What is OSB?

A close-up of oriented strand board. 
Oriented strand board, also known as OSB.

­You've been hanging around the lumber yards lately because you need wood for one of your do-it-yourself projects. You haven't settled on one type of wood yet, but in talking to experts and other homeowners, something has stuck in your ear: OSB.

You've heard this acronym around town. What is it, you ask? While it is a widely used acronym, specifically for ocean groups and religious organizations, for our purposes OSB stands for oriented strand board.


Oriented Strand Board 101

Oriented strand board was created in the late 1970s as inventors extended the use of waferboard. It differs from other wood-scrap products because its rectangularly shaped wood strands are placed strategically rather than randomly. These "cross oriented layers" are manufactured to be water resistant and immune to warping [source: APA Wood].

Manufacturers of OSB panels engineer their product to match a performance-rated scale. Manufacturers want to make sure their product is strong, multifunctional, uniform and workable. It comes in various sizes, usually ranging from a quarter-inch (6 mm) to three-quarters of an inch (18.5 mm), though customers may put in special size requests.


­OSB uses the wood from trees that grow quickly and sustainably, like aspen poplar, southern yellow pine and mixed hardwood species. The process of making OSB involves cutting the logs into strands that are then dried, organized an­d treated with wax, resins, and waterproof heat cured adhesives. To form panels, these strands are grouped into big sheets and pressurized at a high temperature.

OSB has come into fashion as a product with the same purpose and function as plywood — so OSB and plywood compete in the marketplace.


How Are OSB Panels Used?

Oriented strand board is a high strength building material that boasts a wide range of practical applications [source: APA Wood]. Though they can be used to build just about anything, OSB panes are primarily leaned on for the following:

  • Wall and roof sheathing
  • Structural insulated panels
  • Sub-flooring
  • Single-layer flooring
  • Industrial containers
  • Furniture


OSB vs. Plywood

­You're probably familiar with plywood as the main composite-wood product for construction p­urposes. You have doubts about the newness of OSB and its ability to compete with plywood. So let's hear some expert opinions on the matter. Turns out, the hesitation about OSB surrounded plyw­ood when it arrived on the construction scene as a product to replace wood sheathing.

Plywood and OSB are strong, durable and long-­lasting, so you don't have to be concerned about the performance comparison in that area. And, as with any wood product, you need to make sure to select the proper grade. You want a grade that will ensure waterproofing capabilities.


The thing to watch out with OSB is that if the panel is cut at all, this will disable its waterproofing capabilities. OSB has a tendency to swell on the edges when exposed to water, but it resists humidity well compared to plywood [source: University of Massachusetts].

There's no set price for OSB and plywood, so it's difficult to compare prices. In general, though, OSB is less expensive. Price can depend on supply, and when you take a look at the estimated numbers, OSB manufacturers put out almost double of what plywood manufacturers created [source: Conner Industries].