The Bone Timber Trade Glossary

A

ACQ (Alkaline Copper Quaternary) – Modern timber preservative treatment widely used as a lower-toxicity alternative to CCA.

A-frame – Temporary triangular timber structure used for support, lifting or bracing.

Architrave – Decorative moulded trim installed around doors and windows to conceal joints and movement gaps.

Actual Size – The finished dimension of timber after dressing (smaller than nominal size).

Adhesive Failure – Separation in engineered timber due to glue bond breakdown.

B

Back sawn – Timber cut tangential to growth rings, typically producing cathedral grain patterns.

Barge board – Board fixed to gable ends to conceal roof framing and provide a finished edge.

Batten – Narrow timber strips used for fixing cladding, roofing, or panelling.

Bearer – Primary horizontal support member carrying joists in floors or decks.

Bevel – Angled cut or edge detail used for joins or visual refinement.

Bird board – Eaves closure board preventing pest or bird entry.

Blackbutt – Durable Australian hardwood frequently specified for decking and flooring, known for fire performance.

Blue board – Cement-based fibre sheet commonly used as cladding substrate or wall lining.

Blue pine – Treated radiata pine, dyed for identification, used in structural framing.

Bracing – Diagonal structural elements preventing racking or lateral movement.

Bullnose – Rounded timber edge profile commonly used on stair treads and decking.

Bushfire Attack Level (BAL) – Compliance rating defining exposure risk and material suitability.

Butt joint – Simple square-ended timber joint.

Blocking – Short timber pieces installed between framing members for stiffness or fixing support.

C

Cantilever – Structural member extending beyond its support.

CCA Treatment – Copper Chrome Arsenate preservative treatment for durability (legacy but still recognised).

Centres – Framing spacing measured from member midpoint to midpoint.

Chamfer – 45-degree edge cut for safety or detailing.

Chalk line – Marking tool for establishing straight lines.

Chipboard / Particleboard – Engineered board from compressed wood particles and resin.

Chippy – Trade slang for carpenter.

Cladding – Timber boards or panels forming external wall finishes.

Cumaru – Extremely dense imported hardwood used in high-wear external environments.

Cupping – Curvature across board width due to moisture imbalance.

Cypress Pine – Naturally termite-resistant Australian softwood used structurally and decoratively.

Checking – Surface cracking from drying stresses.

Clear Grade – Timber selected for minimal visual defects.

D

Dado – Lower wall section often finished with panelling or mouldings.

Decking – Boards designed for external walking surfaces.

Defects – Natural or machining irregularities (knots, splits, twist).

Delamination – Separation of bonded layers in engineered timber.

Dowel – Cylindrical timber pin used in joinery alignment.

Dressed All Round (DAR) – Timber machined smooth on all faces.

Dressed Timber – Planed timber with a finished surface.

Durability Class – Rating of timber’s natural resistance to decay and insects.

Density – Mass per volume influencing strength, durability and fixings behaviour.

E

End Grain – Exposed fibre structure at board ends.

End Matched – Boards with joining profiles machined into ends.

Engineered Timber – Manufactured products such as LVL, plywood and glulam.

Equilibrium Moisture Content (EMC) – Stable moisture level timber reaches in service conditions.

Edge Glued Panel – Board formed by bonding narrow timber strips.

F

Face – Visible or best-quality surface of timber.

Fascia – Board fixed to roof edges supporting gutters.

Fiddleback – Decorative wavy grain figure.

Finger Jointed (FJ) – Timber lengths joined using interlocking profiles.

Fire Retardant – Treatment or coating reducing flame spread.

Fixings – Nails, screws, bolts and connectors.

FOHC (Free of Heart Centre) – Timber milled away from log centre to improve stability.

Formply – Film-faced plywood for concrete formwork.

Framing Grade – Timber classification suitable for structural applications.

G

Gable – Triangular wall beneath a pitched roof.

Glulam (Glue-Laminated Timber) – Engineered structural beams made by bonding laminations.

Grade – Strength or appearance classification.

Green Timber – Unseasoned timber with high moisture content.

Grey Box / Grey Ironbark – Dense hardwoods suited to demanding external use.

Grain Direction – Fibre orientation affecting movement and machining.

Growth Rings – Annual tree growth layers influencing stability.

H

Hardboard – Compressed fibre sheet material.

Hardwood – Timber from broadleaf species, generally denser and more durable.

Hazard Classes (H1–H6) – Treatment categories defining exposure suitability.

Header – Load-transferring beam over openings.

