Glossary

see beam grid

A subdivion of a genus in the classification of plants. Species of plants are distinguished by the characteristics of fruits,flowers, leaves, bark and wood.

The ratio of the density of wood to the density of water at 4 C. Specific gravity of wood is usually based on green volume and oven-dry weight, in which case it is known as basic specific gravity. See also basic density.

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.

Support point or origin.

Spruce-Pine-Fir, or SPF, is the generic name for a variety of softwood species, even-grained and yellowish-white in colour, imported from North America and used in housing construction frames.

The gaseous form of water at or above the boiling point. Saturated - Steam at 100°C and atmospheric pressure.  

A treatment sometimes carried out before commencing a drying schedule. The timber is subjected to live steam. 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.

All elements used to support or stiffen the slender webs of box and I-shaped beams and to enhance compressive capability of webs at support points or points of high transverse loads.

A long bolt through laminated timber that holds the laminations together.

Timber in which the fibres run parallel to the axis of a piece.

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  

Timber to be used in construction where its strength is the controlling element in its selection and use.

A structural timber resisting compressive forces along the grain.

One of a series of vertical framing timbers used as a supporting element in a wall or partition.

The heat in steam in excess of the amount of heat in saturated steam at a given pressure.

Bracing members required to resists the transverse movement of a structural element.

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 figure caused by irregular grain in the region of the knot. 

Coincident with a tangent at the circumference of a tree or log, or parallel to such a tangent. In practice, it often means roughly coincident with a growth ring.

Reducing gradually in width or diameter.

Woodland of a usually mild climatic within the temperate zone that receives heavy rainfall, usually includes numerous kinds of trees and is distinguished from a tropical rainforest by the presence of a dominant tree.

Dry-bulb - Temperature of air as indicated by a standard thermometer. Wet-Bulb - Temperature indicated by any temperature-measuring device, the sensitive element of which is covered by a smooth, clean, soft, water saturated cloth (wet-bulb wick).  

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

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 structural member resisting tension forces along the grain.

An arch tied at the base with a tension member.

A general term for natural or sawn wood in a form suitable for building or structural purposes.

A joint where a ridge or tongue in one piece fits a matching groove in the other.

A quality of wood which permits the material to absorb a relatively large amount of energy, to withstand repeated shocks, and to undergo considerable deformation before breaking. Specific toughness classification are set out in AS 1720.2 SAA Timber Structures Code - Part 2 Timber Properties.

The elongated cells that constitute the greater part of the structure of the softwoods; 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 platform of a stair.

Joining structural members together so that they form a rigid triangle

The structural member on the side of a framed rough opening to narrow or stiffen the opening. Also the shortened stud (jack stud) which supports a header in a door or window opening.

A frame of members in the same plane joined only at their end and all interconnected to form triangles. 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.

An arch where the main member is made up of elements arranged as a truss

A timber beam reinforced with a trussed metal tension rod (see also barrup truss)

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

Timber in which the average moisture content exceeds 25 %.

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 thin layer or sheet of wood.  Also referred to as decorative wood veneer. More on timber veneers