Glossary

Band Saw. A saw consisting of a continuous piece of flexible steel, with teeth on one of both sides, used to cut logs into cants and also to rip lumber.

Barn hard. Flooring products produced from hardwood barn siding.

Beam. A structural member, usually larger than five inches in width and thickness, used horizontally to support a load applied transversely to it.

Beam Wrap. See Box Beam.

Board & Batten. A type of siding in which narrow strips of wood are used to cover the joints of the boards or plywood used.

Board Foot. A unit of measurement of lumber represented by a board 12 in. long, 12 in. wide, and 1 in. thick or its cubic equivalent. In practice, the board foot calculation for lumber 1 in. or more in thickness is based on its nominal thickness and width and the actual length. Lumber with a nominal thickness of less than 1 in. is calculated as 1 in. The formula for calculating board footage is width x thickness x length divided by 12 if the length is in feet, or 144 if the length is in inches.

Board on Board. A type of siding in which boards are used to cover the gap between boards or plywood used.

Bow. The distortion of lumber in which there is a deviation, in a direction perpendicular to the flat face, from a straight line from end-to-end of the piece.

Box Beam. A built-up beam with solid wood flanges and plywood or wood-based panel product webs.

Boxed Heart. The term used when the pith falls entirely within the four faces of a piece of wood anywhere in its length. Also called boxed pith.

Cambium. A thin layer of tissue between the bark and wood that repeatedly subdivides to form new wood and bark cells.

Cant. A log that has been slabbed on one or more sides. Ordinarily, cants are intended for resawing at right angles to their widest sawn face. The term is loosely used.

Casehardening. A condition of stress and set in dry lumber characterized by compressive stress in the outer layers and tensile stress in the center or core.

Check. A lengthwise separation of the wood that usually extends across the rings of annual growth and commonly results from stresses set up in wood during seasoning.

Circle Saw. A round saw with teeth around the circumference. Also known as a rotary saw.

Circular Saw. A round saw having cutting teeth on its perimeter. Originally common as a head saw in sawmills, it has been largely replaced by thinner band saws. Circular saws remain widely used as trim and cutoff saws.

Corbel. A projection from the face of a wall or column supporting a weight.

Crook. The distortion of lumber in which there is a deviation, in a direction perpendicular to the edge, from a straight line from end-to-end of the piece.

Cup. A distortion of a board in which there is a deviation flatwise from a straight line across the width of the board.

Decay. The decomposition of wood substance by fungi.

Advanced (Typical) Decay. The older stage of decay in which the destruction is readily recognized because the wood has become punky, soft and spongy, stringy, ringshaked, pitted, or crumbly. Decided discoloration or bleaching of the rotted wood is often apparent.

Incipient Decay. The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood. It is usually accompanied by a slight discoloration or bleaching of the wood.

Heart Rot. Any rot characteristically confined to the heartwood. It generally originates in the living tree.

Pocket Rot. Advanced decay that appears in the form of a hole or pocket, usually surrounded by apparently sound wood.

Dote. Dote, doze, and rot are synonymous with decay and are any form of decay that may be evident as either a discoloration or a softening of the wood.

Equilibrium Moisture Content. The moisture content at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

Fiber. A thread-like structure of a plant that contributes to stiffness or strength.

Figure. The pattern produced in a wood surface by annual growth rings, rays, knots, deviations from regular grain such as interlocked and wavy grain, and irregular coloration.

Girder. A large or principal beam used to support concentrated loads at isolated points along its length.

Grade. The designation of the quality of a manufactured piece of wood or of logs.

Grain. The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber. To have a specific meaning the term must be qualified.

Curly-Grained Wood. Wood in which the fibers are distorted so that they have a curled appearance, as in birdseye wood. The areas showing curly grain may vary up to several inches in diameter.

End-Grained Wood. The grain as seen on a cut made at a right angle to the direction of the fibers (such as on a cross section of a tree).

Plainsawn Lumber. Another term for flat-grained lumber.

Quartersawn Lumber. Another term for edge-grained lumber.

Straight-Grained Wood. Wood in which the fibers run parallel to the axis of a piece.

Vertical-Grained Lumber . Another term for edge-grained lumber.

Green. Freshly sawed or undried wood. Wood that has become completely wet after immersion in water would not be considered green but may be said to be in the green condition.

Growth Ring. The layer of wood growth put on a tree during a single growing season. In the temperate zone, the annual growth rings of many species (for example, oaks and pines) are readily distinguished because of differences in the cells formed during the early and late parts of the season. In some temperate zone species (black gum and sweetgum) and many tropical species, annual growth rings are not easily recognized.

Hand Hewn. A timber that has been squared with an ax or adz.

Hardwoods. Generally one of the botanical groups of trees that have vessels or pores and broad leaves, in contrast to the conifers or softwoods. The term has no reference to the actual hardness of the wood.

Heartwood. The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood may contain phenolic compounds, gums, resins, and other materials that usually make it darker and more decay resistant than sapwood.

Lap Joint. A joint made by placing one member partly over another and bonding the overlapped portions.

Scarf Joint. An end joint formed by joining with adhesive the ends of two pieces that have been tapered or beveled to form sloping plane surfaces, usually to a featheredge, and with the same slope of the plane with respect to the length in both pieces. In some cases, a step or hook may be machined into the scarf to facilitate alignment of the two ends, in which case the plane is discontinuous and the joint is known as a stepped or hooked scarf joint.

Joist. One of a series of parallel beams used to support floor and ceiling loads and supported in turn by larger beams, girders, or bearing walls.

Kiln. A chamber having controlled air-flow, temperature, and relative humidity for drying lumber. The temperature is increased as drying progresses, and the relative humidity is decreased.

