Construction Hints

Defect of timber is any features that lowers the technical or commercial value of timber and may leaf to its rejection or its relegation to a lower grade. Example of such are ; Twisting, Decay, swelling etc

Nigeria timber is graded into 7 groups. From N1 - N7 ( according to NCP 2: 1973) u can get copy from Standard Organization of Nigeria SON. N1 is the highest strength Class N7 is the weakest strength Class. Most construction work in Nigeria is done with grading from N4 - N7 ( soft woods). Some of its grading includes; N1 - strongest wood i.e Ekki. N2 - AYO N3 - iroko ( teak), N4 - Abura N3-N4 - Obeche . . N7 - Araba, Apu (softest wood)

Seasoning of timber is the process of allowing timber to dry under atmospheric conditions or reducing moisture content from timber.. This could be Naturally or Artificially induced seasoning.. 1. Natural seasoning : Allowing timber to dry without direct sun light exposure. This could take as much as 6 months. 2. Artificial seasoning : drying of timber using oven. This could take 2 weeks.

Timbers is that part of tree that can be used for structural proposes/construction and carpentry. MECHANICAL properties of timber includes; 1. Strength :- this is the ability of timber to withstand stress or external load. i.e . Bending stress, compression stress, tensile stress, shear stress. 2. Elasticity :- EI Its ratio if Modulus of elasticity to its inertial. PHYSICAL properties of timber includes; 1. Density : this is the ratio its mass and volume. Timber with a close packed grain tends to handle a higher loading than those with much spaced grain. 2. Thermal Expansion. 3. Thermal conductivity 4. Seasoning : this is process of reducing moisture content from timber. This could be natural seasoning or artificial seasoning.

The slenderness ratio of a member is the ratio of the effective length to the appropriate radius of gyration (SR = Le/r or KL/r). NB: this is valid only when the column has equal unbraced heights for both axes and end conditions are same for both axes.