Wood is a hard and fibrous substance which forms a major part of the trunk and branches of a tree. It can also be defined as a natural polymeric material which practically does not age. Wood as a building material falls in two major classes i,e, natural and man-made. With the advances in science and technology, wood in its natural form as timber, lumber, etc. is being rapidly replaced by composite wood materials in which natural wood is just a basic ingredient of a matrix or a laminate. The latter are found to be more useful and adaptable as they may be treated chemically, thermally or otherwise as per requirements. Some examples are plywood, fibreboards, chipboards, compressed wood, impregnated wood, etc.
Wood is a good absorber of shocks and so is suitable for construction work in hilly areas which are more prone to earthquakes. Finally, since wood can be easily worked, repairs and alterations to wood work can also be done easily. Owing to the above mentioned advantages, wood is very widely used in buildings as doors, windows, frames, temporary partition walls, etc. and in roof trusses and ceilings apart from formwork.
Market Forms of Timber :
Battens: Timber pieces whose breadth and thickness do not exceed 50 mm.
Baulk: Roughly squared timber piece, it is obtained by removing bark and Sapwood. One cross sectional dimension exceeds 50 mm, while the other exceeds 200mm.
Board: A plank with parallel sides. Its thickness is less than 50mm and width exceeds 150mm.
Deal: Piece of soft wood with parallel sides. Thickness varies from 50mm to 100mm and width does not exceed 230mm.
Log: Trunk of tree obtained after removal of branches.
Plank: Timber pieces with parallel sides. Thickness less than 50mm and width exceeds 50mm.
Pole: Sound long log of wood, dia does not exceed 200mm, also known as spar.
Quartering: Square piece of timber, the length of side being 50mm to 150mm.
Scantling: Timber piece whose breadth and thickness exceed 50mm,but are less than 200mm in length. These are the pieces of misc sizes of timber sawn out of a log.