Lumber

Lumber is the raw wood material that goes into building houses, fences, and some furniture. Among the more common pieces in construction is the 2 X 4, but lumber is available in many dimensions.

Maybe you've noticed that lumber sizes are often misleading. The "nominal" cross-section dimensions of a piece of lumber, such as 2 X 4 or 1 X 6, are always somewhat larger than the actual, or dressed, dimensions. The reason is that dressed lumber has been surfaced or planed smooth on four sides (called S4S). The nominal measurement is made before the lumber is surfaced.

Board and Lumber Dimensions
One-by (1X) lumber is called "board":

Nominal Size	Dressed Dimensions (inches)
1 X 6	3/4 X 51/2
1 X 8	3/4 X 71/4
1 X 10	3/4 X 91/4

Two-by (2X) and four-by (4X) lumber is called "dimension lumber":

Nominal Size	Dressed Dimensions (inches)
2 X 2	11/2 X 11/2
2 X 4	11/2 X 31/2
2 X 6	11/2 X 51/2
2 X 8	11/2 X 71/4
2 X 10	11/2 X 91/4
2 X 12	11/2 X 111/4
4 X 4	31/2 X 31/2

Board measure is a method of measuring lumber in which the basic unit is 1 foot long by 1 foot wide by 1 inch thick, called a board foot. It is calculated by nominal, not actual, dimensions of lumber. The easiest formula for figuring nominal board feet is:

Thickness x Width x Length
12

The answer is in board feet. Lumber is often priced in board feet. However, most building material retailers and lumberyards also price lumber by the running foot for easier calculation. That is, a 2 X 4 X 8 is priced at eight times the running foot cost rather than as 5.333 board feet.

Lumber is one of the essential building blocks of house construction.

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