Glossary

Absolute humidity is the mass of water vapour (in grams) contained in 1 cubic metre (m³) of air, typically expressed as g/m³.

An abutment is a structural support that anchors and stabilises the end of a span—such as a bridge or arch—by absorbing and transferring loads to the foundation or surrounding soil. The intermediary supports are called piers.

The ability of a building material or construction system to control and reduce sound transmission. In timber construction, acoustic performance refers to how effectively the structure isolates airborne and impact noise between spaces, contributing to occupant comfort and compliance with building standards. Key factors influencing acoustic performance include material density, panel thickness, insulation, junction detailing, and floor/ceiling system design.

Working or applying force at a right angle (90°) to the natural alignment of wood fibres, which can significantly affect strength, appearance, and performance.

Forces or actions that are applied to a structure and must be considered in its design. In timber construction, action loads include dead loads (permanent/static, such as the weight of the structure itself), live loads (temporary/movable, like occupants or furniture), wind loads, snow loads, earthquake forces, and other environmental or accidental actions. Structural engineers assess these loads to ensure the safety, stability, and performance of timber buildings in accordance with the Australian Standards and the National Construction Code (NCC).

A substance used to bond two surfaces together.

The visual and sensory qualities of a material or structure that contribute to its overall attractiveness and design harmony. In timber construction, aesthetic appeal refers to the natural beauty, warmth, grain patterns, colour, and texture of wood, which can enhance both interior and exterior environments. It plays a key role in architectural design, influencing material selection and user experience.

A global framework developed by the United Nations to guide sustainable development at local, national, and global levels, addressing issues like deforestation, pollution, poverty, and urban growth.

The velocity of air in the passages between rows of boards in a rack.

Timber that is dried by exposure to air in a yard or shed, without artificial heat. See also: seasoning.

The direction parallel with the length of the fibres and other longitudinal elements of the wood.

A type of fastener used to attach structural or non-structural elements to concrete. It provides a secure, load-bearing connection between concrete and items like steel columns, timber posts, machinery, or framing systems.

Instrument for measuring the velocity of airflow.

Anisotropic materials have direction-dependent properties, meaning their mechanical or physical behavior changes based on the direction of the force or measurement.

Anti-kickback fingers are pivoting metal or hardened steel teeth that grip and hold timber as it's fed through a machine, allowing movement in one direction only and preventing reverse motion that could cause a dangerous kickback.

An anti-stain chemical is a fungicidal treatment used to protect green (unseasoned) timber from sapstain, bluestain, and mould growth, especially during the early stages after harvesting.

The classification of timber based on its visual characteristics, such as knots, grain, colour, and surface blemishes, rather than its structural strength. Appearance grading is used when timber is exposed in a finished application and aesthetics are a key consideration—such as in interior linings, flooring, or furniture. Grading rules vary by species and product type and are set out in relevant Australian Standards, ensuring consistency and quality in appearance-based applications.

A curved structure resting on supports at each end that supports loads primarily in compression.

The external corner or sharp edge formed where two surfaces or planes intersect, often seen along the edges of sawn or machined timber, stone, or concrete elements.

In the context of timber, construction, or sustainability, an attribute refers to a distinct characteristic or feature of a material, product, or process that can be used to describe, assess, or differentiate it.

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.

A slight, intentional curve or upward arch built into a structural element—usually a beam, joist, or lintel—to counteract deflection under load or improve appearance.

A thin layer of tissue between the bark and wood that repeatedly subdivides to form new wood and bark cells.

A projecting structural member that is rigidly fixed at one end, with the other end extending freely beyond its support.

Measures moisture content by sending a low-frequency electromagnetic field into the timber and sensing changes in capacitance (how the material stores electrical energy), which correlates with moisture levels.

Any natural or artificial system that absorbs and stores more carbon dioxide (CO₂) from the atmosphere than it releases, helping to reduce the effects of climate change.

A drying defect characterised by the presence of compression stresses in the outer zone and tensile stresses in the core. It occurs when rapid drying has caused permanent set of the outer zones of a piece of wood and when the outer layers of timber dry and shrink faster than the inner core, causing internal stresses that can lead to problems during machining or further drying.

A natural, water-based adhesive created from milk protein (casein), known for its strong bond, good water resistance (when properly formulated), and long open time for assembly. It was historically used in plywood manufacturing and has some resistance to water but is not waterproof.

It’s a visual grain pattern formed when wood is flat-sawn (also known as plain-sawn). It is created by cutting tangentially to the growth rings of the log which exposes curved growth rings in the surface, producing the characteristic arched pattern.

Copper Chrome Arsenate, a chemical wood preservative used to protect timber from decay, termites, fungi, and other biological hazards.

In wood anatomy, a general term for the minute units of wood structure that have distinct walls and cavities, including wood fibres, vessel segments, and other elements of diverse structure and function. In dense hardwoods, the fibre cells are thick walled and make up a major part of whole zones of wood. These fibrous zones dry slowly. The arrangement, size, and type of cells affect wood properties like strength, durability, density, grain and texture, moisture movement and drying behavior.

Wood cells are mostly made of:

• Cell walls (composed of cellulose, hemicellulose, and lignin)
• Lumen (the hollow central cavity that may carry water)

The carbohydrate that is the principal constituent of wood and forms the framework of wood cells.

Forest certification refers to the assessment of forest management by an independent third party auditor according to performance criteria for sustainable wood production. The certifications recognised in Australia are:

Responsible Wood is a Standards Australia accredited standards development organisation and is the representative of the Programme for Endorsement of Forest Certification (PEFC) in Australia. The Forest Stewardship Council (FSC) is a non-governmental, international organisation that is dedicated to promoting the responsible management of the world's forests. Find out more about certification and responsible sourcing here.

The documented process of tracking wood or wood-based products through every stage of the supply chain—from the forest of origin to the final product—to ensure they come from responsibly managed forests.

A separation of fibres along the grain forming a fissure but not extending through the piece from face to face. Checks commonly resulting from stresses built up during seasoning. They run radially, across the growth rings and are a lengthwise separation in the wood, typically starting at the surface and extending along the growth rings, caused by the wood shrinking unevenly as it dries.

A wedge-like, sharp-edged tool used for cutting or shaping timber.

Especially in timber or steel framing—a chord is a primary structural member that forms the top or bottom edge of a truss, beam, or structural framework. The term also applies to beam flanges or the perimeter members of a plywood diaphragm.

The external layer or material applied to the outside of a building to provide protection, insulation, and aesthetic appeal. It acts as a skin or envelope, shielding the structure from weather while contributing to its visual appearance. Timber cladding includes natural or treated timber boards and plywood.

The clear horizontal distance between the supports of a load bearing member.

A cleavage test measures the resistance of timber to splitting along its grain—specifically in the radial and tangential planes—by applying a force that attempts to separate or split the wood longitudinally.

