Can You Put Composite Decking Over Existing Deck?

You are looking to replace your existing deck and the option you have in mind is using composite decking. The big question you are asking yourself is, is it okay to put composite decking over your existing deck?

You can place a composite deck over your existing deck frame and save yourself the time and cost it would take to rebuild one from scratch. Your deck will ultimately end up being strong and very durable against the elements.

Composite deck boards consist of mixed wood fibers and plastics held together by bonding agents. Read on and learn everything there is to know about applying composite deck boards to an existing substructure as an alternative to installing a whole new deck.

Can You Put Composite Decking Over Existing Deck

Should You Place Composite Decking Boards Over Wood?

You can refresh your existing wood deck with composite boards. However, here are factors to consider before you decide to place composite boards over your wood deck:

  • Age of your wood deck.
  • Signs of rotting.
  • The type of wood used for your deck.

Your wood deck typically has a lifespan of 10 to 15 years. If your deck is older than this, then putting composite boards over it will result in more rotting due to moisture being retained between the board spaces.

On the other hand, your wood deck may already be rotting, and you don’t know how to tell that it is. A suitable method to investigate this is to poke around with a screwdriver testing for soft spots. Moisture stands as the principal culprit for rotting your wood by creating a breeding ground for wood-digesting fungi that will result in rot.

Have a professional inspect your deck biannually to ensure your wood deck doesn’t rot and attract termites.

Using rot-resistant species of wood for your deck lowers the possibility of your deck rotting quickly. Cypress, mahogany, redwood, and cedar top the list when it comes to rot resistance. Consider whether your deck is made from these strong wood species before resurfacing with composite boards.

If your wood deck has signs of rot, you may have to consider replacing it entirely from the ground up. Doing this will save you the cost that would arise if the existing wobbly, creaky, rotting wood underneath collapsed along with your newly resurfaced composite boards.

Resurfacing Existing Deck With Composite

Composite Decking Over Wood Deck Resurfacing Existing Deck With Composite

Using the right tools and procedures for building your composite deck will enable you to build a durable structure, take a shorter time, and even provide you with a fun experience. Begin by clearing your old deck of any deck furniture and deck railings balusters to provide you with ample workspace. Follow these simple, basic, quick steps:

Step 1: Remove Old Decking and Carry Out Inspection

With the aid of a pry bar, remove your old deck boards. Take some of these boards and utilize them as a temporary block line. Now check your framing for rot, make necessary repairs, and even install additional framing in creaky or wobbly areas.

Step 2: Protective Measures

Apply a good liquid wood preservative such as CopperCoat Green Wood Preservative to all cut ends of your treated lumber frame. The next task is to cover the holes from old nails or screws to avoid water collecting in them. For this, you can use joist protection tape. Use this tape to cover the top of your joists as well to have your deck last longer.

Step 3: Carving and Fastening Your Composite Deck Boards

Cut the composite board ends to a suitable length that will allow for proper gaps on the ends. Secure the deck boards using 8 gauge, 2.5’’ coated deck screws, or approved fasteners. You may use a 1/8’’ drill bit to predrill screw holes. Start by working from the outside of the deck and moving towards the house. A jigsaw will serve you well to make cuts around railing posts.

Step 4: Installing The Middle Boards

Cut your middle boards to length and install them from the breaker board, if using one, moving out to the perimeter boards. Keep in mind to work from the outside railing as you progress toward the house. During your installation process, use spacers to leave gaps between the boards so that when it rains, water can drain. The spacing allows for expansion and contraction of the boards when exposed to heat and also enables small debris to fall through.

Step 5: Finishing Touches and Completion

You are almost done with your installation. Re-install your railing balusters, put back your deck furniture, and enjoy your sturdy new composite deck.

Installing Composite Decking Over Wood Pros and Cons

Decking options have evolved over the past years, so it’s normal to find yourself debating whether it is beneficial to install composite decking over wood. You will find it easier to understand the options you have at hand and the best course of action to take, after comparing the advantages and disadvantages of your building material options.