Heartwood – Inner timber with enhanced natural durability.

Handrail – Safety rail installed along stairs or decks.

Hygroscopic – Property of timber to absorb/release moisture.

I

I-Joist – Engineered structural member with high strength-to-weight efficiency.

Ironbark – Exceptionally hard Australian hardwood.

Interlocking Grain – Alternating fibre direction affecting finish quality.

J

Janka Hardness – Measure of timber resistance to denting and wear.

Jarrah – Durable WA hardwood prized for stability and appearance.

Joist – Horizontal support member for flooring or decking.

Joist Hanger – Metal bracket securing joists.

K

Karri – Australian hardwood used in structural and appearance applications.

Kiln-Dried (KD) – Timber dried in controlled conditions for stability.

Kiln Burn – Discolouration from drying irregularities.

L

Lintel – Structural beam across openings.

Load Bearing – Structural component designed to carry loads.

LOSP Timber – Light Oil Surface Preservative treated timber for above-ground exposure.

LVL (Laminated Veneer Lumber) – Engineered high-stability structural timber.

Lyctine Susceptible – Timber prone to lyctine borer attack.

Lamination – Bonded timber layers forming structural members.

M

MDF (Medium Density Fibreboard) – Engineered board for joinery and interiors.

Merbau – Popular durable hardwood decking species.

Mitre Joint – Angled corner joint.

Moisture Content (MC) – Water percentage affecting timber behaviour.

Mouldings – Profiled finishing trims.

Movement – Dimensional change from moisture variation.

Machine Stress Graded (MSG) – Structurally graded timber assessed mechanically.

N

Nogging – Short bracing pieces between studs.

Nominal Size – Pre-dressed timber dimension reference.

Non-Load Bearing – Component not designed to carry structural loads.

Nosing – Rounded stair tread edge.

O

Oregon (Douglas Fir) – Structural softwood used in beams and framing.

OSB (Oriented Strand Board) – Engineered structural sheet product.

Overlay Flooring – Thin timber flooring installed over substrate.

P

Parquetry – Patterned timber flooring system.

Plywood – Cross-laminated veneer sheet product.

Plank – Long wide timber board.

Plinth – Protective base board at wall junctions.

Plate (Top/Bottom) – Horizontal framing members.

Posts – Vertical structural supports.

Porous – Material prone to moisture absorption.

Prime – Initial protective coating.

Preservative Treatment – Chemical processes improving durability.

Q

Quad – Quarter-round trim moulding.

Quarter-Sawn Timber – Timber cut for improved dimensional stability.

R

Radiata Pine – Widely used Australian plantation softwood.

Ridge Beam – Primary roof apex beam.

Rough-Sawn Timber – Undressed timber with textured finish.

Random Length – Timber supplied in varied lengths.

Riser – Vertical stair component.

Racking – Lateral structural distortion resisted by bracing.

S

Sapwood – Outer lighter timber layer.

Seasoned Timber – Timber dried for stability.

Secret Nailing – Concealed fixing method.

Select Grade – Higher appearance classification.

Shrinkage – Size reduction from drying.

Skirting – Internal perimeter moulding.

Softwood – Timber from conifer species.

Span – Distance between structural supports.

Span Table – Engineering reference for load capacity.

Stud – Vertical framing member.

Structural Timber – Timber graded for load-bearing use.

Surface Check – Minor drying crack.

T

Tallowwood – Dense Australian hardwood suited to wet conditions.

Tannins – Natural compounds causing staining/leaching.

Termite Resistant – Timber naturally or chemically protected.

Timber Frame – Structural system built from timber members.

Tongue & Groove (T&G) – Interlocking board profile.

Treated Pine – Pine preserved for durability.

Truss – Engineered structural framework.

Twist – Spiral distortion along timber length.

U

Underlay – Sub-layer beneath flooring.

Uniform Grain – Consistent fibre pattern.

Unseasoned Timber – High-moisture timber prone to movement.

V

Veneer – Thin timber sheet for appearance or stability.

V-Joint (VJ) – Decorative joint profile.

Void – Empty structural cavity.

W

Warping – Distortion from moisture imbalance.

Weatherboards – External overlapping cladding boards.

Western Red Cedar – Lightweight stable cladding timber.

Wind Load – Structural force consideration.

Workability – Ease of machining or fixing.

Wane – Missing wood or bark edge.

Wet Service Conditions – Environments with sustained moisture exposure.

Z

Zoning (Building) – Local planning controls affecting construction methods and materials.