Dimensional lumber
Categories: Wood | Construction
Dimensional lumber is a term used in North America for lumber that is cut to standardized width and depth specified in inches.
Softwoods
| Softwood Dimensional Lumber Sizes | |||
|---|---|---|---|
| Nominal | Actual | Nominal | Actual |
| 1 × 2 | ¾″ × 1½″ (19×38 mm) | 2 × 2 | 1½″ × 1½″ (38×38 mm) |
| 1 × 3 | ¾″ × 2½″ (19×64 mm) | 2 × 3 | 1½″ × 2½″ (38×64 mm) |
| 1 × 4 | ¾″ × 3½″ (19×89 mm) | 2 × 4 | 1½″ × 3½″ (38×89 mm) |
| 1 × 6 | ¾″ × 5½″ (19×140 mm) | 2 × 6 | 1½″ × 5½″ (38×140 mm) |
| 1 × 8 | ¾″ × 7¼″ (19×184 mm) | 2 × 8 | 1½″ × 7¼″ (38×184 mm) |
| 1 × 10 | ¾″ × 9¼″ (19×235 mm) | 2 × 10 | 1½″ × 9¼″ (38×235 mm) |
| 1 × 12 | ¾″ × 11¼″ (19×286 mm) | 2 × 12 | 1½″ × 11¼″ (38×286 mm) |
| 3 × 4 | 2½″ × 3½″ (64×89 mm) | 2 × 14 | 1½″ × 13¼″ (38×337 mm) |
| 4 × 4 | 3½″ × 3½″ (89×89 mm) | 6 × 6 | 5½″ × 5½″ (140×140 mm) |
| 4 × 6 | 3½″ × 5½″ (89×140 mm) | 8 × 8 | 7¼″ × 7¼″ (184×184 mm) |
Examples of common sizes are 2×4 (also two-by-four and other variants), 2×6, and 4×4. The length of a board is usually specified separately from the width and depth. It is thus possible to find 2×4s that are four, eight, or twelve feet in length.
In The Americas, two-bys (2×4s, 2×6s, 2×8s, and 2×12s) are common lumber sizes used in modern construction. They are the basic building block for such common structures as balloon-frame or platform-frame housing. Dimensional lumber made from softwood is typically used for construction, while hardwood boards are more commonly used for making cabinets or furniture.
The nominal size of a board varies from the actual size of the board. This is due to planing and shrinkage as the board is dried. This results in the final lumber being slightly smaller than the nominal size. Also, if the wood is surfaced when it is green, the initial dimensions are slightly larger (e.g. 1/16″ bigger for up to 4″ nominal lumber, 1/8″ for 5″ and 6″ nominal lumber, 1/4″ bigger for larger sizes). As the wood dries, it shrinks and reaches the specified actual dimension.
Hardwoods
| Hardwood Dimensional Lumber Sizes | |||||||
|---|---|---|---|---|---|---|---|
| Nominal | Surfaced 1 Side (S1S) | Surfaced 2 sides (S2S) | |||||
| 3/8″ | 1/4″ | 3/16″ | |||||
| 1/2″ | 3/8″ | 5/16″ | |||||
| 5/8″ | 1/2″ | 7/16″ | |||||
| 3/4″ | 5/8″ | 9/16″ | |||||
| 1″ or 4/4 | 7/8″ | 13/16″ | |||||
| 1-1/4″ or 5/4 | 1-1/8″ | 1-1/16″ | |||||
| 1-1/2″ or 6/4 | 1-3/8″ | 1-5/16″ | |||||
| 2″ or 8/4 | 1-13/16″ | 1-3/4″ | |||||
| 3″ or 12/4 | 2-13/16″ | 2-3/4″ | |||||
| 4″ or 16/4 | 3-13/16″ | 3-3/4″ | |||||
Sizes for dimensional lumber made from hardwoods varies from the sizes for softwoods. Boards are usually supplied in random widths and lengths of a specified thickness, and sold by the board-foot (144 cubic inches).
Hardwood lumber is commonly sold in a “quarter” system when referring to thickness. 4/4 (four quarters) refers to a one-inch thick board, 8/4 (eight quarters) is a two-inch thick board, etc. This system is not usually used for softwood lumber, although softwood decking is sometimes sold as 5/4 (actually one inch thick).