Glossary

A representative piece of timber of a known moisture content that is placed in a stack, or a predryer or kiln charge, so that it may be removed for comparative examination, weighing, or testing during the drying process.

The fluid in green wood that circulates through a tree’s vascular system, transporting water, nutrients, and sugars between the roots, trunk, branches, and leaves. It plays a vital role in its growth and health.

A non-structural fungal discolouration in the sapwood of timber, often appearing as blue, grey, black, or brown streaks, but does not weaken the wood mechanically.

Outer layers of wood which, in a growing tree, contain living cells and reserve materials such as starch. Under most conditions the sapwood is paler in colour and more susceptible to decay than heartwood.

Sawed veneer (or sawn veneer) is a type of thin sheet of wood produced by sawing a log or flitch, rather than slicing or peeling it (which is more common for veneers). It is typically thicker than other types of veneers and retains more of the wood’s natural character.

Sawn timber refers to wood that has been cut from logs using a saw, typically at a sawmill, into standard shapes and sizes for use in construction, furniture-making, packaging, and other applications.

A scarf joint is a method of joining two pieces of timber end-to-end to create a longer, continuous piece. It's a sloped or angled joint, rather than a straight butt joint, which increases the surface area for gluing or fastening, making the connection stronger and more durable.

To mark for an irregular cut.

Timber that has been dried so that the maximum moisture content anywhere in the piece does not exceed 15%.

Drying timber to a moisture content appropriate to the conditions and purposes for which it is to be used.

Stresses in timber caused by variation in shrinkage as it dries. When timber is seasoned—either by air drying or kiln drying—moisture is lost from the outer layers first, while the inner core still retains more moisture. This uneven shrinkage between the surface and the core creates tensile and compressive stresses within the timber.

Permanent deformation in wood that occurs during drying when the tensile and compressive stress exceeds its elastic limit. Set prevents normal shrinkage of the timber and can lead to more obvious defects such as casehardening.

Occurs during compression, which tends to give the wood a smaller than normal dimension after drying. Compression set is usually found in the inner layers of wood during the later stages of drying but sometimes occurs in the outer layers after extended conditioning or rewetting. Tension - Set that occurs during tension, which tends to increase the dimensions of the wood after drying. Tension set usually occurs in the outer layers of wood during drying.

Separation or breakage of the wood fibres caused by stresses in the standing tree or by felling and handling of the log. It is not caused by shrinkage during drying.

A condition of stress or strain where parallel planes slide relative to each other.

A structural component used to transfer shear forces between two different materials, ensuring they act together as a composite unit—most commonly between steel and concrete or timber and concrete in composite construction. A shear connector resists slipping or separation between two connected structural elements by transferring horizontal (shear) loads at their interface.

A shear panel is a wall or part of a structural system designed to resist shear forces and prevent deformation of the frame under lateral loads.

A prefabricated steel plate or bracket, often with punched or pressed teeth, holes, or tabs, used to secure connections between wood elements—providing strength, alignment, and load transfer.

The reduction in dimension or volume which takes place in timber when the moisture content is reduced below fibre saturation point, expressed as a percentage of the original dimensions or volume. Linear shrinkage occurs in three directions radial, tangential, and longitudinal.

The bottom member of a door or window frame. It is usually angled to shed water.

The bottom-most horizontal component of a framed wall, typically anchored to the foundation slab or subfloor, providing a stable base for the vertical wall studs.

A single-plane sloped roof, typically pitched in one direction, offering a clean, simple aesthetic and effective water runoff.

Sliced veneer is a type of wood veneer made by slicing thin sheets from a log or flitch using a sharp knife, rather than sawing or peeling. This process produces very thin, high-quality layers of wood used for decorative applications.

A unit of timber. Synonymous with pack.

In timber and other wood products, the ratio of deviation of the grain from the long axis of a piece to the distance along the edge that this deviation occurs.

