Framing Lumber and Plywood
Lumber is wood that has been cut into boards or other shapes for the purpose of woodworking or construction. It typically is supplied either rough or finished. Rough lumber is the raw material for furniture making and other items requiring additional cutting and shaping.
It is available in many species, and usually hardwoods are best for most building projects. Finished lumber is supplied in standard sizes, mostly for the construction industry. It is primarily one of a few needle-bearing species such as pine, hemlock, fir or spruce. Rough lumber comes from the sawmill without further cutting or shaping. It is usually sold in random lengths and widths and measured in board feet, a unit of 1″x 1″ x 1′.
It can be available air-dried or kiln-dried. Air-dried lumber is carefully stacked and allowed to dry for several months, depending on thickness. It is used for some outdoor purposes, such as building sheds and fences. Kiln-dried wood is stacked in moisture- and temperature-controlled kilns built for the purpose and dried. It is then ready to be used for furniture-making or other woodworking uses. Finished lumber is usually kiln-dried then planed and cut to predetermined sizes, primarily for use by the construction industry.
These are nominal, rather than actual sizes. When using metric measurements, lumber is measured in actual sizes. When using Imperial measurements, for instance, a 2×4 is actually 1-1/2 by 3-1/2 inches. Other stock is sized in similar manners. The lengths are actual sizes and are multiples of 2 feet. Sizes from 8 to 16 feet (8,10,12,14,16) are commonly available, and larger sizes (18,20,22,24) are sometimes available. Timber is cut in the forest in 24 foot lengths. At the mill, it is recut into 3-8 foot lengths, an 8 foot and a 16 foot length, a 10 foot and a 14 foot length or 2-12 foot lengths.
Lumber is also used to refer to plywood and composite wood products.