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What is Rough Cut Lumber?

Dale Marshall
Dale Marshall

Rough cut lumber is wood that has been cut by a sawmill from a large log. When a log is processed in a sawmill, it is cut into pieces that will be sold as boards, dimensional lumber, veneers and other components. Very rough in texture, this wood nevertheless conforms to the nominal sizing standards for dimensional lumber and boards.

Dimensional lumber, used extensively for framing houses and other structures, is originally cut to certain dimensions of width and thickness. Measured in inches, the most commonly known dimensional lumber is the “two-by-four,” or 2x4 (approximately 5.1 x 10.2 cm). Dimensional lumber is commonly available as various combinations of 1, 2, 3, and 4 inches (approximately 2.5, 5.1, 7.6, and 10.2 cm), although larger sizes are available as well. Lengths are specified separately, as in “an 8-foot 2x4.”

Logs prior to lumber manufacturing.
Logs prior to lumber manufacturing.

Most dimensional lumber is softwood, that is, from coniferous trees like pine. Hardwood, from deciduous trees like maple and oak, is more often used to make veneers and boards and plywood, which in turn are used for paneling, furniture construction, and other such items. The measurement of hardwood boards is different from the “two-by” standards in that only the thickness is generally measured, and boards of varying, non-standard lengths and widths are available in a lumberyard. These boards are delivered to the lumberyard as rough cut lumber, or with one or both sides surfaced.

The most popular measurements for dimensional lumber, which is commonly used for framing houses, are 1.5 inches by 3.5 inches -- a cut known as the two-by-four.
The most popular measurements for dimensional lumber, which is commonly used for framing houses, are 1.5 inches by 3.5 inches -- a cut known as the two-by-four.

Logs are cut shortly after harvesting, but the rough cut lumber still has a very high moisture content and must be dried. The product of a living organism, lumber reacts to environmental influences such as heat and humidity. Much rough-cut lumber will twist and warp during the drying process, and to recover it for productive use, it will be surfaced &emdash; cut, jointed, and planed &emdash; to produce a straight, flat, smooth piece of lumber. This process removes significant quantities of stock, so the final piece of lumber offered for sale will be markedly smaller than the original &emdash; “nominal” &emdash; size of the lumber. A finished 2x4, for example, will measure exactly 1.5 x 3.5 inches (38mmx89mm). Likewise, a hardwood board that's been rough cut to 1 inch (2.54 cm) &emdash; usually referred to as “4/4” &emdash; will be 7/8-inch (2.22 cm) thick if surfaced on one side only, and 13/16-inch (2.06 cm) if surfaced on both sides.

Lumber yards are very careful about labeling their products so that people understand what kind of wood they are buying.
Lumber yards are very careful about labeling their products so that people understand what kind of wood they are buying.

Rough cut lumber is often used by woodworkers because it's much less expensive than finished lumber, which must be surfaced smooth and flat before being sold. In addition to its relatively low cost, rough cut wood is thicker than the surfaced lumber available in a lumberyard, giving more room for error in their projects. In addition, when woodworkers do their own surfacing, they can plane or joint the wood exactly to their specifications, and many report that they can often produce a smoother, flatter surface on the wood than they'd be able to buy from the lumberyard. A major drawback of buying rough cut lumber, though, is that it's still green, and must be dried. A rule of thumb for drying rough cut lumber is to give it a year of drying time for every inch of thickness.

Discussion Comments

Logicfest
Plus, a lot of people just like the look of rough cut lumber in their homes. Lends that famed "log cabin" touch to homes and there are plenty of people who like that.
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    • Logs prior to lumber manufacturing.
      By: vladimirs
      Logs prior to lumber manufacturing.
    • The most popular measurements for dimensional lumber, which is commonly used for framing houses, are 1.5 inches by 3.5 inches -- a cut known as the two-by-four.
      By: Christian Delbert
      The most popular measurements for dimensional lumber, which is commonly used for framing houses, are 1.5 inches by 3.5 inches -- a cut known as the two-by-four.
    • Lumber yards are very careful about labeling their products so that people understand what kind of wood they are buying.
      By: Christian Delbert
      Lumber yards are very careful about labeling their products so that people understand what kind of wood they are buying.