How to Replace Wood Deck Boards With Composite

All wood decks age with exposure to the elements, UV rays, and wear and tear. Maintenance and regular application of sealant, stain, or paint can keep the deck looking good. However, you may want to replace deck boards with composite boards and spend less time doing maintenance.

Before starting, check that the deck joists and structure are sound. Remove the wooden decking and repair or replace damaged joists. Apply joist tape to protect the wooden framework from moisture and install the composite decking. Sit back and enjoy!

In this guide, we’ll discuss replacing wood decking with composite boards and whether you can just put them over existing decking. We provide a step-by-step explanation of how to replace wooden decking with composite decking and identify the general costs of both material and labor. We’ll also look at mixing composite decking with wood decking, and if you should replace the decking with composite. Our aim is to provide you with the information you need to resurface your deck with composite boards.

Replace Wood Deck Boards With Composite

Can You Replace Wood Deck Boards With Composite?

There are many reasons to replace wooden decking with composite, but most boil down to aesthetics and maintenance. Wood ages, fades, grays, cracks, splits, and splinters, whereas higher-end composite decking won’t. So, many homeowners look at their old decks and wonder if they can replace, upgrade, or modernize the old deck.

Replacing the wood decking with composite requires some investigation by either the homeowner or a qualified deck builder. The deck frame is usually as old as the wooden decking, so it should be checked for wear, damage, and rot too.

A poorly maintained deck or one that is fairly old may need more than just the decking replaced. Composite decking weighs more than wood decking, so the framework will need to be able to bear more weight.

Check the joists for rot along the top edge where moisture and dirt collect between deck boards and where fasteners grip. If the surface is rotten, then they won’t hold fasteners well or provide a smooth level surface for new composite planks.

Make sure the joists are level with each other too and don’t sag. Composite decking is more flexible than wood, so it will show the deviations in the framework. It’s also important to check the rim and ledger boards for rot too.

While checking the wood framework, also check that brackets, joist hangers, bolts, and other fasteners are tight and not corroded. Additionally, check the joist spacing. Most composite boards need joists spaced on 16” centers if running perpendicular and 12” centers if laid diagonally.

If the joists, beams, supports, brackets, and fasteners are in good condition and spaced appropriately, then you can replace wooden decking with composite.

Can You Put Composite Decking Over Existing Wood Deck?

Can You Put Composite Decking Over Existing Deck

Placing composite planks over existing wooden deck boards isn’t recommended for numerous reasons. Composite decking is heavier than equivalently sized wood, so you’re more than doubling the dead weight the joists and beams must carry. This increase may cause structural issues or concerns to an inspector.

The top of the joists under most decking experiences some rot over time due to moisture and dirt collecting between the planks. Plus, the joists may have developed some dry rot under the existing decking where it sits on the joists too due to lack of air circulation.

Adding the composite boards over existing decking will decrease the airflow around both types of decking, resulting in accelerated rot and decay of both materials. Remember, composite boards contain wood fiber which is susceptible to moisture damage.

Composite decking is more flexible than wood, so any cupping, twists, lifts, or other deviations in the wood will transfer through the composite material. So, if the hope is to improve the look or aesthetics, this isn’t going to happen. Additionally, if you’re trying to decrease the maintenance, keeping the old decking under the composite decking is more likely to increase the maintenance.

Last but not least, laying composite decking over existing decking will most likely void the warranty. Like wood, composite planks need airflow around them to keep moisture out and prevent damage to the composite material. Most composite manufacturers require adequate airflow around their products for the warranty to be honored.

How to Replace Wood Deck Boards With Composite Decking

Replacing Wood Deck With Composite

Removing and replacing wood decking with composite decking is both an aesthetic and budget decision. If the wood is in good condition, do you try to save it for reuse or sale, or just destroy it and get rid of it? Is the new decking going to image the old or be installed in a different direction or pattern?

Those are questions you need to consider before you begin as they affect how the old will be removed and the new installed. The steps below outline the replacement process.

1 Check the Deck Structure

Start by checking the joists for top rot and spacing. Use a screwdriver to see if the joist wood between the deck boards is punky or rotten. If it is, then you’ll likely be replacing some or all of the joists, so you’ll need to add that to the budget. It’s also best to check the rim and ledger boards too for rot.

A rotting ledger usually means a more involved renovation. Most composite decking can be placed perpendicular to joists spaced at 16” centers and diagonally on joists spaced at 12” centers. If the joists don’t work for the new decking design, they may need to be moved or new joists added – again, a budget consideration. This is also a good time to make sure beams and posts are sound too.

2 Remove the Wood Decking

Depending on the type of fasteners holding the wood planks down, you’ll need a hammer, nail puller, pliers, pry bar, screwdriver, drill with appropriate bits, circular saw, and/or reciprocating saw. Start at one edge or end of the deck, removing one board at a time.

Remove nails and screws if possible before resorting to using the pry bar. Trying to salvage the old decking takes longer, but often causes less damage to the joists.

3 Check the Joists

Once the boards are off, remove any broken fasteners and debris, and assess the joists for soft spots, rot, damage, sagging, and levelness. Even a well-maintained deck will experience damage to the joists over time, so they may need to be shaved, capped, or replaced. Also, check that the joist spacing aligns with your decking plan.

Depending on the condition and spacing, you may need to replace, move, or add joists. It may be possible to plane or chisel out damaged material and cap it with a 1×2 or 2×2 instead of replacing the whole joist – much depends on the span, though.

