for performance in water. It will be built from hardwood veneers and waterproof glue, designed to survive extended submerged use as part of a boat's hull, which is the origin of the name. Marine plywood will offer many years of water resistance and is built to a high level of quality. 

Only A and B-grade panels can be used, ensuring a consistent and attractive look, with an AB panel being the most common. This means that the outward-facing will have a consistent surface with no more than a few small pin knots. Marine plywood is pliable and able to bend to the curved shape of a boat's hull without any compromise on strength or integrity. A downside of marine plywood may be the price tag. If money is no object then there are few better choices, but for some, the cost may be prohibitive for their project.

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Where is Marine Plywood Used in the UK?

While it was originally designed for use on boats, those seeking high-quality water-resistant plywood can achieve great results by using marine plywood. This means that there are a few different uses in modern construction and furniture design.


The strength and water resistance of marine-grade plywood are designed around usage in the hulls of boats, which will be fully sealed to offer many years of great waterproof performance. Resisting against both water damage and damage from collisions, marine plywood is the best-engineered wood product available for boats.


The benefits of marine plywood also make it a popular choice in docks. It can withstand water and other harsh environmental efforts better than other products, requiring little maintenance over the years. Boards of marine plywood can also be used to create lake platforms.

Kitchens and Bathrooms

The high level of moisture within kitchens and bathrooms, both from humidity and water contact, means that a standard plywood board is not suitable for use within them. Marine plywood can be used for a variety of elements, from panelling to cabinets to flooring, offering great strength alongside its water resistance.

Exterior Furniture

The quality water resistance offered by marine plywood makes it suitable for a variety of exterior uses, such as furniture, porches, and pergolas. Things like tables, chairs, and benches will offer both strength and long-term external performance when you construct them from properly sealed marine plywood. Marine plywood will also have an attractive look, with its smooth hardwood finish bringing additional benefits to an outdoor space.

A carpenter wearing a short sleeve t-shirt and apron with a beard and short hair using a CNC machine to customise and cut a piece of plywood.

What Sizes of Marine Plywood Are Available in the UK?

Typical sizes for plywood will be 2440mm x 1220mm, which will come in a selection of thicknesses, depending on the needs of your project, with options including 3mm, 4mm, 6mm, 9mm, 12mm, 15mm, 18mm, 20mm, and 25mm available.

Quality Marine Plywood Delivered Across the UK

Building Materials Nationwide offers a comprehensive range of building supplies delivered across the UK. We work with professionals across the industry, removing the hassle that can come with sourcing materials. Through our website, you’ll find our range of plywood, including marine plywood options. For customers within the industry, we also offer trade accounts, granting access to our wide network of suppliers, our express delivery options, and the services of a dedicated account manager. Sign up for a trade account through our website today.