An architectural feature consisting of a high section of wall that contains windows above eye level, usually located near or at the roofline. Its main purpose is to bring natural light and ventilation into the interior of a building, particularly in large or deep spaces where side windows alone aren’t sufficient.

Wood with narrow, inconspicuous growth rings. The term is sometimes used to designate wood having small and closely spaced pores, but in this sense the term "fine textured" is more often used.

(also known as a lag screw or lag bolt) is a heavy-duty screw with a hexagonal head, designed for joining heavy timber or fixing timber to masonry or metal. It is driven using a spanner or socket wrench, rather than a screwdriver.

Wood with widely spaced and prominent growth rings, which results in a distinct, bold grain pattern. The term describes both the visual appearance and the texture of the wood surface. It is usually caused by fast tree growth and the contrast between earlywood (lighter, less dense) and latewood (darker, denser) becomes more pronounced.

The flattening of single cells or rows of cells during the drying or pressure treatment of wood. Often characterised by a caved-in or corrugated ("washboarded") appearance of the wood surface.

A collar tie is a horizontal structural member used in roof framing to help resist the outward thrust of the roof rafters and prevent the roof from spreading.

A vertical structural element that transfers loads from above (like floors or roofs) down to the foundation.

A force that pushes or squeezes material together, causing it to shorten or compact. It is one of the primary types of stress that materials—like timber, steel, or concrete—experience in structural applications.

A type of structural damage in timber that occurs when the wood is crushed or buckled under compressive stress—usually along the grain.

A fabricated or cast metal bracket into which timber structural members abut, used to joint timber compression elements to other structural members.

A controlled process used to equalise moisture content and relieve internal stresses in timber after or near the end of drying—especially kiln drying.

Conservation is the responsible management and protection of natural resources to ensure they are available for future generations. It involves maintaining the health, biodiversity, and function of ecosystems while allowing for sustainable use where appropriate. In the context of forests, conservation means sustainably managing forests and forest resources to preserve biodiversity (plants, animals, ecosystems), protect soil and water quality, prevent overharvesting and deforestation, ensure long-term wood supply through sustainable yield, and support carbon storage and climate regulation.

A metal connector or reinforcing strip used in timber or steel construction to maintain structural continuity across joints, particularly where elements need to transfer tensile or shear forces.

A planned, intentional gap or groove in a building material—such as concrete, masonry, or plaster—designed to control where cracking occurs due to shrinkage, temperature changes, or movement.

A length of timber laid horizontally on the top of a column to transfer loads and to provide a seat for beams. A compound corbel includes several lengths of timber instead of one.

An adjustment of the readings of the resistance-type electrical moisture meter to compensate for different species of wood. Corrections are tabulated in AS/NZS 1080 1:1997

A defined area of forest, usually with consistent characteristics.

A metal sleeve threaded internally and used to connect threaded rods or bolts.

The slow, continuous movement or deformation of timber (or any material) under a sustained load—even if the load is below the material’s strength limit.

In construction, particularly timber framing, a cripple (or cripple stud) is a short vertical framing member used to fill in spaces above or below a window or door opening, or between a header and top plate or a sill and bottom plate.

A criterion is a category of conditions or processes by which sustainable forest management may be assessed. A criterion is characterised by a set of related indicators that are monitored periodically to assess change. An indicator is a measure (measurement) of an aspect of the criterion. An indicator can be quantitative or qualitative variable which can be measured or described and which, when observed periodically, demonstrates trends.

A cut made across the grain of the wood, typically to shorten the length of a piece of timber.

An arrangement in which the fibres and other longitudinal elements of a piece of wood deviate from a line parallel with the edges of the piece. Cross grain may be either diagonal or spiral grain or a combination of the two.

CLT is an engineered wood product composed of three or more layers of timber boards laminated together, with each layer oriented perpendicular to the adjacent one, providing strength in both directions and excellent dimensional stability.

A method of slicing veneers whereby the average inclination of the growth rings to the wider face is tangential or less than 45 degrees. This method is also known as flat cut.

A shape or structure that resembles a cross—specifically one with four arms extending at right angles from a central point (like a "+" shape).

A concave curvature across the grain or width of the a piece of timber.

To change the properties of an adhesive by chemical reaction (which may be condensation, polymerisation, or vulcanisation) and thereby develop maximum strength.

The decomposition or deterioration of wood caused by fungi, leading to a loss of strength, structure, and appearance over time.

A flat surface or platform, typically made from timber, composite, or other materials, that is constructed outdoors and elevated from the ground. It is commonly used in residential, commercial, and public spaces as an extension of indoor living areas or as walkways, patios, or viewing platforms.

In timber and other forest products, the result of any process that lowers the value of the wood.

A dehumidifier kiln (also known as a DH kiln) uses a heat pump system to both warm the air inside the kiln and remove moisture from it by condensing water vapor—allowing timber to dry slowly and efficiently. 

How It Works:

• Air inside the kiln is warmed by a heat source (typically an electric heat pump).
• The warm air absorbs moisture from the timber.
• The moist air passes over a cold coil inside the dehumidifier unit.
• Moisture condenses into water and is drained away.
• The now dry, warm air is recirculated through the kiln to continue drying.

The separation of plies or laminations through failure of the bond, visible at an edge.

As applied to timber, density is the mass of wood substance and moisture enclosed within a piece expressed in kilograms per cubic meter. As the mass will vary dependant on the amount of moisture in the piece, density is often expressed at a specified moisture content, usually 12%.

The difference between dry and wet bulb temperatures. It is a measure of humidity.

The temperature at which air becomes fully saturated with water vapour, causing condensation to form. In simpler terms, it’s the temperature at which moisture in the air turns into liquid water—like dew, fog, or condensation on surfaces.

Diagonal grain occurs when the natural grain direction of the wood runs at an angle to the edges or axis of the board, rather than straight along its length.

The change of a square or rectangular section timber to a diamond shape during drying. Diamonding occurs where the growth rings pass through diagonal corners of the section of the piece and is caused by the difference between tangential and radial shrinkage. It is a form of distortion.

In building and structural engineering—especially in timber or framed construction—a diaphragm is a horizontal structural element, like a floor or roof, that transfers lateral loads (such as wind or earthquake forces) to the vertical resisting elements (like shear walls or frames).

Movement of water through wood from points of high moisture content to points of low moisture content by molecular diffusion.

A measure of the rate of moisture movement through wood by diffusion as a result of differences in moisture content

In timber and construction, dimension refers to the measured size of a piece of timber, and it can vary depending on whether the timber is nominal, sawn, or machined (dressed). These terms describe how the size is defined and altered through processing.

