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Can You Put Trex Decking Over Plywood?(How To)

When it comes to decking, you have many different options available. Trex decking is often considered because of its beauty and durability. Can you install it over plywood?

Trex decking can be installed directly over plywood but it is not the recommended choice. This is due to the possibility that the plywood would rot and ruin the installation before the Trex has lived out its lifespan. It is possible, but you should inspect the plywood and make sure it is sound if you are going to do so.

Man working on the trex decking

Just because something is possible does not necessarily mean that it is appropriate. That is the case with Trex decking, and there are many things that can be said about it.

Can You Put Trex Decking Over Plywood (How To)

First of all, it is certainly possible to put Trex deck directly over plywood. In fact, plywood will work as a strong subfloor that will hold the decking in place.

At the same time, however, if the plywood is not treated properly, it will rot within just a few years because of exposure. You can use a sealer as well as using caulking on the seams and that will help to slow down the rotting process.

It is always a better choice to pull up the plywood and use the joists to attach your Trex decking. If you don’t want to pull up the plywood, however, just make sure it is in good shape before you get started.

Should You Put Trex Decking Over Plywood

Tools for text decking

Installing Trex decking over plywood is one of the better decking choices you have available. It is a superior decking material that is used by homeowners around the world. Is it also a material that should be considered for your needs?

In order to make the choice as to whether you should use Trex decking or not, you will have to consider the benefits of doing so. They’re actually quite a few reasons why we would recommend using Trex and it can be installed directly over plywood if you seal the plywood and repair any damage first.

Cracking – One of the greatest benefits of using composite decking such as Trex is the fact that it does not crack and splinter. When you put it down, it will stay in place and maintain its shape and beauty for many years to come.

Slipping – One of the issues that are associated with wood decking and other types of decking is the fact that it can get slippery. That is especially true of plastic decking in the winter. Since Trex is not as slippery as other types of decking, it offers benefits for homeowners in wet and cold climates.

Fading – As you are probably aware, many types of decking can fade over the course of time. Trex, on the other hand, is made from fade-resistant material that not only keeps it from fading, but it will also help to maximize the beauty of the surface for a very long time.

Staining – There is nothing quite as frustrating is having a party and somebody spills something on the deck. The wood can stain for a very long time or perhaps even permanently. Trex, on the other hand, is stain resistant so you only need to wipe up the spill after it occurs.

Uniformity – Have you ever tried to match certain types of decking and it is practically impossible to do so? Trex has the benefit of a uniform color from the top to the bottom, so there is no need for you to worry about having that odd piece that looks out of place.

Longevity – You really can’t beat the length of time the Trex will last. Compared with other decking materials that may last a decade or so, Trex can last up to 30 years with a minimal amount of upkeep. There may be some differences as far as geographic location, but it will last a long time.

Maintenance – One other reason why you should choose Trex over other types of decking is the fact that it requires very little maintenance. You can wash it on occasion and even going over it with the pressure washer every few years will do the trick.

Tool Needed To Install Trex Decking Over Plywood

Confused man standing

With any DIY project, it’s important to make sure that you have all the tools that you will need from the start. This helps to prevent unnecessary delays and gets the job done.

These are the tools you should have for installing Trex over plywood:

Saw (Circular Saw, Tablesaw, Chopsaw, or Jigsaw)


Rubber Mallet

Tape Measures

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Straight Edge

Utility Knife

Caulking Gun

Broom and Dust Pan


Plumb Line

This short list of tools is all that is truly necessary to install Trex decking. At the same time, however, you may have other tools that you prefer using. In addition, the type of saw that you use is also up to you. If it can cut wood, it can cut Trex

What Preparation Is Needed To Install Trex Decking Over Plywood

Man working on the trex decking

One important factor to consider when installing Trex over plywood is the fact that you will have to prepare everything properly. Simply putting the boards down overall plywood is a recipe for disaster.

Then again, there are a limited amount of things that you can do to prepare in advance. As long as the plywood is sound and the floor joists are in good shape, you can proceed with the project.

Here are the steps necessary to ensure that everything goes as smoothly as possible.

Protect the Plywood – Admittedly, plywood is not the best material to use in the open air. It will fail prematurely in comparison with other types of decking material but if you prepare it properly, it can make a nice subfloor.

To be honest, people have used plywood for decks for many years. It can make a very beautiful surface, but you need to make sure that it is prepared properly. This includes protecting the upper surface of the plywood with some type of sealer, such as one based on paraffin.

The real key is that you don’t want anything to soak into the plywood unnecessarily. Doing so would cause it to rot, and you want to prevent that at all costs. Unfortunately, you will not be able to reapply paraffin sealer after the installation of Trex, but it is good to have a properly sealed from the start.

Caulking – One of the areas where problems are often seen is where the plywood comes together at the joint. Water can get down in the joint and rot the plywood from underneath or even from the sides. This can be corrected by caulking things in advance.

Use high-quality caulking that is rated for outdoor use. It should also be clear to prevent any unnecessary coloring that may show through the seams in the Trex decking. Be cautious that you don’t create any unnecessary changes in elevation with the caulking. It should be wiped down cleanly.

Inspection – If you already have any rotting or other damage that is occurring in the existing plywood, it is going to cause problems much more quickly. That is why it is important that you inspect the plywood in advance.

If there are any problems associated with the plywood, it should be removed at this point and replaced. You should also carefully inspect the joists to ensure that they aren’t experiencing problems as well under the plywood.

If all else fails, you can always pull up the plywood and install the Trex decking directly on the joists. It takes a lot more work, but it is something to consider.

How To Install Trex Decking Over Plywood

Confused man standing

Now it is time to actually install the Trex decking over plywood. It’s a relatively straightforward process that can be done in an afternoon.

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1. Measure Twice – I’m sure that you have heard the old axiom that you should measure twice, and cut once. That is true, especially of something like Trex. It is much better to have a single piece of board from one side of the deck to the other than to try to splice things together.

You should also make sure that the boards are trimmed on either side by at least 1/4 inch. If you ordered the boards properly, you have a little extra and you can split the cut into both sides to make the ends look as good as you can.

2. Screw Down – Most homeowners are not going to want to see the screws, so there is a secret fixing system used in the installation of Trex. Universal fasteners are connecting two boards together and as you drill down into the joists, you will not see the screws.

This is not a necessary step as you can use deck screws with minimal heads that are countersunk into the Trex. You will still see the holes, but it will save you some money.

3. Cover the Edges – There are fascia boards that can be purchased that match the Trex decking appropriately. When you install these on the edges to cover them, it will make the entire look seamless. It’s a beautiful option that should be considered.

You can install Trex decking directly over plywood but you need to ensure that the plywood is free of any defects before doing so. It is a better option to remove the plywood but if you don’t have that choice, Trex can be installed.

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