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Can You Put Plywood Over Decking? (How To)

If you have a deck that is worn and not looking its best, you have various options to spruce it up.

But if the wood has deteriorated badly and you don’t want to replace it, then putting plywood over it to hide the damage is a great option.

You’ll have a great new deck that will last for years to come and also add value to your home.

You can put plywood directly onto your deck beams, so long as they are still structurally sound. If the deck boards are thick enough and aren’t rotten, you can lay ¾” plywood on top and then secure the boards with ½” screws. This will give you a solid floor and provide a weatherproof area below.

Using pressure-treated plywood is the best option for covering decking as it resists water and pests. You’ll have fewer problems with the boards rotting, so long as you cover the plywood boards with a suitable waterproof material.

If you need to replace deck boards, you are limited to lengths that can be bought at the store, although it does depend on your deck board configuration. The standard treated 5/4″ wood deck boards are often available in lengths of up to 20 feet, with 18 feet, 16 feet, 12 feet, 10 feet, and 8 feet also being common.

While the deck’s framework members must be fastened with nails per construction standards, the decking planks should be attached with screws. Use screws to fasten the plywood to the deck boards to avoid the nail heads popping up later and for a more secure structure.

Make sure that the head of the screw is flush with the plywood and not below it. Any water that lands on the deck will end up pooling in the depression, causing the wood to rot.

Should You Put Plywood Over Decking?

There is a great debate over the installation of plywood on top of a deck. Depending on your local weather conditions and the condition of your deck, there are steps you can take to avoid or minimize future problems.

When plywood is placed over decking, you run the risk of moisture getting trapped underneath, causing it to rot. If the deck is already in poor condition, then putting the additional weight of plywood on top could be a safety risk. If the deck is structurally sound, installing plywood can work.

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After inspecting the deck for damaged or broken structural wood, replace or fix the weakened areas so that the deck is safe to use.

You can install plywood over the deck boards using ½” screws to secure the plywood in place. It is best to only install plywood on decks that are protected from the weather by a roof and screens or windows.

A weatherproof carpet or tile can be attached to the plywood or it can be painted with waterproof paint.

As the deck will not get airflow from between the deck boards after the plywood is attached, it’s a good idea to make sure that the area below the deck is well-ventilated.

What Tools Do You Need To Put Plywood Over Decking?

The tools you need to complete your decking project will depend on the condition of your deck. If it is in good condition, then you’ll need minimal tools.

However, if your deck is in a state of disrepair, you may need a wide variety of hand tools and power tools to complete the job successfully.

A circular saw will help to ensure that your cuts are straight and a good composite blade is the best option. You’ll also need a hand drill, tape measure, set square, and safety equipment. A good countersink tool will make sure that the screws are properly aligned to the top of the plywood boards.

Your circular saw is the best option for the long continuous cuts that you’ll have to make in the plywood boards. You can use a handsaw, but it’s tedious and the result is not always the best.

If you have to replace deck boards, then a drop saw is useful for making accurate cuts at an angle.

Hand drills are common on building sites where one must make multiple holes, but you can also use a power drill.

A long builder’s tape measure is a necessity on any building project and especially if you are covering a large deck.

The set square will be useful to measure angled distances and also help to establish the correct positioning of materials.

It is best not to compromise on your safety equipment, especially if you are using power tools. Wear eye protection and protective shoes or boots. A good pair f safety gloves and some earplugs will help to prevent injuries.

What Preparations Do You Need To Put Plywood Over Decking?

The main concern when covering up decking boards is that the deck is structurally sound.

The addition of the plywood boards adds a significant amount of extra weight which the deck must be able to support safely.

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First inspect the deck, looking for any rotten or damaged structural timber. This wood must be replaced before you cover the deck with plywood. Remove any protruding nails or screws and make sure that any rotten deck boards are removed or replaced.

But before you go ahead and start measuring and installing your plywood, it’s a good idea to check the deck’s structural integrity very carefully.

If the deck boards look shabby and show signs of rot, then it’s very likely that the joists and deck supports are rotting or in danger of rotting too. Before you add the substantial weight of large plywood boards to a possibly unsafe structure, check and replace any structural timber that is compromised.

This may entail removing deck boards and then either cutting out rotten wood or you may be able to remove the damaged wood and screw in additional support next to the affected area.

How To Put Plywood Over Decking

Putting plywood onto an existing deck is a relatively simple task that can be accomplished in a couple of hours.

To install plywood, first, measure the deck and plan the most efficient use of standard plywood boards. Try to minimize the number of joins between boards. Clean the deck boards and cut the plywood as per your plan. Lay out the plywood and double-check the dimensions before screwing them in place.

Check any damaged areas of wood and see if you can buy a single board and cut it to length to fill in all the gaps, as this can save you a lot of money. Then measure the area that you want to cover and buy the largest plywood boards that you can so you minimize the number of joins.

The most typical plywood sheet size is 4 by 8 feet. Additionally, 2 × 2 feet, 2 x 4 feet, and 4 x 4 feet of hardwood plywood are also offered. Longer sheets of plywood, 4 x 10 feet in size, are available for use in construction.

Utility plywood is also available in sheets that are 5 feet wide and lengths of 6, 8, and 10 feet.

Once you’ve selected your plywood, you have a choice of nails or screws. When mounting deck planks, screws are preferable over nails.

Once the plywood is secured, you can install carpeting or tiles or just leave it as is and paint it with a sealer.

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ReadyToDIY is the owner of this article. This post was published on November 11, 2022.

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