1. Sawn - The size of the timber after being sawn from the log, but before further processing like drying or dressing. It may still be rough and slightly oversized.
2. Nominal - The original or theoretical size of the timber when it is first cut from the log, before drying or machining. It’s often a rounded figure and larger than the final size.
3. Machined - The final size of the timber after planing or machining, which smooths the surfaces. This is the actual size used in construction and can be significantly smaller than the nominal size.

Changes in the size of a piece of dry timber as its moisture content changes to be in equilibrium with the surrounding atmospheric conditions.

Submerging timber in a dipping vat containing fungicides or other chemicals to prevent stain or decay.

Change in the colour of wood caused by fungal or chemical stains, weathering, or heat treatment.

A drying defect caused by the differential shrinkage along the three axes of a piece of wood. Distortion may take the form of cup, bow, twist, spring, or diamonding.

A cylindrical timber rod or steel bar generally without nut or thread driven into pre-drilled holes to make a joint.

A mechanical connection formed by inserting one or more dowels into corresponding holes drilled into two adjoining wood members, then gluing and clamping them for a tight fit.

Timber that has been surfaced by planing or machining to remove roughness and ensure consistent dimensions, making it suitable for visible applications or precision joinery.

A generic term for the decay of timber by fungi that at an advanced stage leaves the wood light and friable. The term is actually a misnomer as all fungi needs considerable moisture to grow.

The dry-bulb temperature is the actual air temperature, measured by a standard thermometer exposed to the air but shielded from radiation and moisture.

A dryer is a controlled environment system—such as a kiln or dehumidifier unit—used to reduce the moisture content of timber to a desired level for its intended application.

The process of removing moisture from timber to improve its serviceability in use. Also see: Seasoning.

An imperfection developing during drying that decreases the value of a piece of timber.

A reduction in timber grade and volume as a result of drying defects.

High-temperature drying involves drying timber at temperatures above the boiling point of water, often in the range of 100–130°C, to speed up drying time, reduce costs, and increase throughput in kiln operations.

The material or value lost during the drying of timber, caused by moisture removal and the physical or mechanical damage that may occur in the process.

The loss of moisture from timber or other wood products per unit of time. Drying rate is generally expressed in percentage of moisture content lost per hour or day.

The internal stresses that develop within timber as it dries, caused by uneven moisture loss between the surface and the core. These stresses can lead to defects such as warping, checking, case hardening, and even structural failure if not managed properly.

1. Durability is the natural resistance of timber to biological degradation such as fungal decay, termites, and borers, without the need for chemical treatment.

2. The capacity of a building or its components to perform as intended over time, resisting physical, chemical, and environmental deterioration, with minimal maintenance.

Durability class refers to a timber species’ natural resistance to biological degradation, such as fungi, termites, and borers, especially in untreated form.

Durability is expressed as one of four classes. The value for each species is based on trials of the resistance to both decay and termites of untreated heartwood in the ground. The classes are: Class 1- Timber of the highest natural durability, expected to have a life greater than 25 years in the ground and greater than 40 years exposed above ground;  Class 2 - Timber of high natural durability, expected to have a life of about 15 to 25 years in the ground and 15 to 40 years exposed above ground;  Class 3 - Timber of  moderate natural durability, expected to have a life of about 5 to 15 years in the ground and 7 to 15 years exposed above ground; and Class 4 - Timber of low durability, expected to have a life of 0 to 5 years in the ground and 0 to 7 years exposed above ground. The sapwood of all species is regarded to be Class 4. 

The Building Code of Australia (BCA) requires building material in some building application to have particular characteristics in the early stages of a fire.

These are set out in three indexes:

1. ignitibility index (scale 0-20)
2. spread of flame index (scale 0-10)
3. smoke developed index (scale 0-10)

Specification A2.4 of the BCA calls up tests from AS 1530.2 & 3 to establish the index ratings for materials.

Earlywood (also known as springwood) is the first-formed wood in an annual growth ring, produced when growth conditions (like water and sunlight) are optimal. It is the less dense and larger-celled.

A force acting away from the centroid (or axis) of a structural element, which induces a combination of axial and bending stresses.

Eco-labeling is the process of labelling products with officially recognised symbols or certifications that indicate they meet verified environmental performance criteria, helping consumers make informed, sustainable choices.

The outcomes or impacts—positive or negative—on the structure, function, and biodiversity of ecosystems caused by changes in the environment, land use, species populations, or resource use.

In relation to forest management, ecological sustainability is defined in Australia as "integrating commercial and non-commercial values of forests so that the welfare of society (both material and non-material) is improved, whilst ensuring that the values of forests, both as a resource for commercial use and for conservation are not lost or degraded for current and future generations". This definition has been provided by the Forestry Working Group on Ecologically Sustainable Development (1991) and adopted by the National Forest Policy Statement (1992).

An ecosystem is a biological system made up of all the organisms in a particular area and their physical environment, interacting through energy flows and nutrient cycles. Healthy ecosystems are necessary for maintaining and regulating atmospheric quality, climate, fresh water, marine productivity, soil formation, cycling of nutrients and waste disposal.

Conductive probes inserted into or placed against wood to pass a small electrical current and measure resistance or capacitance, which is then used to calculate the moisture content.

Embodied energy is the sum of all the energy used in the entire lifecycle of a product up to the point of installation, but not including its use, maintenance, or disposal. The embodied energy of a material is usually expressed in the units MJ/kg and that of a sheet building component or element MJ/m².

A coating of moisture-resistant material applied to the end grain of green logs or sawn boards to slow end drying.

The grain shown on a cross cut surface.

A useful management tool that may form part of an overall environmental management system. This process entails a systematic and objective evaluation of how the organisation is performing in relation to its policies, regulatory requirements, environmental management systems, and practices.

Environmental impact assessments predict environmental impacts of a new development at the design stage. They may be required by Commonwealth, State, or Local government legislation dependent upon the scope of the project.

The effects that human activities, natural processes, or industrial operations have on the environment—including air, water, land, ecosystems, and biodiversity.

A set of processes and practices that enable an organisation to reduce its environmental impacts and increase operating efficiency. Formal systems include those prescribed by ISO 14001 and 14004.

Formed by inserting dowels into aligned holes between timber members and injecting epoxy resin to permanently bond the dowels, creating a strong, precise, and load-bearing connection.

A structural or non-structural connection formed by applying epoxy adhesive between two materials (often timber), which then cures to form a rigid, high-strength bond.

In kiln drying, a high humidity treatment in the final stages of drying intended to reduce the moisture content range between pieces of timber and the moisture gradient within pieces of timber. Also known as equalising.

The moisture content at which timber neither gains nor loses moisture from the surrounding atmosphere.

Plywood of naturally durable or treated veneers bonded with waterproof adhesive and capable of withstanding prolonged exposure to severe exterior conditions without failure of the glue-lines.

