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What Size Screws Do You Use for Subfloor? (Answered)

Subfloors are usually attached later on and these floors are mostly screwed or pinned down. Instead of using adhesive or glue, most construction experts suggest to screw them down for the extra strength and support.

For this, you must be very careful with the measurements. Any mistakes made in this case can be very hard to amend.

What size screws do you use for the subfloor?

For the usual subfloors, 3 inches of screws are perfect. The size of the screw depends on the size and thickness of the floorboard. But a regular subfloor is good with any three-inch screw. The screw should go about an inch past the wood of the subfloor. It should touch the joists underneath.

Subfloors usually need screws that are around 3 inches. The screws should go an inch under the wood or the plyboard or the subfloor. If the floor is thick then the screw needs to be thicker as well. So it varies according to floor types.

Plywood subfloor:

For a standard plywood subfloor, the screw should be 3 inches. That is the ideal size and thickness for a plywood subfloor.

OSB subfloor:

OSB subfloors are usually nailed, but if you want to use screws for these types of subfloors then it should be a 3-inch screw. The screw should have an inch under the plywood of the flooring. 

1/2 subfloor:

The standard size of a screw should be 6×1 inches. This way the 1/2 inches plywood will stay stable and not break. It is advised to keep an inch under the flooring for extra support.

1/4 subfloor:

For a 1/4 subfloor the screws should be fixed far from each other, to avoid the risk of breaking. In this case, you can choose smaller screws, but 3-inch screws will work as well.

3/4 subfloor:

The best size of screws for a 3/4 plywood subfloor are the number 8 and number 10 screws. Of course, you can use number 12 screws as well. But size 8 screws are perfect for these types of subfloors.

5/8 subfloor:

A screw of 1 5/8 inches is perfect for a 5/8 inches plywood subfloor. This is an unusual size but still, the size of the screw should be chosen carefully. 1 5/8 inches should be good enough.

23/32 subfloor:

A subfloor of 23/32 inches should have 1-1/4″ screws attached to them. This sized plywood floor needs careful support, so it is best to use a 1-inch screw.

Screws for your subfloor should be selected very carefully. The size of the screws matters a lot as they will keep the subfloor supported. Most of the times a 3-inch screw is perfect for the standard plywood subfloor. 1 3/4 sized wood screws are good as well.

Should I screw down the subfloor? Should the plywood subfloor be nailed or screwed?

With subfloors, you have the complete freedom to either nail or screw the plywood. Any of the two is good.

If you have enough time then you can nail the subfloor. And if you feel the work needs to be done quickly then you can gather your equipment and screw the subfloor easily.

But experts suggest you screw the subfloor rather than nailing them. This is the best way to avoid any unnecessary movement in your subfloor.

Try to screw the subfloor, especially if you have a plywood subfloor. But that is not an absolute necessity. You can go for either. Screwing down the subfloor is recommended.

Subfloors are easy to either screw or nail. There is no instruction saying you have to go for a specific way to attach the subfloor. According to your convenience, you can go for either of the ways. But it is recommended to screw the subfloor.

What kind of screws do you use for the subfloor? What are code-approved screws for the subfloor?

Screws the sizes around 3 inches are mostly used when attaching the subfloors are generally used. Most construct experts use 3 inches screws when using it on the plywood subfloors. But depending on the underlayment there can be multiple types of screws.

Screws of different sizes are usually used. But the type of screws needs to be specific. There are many types of screws and among them mostly three types are used on subfloors-

Metal Screws:

Most of the times, metal screws are used for any sort of flooring, including the subfloors. Metal screws are usually harder and thicker which makes them easier to use and attach. They are also very strong and can give good support to the subfloor.

Galvanized Screws:

Galvanized screws are also used for flooring and attachments. Because these screws provide better support than the other types of screws. They are just like the metal screws so their thickness is perfect for subflooring, especially if there is plywood involved.

Wood Screws:

Though these types of screws are not that much used because they are not strong enough like the metal screws, still for subfloors wooden screws are occasionally used. If the plywood is not too much thick wood screws are used. They provide delicate support to the subfloor.

The type of the screw matters a lot when you are attaching your subfloor. The screw of the floor needs to be enough strong and supportive. Which is why you need to be cautious when selecting the screw.

Can I use deck screws for the subfloor?

Though there are no restrictions to using any kind of screws for the subfloors, deck screws are very rarely used. But there is nothing wrong with using that type of screws.

Most of the construction experts use metal screws but it is absolutely fine to use deck screws for your subfloor.

The only type of screw that are advised to not use are the drywall screws. Other than that you can use any type of screw to attach to your subfloor. So deck screws are also okay to use on your subfloor. Though this is not very popularly used.

Deck screws are good to be used on the subfloors. These screws work just like normal, metal screws. They have enough strength and thickness for the subfloors. Which is why it is okay to use deck screws on your subfloor. Even though it is not a popular practice to use them.

How do you screw down a subfloor?

Screwing a subfloor is a very much easy task and can be done by oneself if the instructions are clear. You just need the right equipment near you and the right set of guidelines.

The instruction vary a little depending on the type of the material of the subfloor. Mostly two types of material are used, plywood and OSB. Depending on the thickness of the material of the flooring your instruction is slightly change-

Plywood Subfloor

This is the most common type of subfloor. For this you will have to-

  • Pre-drill the holes before attaching the subfloor to the main floor to make the job easier.
  • Use heavy duty drill machine to drill the holes.
  • Drive the screws around 8 inches apart.
  • Drive the screws through the subfloor and attach them into the floor joists.

Plywood subfloors are easier to work with as they are more familiar to everyone.

OSB Subfloor

OSB subfloors can be difficult to work as they are not commonly used as subfloor material. You will have to be cautious with the steps of this material-

  • Along each joist run a bread of construction adhesive.
  • Lay the OSB panel along the joists.
  • Nail the panels. You can use common nails or number 10 screws as well. If you are using wood screws, use 1 1/2 sized screws.
  • Make sure to keep the screws 6 inches apart along the edges and 12 inches from the middle point.

Using OSB subfloor may seem difficult as it is not a common material used for subflooring. Which is why you must be extra careful with the procedure. Though the flooring has to screwed down, still you have to use adhesive to keep it more secure.

Screwing the subfloors are not much difficult and you do not need to be an expert in this. You just need to know what type of material you are using and work accordingly with the materials. Make sure to be careful with the steps to get the good result.

Final thoughts

3 inches sized screws are most commonly used to pin down the subfloors. Though the size of the screw usually depends on the thickness of the material of the subfloor. But the standard plywood subfloor will be good and secure with a 3 inches sized screw.