4 Prepare for Composite Decking

If your deck has or needs a railing, now is the time to repair, replace, or install railing support posts and blocking that is code compliant. What was acceptable even 5 years ago isn’t necessarily compliant today.

Once the railing and joists are ready, cover the top of the joists, beams, ledger, band, and rim boards with protective joist tape. The tape seals and protects the wood from moisture and dirt, and seals around fasteners to keep moisture out.

5 Install Composite Decking

Follow the manufacturer’s installation instructions and use the appropriate fasteners for the decking. Make sure the gap between deck boards and at their ends agrees with the product guidelines to allow for expansion.

If the composite decking requires endcaps or protective sealant, use approved products. Once installed, read up on the care instructions for the decking material, sit back, and enjoy your new, low-maintenance deck.

How Much Does It Cost to Replace Deck With Composite?


Best Composite Decking

The cost of replacing wood decking with composite boards depends on several factors such as your zip code and if the work is done by a professional or a DIYer. Other factors to consider are the type and quality of composite decking and the size of the deck or quantity required. The type of fasteners, end caps (if required), sealant for end cuts, and any special tools add to the cost too.

If joist spacing needs adjustment, then it will cost too. If the railings, joists, ledger, rim boards, or any hardware like brackets need repair or replacement, the cost can climb further. Since every deck is different, our focus in this section will be on replacing only the deck boards.

Materials Cost

Composite decking, depending on where you live and the color and quality of the product you purchase, will range from $3 to $15 or more a square foot. The higher the quality, the longer it will last and the less maintenance required. Composite decking will last between 10 and 30 years, again depending on quality, and also the level and frequency of maintenance carried out.

For example, a 12’ x12’ deck would cost between $432 and $2,160 for decking alone. Hidden fasteners to secure 144 sqft of composite decking will add around $113 to the budget. A roll of joist tape runs around $20 and depending on the number of joists and linear feet on the roll, you’ll probably need two.

Adding matching composite fascia to hide the rim and band boards will add approximately $360. So, material costs will range between $945 and $2,673 or more depending on quality and location.

Labor Cost

If you’re doing the removal of the wood decking, any repairs or reconfiguring work, plus installing the composite decking, your labor costs are zero. You may need some bandaids, gloves, safety glasses, and tools, but labor is sweat equity and ‘free’.

You may choose to remove the wood decking and have a pro install the composite decking. If the wood is salvageable, you may be able to use it for another project or sell it to recoup some costs.

Doing the removal will save the installer time and provide them with an unobstructed view of the deck frame’s condition. The saving, though, will probably be less than $100 to $200 in labor since the pros will have it done more quickly.

Expect labor to be 50% to 60% of the total cost, so if materials are $2,673, then the labor will add between $2,673 and $2,940 or more. If the materials are closer to $1,000, then the labor will add $1,000 to $1,100.

Depending on what work is necessary to make the joists usable, the cost will go up based on an hourly rate of $15 to $50 per worker. Thus, the labor costs will range between $1,000 and $3,000.

Can You Mix Composite Decking With Wood?

Mix Composite Decking With Wood

Most composite decks are built on a framework of pressure treated wood, so it’s common to mix the two materials together. Some decks may also have wood decking with composite railings to reduce maintenance. Composite wood doesn’t split or splinter, so handrails and railings always look and feel good.

Composite decking can be mixed with wood decking but the results may not be what you want. Both products are nominally similar in thickness and are available in compatible widths, so they will work together.

It should be noted, though, that composite material is more flexible than solid wood, so deviations in joist levels can cause trip hazards. Composite decking is also available in several different widths, which may add an interesting pattern to the finished deck.

Some considerations to keep in mind if mixing composite with wood decking are fasteners, how the boards wear, handle temperature changes, and respond to moisture. Invisible fasteners versus top fasteners can cause spacing issues. The two products age and wear differently, and usually require different maintenance schedules.

Temperature and moisture cause wood to expand or swell and contract in ways composite doesn’t, and vice versa. Heat typically causes composite wood to expand lengthwise, while wood tends to shrink laterally. Moisture will cause wood to swell vertically and laterally, whereas composite decking’s protective coating keeps moisture out, so it doesn’t swell.

So, while you can mix the two decking materials together, it can lead to some problems over time. Mixing the two materials together often saves money. However, the blending may also create maintenance issues that detract from your enjoyment and relaxation.

Should You Replace Wood Deck With Composite?

Composite decking is made of recycled material, is resistant to moisture, fading, scratches, and insects, and won’t split or splinter. It is finished in a wood-look finish with a grain-like feel so it mimics real wood.

Quality composite decking can last longer than pressure treated lumber and usually requires less maintenance over its lifespan. So, replacing wood decking with composite decking is a good plan.

The big question, though, is the condition of the deck joists, rim and band boards, ledger board, beams, and support posts. If the wooden decking is in poor condition, there’s a good possibility that some or all of the deck substructure will need replacing. In fact, some professionals won’t install composite decking on an existing framework as it is often difficult to level and smooth used joists. Plus, it may not last as long as the new decking.

If you want to just replace the wooden decking with composite material, check that the joists don’t have rot issues. This can be done prior to or after the decking is removed. If the joist spacing and condition are acceptable, then use joist tape to protect the tops of the framework.

This will help extend the lifespan of the deck structure and protect the new boards. Installing composite decking on the existing framework will save time and money and get your deck back in use more quickly.

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