Knot. That portion of a branch or limb that has been surrounded by subsequent growth of the stem. The shape of the knot as it appears on a cut surface depends on the angle of the cut relative to the long axis of the knot.

Loose Knot. A knot that is not held firmly in place by growth or position and that cannot be relied upon to remain in place.

Pin Knot. A knot that is not more than 12 mm (1/2 in.) in diameter.

Sound Knot. A knot that is solid across its face, at least as hard as the surrounding wood, and shows no indication of decay.

Spike Knot. A knot cut approximately parallel to its long axis so that the exposed section is definitely elongated.

Lumber. The product of the saw and planing mill for which manufacturing is limited to sawing, resawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood or hardwood.

Dimension. Lumber with a thickness from 38 mm standard (2 in. nominal) up to but not including 114 mm standard (5 in. nominal) and a width of greater than 38 mm standard (2 in. nominal).

Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in. (standard 38 by 89 mm).

Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market (often differs from the actual size).

Rough Lumber. Lumber that has not been dressed (surfaced) but has been sawed, edged, and trimmed.

Shiplapped Lumber. Lumber that is edge dressed to make a lapped joint.

Structural Lumber. Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.

Surfaced Lumber. Lumber that is dressed by running it through a planer.

Timbers. Lumber that is standard 114 mm (nominal 5 in.) or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, or purlins.

Metal Detecting. The process of scanning materials with an electronic metal detector prior to milling.

Millwork. Planed and patterned lumber for finish work in buildings, including items such as sash, doors, cornices, panel work, and other items of interior or exterior trim. Does not include flooring, ceiling, or siding.

Moisture Content. The amount of water contained in the wood, usually expressed as a percentage of the weight of the ovendry wood.

Mortise. A slot cut into a board, plank, or timber, usually edgewise, to receive the tenon of another board, plank, or timber to form a joint.

Naval Stores. A term applied to the oils, resins, tars, and pitches derived from oleoresin contained in, exuded by, or extracted from trees, chiefly species of pines (genus Pinus). Historically, these were important items in the stores of wood sailing vessels.

Old Growth. Timber in or from a mature, naturally established forest. When the trees have grown during most if not all of their individual lives in active competition with their companions for sunlight and moisture, this timber is usually straight and relatively free of knots.

Ovendry Wood. Wood dried to a relatively constant weight in a ventilated oven at 102°C to 105°C (215°F to 220°F).

Patina. The sheen on any surface, produced by age and use.

Pitch Pocket. An opening extending parallel to the annual growth rings and containing, or that has contained, pitch, either solid or liquid.

Rafter. One of a series of structural members of a roof designed to support roof loads. The rafters of a flat roof are sometimes called roof joists.

Raised Grain. A roughened condition of the surface of dressed lumber in which the hard latewood is raised above the softer earlywood but not torn loose from it.
Rays, Wood. Strips of cells extending radially within a tree and varying in height from a few cells in some species to 4 or more inches in oak. The rays serve primarily to store food and transport it horizontally in the tree. On quartersawn oak, the rays form a conspicuous figure, sometimes referred to as flecks.

Relative Humidity. Ratio of the amount of water vapor present in the air to that which the air would hold at saturation at the same temperature. It is usually considered on the basis of the weight of the vapor but, for accuracy, should be considered on the basis of vapor pressures.

Resaw. (1) To saw a piece of lumber along its horizontal axis. (2) A bandsaw that performs such an operation.

Resawn Lumber. Lumber that has been sawn on a horizontal axis to produce two thinner pieces.

Ring Failure. A separation of the wood during seasoning, occurring along the grain and parallel to the growth rings. (See Shake.)

Ring-Porous Woods. A group of hardwoods in which the pores are comparatively large at the beginning of each annual ring and decrease in size more or less abruptly toward the outer portion of the ring, thus forming a distinct inner zone of pores, known as the earlywood, and an outer zone with smaller pores, known as the latewood.

Ring Shake. (See Shake.)

Rip. To cut lengthwise, parallel to the grain.

Saw Kerf. (1) Grooves or notches made in cutting with a saw. (2) That portion of a log, timber, or other piece of wood removed by the saw in parting the material into two pieces.

Seasoning. Removing moisture from green wood to improve its serviceability.

Air Dried. Dried by exposure to air in a yard or shed, without artificial heat.

Kiln Dried. Dried in a kiln with the use of artificial heat.

Second Growth. Timber that has grown after the removal, whether by cutting, fire, wind, or other agency, of all or a large part of the previous stand.

Shake. A separation along the grain, the greater part of which occurs between the rings of annual growth. Usually considered to have occurred in the standing tree or during felling.

Softwoods. Generally, one of the botanical groups of trees that have no vessels and in most cases, have needlelike or scalelike leaves, the conifers, also the wood produced by such trees. The term has no reference to the actual hardness of the wood.

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

Spike Knot. (See Knot.)

Sterilization. The process of treating wood with chemicals or by steaming to kill fungi or insects.

Structural Timbers. Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.

Stickers. Strips or boards used to separate the layers of lumber in a pile and thus improve air circulation.

Tenon. A projecting member left by cutting away the wood around it for insertion into a mortise to make a joint.

Texture. A term often used interchangeably with grain. Sometimes used to combine the concepts of density and degree of contrast between earlywood and latewood. In this handbook, texture refers to the finer structure of the wood (See Grain.) rather than the annual rings.

Timber. A size classification of lumber that includes pieces that are at least five inches in width and thickness; also classified as beams.

Truss. An assembly of members, such as beams, bars, rods, and the like, so combined as to form a rigid framework. All members are interconnected to form triangles.

Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane.

Virgin Growth. The growth of mature trees in the original forests.

Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.

Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.

Weathering. The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibers with the continual variation in moisture content brought by changes in the weather. Weathering does not include decay.