Non-structural chemical compounds found in wood that can be removed (extracted) using solvents like water, alcohol, or acetone. Unlike cellulose, hemicellulose, and lignin (which form the wood's structure), extractives are secondary substances that vary widely between species.

The process of driving nails directly into the broad, flat face of a wood board to fasten it to another piece, often used in framing, decking, or temporary construction.

The finishing board fixed to the ends of roof rafters or trusses, running along the edge of the roofline. It supports the bottom row of roof tiles or sheeting and provides a mounting surface for gutters.

Any irregularity or imperfection in a tree, log, board, or other wood product. Feature may result from knots and other growth conditions and abnormalities, insect or fungus attack, or during timber processing.

A type of cell in wood, especially in hardwoods, that provides mechanical support. These cells are elongated, thick-walled, and usually dead at maturity.

The point in the seasoning or wetting of timber at which the cell cavities are free from water but cell walls are still saturated with bound water. It is taken as approximately 25-30% moisture content.

A generic term including sheet materials of widely varying densities manufactured from refined or partially refined wood or vegetable fibres. Bonding agents and other materials may be added to increase strength or to improve other properties.

Figure in timber or veneer produced by small, regular undulations in the grain

The visible pattern in wood grain, often highlighted when the wood is cut, planed, or finished. It results from variations in grain direction, growth conditions, knots, and cell structure.

A strong, precision-cut joint where a series of interlocking rectangular profiles are cut into two timber pieces and bonded with adhesive to create a longer or stronger section.

FRL is a three-part rating that indicates how long a building element can maintain its structural adequacy, integrity, and insulation when exposed to fire, typically expressed in minutes (e.g., 90/60/30).

A strip of impervious material fitted to provide a barrier to moisture movement into the interior of a building.

Also called modulus of rupture (MOR), is the maximum stress a material can withstand before breaking in bending.

A large piece of log, sawn on at least two surfaces, intended for further cutting.

A floorboard is a plank or board, typically made of solid timber, engineered wood, or laminated materials, used as part of a finished flooring system.

The covering of internal floors in a building. Timber flooring includes tongue and groove strip flooring, parquetry, panel flooring, particleboard, and plywood.

A structure composed of multiple flat plates connected at angles, forming a continuous, self-supporting shape that can span large distances without intermediate supports.

The total area of land designated for forest use, either for conservation, timber production, recreation, or a mix of purposes.

The planned and regulated actions taken in the establishment, harvesting, maintenance, and regeneration of forests to ensure sustainable land management and ecosystem health.

The Forest Stewardship Council® is an international certification system that promotes responsible forest management by evaluating and accrediting forests and forest product supply chains according to rigorous environmental and social criteria.

A frame is the load-bearing structure of a building, made up of interconnected members such as beams, posts, studs, and joists, designed to support floors, walls, roofs, and other elements. Usually made from sawn or engineered timber and can be assembled on-site (stick framing) or off-site (prefabricated). Includes wall frames: studs, plates, noggings, floor frames: joists, bearers, roof frames: rafters, trusses. 

Timber that is specifically processed and graded for use in the structural framework of buildings, such as walls, floors, ceilings, and roofs. It forms the skeleton of a structure and must meet strength and durability standards appropriate for load-bearing and bracing applications.

Free moisture is the liquid water present in the open spaces (cell lumens and voids) within wood. It evaporates first during drying, before the moisture that's chemically bound to the cell walls.

Fungus (plural: fungi) refers to a group of living organisms—including moulds, yeasts, and mushrooms—that play a key role in the natural decomposition of organic matter, including wood. In the timber and construction context, fungi are most often associated with wood decay, rot, and mould growth, especially in moist environments.

A green shrinkage allowance is the extra thickness or width added to the nominal dimensions of an unseasoned (green) timber board to compensate for shrinkage that will occur during the drying (seasoning) process.

A structural form based on geodesic geometry—specifically using a network of interconnected triangles to form a strong, lightweight, and stable dome or curved surface.

A liquid or paste adhesive that forms a strong bond between wood surfaces when cured or dried, often used in laminating, veneering, or assembling timber products.

Glulam is a structural engineered timber product made by laminating timber boards together with durable, moisture-resistant adhesives, all aligned in the same direction to form a strong, stable member for load-bearing construction.

The designation of the quality of a piece of timber or other manufactured wood products in accordance with standard rules.

Grain is the alignment and appearance of wood fibres in a piece of timber, influencing its strength, workability, and aesthetic appeal.

A green building is a structure that is environmentally responsible and resource-efficient throughout its life cycle—from planning and design to construction, operation, maintenance, renovation, and demolition.

Green timber is wood that has been recently harvested and has not yet been dried, meaning it still holds a significant amount of bound and free moisture from the living tree.

A grillage is a layered grid of beams, often used beneath columns or footings, to spread structural loads over a larger area of ground or foundation material.

Growth rings are the concentric circles in wood formed by the tree’s growth over each year, typically consisting of a light earlywood band (spring growth) and a dark latewood band (summer/autumn growth).

A natural exudation, also called kino, produced in trees as a result of fire or mechanical damage.

A ribbon of gum between growth rings, which may be bridged radially by wood tissue at intervals. Also known as kino

Plates, often steel or plywood, fixed by nails, bolts, or other means to connect timber members in a truss or other frame structure. Gusset plates may be applied to one or both sides of a joint.

A pressed homogenous fibreboard having a mean density of not less than 800 kg/m².

The measure of a wood’s resistance to surface deformation, especially from localized pressure or impact. It’s an important property for flooring, furniture, and other wear-prone surfaces. The most widely used way to measure is the Janka Hardness Test.

Timber derived from deciduous or broadleaf trees (angiosperms), known for having a denser grain structure. It is typically strong and durable.

The wood making up the centre part of the tree, beneath the sapwood. Cells of heartwood no longer participate in the life processes of the tree. Heartwood may contain phenolic compounds, gums, resins, and other materials that usually make it darker and more decay resistant than sapwood.

Wood that has been manually cut and shaped, usually from a round log into a squared or flattened beam, using hand tools like axes, adzes, or broad hatchets.

1. Large-headed nails used in heavy-duty timber fixing or decorative applications.
2. May also describe a textured or studded finish on a surface (e.g., hobnail glass or decorative cladding patterns).

A drying defect which occurs when tensile stresses in the core (usually because of collapse) result in the formation of internal cavities.

Timber that is laminated layer by layer in a horizontal orientation (with laminations lying flat), bonded with structural adhesives to create a strong, stable composite element.

A joint where one piece is notched or grooved to receive the other piece.

A device for automatically regulating the relative humidity of air.

A general term for the presence of water vapour in air. There is a known limit to the amount of water vapour that air can hold at any particular temperature.

An instrument for measuring the humidity of air.

