Georgia Pacific makes both types of structural panels including a plywood subfloor that has been treated to enhance moisture resistance.

Photos: Georgia Pacific

Georgia Pacific makes both types of structural panels including a plywood subfloor that has been treated to enhance moisture resistance.

If you’ve been around long enough, you’ve seen plywood go from being the top structural panel in the industry to becoming an also-ran that's now second to oriented strand board (OSB) in usage among home builders.

To get a sense how widespread OSB usage has become, you can do your own unscientific research. Drive through a subdivision under construction. House after house will be sheathed in the panels made with wood chips.

OSB hit the market in the late 1970s and was almost immediately a hit. According to the Structural Board Association, “in 1980, North American OSB panel production was 751 million square feet (3/8" basis),” says the Website of the Structural Board Association, which dissolved in 2008. “By 1990, this figure was 7.6 billion square feet. In 2005, this figure had grown to 25.0 billion square feet."

The product immediately found an audience with contractors and builders, despite the fact that many thought it looked like chipboard or particleboard, says Mary Jo Nyblad, sales and marketing manager for Boise Cascade’s plywood and particleboard division. “All it takes is for one guy to use it, and more followed,” she says. Boise, which used to make both types of panels, sold its OSB division to Ainsworth Lumber Co. in 2004.

Mainly due to its look, consumers and home buyers had the perception that OSB was cheap and an inferior product, but the panels found success among multifamily builders, Nyblad says. “It was readily accepted because there was no home buyer per se,” she continues. “It was a good fit.” The fact that the panel was economical also played a large role in its acceptance.

At first, plywood and OSB competed hammer and nail for market share. In the 1980s, Nyblad says, OSB started appearing on sidewalls and roofs, but plywood was still largely used for floors. Plywood tried hard to fend off OSB, but it could not compete well against OSB's lower cost. As a result, by the late 1990s, the panels had achieved parity in terms of usage, with OSB continuing to gain.

“In 2000, for the first time, OSB production marginally exceeded plywood production,” according to the Structural Board Association. “By 2006, OSB production grew to nearly 60% of the North American panel market share.” Manufacturers of both panel types agree OSB’s share of the production home market might even be closer to 75%.

To be sure, there is no difference between OSB and plywood as a structural panel, says APA - The Engineered Wood Association. The Tacoma, Wash.-based group is a nonprofit trade association that represents U.S. and Canadian manufacturers of plywood and OSB as well as other structural engineered wood products.

“Both products meet the local and national building codes,” says APA market research director Craig Adair. They are equally interchangeable for walls and roof sheathing, and for flooring underlayment, he adds. Moreover, both panels install fast and easily. Specified correctly, they perform as intended. Manufacturers from both sides claim their products offer better nail holding ability, but Adair says both meet the same requirements.

Still, after Hurricane Andrew tore through South Florida in 1992, leaving well over 250,000 people homeless and almost $30 billion in damage, the Miami-Dade County Board of County Commissioners banned OSB for use as roof sheathing.

Even though OSB dominates the construction market, some contractors and builders have problems with the performance of the product and have remained plywood loyalists. Nyblad says, for example, that there are regional preferences for plywood such as the Northeast, Northern California, Southwest, and Seattle in the rainy season. (In the dry season, these regions use OSB.) Plywood is particularly popular among DIYers and custom builders as well, she adds.

“We typically use plywood for all of our roof sheathing and subfloors,” says Steve Ronchelli, a senior project manager with custom builder Jim Murphy & Associates in Santa Rosa, Calif. Ronchelli says it’s partly due to the performance, but he allows that “it might just be a regional thing.” Northern California is close to the forest of the Pacific Northwest, so the lumber comes from nearby, he adds.

Brian St. Germain, an OSB technical expert at LP Building Products in Nashville, Tenn., says “the main stronghold for plywood is with traditional builders who have stuck with the [product].”

The main main complaint of OSB—its intolerance to moisture—has been largely fixed, manufacturers say and is no longer an issue. “We can get equivalent moisture resistance with different resins and waxes that create water repellency,” St. Germain says.

Each panel has its advantages and drawbacks, which makes it difficult for builders to choose the right product for a particular application. The decision only becomes more time-consuming given manufacturers's claims and counter-claims about a myriad of issues, including some stances that are supported by third-party sources and users and some that are not.

But enough information exists to glean a fairly accurate picture of what each panel--plywood and OSB--can and cannot do. To evaluate the options for your proejct, here's a handy guide that outlines the pros and cons of traditional plywood and OSB in various applications.

Learn more about markets featured in this article: Santa Rosa, CA, Los Angeles, CA.