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Glossary of Timber Terms

Abbreviations and meanings of the timber terms used for finishing, treatment, grading, building and more.

Term Meaning Abb.
Rough Sawn As it comes straight off the saw R/S
Band Sawn    Vertical saw cut B/S
Dressed Four Sides    Dressed smooth suitable for joinery    D4S
Plainer Gauged    Machined at high speed to a standard uniform size for the building market    P/G
Tongue & Groove        T&G
Tongue & Groove V-Joint        T&G V-J
End-Matched        E/M
Pre-primed    Undercoat sealer (oil or water based)    P/P   
Untreated    Untreated    U/T   
H1.2    Boron treated for protection against borer    H1.2         
H3.2    Exterior treated for exposure to weather but not in ground contact    H3.2   
H4    Ground treated for ground contact    H4   
H5    Treated for ground contact ground near fresh water or in soggy ground    H5   
H6    Treated ground for near salt water    H6   
Dressing A    Knot and defect free    D.A      
Dressing B Select    Small tight knots on all 4 faces. Will be able to cut some clear out of the board    D.B. Select   
Dressing B    Tight knots with no restriction on the amount per board    D.B   
Clears    Knot and defect free    CL   
Clears 2     Clean on 2 edges, 1 face and small tight knots on 1 face    CL2   
Dressing Grade    Tight knots that can be cracked with no restriction on the amount per board. Hairline cracks in board are possible D/G   
No.1 Farming Knot size no bigger than 1/3 cross section of the board    No.1   
Boxing    Has spike knots, butterfly knots, loose knots and edge knots    BOX   
Ordinary Building    Pinhole borer, cracked knots, hairline cracks in board, large knots    O.B.   
Double Defect    Open defects on back and face of plywood    DD   
Finger-Jointed        F/J   
Non Durable    0-2 years       
Moderately Durable    2-5 years       
Durable    5-10 years       
Very Durable       10+ years       
Pinhole A hole usually not exceeding 2mm diameter. The insects that create these holes feed off the starch in the sap of the living trees and when the tree is felled, sap dries up and they die    
Gum Vein    A ribbon of gum produced in trees as a response to fire damage       
Shake    Splits in the structure of the wood caused by growth defects or shrinkage stress       
Check A small crack running through the grain of a timber surface usually caused by being dried too quickly      
Moisture Content    The amount of moisture in timber (measured in a percentage)    MC   
Kiln Dried    Has been dried in a kiln to approx 12-15% MC    K/D   
Air Dried    Has been dried by natural air (usually undercover and strip-stacked) to anywhere between 15-15% MC    A/D      
Green    Wet (ranging from 26-100%)       
Lineal Metre    Running metre in .300 multiples    LM   
Square Metre/Area    Length x width    m2   
Cube    Length x Width x Depth    m3   
Purlin    Sits on top of trusses       
Truss    A triangular arrangement of structural members that reduces non-axial forces on the truss to a set of axial forces in the members    
Stud    One of a small series of small closely spaced wall framing members     
Dwang    Block in between studs    
Joist One of a group of light, closely spaced beams used to support a floor deck or flat roof    
Bearer    Heavy section timber which supports joists        
Batten    A long thin piece of rectangular shaped material supporting roof tiles or covering joints between panelings     
Beam    A straight structural member that acts primarily to resist non axial loads    
Post Upright supporting a structure       
Pile A long slender piece of material driven into the ground to as a foundation    
Plinth    Triangular shaped timber for corner.       
Lintel    A beam that carries the load of a wall across a window or door opening    
Jamb    The vertical side of a door or window      
Gable    A roof consisting of two oppositely sloping planes that intersects at a level ridge     
Rafter    A framing member that runs up and down the slope of a steep roof     
Baluster    One of a series of short posts or pillars that make up a balustrade and support the rail at the top and stand on the base at the bottom     
Tread    The horizontal portion of a stair which a user places their foot on      
Riser The vertical portion of a stair