What Is Underlayment Plywood?

What Is Underlayment Plywood?

Underlayment plywood is a special type of construction material that is used as an underlayment for flooring, roofing and other surfaces.

It is typically made from softwood such as fir or pine, with one face sanded and the other either natural or pre-finished.

Unlike conventional plywood, it uses an asphalt saturated kraft paper backing to help provide a moisture barrier and additional soundproofing properties to any floor or roof installation.

Underlayment plywood can also be used as sheathing prior to installing standard roof coverings such as shingles.

In addition, it provides additional support to any tile installation and helps reduce cracking of the grout lines due to imperfections in the subfloor.

What Type Of Plywood Is Used For Underlayment?

Plywood used for underlayment is a very thin, low-cost plywood material typically made from softwoods like pine, poplar, redwood, or cedar.

It is usually 3 to 4 millimeters thick and often known as “Lauan” plywood or “underlayment grade plywood.”

This type of plywood is most commonly used in residential flooring projects as the bottom layer before laying down the finished floor covering.

It helps level out small undulations between the subfloor and serves as an extra layer of protection against moisture and dampness.

Underlayment grade plywood also adds strength to the completed floor system and helps prevent cracking of tile or other soft materials during installation.

Is Underlayment Plywood Waterproof?

Underlayment plywood is not waterproof in itself, however it can act as an effective barrier against water damage when installed with moisture resistant materials.

It is often used in high-traffic areas such as bathrooms and kitchens due to its ability to provide a more secure foundation beneath tiles, vinyl, and other floor coverings while also providing additional protection against moisture and general wear and tear.

As long as the surface of the underlayment plywood is properly sealed and correctly installed, it should help prevent water damage to the overall flooring structure.

What Happens If You Don’t Use Underlayment?

Without an underlayment, your flooring may not last as long, and any imperfections in the subfloor can transfer through to the surface.

This can lead to problems such as warping, cracking, discoloration, damage from moisture and mold growth.

Additionally, without proper insulation you may experience issues with sound transmission and thermal resistance.

An underlayment also helps to protect against everyday wear and tear, helping extend the life of your flooring.

How Do You Install Underlayment Plywood?

Installing underlayment plywood is a relatively simple process, provided you have the necessary materials and tools.

• First, you will need to measure the area in which you are installing the plywood and cut it down to size to fit.
• Once cut, secure the plywood in place with nails or screws, ensuring they are spaced at least six inches apart. Make sure that each nail is set flush with the surface of the board.
• Secure any seams or joints of two pieces of plywood together by double-tapping nails on either side of the joint, then apply a thin bead of construction adhesive along all edges where plywood meets a wall.
• Finally, cover any exposed nail heads with wood filler to create a smooth surface before finishing off your project with flooring material installation.