You may be desirous of using plywood for your outdoor projects but need to be more aware of its susceptibility to the effects of moisture. If such is the case, you can always go for marine-grade plywood. Yes, you heard it right. Plywood comes in different types, and one particular type of plywood gets referred to as marine grade plywood or marine plywood. It is basically the most durable and robust plywood you can ever buy. Besides, it is the highest quality of plywood you can ever purchase.
Marine plywood gets referred to as Marine Grade simply because it is designed to withstand rain, moisture, and snow. Moreover, it gets wrought in Douglas Fir or Western Larch Wood with at least five or more layers of plies. Thus, it is denser and has a few tiny voids and air pockets. Plus, it gets bonded by waterproof adhesives or glues, making it impervious to water or moisture.
Important Marine Plywood Features
If you intend to use Marine plywood, it will be best to know more about it before you even dare to purchase this plywood and use it in your projects. Below are the specific features and properties of marine plywood:
- Marine plywood can remain dimensionally stable even if it comes in contact with moisture or water.
- It gets manufactured using phenolic plastic resin, which makes its surface impervious to moisture and water.
- Each marine ply sheet exhibits a pore-less and smooth surface that resists water, preventing water from imbuing the very fibers of plywood.
- Marine plywood gets wrought in hardwood sheets. Nevertheless, it is very flexible, making it perfect for exterior applications and areas with high moisture and humidity levels.
- You can shape marine plywood with ease since it can maintain its integrity well.
- Marine plywood is also not susceptible to bending, breaking, or snapping under load or pressure.
How Did Marine Plywood Evolve Over Time?
You can trace the history of marine plywood to the 1930s before the Second World War. It was Cornelius Bruynzeel, a Dutchman, who first manufactured marine plywood. During World War II, boat manufacturers built boats using marine plywood. Nowadays, marine plywood has dramatically evolved. Most marine plywood sheets nowadays are wrought in Western Larch or Douglas Fir wood.
Many woodworkers would believe that marine plywood is entirely resistant to rotting and moisture. Yet, it is not entirely immune to decay and moisture. It will help if you treat it with sealant and preservative to ensure that it will be impervious to water and rotting. Besides, you can treat it with paint, polyurethane, or varnish.
How is Marine Grade Plywood Made?
The manufacturing process of marine plywood is similar to that of ordinary and standard plywood. First, five plies of Western Larch or Douglas fir get arranged perpendicularly to ensure their grains alternate between vertical and horizontal directions. This arrangement type of plies provides the plywood with the needed stability and strength.
Afterward, the plies get bonded under intense pressure and heat along with a special waterproofing glue or adhesive. Then, its exterior gets finished with a water-resistant finish. The lack of voids and knots, plus the addition of waterproofing glue, differentiates this plywood type from other plywood types. Besides, marine plywood is made of more plies with higher quality.
Marine-grade plywood is different from pressure-treated plywood, even though it is also pressure-treated. Nevertheless, it does not undergo soaking in special chemicals to enhance its resistance to moisture, mold, and rot. Thus, it is best to reserve the term “pressure-treated plywood” to those plywood sheets that have undergone soaking in specially concocted chemical compounds to enhance their durability.
Advantages of Using Marine Grade Plywood
Using marine-grade plywood has many advantages, and it will help to know them. Below are the succinct benefits of its use in woodworking projects.
- Marine ply will resist rotting, warping, and shrinking, whether used on the subfloor or floor.
- Given the manufacturing process it underwent, it is highly resistant to water and is said to be one hundred percent waterproof.
- The primary upside of the use of marine ply is its remarkable durability. It can last longer outdoors than any plywood. For this reason, it gets preferred for building boats, furniture, and other woodworking projects exposed to moisture and humidity.
- Marine ply doesn’t tend to split and offers a smoother surface than ordinary plywood.
- It is also easier to cut, and you can easily bend it. Thus, it is perfect for many woodworking and construction projects.
- It comes in various thicknesses, giving you enough thickness options.
- Marine plywood gets bonded using waterproof adhesives or glues designed to withstand moisture and high humidity. These adhesives can even withstand exposure to boiling temperatures, enabling them to avoid delamination.
- Marine plywood is easy to work with because of its thin layers of plies. It is also easy to sand and clean. Besides, it is lightweight and comes with very few defects. It may have knots in its plies, but it doesn’t have knotholes that could trap moisture or water.
- It can withstand extreme weather and temperature. Thus, it is reliable.
- Marine ply has more layers, making it more robust than ordinary plywood. Besides, a waterproof adhesive binds these layers, making them withstand heavy loads and resist moisture.
Marine Plywood Grades
Marine plywood doesn’t come in a single grade of plywood. It comes in various grades, and if you intend to use this plywood, it will be best to familiarize yourself with these different grades:
1) A-A-grade Marine Ply
This marine plywood grade comes in dimensions of 4’x8’ or 5’x12’, and ½” thickness.
2) A-B-grade Marine Ply
This marine plywood grade is approximately ¾” thick and around 4’x8’ in dimensions. It is more durable than the A-A grade and doesn’t have open knots.
