There are two main types of lumber. It may be supplied either rough-sawn, or surfaced on one or more of its faces. Besides pulpwood, rough lumber is the raw material for furniture-making and other items requiring additional cutting and shaping. It is available in many species, usually hardwoods; but it is also readily available in softwoods, such as white pine and red pine, because of their low cost.
Finished lumber is supplied in standard sizes, mostly for the construction industry – primarily softwood, from coniferous species, including pine, fir and spruce (collectively spruce-pine-fir), cedar, and hemlock, but also some hardwood, for high-grade flooring. It is classified more commonly made from softwood than hardwoods, and 80% of lumber comes from softwood.
In the United States milled boards of wood are referred to as lumber. However, in Britain and other Commonwealth nations, the term timber is instead used to describe sawn wood products, like floor boards.
In the United States and Canada, generally timber describes standing or felled trees. Specifically in Canada, lumber describes cut and surfaced wood.
In the United Kingdom, the word lumber is rarely used in relation to wood and has several other meanings, including unused or unwanted items. Referring to wood, Timber is almost universally used instead.
Remanufactured lumber is the result of secondary or tertiary processing/cutting of previously milled lumber. Specifically, it is lumber cut for industrial or wood-packaging use. Lumber is cut by ripsaw or resaw to create dimensions that are not usually processed by a primary sawmill.
Resawing is the splitting of 1-inch through 12-inch hardwood or softwood lumber into two or more thinner pieces of full-length boards. For example, splitting a ten-foot 2×4 into two ten-foot 1×4s is considered resawing.