Timber derived from gymnosperm trees, mainly evergreens like pine, fir, and spruce, which grow relatively fast and have a simple cell structure compared to hardwoods.

Segregation of sawn wood items into groups that have similar characteristics, such as thickness, species, grades, and grain patterns, and into classes for stacking or racking, such as width and length.

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

A space frame (or space structure) is a lightweight, three-dimensional structural system made of interconnected linear elements, typically arranged in a triangular or tetrahedral pattern. It is designed to distribute loads efficiently in multiple directions, making it ideal for covering large, open spaces without internal supports.

A species is a distinct type of tree (or other organism) defined by shared genetic and physical traits. In timber, different species yield wood with unique strength, durability, appearance, and workability.

The ratio of the density of a wood species to the density of water, typically measured when the wood is oven dry. See also: basic density.

Specific Gravity = Density of wood​ / Density of water (1 g/cm³)

A form of cross grain in timber in which the fibres take a spiral course about the trunk of a tree instead of the normal vertical course. The spiral may extend in a right-handed or left-handed direction around the tree trunk.

To join the ends of timber elements together.

A defect that occurs when tensile stresses cause the wood fibres to separate and form cracks. Splits are cracks that extend through a piece.

A longitudinal curvature of the edge of a piece of timber, not affecting the face.

A long, gentle bend along the length of a timber piece, viewed when the board is laid flat—causing it to arc sideways rather than lying straight.

SPF refers to a group of softwood species—usually white spruce, lodgepole pine, and subalpine fir—that are harvested, graded, and sold together due to their comparable characteristics.

Water vapour—a colourless gas formed when water is heated above its boiling point and vaporizes.

Steaming treatment is the process of subjecting timber to hot steam, usually in a kiln or chamber, to modify its physical properties, stabilize color, or make the wood more pliable for shaping or drying. See also: reconditioning.

Indentation or compression of the timber or other wood product by the rack stick (used for drying) when the load above is too great for the bearing area. Sticker marks or sticker stain also refers to light areas under the rack stick that form as the rest of the timber darkens.

A supporting element, such as a timber block, steel plate, or rib, that is added to increase the rigidity of a structural member and prevent deflection or local failure.

A stitch bolt is a mechanical fastener that passes through two or more pieces of timber to stitch them together, enhancing composite action and structural integrity in built-up timber assemblies.

Refers to wood in which the fibres (grain) run parallel to the length of the board or log. It’s a desirable grain orientation for many structural and aesthetic applications due to its uniform appearance and predictable performance.

The ability of a member to sustain stress without failure.

Species of timber are classified into groups according to mechanical properties of the wood of that species and AS 2878, Timbers - Classification into Strength Group. There are seven strength groups for unseasoned timber (S1 the strongest to S7 the weakest) and eight for seasoned timber (SD 1 the strongest to SD 8 the weakest).

1. A beam that joins the top of columns and supports the cross members in floors and ceilings.
2. An inclined member that supports the treads of a stair.
3. A deck element in timber bridges that supports transverse deck planks and runs parallel to the beam span.

Structural timber refers to timber products that meet engineering standards (like AS/NZS 1748 or AS 1720 in Australia) for use in applications where the timber must support loads or structural forces.

A structural timber resisting compressive forces along the grain.

A stud is a vertical piece of timber or metal used in framed wall construction to create a rigid structure and support loads or internal finishes.

Superheat is the condition where air or steam is heated beyond the saturation (boiling) point, making it capable of absorbing more moisture from timber during the drying process.

Diagonal or cross-bracing components designed to resist lateral loads and prevent side-to-side motion (sway) in a structural frame.

An increase in the dimensions of wood resulting from an increase in moisture content. Swelling occurs tangentially, radially, and, to a lesser extent, longitudinally.

A swirl figure is a grain pattern in timber that looks like whorls, waves, or swirling lines, typically resulting from abnormal grain direction due to knots, burls, or growth stresses.