Renovating or upgrading an old deck is a common project for homeowners looking to remodel their outdoor space. Or if your existing deck is severely damaged, you may be considering using composite decking to replace it. But there’s a question you may run into when planning a whole new renovation and remodeling program. Can you put composite decking over old deck?

It’s relatively easy to lay composite decks over an existing deck, but there are a lot of risks associated with this approach. This approach requires a lot more consideration and therefore brings more risks than benefits. In this article, we will introduce can you put composite decking over old deck and bring you a detailed evaluation of the approach and the pros and cons.

Can you put composite decking over the old deck?

Simply put, we don’t recommend it. This is because it is very important to make sure that the composite decks are installed in the right conditions. Installing composite decking directly over an old deck means that drainage and air cannot circulate properly. This can lead to the composite material being exposed to moisture for a long period of time, causing serious damage.

However, if the framing of your old deck meets the conditions for installation, then installing composite deck boards on top of it can save you more time and money. Below we will detail how to assess your old deck frames so that you can install them safely.

Assessment of old deck frames

Overall structural integrity

Before installing composite wood decking on an old deck, the structural integrity of the existing framing must be carefully assessed. The integrity of the bottom frame directly determines the longevity and performance of composite decks.

Ensure that the bottom structure (including joists, beams, and supports) is in good condition and able to support the weight of the composite deck. If there are structural problems with the bottom framing of your old deck, please take care of them promptly. Rotting, cracking, or damaged components are serious structural problems and we recommend that you simply remove and replace the subframe.

Can you put composite decking over the old deck?

Simply put, we don’t recommend it. This is because it is very important to make sure that the composite decks are installed in the right conditions. Installing composite decking directly over an old deck means that drainage and air cannot circulate properly. This can lead to the composite material being exposed to moisture for a long period of time, causing serious damage.

However, if the framing of your old deck meets the conditions for installation, then installing composite deck boards on top of it can save you more time and money. Below we will detail how to assess your old deck frames so that you can install them safely.

Assessment of old deck frames

Overall structural integrity

Before installing composite wood decking on an old deck, the structural integrity of the existing framing must be carefully assessed. The integrity of the bottom frame directly determines the longevity and performance of composite decks.

Ensure that the bottom structure (including joists, beams, and supports) is in good condition and able to support the weight of the composite deck. If there are structural problems with the bottom framing of your old deck, please take care of them promptly. Rotting, cracking, or damaged components are serious structural problems and we recommend that you simply remove and replace the subframe.

Composite material compatibility

Composite decking can often be installed on a variety of materials. Wood, concrete, and even existing decking will fit perfectly for composite deck installation. However, you must ensure compatibility, which is the key to a successful installation.

If the framing of the old deck is in good condition and securely fastened, then it can be used as a foundation for the composite decking board. You need to check the manufacturer’s guidelines and recommendations to ensure compatibility between existing materials and composite materials.

Joist spacing

Measure the spacing between the old framing joists. Many older decks have wider spacing between framing joists, usually around 500mm. This does not meet the installation needs of most composite wood decks. It may therefore be necessary to reinforce the timber joists to reduce the spacing in between.

Please check the manufacturer’s installation instructions and guidelines to ensure proper spacing for your installation. Although composite deck board is very durable, it requires more support to ensure safe use.

How to put composite decking over the old deck?

Installing a composite deck over an existing deck structure is fairly simple. But you need to make sure that you perform the steps correctly to avoid incorrect installation of composite deck boards.

Step 1

Start by removing all furniture and railing components from the deck to create enough area for installation. Then use a pry bar to completely remove the old deck so that the composite wood decking can be properly installed. After removal please check to see if the deck framing is rotted following the steps above. If the old framing is sufficient to support the installation of the new decking, continue to the next step.

Step 2

Before installing the composite deck, please corrosion-proof the existing framing. This is to prevent the rotting of the old framing after the composite decking is installed, which could result in damage to the outdoor space.

Apply a professional wood preservative evenly around the edges of the wood framing and use protective tape to cover the holes in the framing. These actions will minimize the likelihood of framing rot and mold and extend the life of the deck.

Step 3

Once you have completed the preparation and inspection, you can begin the installation of the composite deck boards. Cut the composite wood decks to the proper length to allow for proper clearance.

Spacers are installed at the bottom of the deck to allow proper space for drainage and ventilation. Proper deck spacing also helps avoid warping caused by expansion and contraction.

We provide detailed installation videos and installation instructions so you can install your deck properly. If you don’t have enough installation experience, then we recommend contacting the manufacturer or seeking professional help.

Step 4

Now that you have completed the installation of your new decking, you will need to perform a few checks next. Start with a final inspection of the composite decking to ensure that the fasteners and decking are fully secured and intact. Check to make sure the decking is strong enough to not bend and crack under weight.

Conclusion

To summarize, we don’t recommend installing composite decking directly on your old deck. But if the bottom frame is intact, you can install it using the original frame. However, before installing, you must critically assess the integrity of the framing. And consider material compatibility to ensure proper installation.

Strictly follow the correct steps during the installation of the composite deck. Follow the manufacturer’s installation recommendations and local codes to ensure a strong and durable composite decking.

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