Ridetheducksofseattle is reader-supported. When you buy through our links, we may earn an affiliate commission. Learn more

What Kind of Plywood for a Boat Floor? – Marine Plywood

Written by Anthony Roberts / Fact checked by Jonathan Larson

what kind of plywood for a boat floor

It’s normal if your boat floor made of plywood comes off at a certain period. Water intrusion is inevitable so you have to prepare the boat floor replacement plywood. No matter how you work on maintenance, the damage will surface one day. If you use quality wood, the floor can stay intact for a long period. Knowing what kind of plywood for a boat floor is will make it happen.

You have to pick marine plywood for the boat floor as it’s not easily damaged by water. It has more layers than regular plywood so it can guarantee 15 to 25 years of service. Single-layer plywood succumbs to water intrusion in no time. To learn more about the specifics of marine plywood flooring, read on.

Everything You Need to Know About Marine Plywood

The best plywood for the boat floor is marine-grade but the description doesn’t end here. There is more information about it before you work on the flooring or have someone put it on your boat. Apart from being ideal and durable, you can use marine plywood not only on floors but on boat interiors as well. It’s easy to cut as it can be done by a hand saw or any basic tool.


Plywood is categorized through grade and marine plywood is A or B grade. The outer part is A grade, while the opposite side is B grade. The core can be a B grade or much better. It’s usually with 7-ply lamination that is bound by waterproof glue. The thickness would be .75” or thicker because of this finishing.

With core veneers and durability, marine plywood can resist dampness, fungus, and water. It can last for up to 25 years despite exposure to a harsh environment. You’ll find a seal of approval on it. But you can do a test by yourself by doing these steps.

  • Step 1: Cut a piece or more from the plywood
  • Step 2: Put the plywood pieces in a dishwasher and leave them for some cycles
  • Step 3: Let them stay in hot water for a few days
  • Step 4: It’s indeed marine-grade if it survived delamination

After the marine plywood survives this test, here’s what you can expect from it.

1. With the best veneers

This is a vital part of making the thickness plywood strong. The treated plywood doesn’t easily deteriorate because of high-quality veneers that don’t have core gaps. Moreover, these veneers are not likely to be found with defects. They don’t allow water to seep through the core so delamination won’t occur. Additionally, the fungal attack has no chance of persisting. Also, the glue won’t lose its bond.

2. Durability

As your boat traverses the waters, it meets plate actions and floating debris. Still, marine plywood can withstand and even absorb forces. It stands with its excellent quality! It can be compared to a plank of solid wood but there’s a difference as marine plywood is flawless and doesn’t need to be graded out. You can’t go wrong choosing it for boat flooring replacement because it matches any material.

You’ll be amazed at how it can be harmonious with aluminum boat floor and fiberglass boat floor.

3. Wide scope of usage

This plywood has a wide scope of usage. Apart from boats, it’s also used on docks and other projects on the water. You may even use it for your laundry area and kitchen and you won’t regret it. With different uses, one thing is for sure. You won’t need plywood replacement often.

Grading of Plywood

Based on the above statements, marine plywood can be A and B grades. The highest grade is A and this plywood has been sanded so it’s smooth and ready to use. The grade B is usually referred to as wood filler with minor splits and tight knots. The lowest is grade D and it has a lot of imperfections and can have voids too.

Importance of pressure treatment

There are different plywood grades because some of them go through treatment using pressure. A good example of this is marine plywood. It’s an important procedure as it creates protection from rot or decay, termites, fire, marine organisms, and other harmful elements.

Various chemicals are added to the plywood during pressure treatment. The kinds of chemicals embedded in wood fibers depend on the type of wood and climate in the area. Pressure treatment is a simple procedure that happens in a huge chamber where plywood pallets are piled. The vacuum is pulled out from this chamber to get rid of the air that may be present in the wood.

The necessary chemicals are mixed with water or oil and the combination is injected into the wood at 160 psi. It can take 20 to 60 minutes to finish. After the wood receives the chemicals, it proceeds to a drip-dry rack. The weather has a say on the drying time, ranging from 2 days up to 2 weeks.

Substitutes for Marine Plywood


As mentioned, using regular plywood for the boat floor is not advisable. My first recommendation is marine plywood but I’d also like to tell you that reliable substitutes exist. You may get the one that is convenient and accessible for you.

1. Fiber cement board


Many boaters regard fiber cement board as a dependable alternative in boat construction. Thus, there’s no doubt that it’s also a great replacement for boat flooring. This board is composed of cement and wooden fibers. Only a little amount of wood is mixed with cement for more strength.

Cement is the main provider of strength as well as support. In addition, it also established moisture resistance. No wonder you can construct an entire boat by using this material. You may even use it in making furniture since it’s lightweight. Even though it’s not heavy, it’s as durable as hardwood. You may even attach it in curved areas. You’ll like it as it’s cheaper than marine plywood.

2. Weather and boil-proof plywood

Also called WBP plywood, it comes with a highly resistant design. It has a promising ability to counter harsh weather conditions and extreme temperatures. Thin veneers are glued together to implant toughness in this plywood. To produce this kind of plywood, the cross-hatching technique is applied. It results in tough plywood that is light and durable.

Premium melamine is used to bond the veneers. It’s the reason why it can withstand extreme temperatures. Some tests show that it can stay in boiling water without getting damaged for 20 hours. I must say that you should pick this plywood if you usually go boating in hot streams.

3. Thermo lite board

Just like marine plywood, this board is lightweight and sturdy. Hence, it’s a good decision to have this as a boat plywood floor. This material is also seen in many industrial settings. It has a wide range of applications such as boat walls and ceilings, interiors, and furniture. Furthermore, it’s not susceptible to rot so a replacement will be needed after a long time.

You’ll be in awe of how it can handle the impact. It won’t easily wear out from exposure to high temperatures. Thus, this is also found in motor homes and even houses.

4. Wax resin fiberboard

Boaters approve of this as boat floor replacement due to its durability and lightweight. It’s also utilized in many industries. There are a lot of things that you can do out of the combination of wax resin and softwood fibers. This is one of the materials that are used to produce high-quality vessels. It’s dependable in terms of strength and resistance to moisture.

5. Ribbon grain plywood

Its name is derived from the ribbon pattern that forms from the wood grains. But it’s smooth so there’s no need to polish it. Hence, it can save you time during installation. With the cores and veneers, it looks like authentic wood. It’s hard to tell that it’s only an artificial surface.

The grain on this plywood delivers impressive strength and resistance to shock or impact. That’s why it’s not only for flooring but applicable to all boat parts. Despite its affordable price, you can rely on its sturdiness and durability, characteristics that you can also find in marine plywood. It’s the right choice for those who don’t use their boats often.

6. Birch plywood


Another affordable yet reliable substitute for marine plywood is birch plywood. Many boaters will agree with this statement. It’s also used for boat construction but it shouldn’t be submerged in the water frequently. So, it’s not as durable as marine plywood.

It’s made of birch trees and it’s how it got its name. A ring-like structure can be seen on the wood of the birch tree as a sign of strength. It can also last long as a boat floor since it’s not often submerged in the water.

The Bottom Line: What’s Best for Your Boat Floor

You know a lot of things now on what kind of plywood for a boat floor. The primary recommendation is marine plywood since it’s durable as supported by plywood grades A and B which are the highest category. However, there are also other types of plywood or board that can substitute marine plywood. It all depends on your needs and boating activities.

5/5 - (3 votes)