Oriented strand board

Oriented strand board is used in construction for covering walls, floors, and roofs before being covered with a finishing product.

Oriented strand board (OSB) is a type of particle board made with long strands of oriented wood, typically from aspen, cut parallel to their grain. The strands are heat pressed into sheets with adhesive that usually include formaldehyde and used for building construction, mostly for covering walls, floors, and roofs before being covered with a finishing product. The strands of wood can be made from trees in areas burned over by forest fire.

Four grades of OSB are defined in EN 300 in terms of their mechanical performance and relative resistance to moisture:

• OSB/0 – No added formaldehyde
• OSB/1 – General purpose boards and boards for interior fitments (including furniture) for use in dry conditions
• OSB/2 – Load-bearing boards for use in dry conditions
• OSB/3 – Load-bearing boards for use in humid conditions
• OSB/4 – Heavy-duty load-bearing boards for use in humid conditions