plywood

Plywood is a panel made by gluing together thin sheets of wood veneer with adjacent layers having their grain rotated at 90 degrees. This cross-graining gives plywood greater strength, stiffness, and dimensional stability than solid wood. Panels are commonly sold in sheets about 4 by 8 feet (1220 by 2440 mm) and in thicknesses ranging from about 1/8 inch (3 mm) to 3/4 inch (18 mm).

Manufacture: Veneers are peeled from logs, dried, and bonded with synthetic resins such as phenol-formaldehyde or urea-formaldehyde. The veneers are stacked with alternating grain directions and pressed under heat to form a rigid panel. The choice of adhesive and core material governs moisture resistance, strength, and the panel’s appearance.

Types and grades: Plywood includes softwood and hardwood varieties, as well as tropical options. Structural plywood (PS1/PS2 in North America) is designed for load-bearing use, while marine, WBP (water and boil proof), and MR (moisture resistant) grades emphasize moisture exposure. The outer veneers are graded A through D, with higher grades for smoother, more even surfaces such as cabinet doors and veneer faces; Baltic birch is a popular high-grade hardwood option.

Uses: Plywood serves in construction (subflooring, sheathing, roofing), furniture and cabinetry, interior panels, and concrete formwork. Decorative plywood products provide finished surfaces for furniture and doors.

Standards and environmental aspects: Plywood products conform to regional standards (for example, PS1/PS2 in the United States and EN 636 in Europe). Emissions ratings (such as E0, E1) address formaldehyde levels, with low-emission, no-added-formaldehyde alternatives increasingly common. Sustainable forestry practices and end-of-life disposal are considerations in modern plywood manufacture.