QA

How To Install Subfloor Over Joists

Are subfloors installed on top of joists?

Subflooring glue is applied to the tops of the joists. The right glue is very important here, it’s what keeps your floor from squeaking. Matching up with the chalk line, reaching the center of the joist. You can see on the non tongue and groove side of the plywood, joints are made in the center of the joists.

How do you fasten subfloor to joists?

Use a heavy-duty drill to drive Phillips head wood screws through the subfloor into the floor joists. Drive the screws approximately 8 inches apart. To make the job easier for you and the drill, we suggest that you pre-drill holes before screwing the subfloor down.

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.

What is the best way to attach subfloor?

A glue-nailed construction technique is optimal for ensuring a flat, stable floor. Use a solvent-based glue that meets ASTM D3498 performance standards; in cases where latex subfloor glue is required, careful selection is necessary due to the wide range of performance between brands.

What goes on top of subfloor?

Underlayment: Some types of flooring can be installed directly on top of the subfloor, such as vinyl flooring. Other types need a middle layer, called underlayment, such as laminate,carpet and tile.

Do I need two layers of subfloor?

That’s the usual approach. Almost no one puts down double-thick subfloor in residential applications (for cost and handling reasons), and both layers need to be fastened to joists. Only thin underlayment can be fastened just to the subfloor.

Is it better to nail or screw down subfloor?

Using code-approved screws rather than nails is the best option for avoiding movement. If using nails for subfloor installation, stick with ring-shank nails; smooth nails may withdraw easier, leading to squeaks.

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.

Is it better to use OSB or plywood for subfloor?

The National Tile Contractors Association and the Resilient Floor Covering Institute both recommend plywood for subflooring and underlayment, because it doesn’t have the risk of swollen edges that OSB does. Plywood also has a slight advantage in stiffness, which means that subflooring panels need not be quite as thick.

Should I glue subfloor to joists?

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. A quality subfloor adhesive will also increase the overall stiffness of the floor.

What type of wood is best for subfloor?

Plywood is considered the most popular material used for subflooring, it has been used since the 1950s and remains one of the top choices for contractors. Standard plywood works perfectly fine as a subflooring material, but the best option is ¾” tongue-and-groove plywood subflooring.

Can I use regular plywood for subfloor?

Standard plywood can be used for subfloors, but it is more common to use tongue-and-groove sheets that interlock along the edges. The recommended thickness of the plywood subfloor is governed by the spacing of the joists. The type of OSB used for subfloors generally is made with tongue-and-groove edges (T & G).

How thick should subfloor plywood 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.

How long should a subfloor screw be?

You’ll want the screw to go about an inch past the plywood into the joist or underlying layer beneath it. So if your subfloor is 3/4 of an inch thick, any screw about 1 3/4 inches long will do the trick. If the plywood subfloor you’re placing is 5/8 of an inch thick, you need a screw about 1 5/8 inches long.

Does plywood need expansion gap?

APA recommends a 1/8-inch space between panel edge and end joints. Plywood and oriented strand board (OSB), like all wood products, will expand or shrink slightly with changes in moisture content. If the wood structural panels are tightly butted, there is no room for expansion and buckling can occur.

Can you put subfloor over old subfloor?

One of the benefits of removing the old flooring is it allows you the chance to fix any loose subflooring or squeaks by re-securing the main subfloor to the floor joists prior to installing the new flooring. With all that being said though the answer is YES you can install New Wood Flooring over the old.

What do you put between layers of subfloor?

Hardwood Floors To prevent this noisy problem, it’s standard to install a layer of 15-pound felt paper between the subfloor and the hardwood planks. The building paper is relatively inexpensive and provides a cushioning barrier that keeps the two flooring layers from making contact.

What do you put between subfloor and underlayment?

Use building paper! Yep, put down an underlayment of 15-pound felt building paper between a wood subfloor and your hardwood planks, and you can reduce the chance of squeaky floors and control moisture.

How many layers should a subfloor be?

The four layers that make up the wood floor system consist of; the Joists, Sub-floor, Underlayment, and Floor Covering.

Should plywood underlayment be glued to subfloor?

No, you should not glue down your underlayment. Underlayment is is a floating material, the same as your laminate flooring. In most cases, you should not glue or nail your underlayment down. You should always check with the installation instructions of the underlayment for proper installation instructions first.

How do you install subfloor over old subfloor?

Instructions For Installing Another Layer Of Plywood Acclimate the underlayment. Store underlayment in the room it will be installed in for 72 hours before the actual installation. Clean the subfloor. Start installing the plywood. Staple the boards in place. Fill the seams.