Timber is wood used for building/construction works. Timber means ‘to build’. A felled tree is first cut into sizes of suitable lengths called rough timber that are transported to timber yard. By sawing rough timber, it is converted into various commercial sizes like planks, battens, posts, beams etc. Such form of timber is known as converted timber.
Properties of timber suitable for building construction.
- Should be uniform in colour.
- Should have pleasant odour when freshly cut.
- Clear ringing sound when struck indicates the timber is good.
- Good timber should have good texture
- The timber should be of high density
- Timbers should be strong and durable.
- Good timber do not warp under changing environmental conditions.
- Timber should be capable of resisting shock loads.
- Good timber do not deteriorate due to wear. This property should be looked into, if Timber is to be used for flooring.
- Timber should have high strength in bending, shear and direct compression.
- Timber should have high modulus of elasticity.
- Good fire resistance.
- Low water permeability.
- Good workability, should not clog the saw.
- Capable of resisting the action of fungi and insects attack.
- Timber should be free from defects like dead knots, shakes and cracks.
How timber Can be Preserved
Timber is preserved by protection from fungi and insects attack. Timber should be well seasoned before preservatives are applied. The following are the widely used preservatives:
Tar: Hot coal tar is applied to timber with brush. Tar coating protects the timber from attack of insects and fungi.
Paints: Paint improves the appearance of the timber. Solignum paint is a special paint which protects the timber from the attack of termites.
Chemical salt: These are the preservatives made by dissolving salts in water. The salts used are copper sulphate, masonry chloride, zinc chloride and sodium fluoride.
Creosote: Creosote oil is obtained by distillation of coal tar.
Uses of Timber in construction
- Construction of columns, trusses, piles.
- Making of doors, windows, flooring and roofing.
- Construction of railway sleepers, fencing poles, electric poles and gates.
- For temporary works such as scaffolding, centering, shoring and strutting, packing of materials.