Hardwood lumber grades include Firsts and Seconds, FAS One Face, Select and Common. Subcategories of Common lumber include 1 Common, 2A Common, 2B Common, 3A Common and 3B Common.
Lumber grading classifies boards according to size and quality. Boards in the highest grade category, Firsts and Seconds, must be at least 6 inches wide, 8 feet long and contain at least 83 1/3 percent defect-free wood on both sides. Lumber in this category is best suited to applications such as fine cabinetry and furniture production. Boards that meet the Firsts and Seconds defect criteria on only one side belong to the FAS One Face category.
The third-best hardwood lumber grade is Select. Boards in this group must measure at least 4 inches wide and 6 feet long, and have at least one face that meets the FAS One Face defect standards.
Lumber classified as Firsts and Seconds, FAS One Face or Select is ideal for mouldings, door frames and large furniture. Lumber in the lower grades is more suitable for flooring, small furniture and cabinetry, according to Woodworkers Source. It is also less expensive than premium grade lumber. Boards graded 3A Common and 3B Common are usually reserved for utilitarian items, such as fences, storage crates and palettes.