Timber is derived from an old English word timbrian which means to build. Thus timber denotes wood which is suitable for building or carpentry or various other engineering purposes. is a collective term for harvested wood that has been manufactured into boards and planks. This process is part of something called wood production. Timber is predominantly used for structural purposes but has many other uses as well. Timber/lumber is classified as hardwood or softwood. Logs are converted into timber by being sawn, hewn, or split. Sawing with a rip saw is the most common because sawing allows logs of lower quality, with irregular grain and large knots, to be used and is more economical. Types of sawing are
- Plain sawn (flat sawn, through and through, bastard sawn) – A log sawn through without adjusting the position of the log and the grain runs across the width of the boards.
- Quarter sawnand rift sawn – These terms have been confused in history but generally mean lumber sawn so the annual rings are reasonably perpendicular to the sides (not edges) of the lumber.
- Boxed heart – The pith remains within the piece with some allowance for exposure.
- Heart center – the center core of a log.
- Free of heart center (FOHC) – A side-cut timber without any pith.
- Free of knots (FOK) – No knots are present.
Qualities of good timber
- Hard and shiny appearance
- Should be free from serious defects such as dead knots, flaws, shakes, etc.
- Should be durable, resistant to fungi, chemicals, acids and atmospheric actions
- Timber should be sufficiently elastic especially for carriage shafts, cricket bats, bows, etc.
- Should have straight fibers
- Should be fire resistant
- Should be sufficiently hard to resist mechanical wear and tear
- Should be structurally sound and must emit a clear ringing sound when struck.
- It must have a uniform structure (firm fibers, hard and compact medullar rays and close and regular annular rings)
- It must have low water permeability
Market forms of timber
Timber when converted to suitable commercial sizes are available in various forms in the market
- Battens
- Boards
- Logs
- Planks
- Poles
- Baulks
- Quartering
- Scantling