A Buyer's Guide to Lumber

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Wood sawn from trees by section and sold by dimension is known as lumber. This wood is available as softwood (cut from needle-bearing conifers like pine, fir, hemlock, cedar, redwood) and hardwood (sawn from deciduous, or leaf-bearing, trees such as oak, maple, walnut and cherry). There are two methods of mill sawing. The most common is plain, or flat, sawing, in which cuts are made tangent to (they follow) the tree's growth rings, yielding a face-grain board. Quarter-sawing, a somewhat less economical method, entails making cuts perpendicular to the growth rings, and produces straight-grained wood with better warp resistance.

All lumber is sized and priced by its rough mill-sawn dimensions, but the finished product may be reduced in size by up to one-third after the surface-planing process is complete. Hence, a nominal 2X6 measures only l½" X 5½" in actual dimension.

A piece of lumber less than 2" thick and from 2" to 16" wide in nominal dimension is a board. Boards less than 6" wide are called strips. Dimension lumber used for framing work is between 2" and 4½" thick and up to 16" wide. Timbers measure at least 5" on any surface. Normally, lumber is available in lengths between 6' and 20' in standard 2' multiples.

Lumber is sold by the board foot, each unit being equivalent to a rough board measuring 1" thick, 12" wide and 12" long—144 cubic inches of wood all told. Wood less than 1" thick is counted as a full inch, and stock over 1" is figured by the next larger ¼". Thus, an 8'-long 1 X 6 contains four board feet... as does a strip measuring 1 3/8" X 2" X 16'. To figure board feet, multiply thickness by width in inches, then multiply by length in feet and divide by 12. Often, retail dealers sell lumber by the lineal, or running, foot which is the standard practice for moldings and other factory-shaped wood. Discount houses even sell by the piece, to make shopping easier.

Wood is graded according to quality, which is determined by the size of the board and the number and significance of defects such as knots, checks and shake, pitch pockets and wane (rounded edges). Both hardwood and softwood are further graded by intended use, which takes species, structural integrity and appearance into account.