Glossary

Timber that is sawn so that the growth rings are inclined at less than 45 degrees to the wide face.

A rigid or flexible barrier used to direct and control the flow of air.

In timber drying, a group of timber with similar drying and product characteristics.

Structural member, other than a triangulated frame, which supports load primarily by its internal resistance to bending.

A bearer is a primary load-bearing timber or beam placed horizontally, typically used in timber-framed floors, to support joists and distribute loads to the supporting structure below.

A raised strip of land, soil, or other material, often used in landscaping, construction, or environmental management to control water flow, provide support, or serve as a barrier.

A bevel is an edge or surface that has been cut at an angle other than 90 degrees to the adjacent face, commonly used in timber joints, trim work, and finishes.

The breaking down of timber by natural or biological agents such as fungi and insects.

Biodiversity is the variety of all life forms: the different plants, animals, and micro-organisms, their genes and the ecosystems of which they are a part. Biodiversity underpins the processes that make life possible.

The term used to describe all living things in a defined environment, including both flora (plant life) and fauna (animal life).

Bird’s eye refers to a distinctive grain pattern found in some hardwoods. It is the figure on the surface of wood that has numerous rounded areas resembling small eyes.

A bird’s mouth is a V-shaped or L-shaped notch cut at the end of a rafter, allowing it to rest snugly on the wall top plate and provide a strong, seated connection.

In the timber and construction industry, a board refers to a flat, rectangular piece of sawn, dressed, or manufactured wood, typically used in building, furniture, flooring, or cladding applications.

A boreal forest is a cold-climate forest found in the northern hemisphere, dominated by coniferous species, with long, cold winters and short, mild summers.

A botanical name is the formal scientific name conforming to the International Code of Botanical Nomenclature (ICBN) and, if it concerns a plant cultigen, the additional cultivar and/or group epithets must conform to the International Code of Nomenclature for Cultivated Plants. The botanical names of Australian and imported species of timber and their relationship to trade names are defined in AS 2543 Nomenclature of Australian Timbers and AS 1148 Nomenclature of Commercial Timbers Imported into Australia.

Refers to the water held within the cell walls of the wood, as opposed to free moisture, which is held in the cell cavities (lumens).

Moisture that is held within the cell walls of wood through molecular attraction. The water is weakly bound chemically to the molecules of the cell wall and energy is required to break them free. It is different from free water, which is found in the cell cavities (lumens) and is not chemically bonded to the wood structure.

A curvature in the longitudinal direction of a board causing the wide face to move away from a flat plane. It is a type of warp that occurs when a piece of timber bends along its length, creating a curved or arched shape when viewed from the side.

A bowstring truss is a curved-top, straight-bottom truss designed to distribute loads efficiently across wide spans—often used in roof systems for warehouses, gymnasiums, aircraft hangars, and industrial buildings.

A closed-section structural member formed by connecting flat components (like timber planks, LVL, or steel plates) into a rectangular hollow box, offering high bending and torsional resistance.

Secondary structural elements that do not support gravity loads but do provide stability and resistance to forces such as wind, earthquakes, or lateral loads. It helps prevent a building or structure from racking, swaying, or collapsing by keeping it square and rigid.

Bracing installed between floor joists to stiffen floors and distribute live loads.Also called cross-bridging.

In wood, any decay caused by fungi that attack cellulose rather than lignin, producing a light to dark brown friable residue.

The Building Material Ecological Sustainability Index (BMESI) is based on life cycle assessment (LCA). BMESI is a tool or metric used to assess the environmental impact and sustainability of building materials over their entire life cycle. It typically combines several ecological criteria into a single score or index to help architects, builders, and specifiers make informed, environmentally responsible choices.

1. A hard, woody outgrowth on a tree, more or less rounded in form, usually resulting from the entwined growth of a cluster of buds. Such burls are the source of the highly figured burl veneers used for purely ornamental purposes.

2. In lumber or veneer, a localised severe distortion of the grain generally rounded in outline.

The ability of a building material or construction system to resist ignition, fire spread, and structural damage during a bushfire event. In timber construction, bushfire performance is assessed based on compliance with Australian Standard AS 3959: Construction of buildings in bushfire-prone areas, which assigns Bushfire Attack Levels (BALs). Timber products must meet specific requirements for flame resistance, ember protection, and radiant heat exposure to be used safely in designated BAL zones.

A butt joint is a basic connection in which the end of one piece of timber is butted up against the face, end, or edge of another and fastened using nails, screws, dowels, or glue.