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Can You Just Replace Deck Boards with Composite?

December 15, 2023

As a relaxing and entertaining outdoor deck, you probably use it a lot. You spend a lot of enjoyable time with your family and friends in your outdoor living space. While the framing of your outdoor deck can last for decades, the boards on it wear out quickly. This has left many people wondering if they can replace the wood deck boards with composite wood decking while still using the original framing of the wood deck.

There are a few things you need to do before replacing wood deck boards with composite decking material. This is true even if you are using a building kit that offers high-quality composite materials for rebuilding projects. However, if you plan ahead, installing composite decking boards over your existing deck structure can save you a ton of money. Homeowners want to make sure everything is up to code and that the joists don’t start to rot.

Why Use Composite Wood Decking Instead of Wood Decking?

The main reason for using composite decking boards instead of wood decking is to save money on maintenance. Composite wood decking is easier to maintain than wood decking because it doesn’t require staining or sanding. Installing composite decking over an old deck is also usually much more cost-effective than replacing the whole thing. If you’re replacing a damaged surface, laying down composite decking instead of wood can even make your home worth more.

Composite wood decking offers these benefits in addition to the low-maintenance benefits:


Composite decking is made from a homogeneous blend of wood fibers and recyclable plastic. They come in a variety of colors, so there is no need for staining. And because the color is part of the wood decking, it won’t scratch like wood decking. On wood decking, scratches show through the stain on bare wood. But on composite wood decking, scratches are hard to see. You can also use a heat gun to repair them if necessary.



Older composite wood decking is known to be slippery. But quality modern composite decking will not be slippery. This is because they usually come with a non-slip wood grain or grooved surface. These surface textures increase the friction of the decking, allowing composite wood decking to avoid becoming slippery when wet.

UV Resistant

Compared to regular wood decking, composite wood decking has excellent UV resistance. This is due to the fact that the manufacturer adds UV inhibitors during the production of composite decking. Therefore, building an outdoor living space with composite wood decking means that you don’t have to worry about it fading over the years.

Moisture Resistance

Finally, composite wood decking is manufactured with a plastic component. That’s why it boasts even better moisture resistance than wood decking. And the new generation of capped composite decking is even better at resisting moisture!

All this makes composite wood decking durable and comfortable to walk barefoot. That’s why composite decking is the preferred alternative to wood decking for people today.

What to Look for in the Substructure When Replacing Wood Decking with Composite Decking

Years ago, standards for deck construction were set. This is good news for contractors and do-it-yourselfers. Most of the wood substructure that supports wood decking – posts, beams, and joists – is also adequate to support composite wood decking.

If you want to replace your wood decking with composite wood decking. Then you will need at least 4×4 posts. One can see if the existing posts fulfill the need by measuring the surface of the posts.

The joists are spaced 16 inches from the centerline at right angles to the deck boards above. The centerline of a joist is usually in the middle of its narrow side. For example, the centerline of a 2×6 joist is ¾ inch on its thinner side. Diagonal trim boards can improve the appearance of a deck, but they need to be supported by joists. The distance between the joists and the centerline of the trim board should not exceed 12 inches. If you want to install a portion of the diagonal boards, you will need to modify the joist spacing below the deck according to this sizing standard.

In addition, you should thoroughly inspect the fasteners. Make sure they haven’t loosened due to the expansion and contraction of the lumber substructure. A little corrosion on bolts, nail heads, and washers is normal, but too much corrosion can damage fasteners. If corrosion is more severe in these areas, you’ll need to repair or replace them promptly. Avoid corroded fasteners that will compromise the structural stability and longevity of your new deck.


Can Composite Decking be Installed Directly on the Wood Boards?

No, this is not a recommended practice. Many times, joists are replaced, secured, or repaired at the same time as the deck trim boards are replaced. This is because dry rot is often found underneath the decking, usually where fasteners pass through the joists. Before laying new deck boards, the old deck trim boards must be removed. so that the joists and beams can be inspected and fastened if necessary.

Installing new deck boards over an old deck can shorten the life of the new material considerably. When wet, water can easily pool in the joints between the two materials. The only area that should touch this area is the top of the joists. On both sides, most of the decking should be visible.

If you lay new deck boards over old deck boards, there won’t be much room for them to dry out. And both the old and new deck boards will probably break down faster. In the case of manufactured products, installing them over old decking or solid surfaces is a no-no and will likely void the warranty.


How Much Does it Cost to Replace Wood Decking with Composite Decking?

Before installing a new deck, you will need to remove the old deck boards. Removing the old deck usually costs between $5 and $10 per square foot. And installing a new deck costs between $3 and $12 per square foot. If you do it yourself, installing new composite wood decking can cost between $8 and $22 per square foot.

If you’re looking to repair more than just the surface of your deck, the cost of purchasing composite wood decking can be even higher.

How to Install Composite Decking on an Existing Deck

Laying new composite wood decking over old deck framing is very simple and requires only a few steps.

Step 1: Remove the Wood Deck Boards

Use a drill, hammer, or pry bar to remove the boards you don’t want, starting at the edge of the deck. A circular saw or chisel may be necessary to remove broken sections.

Step 2: Look for Rotted or Buckled Joists.

Use a screwdriver to check for soft spots or loose fasteners where the substructure touches each other. Use a chisel to repair any minor damage before you begin reinstalling the composite wood decking. You may also need to use joist protection tape to seal the decking fasteners and prevent water ingress. This will prevent future damage or rotting of the joists.


Step 3: Installing Composite Decking

Use 3-inch deck screws to attach the new boards to the joists. You can also use a hidden fastener system to make the composite decking boards fit snugly into the joists that support the planks.

