Oriented Strand Board (OSB)

Oriented strand board (OSB) is a wood panel used as a sheathing material for floors, walls and roofs. OSB has grown enormously in popularity over the past decade because it's economical and has excellent racking resistance, which is the ability to strengthen a building against horizontal loads such as extreme winds or the force of earthquakes.

The predecessor to OSB was waferboard and, occasionally, this name is mistakenly used. Although some waferboard is still manufactured, it is rare. Both products are manufactured from strands 6" (150 mm) long and 1" (25 mm) wide that are obtained from small diameter logs that otherwise go unused in commercial building.

During the manufacturing process, OSB strands are oriented in one direction as they are placed on a mat prior to pressing. Like plywood, where alternating veneers are perpendicular to each other, OSB layers are also placed perpendicular to each other. Exterior or surface layers consist of strands aligned in the long panel direction; inner layers consist of cross- or randomly-aligned strands. This means the completed panel, like plywood, has good strength across its length and width. Waferboard, on the other hand, has a random arrangement of strands and therefore less strength.

Like structural plywood, OSB is manufactured using waterproof glues to ensure that strength is maintained even if the panels become wet.

OSB is recognized by all the major U.S. model code agencies through the adoption of DOC PS2-92 Wood-Based Structural Use Panels. OSB certified to CSA 0325 and CSA 0437 is accepted in the National Building Code of Canada. OSB certified to EN 300 is recognized for structural use in Europe. In Japan, North American OSB is certified to meet the JAS standard for structural panels.

For more information on OSB visit:

APA- The Engineered Wood Association