3) B-B Marine Plywood Grade
You will commonly find this marine plywood grade in the market, and it features a face-back structure.
4) Medium-density Overlay (MDO)
This grade of marine plywood is wrought in a high-quality resin-impregnated fiber overlay and manufactured in a high thermosetting. This overlay gets attached to one side under intense temperature and pressure. You will find its veneer under the surface perfect for painting because it is smooth.
MDO is known for its remarkable durability, strength, and dimensional stability. You can often purchase this in dimensions of 4’x8’, and it may come in different thicknesses like 3/8”, 5/8”, ½”, and 1”. It is also highly resistant to scratching and denting. Besides, it is weather-resistant and damage-resistant.
Applications and Uses of Marine Plywood
Marine grade is a particular type of plywood because it is highly resistant to water and moisture. As such, it gets often used in areas exposed to moisture and water. Below are the different uses and applications of marine plywood:
- You can use marine plywood for patio furniture like tables, chairs, and benches.
- You can use it for making pergolas.
- It also gets used for building lake platforms from where you can laze around while fishing and suntanning. You can apply an additional waterproof sealant to these plywood sheets to make them impervious to the effects of water.
- You can also use marine plywood for making planters. Planters, of course, are exposed to water and moisture. As such, you will need a special material capable of resisting water and moisture. Thus, marine plywood is ideal for such applications.
- You can also use marine plywood to build porches and decks. Nevertheless, you still need to stain and seal this plywood to ensure it will be invulnerable to rotting and decaying.
- Marine plywood gets also used in the building of boats. It also gets used for making sailing equipment. You can buy boats made of marine plywood. Moreover, it is perfect for making boats and structures because of its high resistance to water and moisture. Besides, with the addition of sealant, you can make the marine plywood entirely impenetrable to water.
- You can also use marine plywood for the subfloors of the kitchen and bathrooms. Since spills and overflows are common in toilets and showers, using marine plywood can help stabilize the subfloor and make it resistant to water and moisture.
- You can also use marine ply for kitchen and bathroom walls. These walls, of course, are exposed to water splashes, and if you don’t use a waterproof material for these walls, they might decay or rot soon. Using marine plywood for this purpose is one of your best options.
- You can also use it for making boat docks. Before, traditional sanded lumber was used for boat docks. However, marine plywood overtakes traditional sanded lumber as a preferred material for this application. Besides, you can further enhance the durability and longevity of boat docks made of marine plywood by providing these boat docks with waterproofing treatment.
Sheathing and Marine Grade Plywood: Which is Better?
One of the distinctive characteristics of marine grade plywood is its high-quality veneers. This characteristic distinguishes it from standard plywood sheaths. Besides, it uses high-quality waterproofing adhesives that further enhance the properties of marine plywood.
Unlike regular sheathing plywood made of fewer and thicker plies, marine plywood is made of many thinner plies with quality veneers. Thus, it doesn’t have larger knots and voids compared to the standard sheathing plywood. Sans these voids and knots, it is almost impenetrable to water and moisture and is not susceptible to delamination or rot.
Since marine plywood gets wrought in multiple thinner layers, it doesn’t have larger knots and voids. Besides, its plies are alternately oriented, providing it with sufficient strength. Plus, its full-face veneers offer increased durability and stability that you will not find in regular sheathing plywood.
Marine plies consist of hardwood fibers. The manufacturing of these hardwood plies undergoes a meticulous process to produce quality hardwood plies sans any knots or voids. Furthermore, the adhesives used to bond these plies are of excellent quality and can withstand continuous exposure to high temperatures and water. Thus, marine plywood is not susceptible to delamination and has remarkable durability.
Marine-grade plywood is indeed durable and robust. Yet, before you use it in structural projects, you should seek the approval of your local building code authority.
How Strong is Marine Plywood?
Marine plywood gets designed to withstand long periods of exposure to water and moisture. Manufacturers design these plywood sheets to be tough and durable to withstand weathering and rotting. Besides, the secret to its remarkable durability lies in the adhesives that bond the high-quality plies.
These adhesives are powerful and have waterproofing properties. Additionally, the manufacturing of marine plywood undergoes meticulous processes, including vacuum pressure treatment, further enhancing its stability and strength.
Why Is It Important to Use Waterproofing Adhesive?
There is a need to use waterproof adhesive because it defeats the purpose of marine plywood if ordinary adhesives are used to bond the plies of this plywood. Because of the waterproofing glues, however, the stability and durability of this plywood are increased, making it ideal for use in areas exposed to high moisture level and humidity.
With waterproof glues, the stability of the plywood is ensured, and the plies get bonded without worrying about falling apart.
Conclusion
Marine grade plywood is indeed a premium grade plywood that can resist water and high temperature. They can stay in boiling water for five hundred hours without breaking or falling apart. Thus, marine plywood sheets are preferred for outdoor furniture, patio furniture, and boats and ships.
You can never use ordinary or standard regular plywood for the abovementioned applications because they will warp and rot soon. However, with the use of marine-grade plywood, you can ensure that your projects will last and retain their integrity despite being exposed to the harsh elements of nature.