Wood Terms - A Lumber Glossary from A - Z

Dressed and Matched

Drop Siding

Lumber that has been dressed on two sides.

A rectangular channel cut partway into a board.

Grain which is darker than the rest and should not be confused with pitch streaks.

Diameter at Breast Height

A specialized mallet helpful in minimizing damage to the struck surface and in controlling striking force with minimal rebound from the striking surface.

The weight of the structure itself; which includes built-in benches, the plank system, support structure and any railings, and other permanent features.

A beetle that is about ¼ inch long and very destructive to structural beams.

The decomposition of wood by fungi

• Advanced Decay – The older stage of decay in which the destruction is readily recognized because the wood has become punky, soft and spongy, stringy, pitted, and crumbly.
• Brown Rot – In wood, any decay in which the attack concentrates on the cellulose and associated carbohydrates rather than on the lignin, producing a light to dark brown residue.
• Dry Rot – A term loosely applied to any dry, crumbly rot but especially to that which, when in an advanced stage, permits the wood to be crushed easily to a dry powder.
• Incipient Decay – The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness 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.
• Soft Rot – A special type of decay developing under very wet conditions in the outer wood layers, caused by cellulose-destroying micro-fungi that attack the secondary cell walls and not the intercellular layer.
• White Rot – Any decay or rot attacking both the cellulose and the lignin, producing a generally whitish reside that may be spongy or stringy rot, or occur as pocket rot.

A knot is disintegration of wood due to the action of wood-destroying fungi.

Trees that have broad leaves that are shed in the fall. It is usually it is a hardwood.

Boards used for the surface of a deck; lumber expressed in nominal terms as being 2” to 4” thick and 4” and wider. Decking is usually surfaced to single tongue and groove in 2” nominal thickness. In 3” and 4” nominal thickness it may be double tongue and groove and worked with rounded or V edges, striated, or grooved. Decking is widely used for roofing and flooring.

An irregularity found in a board that lowers its strength and value. Common defects are checks, knots, staining, etc. Conk, crook, decay, split, sweep, or other injury in the wood that decreases the amount of useable wood that can be obtained from a log.

The amount of sag in a counter, floor, joist, or shelf caused by the weight its supporting. Vertical distance between the chord and the skyline measured at midspan; frequently expressed as a percentage of the horizontal span length.

Insects that destroy foliage.

Any defect that lowers the grade or quality of a log.

Developed to reduce humidity in store rooms and basement conditions.

The separation of layers in laminated wood or plywood caused by failure of the adhesive itself or of the interface between adhesive and adhered.

Removal of part or all of the lignin from wood by chemical treatment.

Metal grid used with a skidder for removing limbs.

Study of the identification of trees.

The weight of a body or substance per unit volume.

A procedure for segregating wood according to density, based on percentage of latewood and number of growth rings per inch of radius.

Deduction from taxable income derived from wasting assets. The Internal Revenue Code of the United States permits the calculation of depletion allowances either on the basis of a percentage of the gross income from the property in question or on a per-unit-of-product basis. Depletion differs from depreciation in that the asset subject to depletion cannot be replaced; a mine or an oil field cannot be replaced in the same manner that a factory or machine can be replaced.

A measurement of strength in lumber, involving basic properties of wood. They are: compression perpendicular to grain (Fcl), fiber stress in bending (Fb), horizontal sheer (Fv), modulus of elasticity (E), and tensions parallel to grain (Ft).

Double End Trimmed

The temperature at which atmospheric water vapor condenses out as a liquid.

Douglas Fir

Douglas Fir-Larch

A measuring instrument with a circular graduated face and a pin which activates a rotating pointer to measure variation in movement in thousandths of an inch.

Cross grain exhibiting deviation of the growth-ring plane from the longitudinal axis, commonly the result of sawing boards other then parallel to the bark of the log.

Classification of trees based on the diameter of outside bark measured at D.B.H. In forest surveys, each diameter class encompasses approximately 2 inches: the 6-inch class would include trees 5.0 through 6.9 inches in D.B.H.