A hygroscopic material is one that naturally takes up and releases moisture from the air, seeking equilibrium with the ambient relative humidity.

A device for automatically regulating the equilibrium moisture content of the air. See also: Humidistat.

A hyperbolic paraboloid shell is a thin, curved structural form with a saddle shape, known for being strong, lightweight, and efficient—despite often being made from straight beams or timber members.

As applied to timber's moisture content, the tendency of dried wood to reach equilibrium with any specified temperature and relative humidity at a lower moisture content when absorbing moisture from a drier state than when losing moisture from a wetter state.

Grain where the angle of the fibres periodically changes or reverses in successive layers.

Grain where the fibres contort and twist around knots, butts, curls, and so on. Also called wild grain.

ISO 14000 is a series of standards that help organisations minimise their environmental impact, comply with environmental laws, and continually improve their environmental performance.

An isotropic material behaves consistently in all directions, with no variation in mechanical or physical properties regardless of the direction of applied force or stress.

The upright component forming the side of a door or window frame, helping support the structure and ensure proper installation and operation of the door or window.

A device used to set a dimension, angle, or shape for fabrication

Joinery is the specialised woodworking trade focused on making joints that connect pieces of timber in non-structural or semi-structural applications, often with an emphasis on precision, fit, and finish.

A prepared connection for joining pieces of wood or veneer.

Species of timber are classified into joint groups according to their mechanical properties. There are six joint groups for unseasoned timber (J1, the strongest to J6, the weakest) and six joint groups for seasoned timber (JD1 to JD6).

A horizontal support member that spans open spaces, typically supporting a floor, ceiling, or roof deck, and transferring loads to vertical structural elements like walls or beams.

The cut made by a saw blade.

Kerfing refers to the process of making a series of closely spaced cuts (kerfs) in a piece of wood to allow it to bend or flex more easily, or to describe the cut made by a saw blade itself.

Kerfing for Flexibility (Shaping Timber) - A woodworking technique where multiple shallow cuts are made across the grain to allow a straight piece of timber to bend.

Kerf as the saw blade cut width - Kerf also refers to the width of material removed by a saw blade during cutting.

A kiln is a controlled chamber used to artificially dry timber by applying heat, air circulation, and humidity control. The process, known as kiln drying, reduces the moisture content of timber to make it stable, strong, and suitable for use in construction, furniture, and manufacturing.

Kiln-dried timber is wood that has been dried using heat, airflow, and humidity control in a drying kiln, typically to a moisture content of 6–15%, depending on the end use.

A knee brace is a short, angled timber or metal brace placed between a post and a beam, forming a triangular structure that adds stability and strength.

A knot is the visible portion of a tree branch embedded in the surrounding wood of the trunk or main stem. In sawn timber, it appears as a circular or oval mark that can vary in size, shape, and firmness. The shape of the knot as it appears on a cut surface depends on the angle of the cut relative to the long axis of the knot.

Is a term used to describe the use of a label or certification mark that indicates that the timber product has been produced from a certified forest and the chain of custody verified. Labeling in this way relates only to the how the timber has been grown and manufactured, not the quality of the product or its fitness for purpose.

Laminated timber consists of thin boards or planks (lamellae) glued together, usually with the grain running in the same direction, to form a larger structural member.

Laminated Veneer Lumber (LVL) is an engineered wood beam or plank made by laminating multiple layers of thin wood veneer sheets together, with all grain aligned parallel, to form a strong, uniform material ideal for load-bearing applications.

A joint made by placing one member partly over another and bonding the overlapped portions.

The thermal energy required for a substance to change state (solid ↔ liquid ↔ gas) at a constant temperature and pressure.

A force applied horizontally to a structure in any direction, such as a force caused by wind or earthquake.

Movement in a structure that is perpendicular to the major axis of loading, i.e. usually horizontal movement

Latewood (also called summerwood) is the part of the growth ring formed after earlywood, consisting of smaller, thicker-walled cells, making it stronger and denser. It is the denser and darker portion of a tree’s annual growth ring, formed later in the growing season (typically in late summer or autumn).

Perfectly horizontal.

A Life Cycle Assessment (LCA) is a comprehensive method for evaluating the environmental impacts of a product, process, or activity across its entire life cycle — from raw material extraction to end-of-life disposal

Key Steps in an LCA:

• Goal and Scope Definition - What is being assessed and why.
• Inventory Analysis (LCI) - Quantifies inputs (materials, energy) and outputs (emissions, waste).
• Impact Assessment (LCIA) - Evaluates potential environmental impacts (e.g. global warming potential, water use, pollution).
• Interpretation - Draws conclusions and identifies improvement opportunities.

The sum of all energy inputs required to create, use, and ultimately dispose of or recycle a product or building over its full life cycle.

LOSP is a non-water-based wood preservative treatment that uses a light organic solvent (like white spirit) as a carrier for biocides, making it ideal for finished or machined timber products where dimensional stability is important.

A horizontal element below a window that reflects direct sunlight up onto a ceiling surface

In building and construction, lining refers to the internal covering of walls, ceilings, or other surfaces, typically made from timber, plasterboard, plywood, MDF, or composite panels. It provides both aesthetic finish and sometimes functional benefits like insulation, acoustic control, or fire resistance.

A live load is the non-permanent load on a structure that can move, change, or shift during its use, including people, furnishings, equipment, and vehicles.

Longitudinal means along the grain or in the direction of the wood fibres, usually from end to end of the tree or timber piece.

Loose assembled means that timber parts or components are fitted together without permanent fixing (e.g. glue, nails, or screws), allowing for easy transport, adjustment, or later final assembly. Timber elements are fabricated off site but not connected together until delivered to site just prior to installation.

A general term (mostly used in North America) for wood that has been processed into beams and planks—typically by sawing logs—for use in construction, furniture, and other wood-based applications.

A lumen is the inner space or hollow interior of a wood cell, especially in conductive cells like vessels, tracheids, and fibres, which helps in transporting water and storing materials.

a Lyctid borer (also known as a powderpost beetle) is a wood-boring insect from the Lyctidae family that attacks the sapwood of certain hardwoods, causing damage by reducing the timber to a fine, powdery dust.

Lyctid susceptibility describes the likelihood that a timber species will be attacked by Lyctid borers, based on the presence and accessibility of starch in the sapwood.

Timber sections fastened together using mechanical means (not glue) to form a larger composite element, typically used in floors, beams, or walls to improve structural performance.

An engineered wood product made by breaking down hardwood or softwood residuals into wood fibres, combining them with wax and resin binders, and pressing the mixture into dense, flat panels under heat and pressure. It is widely used in furniture, cabinetry, interior linings, and joinery.

A surface-level fungal growth that thrives in damp, stagnant conditions, feeding on organic matter like timber or drywall, and can lead to discoloration, musty odors, and early surface decay if left untreated. It usually appears as tiny black spots that cover the timber surface.

