Differences between subflooring

So what is OSB and how is it different from plywood?

Plywood is made from thin sheets of (usually southern pine) veneer that are cross-laminated and glued together with a hot-press, forming 4 foot x 8 foot sheets. Installation usually consists of gluing and nailing the sheets to the floor joists. CDX Grade is the most commonly used exterior structural subfloor throughout the industry.


OSB Sub flooring looks like, and is, a bunch of wood chips glued together. Installation usually consists of gluing and nailing the OSB sheets to the floor joists.

Plywood and oriented strand board (OSB) are similar, yet different. They are made similarly yet react differently when they get wet. OSB may be less expensive, but if cuts are made to the surface, it loses its waterproof quality.

Some OSB panels react differently from plywood when they get wet. When OSB is manufactured the cut edges are sealed with a special waterproof paint. Carpenters destroy the watertight integrity of OSB each time they make a cut that exposes wood fiber edges. These cut edges are prone to swelling after they get wet. It is possible to seal these edges after they are cut, but it may be tough to find a carpenter willing to take the time to perform this extra step.

Lumber products are true commodities. Prices of these products can fluctuate wildly with changes in supply and demand. Currently where I live the prices of plywood versus OSB are very close. A piece of one half inch plywood that a builder would use on a roof or a sidewall only costs $1.02 more than a similar piece of OSB. A sheet of 3/4 inch sub-floor plywood costs just $4.38 more than the same sized piece of OSB. If you desire to use plywood on your new home, the extra cost may only be several hundred dollars