Softwood Lumber Glossary

Board Foot
The basic unit of measurement for lumber. One board foot is equal to a 1-inch board, 12 inches in width and 1 foot in length. Thus, a 10-foot long, 12-inch wide and 1-inch thick piece would contain 10 board feet. When calculating board feet, nominal sizes are assumed.

Building Code
A set of regulations governing construction in a particular political subdivision, such as a city or county. The building code spells out certain requirements pertaining to such criteria as lumber strength, values, grades, and spans.

Bullnose
The process of rounding an edge of a board used as shelving, stadium seating, stepping, etc.

Center-to-Center Spacing
The spacing between structural members determined by measuring from the center of one to the center of the next, e.g. "16-inches o.c." Chamfer - A bevel or slope created by slicing off the square edge or end of a piece of wood or other material.

Chord
The top or bottom member of a truss, to which the web members are attached.

Design Value
A measurement of strength in lumber, involving the basic properties of wood. These are: fiber stress in bending (Fb), tension parallel to grain (Ft), horizontal shear (Fv), compression perpendicular to grain (FcI), and modulus of elasticity (E).

Dimension Lumber
Lumber that is from two inches up to, but not including, five inches thick, and that is two or more inches in width. Dimension also is classified as framing, joists, planks, rafters, etc.

Dry
Seasoned, usually to a moisture content of less than 19%.

Fascia
A broad, flat, horizontal surface, sometimes used to cover a joint, or as the outer edge of a cornice. Also facia.

Fingerjoint
A method of joining two pieces of lumber end-to-end by sawing into the end of each piece a set of projecting "fingers" that interlock. When the pieces are pushed together, this forms a strong glue joint.

Fire-Retardant
A chemical applied to lumber or other wood product to slow combustion and flame spread.

Framing
Lumber used for structural members in a house or other building. The skeleton to which roofs, floors, and sides are attached.

Glulam
A shorthand version of Glue Laminated. Glue Laminated is a process in which individual pieces of lumber or veneer are bonded together with an adhesive to make a single piece, with the grain of each piece running parallel to the grain of each of the other pieces.

Green
Unseasoned; not dry. Lumber with a moisture content of 19% or more.

Grademark
A stamp or symbol indicating the grade, quality and/or intended use of a piece of lumber, plywood, or other wood product. To be recognized as "grade marked," the product must bear an official stamp issued by a grading agency and applied by a qualified grader, or it must be accompanied by a certificate attesting to the grade.

Grading Rules
A set of criteria by which to judge various pieces of lumber or panels in terms of strength, appearance, and suitability for various uses. Regional grading agencies draw up rules for grading based on the voluntary product standards issued by the U.S. Bureau of Standards.

Grain
A general term referring to the arrangement, appearance, and direction of wood fibers. Among the many types of grain are fine, coarse, straight, curly, open, flat, vertical, and spiral.

Hardwood
A general term referring to any variety of broad-leaved, deciduous trees, and the wood from those trees. The term has nothing to do with the actual hardness of the wood; some hardwoods are softer than certain softwood (evergreen) species.

Header
A beam fitted between trimmers and across the ends of tailpieces in a building frame; a horizontal support at the top of an opening.

I-joist
A beam whose cross section resembles the letter "I"; one in which the top and bottom flanges (such as 2x4s) are connected by thinner material (such as plywood or OSB).

Joist
A piece of lumber two to four inches thick and six inches wide, used horizontally as a support for a ceiling or floor. Also, such a support made from steel, aluminum, or other material.

Kiln Dried After Treatment (KDAT)
Treated lumber that has been seasoned in a kiln to a predetermined moisture content following the treating process.

Knot
A branch or limb embedded in a tree and cut through in the process of manufacturing. Knots are classified according to size, quality and occurrence. In lumber, the size classifications are: Pin knot, one not over 1/2-inch in diameter; Small, a knot larger than 1/2-inch but not over 3/4-inch; Medium, larger than 3/4-inch but not over 1 1/2-inches; Large, over 1 1/2-inches in diameter. Laminated Veneer Lumber - LVL - Structural wood members constructed of veneers laminated to make a "flitch" from which pieces of specific sizes can be trimmed.

Lath
A thin, narrow wooden strip, used as a backing for wall plaster or other materials.

Manufactured Housing
Housing units partially or completely built in a factory.

Millwork
Lumber that has been remanufactured into door and window parts or decorative trim. Generally made from the shop grades of Ponderosa Pine, Sugar Pine, White Fir, Douglas Fir, or Western Hemlock.

Modular Housing
A type of housing in which major components are assembled in a factory and then shipped to the building site to be joined with other components to form the finished structure. The components are usually uniform incremental sizes, permitting some flexibility of design while maintaining the structure of individual elements. Sometimes called "prefabricated" or "prefab" housing by laymen; these terms are avoided by the industry because of negative connotations.

