In American English, the term lumber refers to timber that has been through some amount of preparation for use. In British English, this would be called timber. There are several ways of categorizing lumber. Softwood lumber, used in contrast to hardwood lumber, is one of these types.
Softwood lumber comes from conifers, which are mainly pines and fir trees. Most softwood trees are evergreens: larch, bald cypress, and tamarack are exceptions. Typical softwood lumber sources include such trees as cedars, firs, hemlocks, pines, and redwoods. In grading lumber, aspen — a hardwood — is graded with the softwoods, which means that it can be used for the same purposes.
In 2008, Russia was a world leader in lumber exports, producing 40% of the world’s exported softwood and hardwood logs. However, many countries not only produce, but also export, softwood lumber, including Argentina, Austria, Bolivia, Brazil, Chile, Czech Republic, Estonia, Finland, France, Germany, Honduras, Latvia, Lithuania, Mexico, New Zealand, Paraguay, Republic of South Africa, Romania, Russia, Sweden, Switzerland, Ukraine, United States, and Venezuela.
Softwood lumber is generally classified in three different ways, although the systems used in different countries are different. First, it is classified by use, and assessed for its strength and stress-bearing qualities. Second, it is classified by its dimensions. This, obviously, varies depending on the unit of measurement used in the locale. Third, it is classified by finish. Here, too, different names may be used.
In the United States, softwood lumber is usually used in construction of homes and other buildings or remanufactured for use in other products. Construction lumber may be appearance lumber, stress-graded, or non-stress-graded. Each piece of lumber is stamped with its grade, which is given with the understanding that the lumber will be used as is, not reshaped prior to use.
Size classifications for softwood lumber in the United States are done by inches and feet. Softwood lumber is usually manufactured in lengths that are multiples of two feet (about .6 meters), and is usually between two and 16 inches thick (about five to 40.5 centimeters). There is a difference between the dimensions used to refer to the lumber, called the nominal dimensions and the actual dimensions. A so-called “two by four” actually has dimensions of 1.5 by 3.5 inches (38 by 89 millimeters). Lumber with a nominal thickness of less than two inches (about five centimeters) is called boards.
Third, in the United States, softwood lumber is classified by whether its surface has been planed or patterned; or untreated, that is, whether it remains rough-sawed. If it has been planed on all sides and is ready to be used, surfaced on all four sides, then it may be called S4S for short.
