When you purchase a piece of lumber labeled as “2×6,” it’s important to note that the name refers to the nominal dimensions, which are the dimensions before the lumber is planed and dried. The actual dimensions, which are the true measurements of the board, are typically smaller. Here’s a breakdown of the actual size:
Nominal vs. Actual Dimensions
Lumber dimensions are given in nominal sizes, which are the dimensions before the drying and planing process that smooths and reshapes the wood. The nominal size for a 2×6 board is 2 inches by 6 inches, but due to the drying and planing, the actual size of a 2×6 is typically:
- Actual dimensions of a 2×6: 1.5 inches by 5.5 inches.
This reduction in size happens as the wood loses moisture and is planed to create a smooth, uniform surface.
Why Does This Happen?
The difference between nominal and actual sizes stems from the way wood is processed in mills:
- Sawmilling: When logs are initially cut into boards, the rough-cut dimensions are close to the nominal size.
- Drying and Planing: After drying, the wood shrinks slightly and is then planed to achieve a smooth, uniform finish. This final smoothing reduces the dimensions.
For example, a board labeled as “2×6” starts as a rough cut at approximately 2 inches by 6 inches but is then planed down to 1.5 inches by 5.5 inches to give it the smooth, usable surface that most consumers are familiar with.
Standard Lumber Sizes
Here is a quick reference for several common lumber sizes and their actual dimensions:
- 2×4: 1.5 inches by 3.5 inches
- 2×6: 1.5 inches by 5.5 inches
- 2×8: 1.5 inches by 7.25 inches
- 4×4: 3.5 inches by 3.5 inches
These actual sizes are standard across most lumber types, whether you’re buying softwoods like pine or hardwoods.
Impact of Planing on Wood Dimensions
The planing process is designed to remove rough surfaces, but it also results in the shrinkage of the board’s dimensions. Therefore, while the initial lumber is slightly larger, planing brings it to a finished size. Some retailers may offer rough-cut lumber that retains its larger dimensions (like 2 inches by 6 inches), but the most commonly available lumber has already been planed down.
Exceptions to the Standard Sizes
Although the standard for a 2×6 is 1.5 inches by 5.5 inches, there are sometimes variations:
- Rough-cut lumber: This type of lumber retains its nominal size and may still be close to 2 inches by 6 inches.
- Pressure-treated lumber: Often has slightly different final dimensions due to the chemicals used in the treatment process, although the difference is typically minor.
Practical Use of 2×6 Lumber
Understanding the actual dimensions is important for projects that require precise measurements. The 1.5-inch by 5.5-inch board is used in a variety of applications, such as framing, shelving, and constructing outdoor structures like decks. When planning a project, it’s always important to account for the actual size rather than the nominal size to avoid measurement errors and ensure proper fitment.
The actual dimensions of a 2×6 piece of lumber are 1.5 inches by 5.5 inches, not the 2 inches by 6 inches suggested by its nominal designation. This difference arises due to the natural shrinking of the wood during the drying and planing processes. Understanding this distinction is crucial for accurate project planning and execution, particularly in construction and woodworking where precise measurements are required.