Things to Consider Before Installing Composite Decking on an Old Deck

Homeowners who have used their wood decks for many years, no longer want to invest too much time and cost in maintaining their decks. So when they have used their wood decks for many years, they intend to resurface their outdoor decks with composite wood decking.

Despite what many homeowners think, there are many things to consider before refurbishing an old deck. These issues will not only affect the appearance of the deck, but also its safety and longevity.

The following five questions will help you figure out if you can start reinstalling right away. Or if your framing needs some work before you begin.


What Is the Current Condition of Your Deck?

Have a licensed deck inspector, such as custom deck creations, come out and do a thorough inspection. This will give you an idea of what the current condition of your deck is. This will give you an idea of how strong the deck structure is and how much weight it can hold.

The North American Deck and Railing Association (NADRA) can provide a list of qualified local deck builders. You can also contact them to inspect your old deck.

They will look for the following three main problems or issues:

Signs of Deterioration

Pressure-treated lumber is the most common type and is considered the best material for building deck framing. It can withstand many types of damage caused by weather, but it can also deteriorate over time. Moisture and rot are usually the main causes.

For some reason, if your framing shows any signs of damage, you should probably rebuild it. It’s not always clear-cut, so it’s best to ask a professional inspector to help you decide.

Experts say you should have a professional inspect your deck every three to five years. That way, you’ll be able to address any issues before they become dangerous or cost more to fix.


Damage to the Concrete Foundation

The next thing you should check if you can is the concrete footings. Depending on how good they are, you may need to have the framing redone.

If there are two or three posts that are not up to snuff, but the frame is intact. It might be possible to pour new concrete footings under them. On the other hand, if most or all of the foundation needs to be replaced, or if the deck is low to the ground. Then you may need to take the frame apart and rebuild the entire frame.

Overall Structural Capacity

The strength of the deck depends on the foundation and framing. They must be able to withstand the weight of the new composite decking.

Composite wood decking is usually much heavier than wood decking. That means your building must be able to safely handle that much weight and still have enough life left in it.

composite deck boards

How old Is the Existing Deck?

Age is not the most important thing to consider, but it is something to think about. This is because it usually says a lot about how good the overall quality of the deck is.

In most cases, wood framing will last 20 to 40 years. But if your deck is at least 15 years old, it doesn’t make sense to just put down new composite wood decking without new framing.

Composite decking can last up to 25-30 years, and even longer with proper maintenance. Therefore, you want to make sure that the deck framing lasts as long as the composite decking.

Is the Deck Attached to the House?

Decks that are 20 years old or older are usually attached to the house due to building codes at the time.

If you want to keep the framing you already have, you need to make sure that the ledger boards (the boards that connect the deck to the house) have the correct waterproofing on them. If it’s not, then water may have accumulated behind the boards for years and rotted from the inside.

You can drill holes in the ledge to check for damage, but this is not the best method. If there is no waterproofing, you will almost certainly need to replace the deck’s framing.

It’s best not to take any chances. This is because the most common reason for a deck to fail is that the ledger boards have not been installed correctly.


How Tall is the Deck and How Was it Built?

How tall is the outdoor deck you already have? Is it almost level with the ground, or is it closer to a second story?

You need to be extra careful with taller decks that are not on the ground. The framing and foundation must be intact and meet the minimum safety standards set by your state’s residential codes. This is especially important if you want to change the plan or design of the space.

When people update their decks, they usually also want to make changes to the following areas:

  • Adding a new floor
  • Increase the size of the deck
  • Adding or widening stairs
  • Installing a hot tub
  • Build a gazebo
  • Changing the look of a fence
  • Installing an outdoor kitchen

It’s reasonable to want to change the look of a deck or add something new to it. However, any of these changes will affect whether the framing underneath needs to be altered or replaced to provide support. Aesthetically, economically, and from a safety standpoint, it’s usually best to replace the entire frame if you want to change the design of your deck.


Is There a License for the First Build?

This last question may not be the first one that comes to mind. But it’s important to know if the original deck had a permit. Visit your city’s building department or call them to find out.

You should know that if your deck does not have a permit. The building department may charge you a permit fee and a small fine. They may also want to perform an inspection, which could mean digging into the foundation of the deck. This is not common, but it can still happen.

You should be aware of this because whether or not you have a permit for your existing deck can change the course of the project. If you are going to be working on any of the three sections, your deck builder will need to obtain a permit:

  • Framing
  • Fencing and walls
  • Stairs

Even if you only want to change the surface of your deck, new stairs are almost always installed when resurfacing your deck. The steps are usually the first part of the deck to start collapsing, and you will need a new permit to build new steps.


If your old deck is not permitted, you may need to replace the framing rather than just make a few changes. This may seem like a lot of work, but regulations state that if you make any changes, you must bring the entire structure up to code. Materials are cheap, but labor costs are usually the same or higher than taking apart the framing and putting it back together.

If your old deck is permitted, the process is much easier. Your deck can be resurfaced as long as the framing is secure and the design is not changed. Be sure to check with your local authorities first, however, as laws may vary from region to region.

In a Nutshell

Laying composite wood decking over a wooden deck is a good idea. This is because composite decking is stronger and requires less maintenance. However, the structure underneath the deck determines how long your new deck will last.

First, have a professional look at your deck. Then, make your choice, keeping in mind any changes you want to make to your plans, any permits you need, and your budget.

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Galen Content Writer
Galen is a content creator and decorator with five years of experience designing home decor. In his daily life, Galen is constantly on the lookout for the latest, great examples of house design and further optimizes his solutions. Additionally, he writes articles related to outdoor design, interior design, and architectural decorating materials to help brands build more engaging relationships with their audiences.
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