Pressure Treated Plywood vs Marine Plywood

Image of plywood, but which one is better? Pressure treated plywood vs marine plywood

Plywood is a great building wood material and is loved by many in the United States when it comes to the construction of furniture and even houses. There are different types of plywood that you can use for various projects. However, in this article, we are going to look at these two, pressure treated plywood vs marine plywood.

Marine plywood is strictly a product of Douglas fir and Western larch woods; glue is applied on the surface of marine plywood to keep it waterproof, unlike pressure treated plywood. On the other hand, treated plywood is created using softer wood compared to its marine counterpart. The softwood allows for better absorption of the chemicals that protect it from mold and fungi.

The differences between these two, marine plywood and treated plywood, include the wood types as well as the quality of the individual boards used in the building the panel. Additionally, the glue type and curing method make essential components of the two.

Let’s look at them in details:

Pressure Treated Plywood

Treated plywood presents an essential building block for virtually everything in your house. This product is lightweight, yet stiff and long-lasting. Preservatives are added to the surface of the wood, which penetrates deeply into the wood layers. These preservatives offer protection against decay as well as termite invasion. 

Once you have installed this treated plywood, you can paint it like you can paint the untreated one.

Marine Plywood

Treated plywood is created using softer wood compared to the marine plywood, softwoods allow for excellent absorption of the chemicals which are responsible for the protection against mold and fungi.

With time, the chances of chemicals present in the marine plywood can leach to the areas around it, one way of minimizing leaching is by sealing the surface of this wood using varnish or paint.

Should You Seal Marine Plywood?

Usually, you will find that the marine plywood is thicker than standard plywood; therefore, you’ll need to apply more layers of sealer to extend its lifespan. Generally, you should add as many coats of a sealant as there are the layers of the plywood. If, for example, your plywood has 6 layers of wood, ensure that you add 6 layers of sealant.

Is Treated Plywood Waterproof?

The marine-grade plywood, commonly referred to as marine plywood, is not waterproof as many people often claim. This wood is not treated using chemicals and not rot-resistant as well. However, this wood is a good-quality, hardwood plywood created with waterproof glue.

How to Seal Marine Plywood

Marine plywood is a wood type created specifically for usage in areas with high humidity levels. One unique thing about this type of wood is that it can resist water and moisture on its own. 

Even so, the material components of this wood are not sufficient to block all moisture from entering into the wood. Therefore, I’d like to encourage that you further use a sealer to coat the marine plywood so that you can block all moisture from getting into the wood through the pores.

Here are the necessary steps that you need to follow when sealing marine plywood:

Materials

You will need the following items as you look to stain your marine plywood:

  • Paper towels
  • Acetone
  • Sandpaper
  • Foam roller
  • Sanding block
  • Paint basin
  • Epoxy moisture sealer
  • Tipping foam brush

Step One

The first thing you should do is wipe the surface of the marine plywood using paper towels or soft cloth that you have dipped in acetone. This process helps with the removal of other contaminants from the surface of the wood even as you prepare it for sealing. Give the acetone some time to dry before you can move to the next step. The drying time of acetone is about one to two hours.

Step Two

Use sandpaper and a sanding block to sand the marine plywood. Use fine-grit sandpaper to sand the wood for a while so that you achieve a smooth surface. Wipe away any particles of the sawdust with a soft cloth.

Step Three

Pour a little amount of epoxy moisture sealer into the paint basin. You should have a small amount of sealer inside your basin because it dries quickly.

Step Four

Put your foam roller inside the sealer. Roll your brush against the side of the paint basin so that you can remove most of the sealer from your roller.

Step Five

Follow the above procedure by rolling the sealer across the marine plywood. Roll the paint within a 2-by-2-foot area so that the sealer won’t dry before you cover it.

Step Six

Press hard on the roller so that you can cover the plywood with a thin layer of the sealer. Ensure that you are working in small areas until you cover the entire piece of plywood with a thin coat.

Step Seven

Follow the above step by dragging a foam tipping brush over the sealer when it is still wet so that you can remove the brush marks from the epoxy sealer. Ensure that you are dragging the brush across the surface in a horizontal manner.

Step Eight

Give the coat about one to two hours to dry. Follow this step by adding many thin layers. Tip each coat after you apply and remember to drag the brush in a different direction every time. 

Remember that you need to tip the second coat vertically, do the third coat in a horizontal direction. Apply up to five thin layers of epoxy sealer.

Watch the video below and learn how to waterproof a plywood:
Advantages of Plywood
  • This material has good strength and durability if you compare it with a Medium Density Fiberboard (MDF).
  • You can find it in different thicknesses ranges from 6mm to 32mm.
  • Plywood is a product of several different wood species.
  • This material is not prone to damage due to water like MDF.
  • You can polish or paint it with so much ease
  • It holds the screws well.
  • You can cut it in any shape.
  • This material resists shrinking, twisting warping, and cracking.

Disadvantages of Plywood

  • It is prone to splintering, especially from the edges during transportation.
  • This wood is difficult to cut.
  • It emits VOCs (Volatile Organic Compound) that can irritate the eye.

Conclusion

Overall, marine plywood is excellent for the construction of boats, houseboats, and any other water projects. A regularly treated plywood makes an excellent choice everyday projects around the homestead, for example, wall as well as floor sheathing. However, it does not break any bone if you use marine plywood for non-water related projects. Considering that marine wood is waterproof, it guarantees a longer service life than the treated plywood. Marine plywood is expensive, despite that, the longevity of the project justifies the cost. So, 

Pressure Treated Plywood vs Marine Plywood, Which One Do you Choose?

Having read this article, you know that marine plywood is a more durable material than the pressure treated plywood. Therefore, you will have to spend extra so that you land the marine plywood for your different woodworking projects.

Having read this blog post, I hope you found it helpful, especially if you are looking to buy one of these two products. If so, kindly share with your opinion or ask a quest regarding woodworking on the comment section below!

4 thoughts on “Pressure Treated Plywood vs Marine Plywood”

  1. The Marine plywood is made of a more durable material, thus making it a bit more expensive than the pressure treated plywood. If I am undertaking a short term woodworking project and I can’t afford the Marine plywood, can you recommend the use of the pressure treated plywood?

    1. Wood Critique

      Hello Grace,

      Both Marine plywood and pressure treated plywood are reliable building materials for your different woodworking projects.
      They are both durable especially under proper maintenance. If you are to choose between the two, marine plywood has an edge over a pressure treated plywood interms of durability and resistance to environmental elements but you will have to pay more to acquire this product.

      You don’t have to necessarily look at a pressure treated plywood as a short term solution because it is also a durable product if properly maintained.
      If you don’t have issues paying a little more, use Marine Plywood. And it is great if you are living in regions with high levels of humidity or along the coastlines.

      Thanks.

  2. very good info. I am making landing pads for my Super C motorhome leveling jacks. 3/4 ” ply stacked 3 high.

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