Oriented Strand Board (OSB)

Oriented Strand Board (OSB)
Oriented strand board (OSB) is an engineered wood product that’s manufactured from adhesives and rectangular-shaped wood strands that are arranged in cross-oriented layers. The cross orientation of the layers adds strength to the panel, making it well suited for use as a structural construction panel.

OSB is great for any application where you would use sheathing-grade plywood. It can be cut with all power saws but is not suited to shaping, sanding, or other milling operations. It’s commonly used as wall, roof, and floor sheathing.

OSB in production before pressing in a thermal press
Oriented strand board is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips compressed and bonded together with wax and synthetic resin adhesives (95% wood, 5% wax and resin).

The adhesive resins types used include: urea-formaldehyde (OSB type 1, non-structural, non-waterproof); isocyanate based glue (or PMDI poly-methylene diphenyl diisocyanate based) in inner regions with melamine-urea-formaldehyde or phenol formaldehyde resin glues at surface (OSB type 2, structural, water resistant on face); phenol formaldehyde resin throughout (OSB types 3 and 4, structural, for use in damp and outside environments).

The layers are created by shredding the wood into strips, which are sifted and then oriented on a belt or wire cauls. The mat is made in a forming line. Wood strips on the external layers are aligned to the panel’s strength axis, while internal layers are perpendicular. The number of layers placed is determined partly by the thickness of the panel but is limited by the equipment installed at the manufacturing site. Individual layers can also vary in thickness to give different finished panel thicknesses (typically, a 15 mm (0.6 in) layer will produce a 15 cm (5.91 in) panel thickness). The mat is placed in a thermal press to compress the flakes and bond them by heat activation and curing of the resin that has been coated on the flakes. Individual panels are then cut from the mats into finished sizes. Most of the world’s OSB is made in the United States and Canada in large production facilities. The largest production facilities can make over 1,000,000 square feet (93,000 square metres) of OSB per day.

Oriented Strand Board (OSB)


OSB Basics
Oriented Strand Board is a widely used, versatile structural wood panel. Manufactured from waterproof heat-cured adhesives and rectangularly shaped wood strands that are arranged in cross-oriented layers, OSB is an engineered wood panel that shares many of the strength and performance characteristics of plywood. OSB’s combination of wood and adhesives creates a strong, dimensionally stable panel that resists deflection, delamination, and warping; likewise, panels resist racking and shape distortion when subjected to demanding wind and seismic conditions. Relative to their strength, OSB panels are light in weight and easy to handle and install.

OSB is produced in huge, continuous mats to form a solid panel product of consistent quality with no laps, gaps, or voids. Finished panels are available in large dimensions, minimizing the number of joints that can “leak” heat and admit airborne noise.

Common OSB Applications

APA-trademarked OSB is suitable for a variety of end uses including subflooring, single-layer flooring, wall and roof sheathing, sheathing ceiling/deck, structural insulated panels, webs for wood I-joists, industrial containers, mezzanine decks, and furniture.

Panel Performance Categories

5/16, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4, 7/8, 1, 1-1/8.

Panel Sizes

4′ x 8′, 4′ x 9′, 4′ x 10′; manufactured in 8′ X 24′ or larger panels which can be custom-cut by most manufacturers.

APA OSB Trademark


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