From Log to Graded Lumber

This chapter focuses on what happens after harvest, specifically how logs become graded lumber for use as building materials. It examines essential structural aspects, such as sizes and end-use categories, species groups, and stress grades, as are the various grading methods aiming to equip readers with a holistic understanding of the entire “log-to-graded lumber” process. Surfacing lumber refers to planing and/or sanding the board to have a smooth surface and uniform size. Sawn lumber is classified into three categories based on thickness: dimension lumber, boards, and structural timber. The lumber grading process and its associated rules ensure consistency of products across lumber mills while providing a basis for common understanding of lumber properties and other characteristics among manufacturers, distributors, users, and consumers. Machine stress rated lumber is dimension lumber that is machine tested to measure flatwise modulus of elasticity or bending stiffness.