Plywood vs. OSB (Oriented Strand Board): Key Differences

The typical wood-framed residential flooring system is more complex than you might think. In addition to the visible surface flooring material (carpet, tile, or hardwood), there is usually a padding layer underneath which is a subfloor that serves as the foundation and structural reinforcement for the floor. The subfloor consists of sheets that are nailed or screwed to the joists and form the base for the underlayment and surface flooring material.

The terms underlayment and subfloor are often used interchangeably, but they are actually separate layers. Subfloors are always a layer of well-constructed boards - usually plywood or oriented strand board, or occasionally particleboard. 

 Oriented Strand Board

Of the two most common subfloor materials, builders often debate which is best: plywood or oriented strand board. Plywood is familiar to most people - it is a type of board made from multiple layers of wood, with the layers running in opposite directions from each other.

OSB (oriented strand board) is a different form of aboard. While the name may not be familiar, you may recognize the material. OSB, sometimes called particleboard, consists of large, flat pieces of wood arranged in multiple layers and sealed together with phenolic resin to make a panel.

Plywood vs. OSB (Oriented Strand Board): Key Differences

Plywood subfloors are typically made of 1/2" to 3/4" thick plywood that has a rough side (downward facing) and a smooth side upward facing. Sheets typically measure 4 x 8 or 4 x 12 feet. Plywood is made by gluing thin layers of solid wood together at 90-degree angles and pressing them together as the glue dries to form a very strong structural panel. In the 1950s, this material quickly replaced solid wood planks as the subflooring material in homes.

Basswood Plywood

Standard plywood can be used for subflooring, but it is more common to use tongue-and-groove boards that interlock along the edges. The recommended thickness of plywood subflooring depends on the spacing of the joists. Some experts recommend that 15/32-inch plywood should be standard if the subfloor joists are spaced 16 inches or less apart, but if the joists are spaced further apart, slightly thicker 3/4-inch plywood should be used. However, please consult your local code authority for official recommendations.

OSB (oriented strand board) is made of large, flat pieces arranged in up to 50 layers that are glued together and pressed into thin sheets. Because it uses leftover wood, OSB tends to be cheaper than plywood and more uniform because it is free of knots and other defects that can be found in plywood.OSB began to be used as a subflooring material in the 1970s.

Fire-Proof Plywood

The type of OSB used for subflooring is usually made of tongue and groove edges (T & G). The standard subfloor for joists spaced up to 16 inches apart is a 23/32 inch T & G board. Some local codes may require 1" thick boards for joists spaced up to 24" apart; for these, you may need to purchase them from an architectural lumber yard, as they may not be in stock at a typical home improvement center.

Treezo Group is one of the largest manufacturers of boards, millwork, and so on products in China. Our corporate goal has always been to provide the healthy, environmental-friendly, and complete selection of building material products available in the marketplace today. To discuss in detail whether plywood or an OSB is right for your project, please contact us.