Efficient use of our nation’s timber resource is a vital concern. Because a major use of wood in the United States is in construction, particularly housing construction, good practice in this endeavor can have a profound impact on the resource. This handbook is intended as an aid to more efficient use of wood as a construction material. It provides engineers, architects, and others with a source of information on the physical and mechanical properties of wood and how these properties are affected by variations in the wood itself. Continuing research and evaluation techniques hold promise for wider and more efficient utilization of wood and for more advanced industrial, structural, and decorative uses.
This handbook was prepared by the Forest Products Laboratory (FPL), a unit of the research organization of the Forest Service, U.S. Department of Agriculture. The Laboratory, established in 1910, is maintained at Madison, Wisconsin, in cooperation with the University of Wisconsin. It was the first institution in the world to conduct general research on wood and its utilization. The accumulation of information that has resulted from its engineering and allied investigations of wood and wood products over nine decades—along with knowledge of everyday construction practices and problems—is the chief basis for this handbook.
The Encyclopedia of Wood was first issued in 1935, and slightly revised in 1939, as an unnumbered publication. Further revisions in 1955, 1974, and 1987 were published by the U.S. Department of Agriculture as Agriculture Handbook No. 72. This current work is a complete revision of the 1987 edition. This revision was necessary to reflect more recent research accomplishments and technological changes.
The audience for The Encyclopedia of Wood is fairly broad. Therefore, the coverage of each chapter is aimed at providing a general discussion of the topic, with references included for additional information. Past versions of The Encyclopedia of Wood tended to report only the findings and applications of FPL research. Although the handbook is not intended to be a state-of-the-art review, this approach would now leave significant gaps in some important areas. The current edition has broadened the sources of information to provide better coverage of important topics.
The organization of this version of The Encyclopedia of Wood is similar to previous ones, with some modifications:
Consistent with movement by many U.S. standards agencies and industry associations toward use of metric units and nearuniversal implementation of metric usage in the international community, units of measurement in this version of the handbook are provided primarily in metric units, with customary inch-pound equivalents as secondary units. All conversions in this handbook to metric units, including conversions of empirically derived equations, are direct (or soft) conversions from previously derived inch-pound values. At some future time, metric expressions may need to be derived from a reevaluation of original research.