Diameter measurement of a standing tree or log in which the estimated or actual thickness of the bark is discounted.

Maximum diameter of trees to be cut, as in a timber sales contract.

Measurement of trees diameter in which the bark is included.

Tape measurer specially graduated so that diameter may be read directly when the tape is placed around a log or tree stem.

Spade-like tool used to prepare planting holes for seedlings. Dibbles are most commonly used in the South but are used in other areas for planting contained seedlings.

Certain hardwoods in which the pores tend to be uniform in size and distribution throughout each annual ring or to decrease in size slightly and gradually toward the outer border of the ring.

Dimension

Framing lumber; generally applied to lumber when the nominal size is 2 inches thick and 2 or more inches wide. The National Grading Rule for Softwood Dimension Lumber defines “dimension” as lumber from 2 through 4 inches thick and 2 inches and wider.

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

Cost that varies in direct proportion to production and is attributable to a specific factor of production.

Predetermining the way a tree will land when it hits the ground. When shears are used, the wedge-shaped blade provides a lever that directs the tree into its lay.

Spreading seeds over the forest seedbed by hand or machine. This practice is used to assist or supplement natural seed fall and to achieve regeneration.

Changes in the color of wood which affect only its appearance.

Decking

A pattern with a thick and a thing edge and lap joint.

The most numerous and vigorous species in a mixed forest. Larger-than-average trees with well-developed crowns extending above the general canopy level and receiving full light from above and partial light from the side.

Synonymous with ‘decay’ and are any form of decay which may be evident as either a discoloration or a softening of the wood.

Mechanized cutting tool for felling trees; works like a pair of scissors. One blade is slightly offset, but both work against the other. Some work edge to edge.

A winch consisting of two drums controlled separately, one for the dragline and the other from the haul-back line. Sometimes mounted on and powered by a tractor.

Both ends cut reasonably square by a saw.

A method of joining wood at the corners by the use of interlocking pins and tails; a tenon that is shaped like a dove’s spread tail to fit into a corresponding mortise.

A wood pin used to align and hold two adjoining pieces.

A circular metal pin with a raised point that is inserted into a dowel hole and used to locate the exact center on a mating piece of wood.

A cylindrical wooden pin that is used to reinforce a wood joint.

A type of Japanese woodworking saw that is used for fine joinery work such as dovetails. Its western equivalent is a back saw.

A tool having a blade with a handle at each end; by drawing it towards you, you can shave surfaces.

A mechanism used to make drawers slide in and out.

A device installed in a cabinet to limit the drawers’ movement.

Lumber that has been worked with a tongue off center on one edge of each piece and a groove on the opposite edge to provide a close joint by fitting two pieces together.

Shaping the cutting edge of a chisel to correct the bevel.

An implement with cutting edges or a pointed end for boring holes in hard materials, usually by a rotating abrasion or repeated blows; a bit.

The portion of a band saw’s pulley-like drive system that propels the blade forward.

A lumber pattern with lap or tongue and groove joints.

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

An enclosed chamber in which temperate and humidity conditions are subject to control for the purpose of drying lumber.

A term loosely applied to many types of decay but especially to that which, when in an advanced stage, permits the wood to be easily crushed to a dry powder; the term is actually a misnomer for any decay, since all fungi require considerable moisture for growth.

The strength of an adhesive joint determined immediately after drying under specified conditions or after a period of conditioning in a standard laboratory atmosphere.

A paneling product used as an interior wall and ceiling covering made of gypsum plaster with paper facings. The gypsum plaster may be reinforced with recycled fiber.

Generally lumber of a low grade used to separate and bind ship cargo; stakes, stripes and other pieces that are needed in holding and protecting merchandise on railroad cars and truck shipments.

A general term for permanence or lastingness; frequently used to refer to the degree of resistance of a species or of an individual piece of wood to attack by wood-destroying fungi under conditions that favor such attack.