The lumber grading system used by WWPA and NLM A classifies lumber into boards, dimension, and timbers. For 2-4 inch thick lumber, which category is used?

The lumber grading system used by WWPA and NLM A classifies lumber into boards, dimension, and timbers. For 2-4 inch thick lumber, which category is used?

• A. Planks
• B. Lumber
• C. Sections
• D. Dimension

Answer: (D)

The classification is based on how thick the piece is crosswise. Boards are the thinner stock, dimension covers the standard framing sizes, and timbers are the thicker members. Since 2 to 4 inches in nominal thickness falls into the middle range used for typical framing members (like the common 2x4, 2x6, etc.), this lumber is categorized as dimension. Note that actual thickness may differ from nominal sizes, but the naming convention still places these in the dimension group rather than boards (too thin) or timbers (too thick).

The classification is based on how thick the piece is crosswise. Boards are the thinner stock, dimension covers the standard framing sizes, and timbers are the thicker members. Since 2 to 4 inches in nominal thickness falls into the middle range used for typical framing members (like the common 2x4, 2x6, etc.), this lumber is categorized as dimension. Note that actual thickness may differ from nominal sizes, but the naming convention still places these in the dimension group rather than boards (too thin) or timbers (too thick).