A mill is a manufacturing plant that converts logs into processed wood products through cutting, sawing, drying, grading, and sometimes chemical or mechanical treatments.

The weight of moisture contained in a piece of timber expressed as a percentage of the oven dry weight.

Categorizes timber into different levels of moisture (usually expressed as a percentage of the wood’s dry weight), helping ensure the timber is appropriate for its intended use or environment (e.g. interior, exterior, structural).

A progressive decrease (or increase) in moisture content between the core and the surface of a piece of wood.

An electric resistance moisture meter determines how much moisture is in timber by measuring the resistance to an electric current passed between two metal pins. Dry wood has high resistance, while moist wood conducts electricity more easily (lower resistance). They are usually calibrated for Douglas Fir. The reading must then be corrected for temperature and species.

The transfer of moisture from one point to another within wood or other materials.

An environment that has a single species of animal or plant dominant, usually associated with the artificial environments created by intensive agriculture.

A mortice and tenon joint is one of the oldest and strongest woodworking joints, used to connect two pieces of wood—typically at 90 degrees—by inserting a tenon (a protruding tongue) into a corresponding mortice (a slot or hole).

A fungal growth on timber or other wood products at or near the surface and, therefore, not typically resulting in deep discoloration. Mould is usually ash green to deep green, although black and yellow are also common. See also: Mildew.

The extent of expansion and contraction which occurs with dried wood as its moisture content responds to changes in relative humidity in service.

MRTFC is the design and construction of medium-density housing using timber structural framing, offering a cost-effective, sustainable, fire-rated, and code-compliant alternative to concrete or steel.

Nail-Laminated Timber (NLT) is an engineered wood product composed of dimensional lumber boards nailed together, typically used in floors, roofs, and walls for commercial and institutional buildings.

A nail plate connector (also known as a gang nail plate) is a stamped steel plate with embedded nails or teeth that mechanically fix timber members by being pressed or rolled into the surface, forming a strong, rigid joint.

A nail plate truss is a structural framework made from timber joined at the joints using metal plates with embedded nails or teeth, which are pressed into the timber to form strong, rigid connections.

A nail ring or ring shank nail is a mechanically fastened nail with circular grooves around the shank that provide extra grip when driven into wood.

(also known as a nog, dwang in New Zealand, or blocking in North America) is a short, horizontal bracing member placed between framing elements (such as studs or joists) to provide lateral support, reduce movement, and improve the stiffness and stability of the structure.

Nosing is the rounded, beveled, or squared front edge of a stair tread that extends slightly over the riser, improving both safety and aesthetics.

For the purposes of the National Forest Policy Statement, old growth forest has been defined as "Forest that is ecologically mature and has been subject to negligible unnatural disturbance such as logging, roading, and clearing". The definition focuses on forests in which the upper stratum or overstorey is in the late mature to over mature growth phases

A lightweight, triangulated structural system used in floors and roofs, consisting of top and bottom chords connected by open, diagonal or vertical web members, which create a rigid frame with voids for service routing.

Open-grained wood is timber with a surface texture that shows distinct pores or grain lines (also known as coarse textured), even after it has been sanded smooth. The surface may feel slightly uneven or have visible grooves.

Common open-grained woods: Oak, Ash, Mahogany, Walnut, Chestnut

A large, broadleaf deciduous tree known for its very large leaves, and its light-colored, fine-grained hardwood used in furniture, cabinetry, musical instruments, and veneers. The Indigenous Lakwungen people of Vancouver Island knew it as the ‘Paddle Tree’ and created paddles and spindle wheels from its wood.

Organic building materials are materials composed of or derived from carbon-based natural sources, such as wood, plant fibres, or animal by-products, often used in sustainable and climate-conscious construction.

Refers to a condition where all moisture has been completely removed from a piece of wood by drying it in an oven at a standard temperature (usually around 103–105°C) until it reaches a constant weight. 

What "oven dry" Means: Oven-dry wood = 0% moisture content. Used as a reference point to calculate the moisture content (MC) of timber.

The end of timber that is unsupported by rack sticks and extends beyond the ends of most pieces in an air-drying stack, rack, pack, or unit of timber.

A unit of timber units that have been grouped together for storage, handling, transport, or sale. It's a standard unit used in sawmills, warehouses, and construction supply to manage and move timber efficiently.

A strip of wood or another material that is placed between rows of timber or other wood products in a rack. Rack sticks are placed at right angles to the long axis of the timber to permit air to circulate between the layers. Also referred to as "sticker" or "stripper".

A parabolic arch is an arch in which the intrados (the inner curve) follows the shape of a parabola, typically opening downward and symmetric around its central axis. 

Why use a parabolic arch? It provides excellent structural efficiency, material efficiency, and visual elegance.

Flooring made up of small, matching pieces of timber laid on a substrate in a geometric patterns.

Particle board is an engineered wood product made from wood chips, sawmill shavings, or sawdust (ligno-cellulosic material bonded) that are mixed with a synthetic resin or binder and pressed into flat sheets under heat and pressure.

A party wall is a wall that sits on the boundary between two properties and is used by both as part of the structure of their buildings. Typically found in terrace houses, townhouses, duplexes, or row housing, it can be either part of both buildings (a shared wall), or entirely on one property, but supports or divides both.

A surface change due to age or use, such as the fine oxidation of copper or the weathering of wood.

Peeling is a mechanical process in which a debarked log (called a bolt) is rotated against a stationary knife, shaving off a continuous thin sheet of wood — like unrolling a roll of paper.

Common Applications: Plywood, LVL (Laminated Veneer Lumber), decorative veneers, panel products and formwork boards.

Alternative compliance pathways that demonstrate a building meets the requirements of the National Construction Code (NCC) without strictly following the Deemed-to-Satisfy (DTS) provisions. Performance Solutions allow for flexibility and innovation in design, including the use of timber in complex or non-standard applications. They must be supported by evidence—such as expert judgment, modelling, or testing—to prove they achieve the relevant Performance Requirements of the NCC.

A performance-based approach sets measurable performance criteria (e.g., fire resistance, structural strength, thermal efficiency) and allows flexibility in how those criteria are met, encouraging innovation and alternative solutions.

A change in the properties of wood which can occur during drying when stressing exceeds the elastic limit. Permanent set prevents normal shrinkage of the timber and can lead to more obvious defects such as casehardening and honeycombing. Permanent set is the amount of permanent deformation left in timber after a load is removed, meaning the timber does not return to its original shape or dimension.

The ease with which a fluid flows through a porous material (wood) in response to pressure.

A pier is a column-like support, often made of concrete, masonry, steel, or timber, that bears vertical loads and helps support a structure above it.

