Construction Hints

1. Strength : The ability if a timber to withstand stress or external load.    i.e   -Bending parallel to the grain,   -Compression parallel and     perpendicular to the grain,    -Tensile parallel to the grain    -shear parallel to the grain. 2. Elasticity: modulus of elasticity by Inertial. Elasticity = Elasticity x Inertial

1. Density: This is the ratio of mass per volume of a timber structures. Timber with a close packed grain tends to handle a high density than those with much spaced grain. 2. Seasoning: This is process of reducing moisture content from from timber. 3. Thermal conductivity. 4. Thermal Expansion.

Factors are used in all engineering design to allow for variability in loading, material, workmanship etc..which can not be define with absolute certainty, here, the strength of the material or structural element must always exceed the effects of loadings by margin of its factor of safety. Factor of safety =  material strength/design load or Ultimate stress/actual stress NB:- Safety factor applied at one point in design is called overall safety factor, Applied at several points is called partial safety factors.

In engineering, it is called the safety margin required in order to insure safety during loading or the remaining strength after load is applied. It can also be said to be how much of structures total capacity is held in reserve during loading of structural elements. Margin of safety = (Failure load/Design load ) - 1

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.