Nominal Measure
The nominal or common-named sizes of lumber, usually expressed in terms of the nearest inch regardless of actual surface, or net, sizes.

Old Growth
Biologically, a stand of timber that is near its climax; such trees may be 200 years old or more. In timber management planning, old growth also refers to timber that is older than the rotation age planned for future forests; this definition may include trees that are 100 years of age, or less.

Oriented Strand Board (OSB)
A structural panel made of narrow strands of fiber oriented lengthwise and crosswise in layers, with a resin binder. Depending on the resin used, OSB can be suitable for interior or exterior applications.

Pallet
A portable platform used as a base for storing, stacking, and transporting goods in a unit.

Panel Product
Any variety of wood products such as plywood, particleboard, hardboard, oriented strand board, or waferboard, sold in sheets or panels. Although sizes vary, a standard size for most panel products is 4x8 feet.

Picket
A sharpened or pointed stake, post, or pale, usually used as fencing.

Plywood
A flat panel made up of a number of thin sheets, or veneers, of wood in which the grain direction of each ply, or layer, is at right angles to the one adjacent to it. The veneer sheets are united, under pressure, by a bonding agent.

Preservative
Any substance applied to wood that helps it resist decay, rotting, or harmful insects.

Pressure-Treating
A process of impregnating lumber or other wood products with various chemicals, such as preservatives and fire-retardants, by forcing the chemicals into the structure of the wood using high pressure.

Railroad Tie
A piece of industrial lumber used to support rails on a roadbed. In Britain and other countries, a "Sleeper".

Random Lengths
Lumber of various lengths, usually in even two-foot increments. Lumber offered as random-length will contain a variety of lengths which can vary greatly between manufacturers and species. A random-length loading is presumed to contain a fair representation of the lengths being produced by a specific manufacturer.

Ridge Beam
A horizontal timber to which the tops of rafters are fastened. Also called a Ridge Board or a Roof Tree.

Roof Truss
An engineered building component supporting the roof in place of rafters. Roof trusses are usually constructed in a triangular shape with a number of interconnected pieces that spread a load evenly across the truss.

Rough Lumber
Lumber which has not been dressed or surfaced but has been sawn, edged, and trimmed.

Sheathing
Plywood, waferboard, oriented strand board, or lumber used to close up side walls, floors, or roofs preparatory to the installation of finish materials on the surface. The sheathing grades are also commonly used for pallets, crates, and certain industrial products.

Site-Built
A structure constructed at the site where it is to remain.

Softwood
A general term referring to any variety of trees having narrow, needle-like or scale-like leaves, generally coniferous. The term has nothing to do with the actual softness of the wood; some "softwoods" are harder than certain "hardwood" species.

Southern Yellow Pine
A species group, composed primarily of Loblolly, Longleaf, Shortleaf, and Slash Pines. Various subspecies are also included in this group. This group refers to the southeastern United States, from Texas to Virginia.

Species
A category of biological classification; a class of individuals having common attributes and designated by a common name. "Species" is always properly used with the "s" when referring to trees or other biological classifications.

Spindle
A narrow, turned piece of wood.

Spruce-Pine-Fir
Canadian woods of similar characteristics that have been grouped for production and marketing. The S-P-F species have moderate strength, are worked easily, take paint readily, and hold nails well. They are white to pale yellow in color. The largest volume comes from Eastern Canada (Saskatchewan and east), where the principal species in the group are: Red Spruce, Black Spruce, Jack Pine, and Balsam Fir. The principal species of the group originating in Western Canada (British Columbia and Alberta) are White Spruce, Engelmann Spruce, Lodgepole Pine, and Alpine Fir. Some lumber production in the New England States also is marketed as Spruce-Pine-Fir (south).

Stud
A framing member, usually cut to a precise length at the mill and designed to be used in framing building walls with little or no trimming before it is set in place. Studs are most often 2x4s, but 2x3s, 2x6s, and other sizes are also included in the stud category; studs may be of wood, steel, or composite material.

Treated
Wood products infused or coated with any variety of stains or chemicals designed to retard fire, decay, insect damage or deterioration due to weather.

Veneer
Wood peeled, sawn, or sliced into sheets of a given constant thickness and combined with glue to produce plywood or laminated-veneer lumber. Veneers laid up with the grain direction of adjoining sheets at the right angles produce plywood of great stiffness and strength, while those laid up with grains running parallel produced flexible plywood most often used in furniture and cabinetry. White Wood - 1. Wood products intended for treating, but not yet treated. 2. A designation applied to a number of species, such as White Fir.


Source: Terms of the Trade, Published by Random Lengths, www.rlpi.com; reprinted with permission granted by the publisher