PEC is a water-based wood preservative used primarily for heavy-duty timber applications, such as utility poles, railway sleepers, and marine structures. It is a modified form of traditional creosote, designed to improve handling, appearance, and environmental performance.

A pile is a deep foundation element used to carry structural loads from a building or bridge down through weak surface soils to firmer ground or rock layers below.

A pin joint is a movable connection between two structural elements that allows them to rotate relative to each other, while transferring axial forces (tension or compression) and blocking sideways or vertical movement.

The small soft core occurring in the centre of a tree trunk, branch, twig, or log.

Plain-sawn timber (also called flat-sawn timber) is wood that has been sawn tangentially to the growth rings of a log, producing boards where the grain runs in wide, wavy patterns. It’s the most common and cost-effective sawing method used in the timber industry.

An intensively managed stand of trees of either native or introduced species, created by the regular placement of seedlings or seed.

The term plate generally refers to a horizontal structural element, often used in framing, load transfer, or connection roles. Its specific meaning can vary depending on context — particularly in timber construction, steelwork, or general building structures.

Common types: 

• Top Plate - Sits at the top of a timber wall frame; supports roof framing like trusses or rafters
• Bottom Plate (or Sole Plate) - Sits at the base of a wall frame; anchored to the floor or slab
• Wall Plate - Generic term for timber elements that distribute loads across a wall
• Sill Plate - Horizontal member fixed to a foundation, supporting vertical studs

In the timber and construction industry, plumb refers to something being perfectly vertical — that is, aligned with the direction of gravity or a true upright line.

A ply is one of the individual layers of veneer in a panel product like plywood, bonded with adhesive so that adjacent layers are oriented with alternating grain directions for strength and stability.

Plywood is a panel product composed of three or more layers of wood veneer, bonded under heat and pressure with strong adhesives, with each layer's grain direction alternating.

A pocket is a cut-out, slot, or cavity formed in timber, concrete, or masonry to receive another element—such as a beam end, sliding door, bracket, or connection hardware.

A pole is a straight, round timber member, typically derived from small-diameter logs, used in structural or utility applications for support, suspension, or framing.

Polyethylene Glycol (PEG) is a water-soluble polymer that can be absorbed into timber to help control shrinkage and distortion as the wood dries.

A portal frame is a planar structural frame in which lateral loads (like wind or seismic forces) and vertical loads (like roof weight) are resisted and transferred through rigid, moment-resisting connections between rafters (horizontal members) and columns (vertical members).

A post is a vertical timber or structural element that carries and transfers compressive loads from the structure above to the support below.

A post and beam structure is a framing system where vertical posts (columns) support horizontal beams, which in turn support the roof or upper floors. The load is carried through these key structural elements to the foundation.

A predryer is a climate-controlled chamber used to gently remove excess moisture from green (unseasoned) timber before it enters a conventional dry kiln. It helps reduce the moisture content gradually, typically from above fibre saturation point (~25–30%) down to a level more suitable for final kiln drying (around 20–30%).

A preservative is a chemical substance applied to timber to protect it from biological threats such as:

• Fungi (rot and decay)
• Insects (like termites and borers)
• Mould
• Marine borers (in coastal or underwater applications)

They extend the life of timber by making it more resistant to deterioration, especially in outdoor, damp, or ground-contact conditions where untreated wood would decay.

Presurfacing is the initial, light machining of green rough sawn timber to create a more uniform surface, making it easier to inspect, grade, or prepare for final finishing. It is intended to permit drying by a schedule more severe than the prescribed schedule for rough sawn timber, achieving faster drying and fewer drying defects.

Pretreatment - steaming refers to a pre-processing step where timber is exposed to steam (moist heat) before further treatment or processing. It is typically done in a controlled environment like a steaming chamber or kiln. It is often done to fix or enhance colour.

A psychrometric chart or psychrometric table is a graphical tool used in engineering and building design to illustrate the physical and thermal properties of moist air. It helps assess risk of condensation or mould growth in timber or other materials.

The psychrometric chart plots the relationships between several properties of air such as dry bulb temperature, humidity ratio, relative humidity, wet bulb temperature, dew point temperature, enthalpy, specific volume. 

In a mass timber building, a psychrometric chart might be used to:

• Predict moisture accumulation in building envelopes
• Design ventilation systems that maintain healthy humidity levels to protect wood
• Evaluate indoor air comfort in naturally ventilated or passive buildings

A purlin is a horizontal structural member used in roof framing. It runs parallel to the ridge of the roof and supports the roof covering (such as roofing sheets or tiles) by transferring loads to the primary structural elements like rafters or trusses. Purlins usually span at right angles to the slope of the roof

Push-pull racking refers to storage systems designed to handle and organise long, heavy timber products (like beams, planks, or panels) using mechanical or manual force to push in or pull out the items from racks. A method for building racks where alternative boards in alternative layers are kept flush with alternate ends. This gives a checkerboard arrangement at the ends of the rack. It is also called topping & tailing.

A method of slicing veneers whereby the average inclination of the growth rings to the wide face is greater than 45 degrees.

Timber in which the average inclination of the growth rings to the wide face is not less than 45 degrees.

Timber drying rack (in a sawmill) - A unit of timber where each layer is separated and spaced for drying with rack sticks.

Storage rack for timber - A rack is a physical structure used to store and organise timber, often in a warehouse, workshop, or on a construction site.

A racking frame is a load-bearing structural frame built to resist horizontal (lateral) forces that might otherwise cause the structure to deform, twist, or collapse sideways.

A temporary assembly tool or fixture made up of guides and supports that helps maintain correct stick alignment, square sides, and plumb ends during the construction of timber racks or frames.

One of a series of roof support timbers that provide principal support for the roofing material. Rafters usually span parallel to the slope of the roof.

Roughened surface of timber and other wood products, particularly softwood, after planning, caused by the projection of early wood or latewood above the surface.

Rays (also known as medullary rays) are ribbon-like structures of cells that extend radially from the centre of the tree (pith) outward to the bark. They are part of the tree’s natural anatomy and serve to store and transport nutrients across the wood (perpendicular to the grain).

In the context of timber drying, a reconditioner refers to a process or chamber used to treat timber that has experienced collapse during drying, particularly in refractory species. It is usually a chamber into which wet steam (not more than 100°C) is injected for several hours to recondition timber.

Reconditioning treatment involves exposing kiln-dried timber to high humidity and moderate heat (typically using steam or moist air) to equalise moisture throughout the board and relax internal stresses. It is usually applied after drying to restore the shape of collapsed or distorted wood.

A Recorder–Controller is an instrument or device that both:

• Records data over time (Recorder), and
• Controls a process based on input signals or set parameters (Controller)

It is an instrument that continuously records dry- and wet-bulb temperatures of circulated air in a dryer or kiln and regulates these conditions by activating automatic heat and humidification systems. It is used in kiln drying, preservative treatment, and quality assurance.

