Glossary

Parallel to the growth rings of the tree, or perpendicular to the radius, following the curvature of the annual rings.

Taper is the change in cross-sectional dimension (usually diameter or width) of timber along its length, typically measured as reduction per unit of length (e.g. mm per metre).

A temperate forest is a forest ecosystem that occurs in mid-latitude regions, where the climate supports deciduous, evergreen, or mixed forests, depending on the region and rainfall. A temperate forest usually includes numerous kinds of trees and is distinguished from a tropical rainforest by the presence of a dominant tree.

Temperature is a measure of the thermal energy (heat) of a substance or environment. In the timber industry, temperature is critical for processes like kiln drying, moisture control, and timber preservation.

A state or condition of being pulled or stretched by a force.

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.

Whitish ant-like social insect of the order Isoptera found in warm and tropical regions. Some species feed on wood, causing damage to furniture, buildings, and trees.

Characteristic determined by the size and quality of the wood elements. Descriptive terms include fine, medium, uniform, even, uneven, coarse.

A measure of how well a building or material maintains comfortable indoor temperatures by resisting heat transfer. In timber construction, thermal performance refers to the insulating properties of timber and how it contributes to energy efficiency by reducing heating and cooling demands. Key factors include thermal conductivity, building envelope design, insulation, glazing, and air tightness. Thermal performance is assessed using energy ratings and compliance with Section J of the National Construction Code (NCC).

A tie is a tensile element used to connect and stabilise parts of a structure, often preventing components like walls or arches from moving apart under load. It is a structural member resisting tension forces along the grain.

A tied arch is an arch in which the ends are connected by a tie (often a beam) that carries the horizontal forces in tension, allowing the arch to transfer vertical loads efficiently without spreading at the base.

Timber is wood that has been harvested from trees and prepared for use in construction, joinery, furniture, and other applications.

A method of joining two flat timber boards by inserting the tongue of one board into the groove of another, commonly used in flooring, wall paneling, and decking.

Toughness is the capacity of timber to withstand impact or sudden loading without cracking, splintering, or failing — it reflects how well the material can absorb energy before failure. Specific toughness classification are set out in AS 1720.2 —2006, titled Timber Structures – Part 2: Timber Properties. The toughness data in AS 1720.2 is essential for engineers and designers when selecting timber for applications where resistance to impact or sudden loads is critical. 

A tracheid is a long, narrow, hollow wood cell with thick walls that conducts water vertically through the tree and contributes to the strength and stiffness of timber. They constitute the greater part of the structure of the softwoods and are also present, but uncommon, in some hardwoods.

The accepted regional names given to particular species by industry. Trade names are standardised in AS 2543, Nomenclature of Australian Timbers and AS 1148, Nomenclature of Commercial Timbers imported into Australia.

Timbers sawn so that there are both back sawn and quarter sawn sections in the piece.

The horizontal component of a stair that forms the surface of each step and supports the weight of users moving up or down the stairs.

Triangulation is the use of triangular arrangements of structural members to ensure rigidity and stability in a frame or structure, as triangles are the only shape that cannot be deformed without changing the length of a side.

A trimmer is a timber beam or joist that is installed to support the ends of cut or interrupted framing members, transferring loads around an opening. It is the structural member on the side of a framed rough opening to narrow or stiffen the opening.

A truss is a rigid structure composed of straight members connected at joints (nodes), arranged in triangles, which efficiently transfer loads through tension and compression. Primary stresses are axial so that if loads are applied at the joints, the stress in each member is in the direction of its length.

A trussed arch is an arched structure made up of interconnected triangular units (a truss) that work together to distribute loads efficiently along the curve of the arch. Used in large-span roofs, sports halls, agricultural buildings, and architectural pavilions.

A trussed beam is a composite structural member made by connecting a top and bottom chord with a web of diagonal and vertical members (forming a truss), creating a strong and efficient beam structure. Commonly used in roof trusses, floor systems, bridges, and long-span structures. 

(See also barrup truss). 

A spiral distortion along the length of a piece of timber.