Characteristics

• The wood strands that make up OSB come from small, fast-growing trees rather than larger growths. These strands are processed with a resin that binds them together. OSB boards are easily identified by their look, which appears to be "A bunch of wood chips glued together," notes Paul Fisette of the University of Massachusetts. A technological improvement over other compressed wood particle and chip boards of the 1960s, OSB was first created in 1991 in New Hampshire.
  
  

Use

• In addition to its use in commercial construction as an alternative to standard plywood sheeting and subflooring, OSB can be made into oversized panels for special applications because it is not restricted by the size of the trees it comes from like other types of wood. It is also growing in popularity as a furniture material.
  
  

Restrictions

• Oriented strand board panels can be used in most circumstances where plywood is normally used, subject to local building codes. These codes sometimes place additional restrictions on OSB use in areas exposed to dampness. In California, adequate ventilation must be installed whenever OSB is used in humid areas and if OSB panels are exposed to moisture before installation, they must be dried to 16 percent or lower moisture content.
  
  

Benefits

• Although similar to plywood in most respects and treated as nearly the same by APA, which approves most wood panels for construction use, tests conducted by the University of Illinois indicate that OSB performs as well as or better than plywood in holding up under the impact of the hardware these woods are exposed to in construction settings. Due to its man-made origins, OSB is more consistent in strength than plywood, as it is not weakened by knots. Additionally, because it is made by young-growth trees, which can be easily replenished, OSB reduces the destruction of old growth forest for construction purposes and the attendant destruction of animal habitats.
  
  

Considerations

• OSB's primary weakness is its susceptibility to moisture damage and rot along its edges. Manufacturers treat the edges prior to shipping the panels for sale, but because construction applications frequently require cutting the material on site, untreated edges may become exposed to moisture. These cut edges should be primed before use. Also, OSB comes in different grades for different uses. Exposure 1-rated OSB is intended for interior applications only, while exterior-rated OSB will be stamped with an inspecting agency's seal, the manufacturer's name and the symbol PS2.