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Can You Put Plywood Over Floor Joists? (How To)

Plywood has become a less expensive material to cover large areas and the thicker products are suitable for use as flooring.

However, there are certain standard fitment procedures that you should follow to avoid problems later on.

When using plywood sheets to cover floor joists, they should be installed with the longest side, 8 feet (2,440 mm) towards the joists, and staggered. This ensures that the ends don’t touch the same joist, giving one the strongest method of fitting. The boards are then glued and screwed in place.

It is usually good practice to use plywood for subflooring, to which carpeting or tiles are then attached.

The best way to fasten your subfloor panels to joists is to glue and then screw them. DIY enthusiasts often wonder whether it is a good idea to glue the plywood to the joists, with the best solution being to always glue the plywood.

Although it is not required by law, utilizing subfloor glue or adhesive is a common practice among contractors, as it can help to stop floor squeaks by lowering the possibility of movement at the panel-to-joist connection.

To increase strength, plywood should always be installed with the grain going across the joists rather than along them. They will split down the grain if they are laid lengthwise on a joist, which could result in catastrophic damage or injury.

The board will be stronger if the space between the joists is narrower. Plywood should have a minimum depth of ½” or 12mm.

Should You Put Plywood Over Floor Joists?

Contractors will often use plywood as the subfloor material when constructing houses.

Due to its strength and longevity, plywood is an ideal material to use for high-use areas.

Plywood is made up of different layers that are glued at 90° to each other. This gives the board great strength, making it the perfect solution for use in flooring applications. The plywood must be properly oriented on the joists to avoid splitting and for maximum strength.

If your floor slants, it is typically caused by foundation or house settling issues. The best solution to this problem is to take off the plywood subfloor and level it by adding joists. After that, you can put down a new subfloor.

When the edges of the floorboards are lifted, the floor develops a “cup” shape in the center. Cupping often results from varying humidity levels in the floorboards and plywood subfloors.

When cupping happens, the floor boards’ bottom sides absorb greater amounts of moisture than their top sides. This causes the top and bottom to expand to varying degrees and take on the shape of a “cup.”

You can avoid the problem by ensuring that the floors are waterproof and that the space under the floor is well-ventilated.

Older homes frequently have floors that make noises when you walk on them or they creak. Because of this, it’s usual for householders to disregard these disturbances. It’s crucial to realize, though, that a creaking sound could also indicate that the subfloor’s attachment to the joists beneath isn’t adequate.

Additionally, creaking can be a sign that the plywood or OSB was the incorrect thickness. If you hear creaking, it’s crucial to thoroughly inspect the subfloor to

An uneven floor might have many distinct causes. The floor joists may be split or bent, but it is also possible that the subfloor is twisted and loose.

Another possibility for an uneven floor is that the foundation or supporting walls may have settled over time. Examine the subfloor and check for each of these problems to ascertain what needs to be corrected before reaching a diagnosis.

Usually, a sinking floor indicates improper subfloor installation. It may also be a sign that the subfloor needs to be changed if the floor has too much give to it or feels “spongy.”

A floor’s joists may rot from too much moisture, causing some places to sag. The replacement of the plywood subfloor beneath a sinking floor is the best solution.

What Tools Do You Need To Put Plywood Over Floor Joists?

If your joists are solidly constructed and there is no movement, you can usually just glue and screw the plywood directly to the joists.

However, older floors can be a problem, as you may need to repair the joists before you can attach the plywood subfloor.

You don’t need too many tools to attach plywood to joists. To cut the plywood you need a circular saw with a good-quality combination blade. An electrical drill will help to screw in the floor screws quickly and easily and you may also need a drill to make pilot holes for your screws.

The usual safety equipment is advisable when using power tools, with eye protection being a priority, followed by safety boots or shoes. A pair of leather gloves may also come in handy.

To take measurements you’ll need a long builders’ tape measure and it helps to have a straight edge or ruler and pencil to draw a straight line.

What Preparations Do You Need To Put Plywood Over Floor Joists?

Attaching plywood to floor joists is normally a simple process if the joists are not rotten.

Any damaged or rotten joists will need to be removed and new wood or replacement joists installed before attaching the plywood subfloor.

Copyright protected content owner: and was initially posted on November 20, 2022.

After inspecting and brushing the joists clean, take careful measurements to ensure that the plywood will fit perfectly. After cutting the plywood, apply glue to the joists and then lower the plywood onto them. Make sure that the plywood is staggered between the joists.

For maximum strength, ensure that the long edges are at 90° to the direction of the joists. Then screw the plywood to the joist, making sure that the screw head is flush with the plywood.

Avoid driving the screw below the plywood surface as any moisture will pool there and cause the wood to rot.

How To Put Plywood Over Floor Joists

Plywood is extremely strong, so it makes the perfect subfloor material as long as you follow some basic rules.

When measuring your floor, make sure that the long edge of the plywood is placed across the direction of the joists to ensure maximum strength. If the floor is not completely stable, you can insert additional support between the joists and screw the plywood into them.

Copyright article owner is for this article. This post was first published on November 20, 2022.

To prevent the floor from squeaking or moving, it is best to apply an adhesive to the top of the joists so that the plywood is held in place by both the screws and the glue.

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ReadyToDIY is the owner of this article. This post was published on November 20, 2022.

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