The recommended thickness of the plywood subfloor is governed by the spacing of the joists. Some experts suggest that 15/32-inch plywood should be standard if the underlying floor joists are spaced 16 inches apart or less, but slightly thicker 3/4-inch plywood should be used for joists spaced further apart.

How thick should my plywood subfloor be?

The minimum thickness of plywood for subflooring is about 5/8 inch. Since it does not hold fasteners as well as plywood, OSB must be a little thicker, or at least 23/32 inch. There are several factors that determine what subfloor thickness is optimal for added benefits like insulation.

Can I use 1/2 inch plywood for a subfloor?





Glue is sprayed between each layer and the sheet is hot pressed. CDX plywood should be a minimum of 7/16 inch thick. The thicknesses are as follows: 7/16-, 15/32- and 1/2-inch-thick panels require joists spaced 16 inches on center; 19/32- and 5/8-inch-thick panels require joists spaced 20 inches on center.

How thick should plywood be under hardwood flooring?

For hardwood finish flooring, which average about 3/8-inch to 3/4-inch in thickness, 1/2-inch to 3/4-inch-thick plywood is the preferred subfloor, though there are a variety of grades designed for specific applications. Using tongue-and-groove plywood can reduce squeaks, as the sheets will seat together better.

Do you need 2 layers of subfloor?

The subfloor has to be attached to the joists, and two subfloor layers glued together or just nailed through to the joists, is no different than one thicker subfloor layer.

How thick should plywood be to walk on?

The thinner plywood is acceptable when the joist spacing is 16 inches. If you plan to finish the floor in the attic and turn the room into a living space, however, you should always use 3/4-inch plywood. Thinner plywood can flex when you walk on it — even with 16-inch spacing — and this will damage the flooring.

What kind of plywood do you use for subfloor?





Standard plywood can be used for subfloors, but a better material is 3/4-inch tongue-and-groove plywood subflooring. The tongue-and-groove edges interlock to resist movement along the panel edges and create an overall stiffer floor.

Is it better to use OSB or plywood for subfloor?

OSB has a lower resale value than plywood due to its lower strength. For this reason, few homeowners prefer OSB in their homes. Apart from costs, plywood is superior in all the other areas, such as the strength of the structure. For this reason, it’s a superior material for use on the subfloor.

Does subfloor need to be tongue and groove?

For subflooring, you use tongue and groove plywood. The tongue and groove are only along the 8 foot edges. On the four foot edges, your seams will fall on joist tops, so no need for tongue and groove. But to start off, we will need to remove the tongue so the plywood is tight with the exterior ICF walls.

What size screws 3/4 plywood subfloor?

The proper steel screw sizes for securing 3/4-inch plywood to the floor joists are #8, #10 and #12 screws. The number refers to the thickness of the screw. Each is available in lengths from 1 1/4 to 3 inches. Typically, the 3-inch variety is used to secure plywood subfloors.

What thickness subfloor is recommended?



The recommended thickness of the plywood subfloor is governed by the spacing of the joists. Some experts suggest that 15/32-inch plywood should be standard if the underlying floor joists are spaced 16 inches apart or less, but slightly thicker 3/4-inch plywood should be used for joists spaced further apart.

Should I put tar paper under subfloor?

Foam, felt and rubber are the best choices for laminate underlayment. Do not select tar paper to go under laminate or vinyl flooring, because the odor can penetrate the air and the fumes can be toxic, according to Uooz.

Should I screw down subfloor?

Ideally, nail down your subfloor using corrosion-resistant nails that will securely hold it in place and last a long time. Screws are a great alternative that you can easily remove, but they are not as sturdy. Screws are superior in terms of reducing floor squeaks, but the installation is slower.

How much gap do you leave in a subfloor?



1/8-inch

1. Improper spacing. To avoid buckling, subfloor panels should be spaced with a 1/8-inch gap at all edges and ends to provide room for naturally occurring expansion. Tongue-and-groove edges on many premium floor panels, such as Weyerhaeuser’s Edge Gold® OSB panels, are designed to self-gap.

Should plywood be glued to the floor joists?

How to Adhere Your Subfloor Panels to Joists. To glue or not to glue? The answer: Glue. Although using a subfloor adhesive (or subfloor glue) is not required by code, it is a standard practice that can help prevent floor squeaks by reducing the chance for movement at the panel-to-joist connection.

Which way do you lay plywood subfloor?

Install plywood underlayment smooth side up. To avoid damage to the surface, install underlayment immediately before laying the finish flooring.

Should subfloor be parallel or perpendicular?



Underlayment panels should be installed with the long direction, or strength axis, perpendicular to floor joists, never parallel to the subfloor seams. All panel edges should be staggered at least 2 inches to the subfloor seams for increased stability.

How many layers of plywood do you need for a subfloor?

If you are using plywood for your subfloor, you should use a minimum of one layer that is between ¾” and ⅝” thick. This thickness will suffice for most floors; however, codes will vary and a second layer is a good idea if your floor covering is going to be a heavy material like ceramic tiles or natural stone.

How many screws do I need for a 4×8 subfloor?

When securing OSB or plywood subflooring, you should use a screw every 8 inches along the floor joist or truss. So, you’ll need 12 screws down the 8-foot length of OSB or plywood. If your floor joists or trusses are 16 inches on center, you’ll need 48 screws per 4×8 sheet.

Should a subfloor be nailed or screwed?

Screws, if driven properly, prevent creaking floors. A screw firmly holds the subfloor in place, which ensures a squeak-less floor for years to come.

Can you use drywall screws for subfloor?



Whatever you do, don’t use drywall screws for the subfloor. While these screws work well for the needs of drywall panels, they are simply not strong enough for the rigors of subfloor use. Under the stress of regular wear and tear, drywall screw heads usually snap off if they are employed in the subfloor.