Glossary

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

Sawn - The nominal dimension of the board plus the overcut to allow for shrinkage. Nominal - The general intended size of the dry rough sawn board. Machined - The actual size of a machined or moulded board.  

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 joint where the pieces of timber are joined by dowels running either longitudinally or transversely through the joint.

Timber finished to a smooth surface on one or more surfaces.

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.

A chamber or apparatus used for drying or conditioning timber or veneer in which the temperature, humidity and velocity of the circulating air are usually controlled.

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

In kiln-drying wood, use of dry-bulb temperatures of 100 C (212 F) or more.

The reduction in volume and grade quality that can be attributed to the drying process. Pre-treatment - Special process taken before drying or early in the drying process to accelerate drying rate, modify colour, or prevent checks and other drying defects.  

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 force per unit area that occurs in some zones of drying wood. It results from the uneven shrinkage that occurs with normal moisture gradients and from the set that develops in wood. A term loosely applied to any dry, crumbly rot but especially to rot that, when in an advanced stage, permits the wood to be crushed easily to a dry powder. The term is actually a misnomer for any decay, since all fungi require considerable moisture for growth.  

1. The natural resistance of timber to biodeterioration due to fungi, insects and mechanical breakdown caused by weathering, checking and splitting. 2. In building, the efficacy of details in preserving or protecting the fabric of the building from decay or deterioration.  

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: (1) 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. (2) 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. (3) 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. (4) 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. 

The less dense, larger celled, first formed part of a growth ring. Also called "springwood".

Loads that are applied off the central axis of a structural member.

Eco labeling is a form of third party certification of a product that confirms that the product meets particular environmental criteria. Eco labels are designed to help consumers choose products that do less damage to the environment. Criteria for a product group are generally developed by the application of a life cycle assessment approach.

Ecology is defined as the study of the interrelations between living organisms and their environment, including both physical and biotic factors. Therefore ecological consequences refers to the changes the environmental effect may have on the relationships between living organisms and their environment.

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).

A natural system that functions as unit. It is assemblage of living organisms together with their non-living environment in a particular area. Healthy ecosystems are necessary for maintaining and regulating: atmospheric quality, climate, fresh water, marine productivity, soil formation, cycling of nutrients and waste disposal.

Pins or blades on electric moisture meters, usually made of steel, used to penetrate and contact the wood. Insulated - Electrodes that are coated with an insulating material to limit or control the point of contact between the electrode and the wood.  

The amount of non-renewable energy used to extract and process raw materials into finished building components. 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.

Environmental audits are 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 environment is defined as the physical and chemical surroundings of an object, the cultural, aesthetic and other factors which contribute to quality of life. Therefore environmental impacts refers to the effects on the surroundings, primarily physical things.

Environmental management systems are systems that ensure the organisation is working within the framework of ecologically sustainable development. These systems can be formal or informal. Formal systems include those prescribed by ISO 14001 and 14004.

A joint in which the parts are joined by dowels that have been set in oversized holes with epoxy resin.

A joint in which the parts are bonded using an epoxy resin adhesive.

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.

Substances such as tannin in wood that are not an integral part of the cellular structure and can be removed in solution by solvents, such hot or cold water, that do not react chemically with wood substances.  

Nailing at right angles to the surface.

A vertical board nailed to the lower ends of rafters.

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.

Small diameter, thick walled cells in hardwoods. Fibres dominate the structural behaviour of hardwoods.

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 pattern produced on the cut surface of wood by annual growth rings, rays, knots, deviations from regular grain such as interlocked and wavy grain, and irregular coloration.

An end joint in which wedge shaped projections in one piece of timber fit matching recesses on the other piece and are bonded together by an adhesive.