Recording Function:

• Continuously logs process data such as: Temperature, humidity, moisture content, pressure.
• Stores this data for monitoring, analysis, and compliance.

Controlling Function:

• Automatically adjusts equipment or conditions to maintain desired settings. (E.g. turns on/off fans, heaters, or vents in a timber drying kiln.)
• Uses feedback loops like PID control (Proportional, Integral, Derivative) to fine-tune outputs.

In kiln or veneer drying, a process whereby dried material found to have a moisture content level higher than desired is returned to the dryer for additional drying.

In timber drying this term is used to indicate high resistance to moisture loss during drying. The term refractory refers to wood species or wood types that are difficult to dry without developing defects such as:

• Surface checking (cracks on the outside)
• Internal checking (cracks inside the timber)
• Collapse (cell wall deformation)
• Honeycombing (internal splits)

A regrowth forest is a forest stand composed of young or intermediate-aged trees that have re-established after the original vegetation was removed or significantly disturbed.

A measure of the amount of water vapour in the air relative to the maximum amount the air can hold at a given temperature. It is expressed as a percentage and changes with temperature and atmospheric conditions.

Resins are organic compounds that are either naturally secreted by plants (like pine trees) or synthetically produced to serve as glues, sealants, finishes, or structural binders in wood-based materials.

Resorcinol glue (or resorcinol formaldehyde adhesive) is a high-performance, waterproof adhesive commonly used in the timber industry for structural bonding applications where durability, moisture resistance, and strength are critical.

The surface left exposed when one board is fastened over another; the edge of the upper set slightly back from the edge of the lower.

The persistent echoing of sound within an enclosure after the original source of the sound has stopped, due to repeated reflection between the enclosing surfaces which causes the sound to linger or echo before gradually fading away.

Ribbon figure is a decorative grain effect caused by interlocked grain, producing a striped or ribbon-like appearance—typically visible in quarter-sawn hardwoods like sapele, mahogany, and blackbutt.

The ridge is the topmost line or beam of a sloped roof, where the opposing roof planes intersect, often running horizontally along the length of the roof.

A beam located at the highest part of the roof to support the upper ends of the common rafters.

Refers to the process of cutting timber lengthwise —in the direction of the grain—typically to reduce the width of a board or log.

A long, thin strip of material—usually made from timber, metal, or plastic—that is fixed horizontally across the rafters or trusses of a roof. It serves as a structural support and fixing point for roofing materials like tiles, slates, or metal sheets.

A distinctive grain pattern in the wood that resembles twisting ropes or cords. It appears as long, wavy, and intertwined lines, often with a three-dimensional look.

A type of wood veneer made by peeling a log in a continuous sheet, much like unrolling a roll of paper. It’s one of the most efficient and economical methods of producing veneer, and is commonly used in plywood and engineered wood products.

Rough sawn refers to timber that has been cut from a log but not yet planed, dressed, or smoothed. It retains its coarse, textured surface directly from the sawmill.

Timber that is used in its natural, rounded form—as it comes from the tree—with minimal processing or milling. It is typically debarked but not sawn into planks or boards.

In the context of woodworking and construction, "rout" refers to the process of hollowing out or cutting a groove, channel, or shape into the surface of wood (or other materials) using a tool called a router.

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.

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.

Unseasoned timber is timber with a moisture content typically above 25–30%, meaning it has not undergone drying through air drying or kiln drying.

In kiln drying, a material with high resistance to vapour movement that is applied to the surfaces of a dry kiln to prevent moisture migration.

A vapour barrier (also called a vapour retarder) is a membrane or coating that reduces or blocks water vapour diffusion through building elements, protecting the structure and internal finishes from moisture damage.

A veneer is a thin layer of high-quality wood cut or peeled from a log, used to provide a decorative or functional surface over a less expensive or engineered base material.

Veneering is the technique of bonding a thin slice of decorative wood (typically 0.5–3 mm thick) onto a core material, enhancing visual appeal while reducing material use and cost.

Is designed to resist bending loads applied parallel to the wide face of the laminations. For vertical loads, this means that the wide face runs vertically.

The absence of wood on any face or edge of a piece of timber, leaving exposed the original underbark surface with or without bark. Wane is the presence of bark, lack of wood, or rounded log surface on the edge or corner of a sawn timber piece, caused by cutting close to or beyond the round outer edge of the log.

The absence of wood, other than wane, from the arris or surface of a piece of timber. Want is a term used to describe a missing corner, edge, or portion of timber that results in it not having full rectangular or square cross-section dimensions.

Warp is a defect in timber where the wood deforms out of shape—such as twisting, bowing, cupping, or crooking—due to uneven moisture loss, internal stresses, or growth irregularities.

In drying timber and other wood products, the application of external loads to a rack, stack, or pack of the timber to prevent or reduce warp.

A substance or finish that prevents or slows the penetration of water into a material’s surface, helping to protect it from swelling, decay, warping, staining, or mould.

A water-repellent preservative is a liquid wood treatment that both protects timber from biological attack and slows water absorption, helping to prevent swelling, shrinking, warping, and surface cracking.

A wavy figure is a visually striking grain pattern in timber caused by irregular or wave-like fibre alignment that reflects light unevenly, creating a sense of depth and movement in the wood surface.

A long, narrow, overlapping timber board fixed horizontally to the outside of a building, where each board overlaps the one below to create a weather-resistant barrier.

The mechanical or chemical disintegration and discolouration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibres with the variation in moisture content. Weathering does not include decay.

The web is the intermediate section of a structural beam or truss, positioned between the flanges, that transmits shear forces and helps maintain the shape and strength of the member under load.

The wet-bulb temperature is measured using a thermometer whose bulb is wrapped in a water-saturated cloth (called a wick). It reflects the cooling effect of evaporation. It is always lower than or equal to the dry-bulb temperature and it indicates the humidity level: the more moisture in the air, the closer WBT is to DBT. Wet-bulb temperature is important in kiln drying, as it helps determine how fast timber can safely lose moisture

In wood, any decay caused by fungi that attack both cellulose and lignin, producing a generally whitish residue that may be spongy or stringy or occur in pockets.

An unusually striking or chaotic grain pattern that differs from the uniform or straight grain seen in most cuts, often used for decorative purposes.

Wind bracing is the use of diagonal members, rigid sheathing, or steel straps in a building’s framework to resist sideways (lateral) loads from wind pressure and transfer those forces safely to the foundation.

A wind post is a steel or timber post fixed vertically within or against a wall to help it withstand lateral forces, particularly from wind pressure or suction.

Workability is the measure of how well timber responds to various processing operations like sawing, planing, drilling, sanding, gluing, nailing, and finishing. The degree of ease and smoothness of cut obtainable with hand or machine tools.