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FOREWORD

Wood in the form of lumber and timbers has been used as a major structural material for centuries. Originally the material of craftsmen, wood is now the material of the engineer who uses technical data to design todays' sophisticated structures.

Wood Structural Design Data, 1986 Edition, provides information relating to design of typical wood structural members. These data are augmented by reference to the National Design Specification for Wood Construction, particularly on the subject of design stresses. Wood Structural Design Data was first published in 1934, with revised editions issued periodically to take into account new data and developments in wood design.

Tabular data in this volume are presented primarily as a convenient aid in design of the most frequently encountered elements of wood structural framing. Hence, certain subjects are only summarized in the text to indicate their relationships to the tabular data. More detailed information is available in other publications, many of which are listed as References.

In preparation of this and previous editions, information from the regional lumber manufacturers associations provided valuable data. Reports and other publications from the Forest Products Laboratory, U. S. Department of Agriculture, were important sources of fundamental information.

Tabular data relate to dressed sizes conforming to the American Softwood Lumber Standard, Voluntary Product Standard 20-70, U.S. Department of Ccmmerce, National Bureau of Standards.