Although skeptical builders avoided oriented strand board (OSB) when it was first introduced commercially in the 1980s, today it dominates the U.S. sheathing market, far outstripping plywood with about 64% of sales. Improved resins, better water-resistance, and especially lower costs have helped make OSB the first choice for many builders even though plywood production can be counted in the billions of square feet annually.
From a structural standpoint, OSB and plywood share many performance characteristics and can be used interchangeably in a given application. Both are engineered wood products. “The amount of wood and the equipment to process them is a little different but it’s still the same basic concept,” says Dr. Joseph Loferski, a professor in Virginia Tech’s Department of Sustainable Biomaterials. “You’re going to take a tree, chop it into smaller pieces, put glue on it, and glue it back together. That’s basically the process.”
In comparing these two panel products, many of the fundamentals haven’t changed much since Sean Groom took a deep dive in this article for Fine Homebuilding magazine back in 2005. Yet the question of which one is better still pops up, especially as the dynamics of building assemblies change. Tighter building enclosures and more insulation have made builders more sensitive to the nuances of moisture management and air control. Those focused on sustainable design are starting to ask questions about embodied carbon—a topic that wasn’t on the radar a decade and a half ago.
Water-resistance is still a factor
How these panel products react to water was, and is, a key difference. Plywood is a sandwich of thin plies of wood, with grain direction alternating 90 degrees from one ply to the next. OSB is a mat of wood strands compressed under pressure and heat into a…
Get building science and energy efficiency advice, plus special offers, in your inbox.