D to G of sawmill terminology

Glossary D – G

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DBH (Diameter Breast Height)
The diameter of a tree at breast height (4.5 feet above ground), together with the estimated height of the usable logs in a tree is used to determine the volume of lumber likely to be yielded in a log depending on the log scale used.

Debarker Machine
Used to remove the bark from logs or bolts prior to processing into chips, lumber, or other wood products.

The decomposition of wood substance caused by the action of wood-destroying fungi, resulting in softening, loss of strength, weight, and often in change of texture and colour.

Term applied to trees (commonly broadleaf) that usually shed their leaves annually. Also known commercially as hardwoods.

Crook, conk, decay, split, sweep, or other injury that decreases the amount of usable wood that can be obtained from a log.

As usually applied to wood of normal cellular form, density is the mass per unit volume of wood substances enclosed within the boundary surfaces of a wood-plus-voids complex. It is variously expressed as pounds per cubic foot, kilograms per cubic meter, or grams per cubic centimeter at a specified moisture content.

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

Dimensional lumber
Lumber cut to any predetermined size.

Double cutting
The process of utilising both sides of the blade while in the horizontal position, to double the cutting capacity. i.e. a 6″ blade can double cut a 12″ board.

Dressed lumber
Lumber that has been trimmed and planed at the sawmill. The dressed size is the cross-sectional dimensions of lumber after planning.

Dry lumber
As applied to softwoods, lumber sold as ‘dry’ or ‘kiln dried’ is at 19% or lower moisture content. Hardwoods are generally considered dry when at 10% or lower moisture content, although there is no definitive standard as with softwood species.

Dry weight
The oven-dry weight, or simply dry weight, is the weight of the wood after drying to a constant weight at a temperature slightly above the boiling point of water (215°F – 220°F).

A general term for permanence or resistance to deterioration. Frequently used to refer to the degree of resistance of a species of wood to attack by wood-destroying fungi under conditions that favor such attack. In this connection, the term ‘decay resistance’ is more specific.


Processed lumber with no remaining bark/wane.

Lumber cut on circular or band head rigs from the outside portions of logs; does not have square edges. These pieces must be passed through a machine called an edger that can make two or more lineal cuts simultaneously. Square-edged lumber must be trimmed to length.


Fillet Stacking
Where thin pieces of wood/plastic is placed between layers of stacked lumber to allow movement of air to assist in drying. This also prevents staining. The opposite of this is block stacking.

(1) Wood products such as doors, stairs and other fine work required to complete a building, especially the interior. (2) Coatings of paint, varnish, lacquer, wax, or other similar materials applied to wood surfaces to protect and enhance their durability or appearance.

Fixed costs
Operation costs that will remain relatively constant for all levels of output.

Lumber used for the structural member of a building, such as studs and joists.

Front end loader
Wheeled or tractor loader, with a bucket or fork hinged to lifting arms, that loads or digs entirely at the front end; Track or rubber-tired machine equipped with forks.


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

The classification of the quality of a manufactured piece of wood or of logs, based on criteria of quality such as natural characteristics and strength.

Amount by which the grade increases or decreases in a unit of horizontal distance.

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

  • Coarse-grained wood has wide, conspicuous annual rings in which there is considerable difference between earlywood and latewood.
  • Fine-grained wood has narrow, inconspicuous annual rings.
  • Cross-grained wood has fibers that deviate from a line parallel to the sides of the piece.
  • Curly-grained wood has fibers that 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.
  • Edge-grained lumber has been sawn so that the wide surfaces extend approximately at right angles to the annual growth rings, or usually anywhere from 45° to 90° (also known as vertical-grained lumber).
  • End-grained wood is as the grain is seen on a cut made at a right angle to the direction of the fibers.
  • Fiddleback-grained wood is a figure produced by a type of fine wavy grain found, for example, in species of maple; such wood traditionally being used for the backs of violins.
  • Flat-grained lumber has been sawn parallel to the pith and approximately tangent to the growth rings, or at an angle below 45° with the surface of the piece.
  • Interlocked-grained wood has grain in which the fibers put on for several years may slope in a right-handed direction, and then for a number of years slope reverses to a left-handed direction, and so on and so forth. Such wood is exceedingly difficult to split radially.
  • Open-grained wood is the common classification for woods such as oak, chestnut, ash, and walnut that have a distinctive difference in pore sizes between earlywood and latewood.
  • Plain sawn lumber, side/slash grained wood are all alternatives flat-grained lumber.
  • Quarter sawn lumber is another term for edge-grained lumber.
  • Spiral-grained wood has fibers that take a spiral course about the trunk of a tree instead of the normal vertical course. This is a form of cross grain.
  • Straight-grained wood is that in which the fibers collectively take the form of waves or undulations.

Hinged mechanism/set of jaws capable of being opened and closed; used to grip logs during yarding or loading; Hydraulically operated arms, used to either lift and load, or lift and skid, trees. May be of the following types: swivel, stationary, self-centering, parallelogram, or bunk.

Freshly sawed lumber, or lumber that has received no intentional drying.

Green weight
Refers to the weight of freshly harvested wood that has the same moisture content as the standing tree. Moisture content (MC) is defined as the weight of water in the wood expressed as a percentage of the weight of the oven-dry wood (wood from which all moisture has been removed).

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 (eg. 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 (eg. Black gum and sweet gum), and many tropical species, annual rings are not easily recognized.

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