Plywood is one of the most versatile and widely used building materials in construction, furniture making, and DIY projects. Despite its ubiquity, many people don’t fully understand the different types, grades, and applications of this engineered wood product. Whether you’re a seasoned contractor or a weekend warrior tackling your first project, understanding plywood basics will help you make better material choices and achieve superior results.

What Is Plywood?

Plywood is an engineered wood product made by gluing together thin layers of wood veneer, called plies, with the grain of adjacent layers running perpendicular to each other. This cross-grain construction gives plywood its exceptional strength and dimensional stability, making it stronger than solid wood in many applications.

The manufacturing process involves peeling thin veneers from logs, drying them, applying adhesive, and pressing them together under high heat and pressure. The result is a material that resists warping, splitting, and shrinking while maintaining excellent structural integrity.

Understanding Plywood Grades

Plywood grading can seem confusing at first, but it’s actually quite straightforward once you understand the system. Grades are determined by the quality of the face and back veneers, with letters A through D representing different quality levels.

Grade A represents the highest quality veneer with a smooth, paintable surface. It’s sanded smooth and has minimal defects, making it ideal for applications where appearance matters. Any defects are limited to small pin knots and minor repairs.

Grade B offers a solid surface with minor defects that have been repaired. Small knots up to 1 inch in diameter are acceptable, along with minor splits and discoloration. This grade works well for applications that will be painted or where minor imperfections won’t be visible.

Grade C allows larger defects including knots up to 1.5 inches in diameter, knotholes, and splits. While structurally sound, this grade isn’t suitable for exposed applications where appearance is important.

Grade D is the lowest grade, permitting the largest defects including knots and knotholes up to 2.5 inches in diameter. This grade is typically used for structural applications where it won’t be seen.