If you are planning to build something out of wood, plywood is of course a very common and popular material to choose from. It is much more affordable than solid lumber and has many benefits too. That said, you have some choices to make.
There are different types of plywood and not all of them are ideal for the same purposes. Today, we want to compare two specific types – marine-grade plywood and pressure-treated plywood. Let’s figure out what both of these types are and what they are used for, so you can make an informed decision.
Marine Grade vs. Pressure-Treated Plywood: What Are the Differences?
Before we talk about which one of these two types of plywood you should use for specific situations, let’s first figure out what makes them different from each other. There are quite a few notable differences that will determine which one of these you use for specific projects.
1. Hardwood vs. Softwood
One notable difference here is that marine-grade plywood is usually made out of extremely high-quality hardwood. On the other hand, pressure-treated plywood is generally made out of softwood. This in itself leads to many of the other differences that we will discuss further below.
For instance, hardwood is of course much harder and more durable than softwood. Hardwood has greater impact resistance than softwood. Hardwood also has greater resistance to fire, as well as various other elements. It in itself is more water-resistant than softwood. That said, hardwood plywood is often more expensive than softwood plywood.
2. Grade
Do also keep in mind that there are various grades of plywood, which refers to their quality. Specifically, this refers to the quality of the veneers that were used in the construction of the plywood.
Generally speaking, with marine grade plywood, only the highest grade and the best of plywood veneers are used. These are made without any gaps or knots at all. On the other hand, pressure-treated plywood may be fairly low-grade plywood that does have knots and gaps in it.
It’s generally just normal indoor or structural quality plywood that has been treated with a special process, something that we will discuss directly below.
3. Production Process
By production process, we are talking about how these two types of plywood are made.
Marine-grade plywood is designed with very special waterproof glue that is then tightly pressed together.
On the other hand, pressure-treated plywood is coated and soaked with a variety of dangerous chemicals. It is of course also treated with a great amount of pressure.
These differences, especially in terms of the waterproof glue used, and the chemicals used then also lead to a variety of other differences that we are about to discuss.
4. Water Resistance
One of the biggest differences here has to do with water resistance. As you can probably guess, marine-grade plywood is designed to be totally waterproof. It is designed with special waterproof glue that does not allow water to soak into the wood.
This means that marine-grade plywood can be used for applications that involve a lot of water, and it can even be totally submerged without absorbing much liquid. On the other hand, pressure-treated plywood, although it is fairly water-resistant, is by no means waterproof. It’s definitely not something that you can submerge underwater.
5. Overall Durability
The simple fact of the matter is that marine-grade plywood is more durable than pressure-treated plywood.
It’s a harder and higher-grade type of plywood that has more impact resistance and is able to bear more weight. Marine-grade plywood is often made with many more plies or layers and is much thicker in general as well.
6. Rot Resistance
An interesting thing to note is that pressure-treated plywood is resistant to rotting. This is the biggest benefit that this pressure treatment and chemical treatment process has. It’s specially designed to make this type of plywood resistant to rotting. Now, although marine-grade plywood does not have this kind of rot prevention treatment, the fact that it is waterproof does also mean that it is great at preventing rotting from occurring.
Generally speaking, they’re both fairly resistant to rotting as well as to pests, although pressure-treated plywood may be slightly more so.
7. Price
The other difference here has to do with the overall cost. For a sheet of 1/4-inch marine grade plywood, expect to spend around $65. Pressure-treated plywood on the other hand is generally more affordable. It can cost anywhere from 50% to 75% of what marine-grade plywood costs.
When to Use Marine Grade Plywood?
If you are worried about water, then it is marine-grade plywood that you want to use. Marine-grade plywood is often used for structures that are constantly exposed to the elements.
Moreover, this type of plywood is generally used for building wooden boats, docks, jetties, piers, and other such things. If the object in question is going to be submerged, or partially submerged, then it is marine-grade plywood that you want to use.
When to Use Pressure Treated Plywood?
Pressure-treated plywood is a great option to go with for interior structural purposes, as well as for many outdoor purposes.
Most people would use pressure-treated plywood to build fences, patios, balconies, and other such things. The trick is of course that you do need to seal pressure-treated plywood when it is being used outdoors.
Alternatives to Marine and Pressure Treated Plywood
There are of course some good alternatives to both marine grade and pressure treated plywood that you should consider using:
- One good option to go with here is basic structural plywood. It’s basically just pressure-treated plywood that hasn’t been pressure-treated. It is therefore ideal for indoor use, for structural purposes, and it doesn’t cost quite as much as the pressure-treated variety.
- If you want a very good-looking type of plywood, go for something like oak, maple, or mahogany plywood.
- If you just need something super affordable that doesn’t really need to be structural in nature, then other types of engineered wood like MDF, particleboard, or HDF are all good options.
Summary
Now that you know what the differences between marine grade plywood and pressure-treated plywood are, you can make an informed decision between the two.