Pros of Composite Decking

  • It requires minimal maintenance.
  • It is environmentally friendly. Composites are made up of recycled fibers and plastics.
  • Composites have an authentic look. Unlike plastic decks, composite deck boards have a similar appearance to wood boards.
  • Highly durable. It can last up to 30 years which is more than double the lifespan of wooden decks.
  • Have a variety of colors. Composites can be purchased in different colors according to your desire hence it will save you that extra cost and time of having to paint over your deck boards.
  • Composite boards do not split. They are made of a stronger material that is less likely to split when handling it during installation.
  • The material is highly resistant to water.
  • They are insect-resistant.
  • Composite boards do not fade as quickly as wood.

Cons of Composite Decking Over Wood Decking

  • Molds on your old decking may rot your new deck. If you do not carry out proper inspection, the molds on your previous deck may gradually eat away at your new deck.
  • The deck will collapse if the underlying wood support structure is inadequate. Rot in your wood foundation will make the whole deck structure weak.
  • The double-layer may stink on hot steamy days. As gunk between the deck layers molds in the heat, a fowl displeasing smell may be produced.
  • Trapped water may lead to an early demise. Water may eventually slip in between the board layers and provide breeding grounds for wood digesting fungi.
  • Mold stains that do not wash away may form on your top deck. The rotting wood layer underneath may migrate upwards and begin to stain your deck.
  • May get too hot for bare feet in the summer. Since this material is not natural wood, it tends to get uncomfortably hot on bare feet during the high summer heat.
  • It is more expensive than wood. The price of composite decking will discourage you from purchasing them if you are on a tight budget.

Can You Put Deck Boards Over Plywood?

You can put deck boards over plywood. After setting in place your floor joists, install your plywood decking as the base and follow up with composite decking over the plywood. Laying plywood sheet before you fix your deck surface distributes the weight evenly providing a sturdier deck.

You will want your outdoor deck to be constructed from rigid materials that can withstand high heat, heavy snow, wind-driven moisture, and humidity. However, the reason why most plywood decks fail prematurely is due to weak frames underneath that may collapse when faced with too much weight. Plywood decks alone can be weak and prone to suffering from severe warping. Water may collect in the warps and result in rotting.

Plywood floors can be beautiful, nonetheless, you have to ensure it is well ventilated, dry, and elevated off the ground. Cover your exterior rated plywood’s upper surface with a waterproof paraffin based seal that will ensure water does not sip into the material. With your plywood sealed, you will prevent it from rotting. Remember to apply the seal annually.

Cost To Replace Deck Boards With Composite

As you prepare to get rid of your old deck and replace it with a new composite deck, you are bound to be curious as to how much it will cost you to complete this process and end up with your desired deck. Composite decking will cost you more to install when compared to wood decks. Regardless, you will discover that in the long run, the lifespan and low maintenance of the material will prove to be much cheaper.

Before getting down to the numbers, there are pricing aspects to consider before making any estimates on how much money you will spend to replace your deck.

Your Deck Size

I’ll put it plainly; it will cost you more to replace a larger deck than a small one.

Shapes, Angles, and Corners

Your labor and material price will exponentially climb the more irregularly shaped your deck. A simpler deck design is more pocket-friendly.

Removal of Old Decking

You can save yourself that extra penny if you can remove the old deck yourself. However, if you have no experience, leave it to the professionals to avoid damage.

Railings and Extra Fittings

The cost of your deck railings is an important pricing aspect to consider, but most people tend to forget the cost of putting in railings when calculating the total price. You might also need to add the cost of plumbing and electric services if any pipes or wires are to be part of your deck.

Timing of Replacement

The majority of homeowners choose to fix their decks during spring. At this time materials are priced higher due to greater demand, and you may even experience some delay in having the materials delivered to you.

Cost Summary
Replacing Decking Cost Per Square Foot $16 – $25
Labor Costs Average Labor Cost Per Hour


Railings Materials Cost Per Linear Foot $46 – $87
Substructure and Other Modifications Cost Per Square Foot $5 – $15

Installing a composite deck will cost you an average of $6050.


Using composite decking to replace a worn or rotting deck surface is a common practice, provided the existing framework is in good condition. It saves money, time, and is more environmentally friendly than ripping it all out and starting fresh too.

Replacing the old boards with composite boards will also give you a new-looking deck that will last longer and is more durable. Don’t forget to enjoy the rebuild and enjoy your deck.

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