In a building-trade chat room last year, a contractor in Chicago posed a question: “What are your guys' thoughts? We pretty much hate OSB. We've found it to have problems with expansion, and it is softer underfoot than ply. But I have talked with many builders who pretty much only use OSB.”

The answer is much more complicated than this question makes it seem. Is plywood in fact better than OSB? It depends on whom you're asking, where they build, what the climate there is like, and numerous other variables. What is certain, however, is that both products have their strengths and their loyalists who swear by their performance.

Plywood, which appeared around the turn of the 20th century, is the granddaddy of structural panels. According to the Tacoma, Wash.–based APA-The Engineered Wood Association, the product is comprised of thin sheets of veneer that are covered with adhesive, laid in cross layers, and pressed together. Cross-laminating adjacent layers, the association says, makes plywood an extremely strong, lightweight, and versatile panel that is resistant to shrinking and expansion.

OSB, on the other hand, is the relatively new kid on the block. Introduced around the late '70s, the product now accounts for about 60 percent of the panel market, and the industry says its market share is still rising. About 10 percent to 15 percent heavier than plywood, OSB—which uses trees more efficiently—is made from 3- to 4-inch wood strands that are applied in layers and pressed together with resin. Much like plywood, APA says, the layers are oriented at right angles to one another for strength and stiffness.

Given their different compositions, it is tempting to say that one is better than the other, but as far as APA is concerned, both are interchangeable for routine construction applications. “That's because both products, although different in composition and appearance, are manufactured according to the same performance standards,” APA writes. “These standards apply the same performance criteria to both products for their designated end uses—sheathing, single-layer flooring, and exterior siding.”

But there is more to the story. Ask OSB and plywood manufacturers, and both groups are likely to tell you that its product is better. In many cases, a couple of these manufacturers make both products, which complicates things even more.

“We don't ever say that OSB is not a good product,” says Chris H. Beyer, director of marketing services for Georgia-Pacific Building Products, which makes both products. “But plywood is better. [Plywood] has performance benefits that are important, and it is more versatile, especially when you talk about flooring options.”

In a 2003 technical paper, Georgia-Pacific stated that plywood holds up better under excessive wettings, has an all-wood surface that results in better glue adhesion, and is 15 percent lighter than OSB so it puts less stress on the floor framing system. Beyer further states that plywood is more forgiving than OSB and also helps create a quieter floor. “Tests indicate that it holds nails better, too,” Beyer adds.

Arthur Rutenberg Homes in southwest Florida is fiercely loyal to ply. “We have always used plywood,” says purchasing director Ron Tyre. “We build custom homes for low maintenance and for longevity, and we don't use OSB. It's just an inferior product to plywood.”

Dominic Jansen, technical director for the Ontario, Canada–based Structural Board Association, a group that represents OSB manufacturers throughout the world, disputes Beyer's claim that plywood holds nails better than OSB. “Both products have the same nail-holding characteristics,” Jansen says. Moreover, Jansen adds, OSB offers more control over the production process so panels can be 4x9, 4x10, even 8x16. “With more houses having taller walls, OSB meets those builders' needs,” he says.