Assessment of the extent of usage and quality of timber as a building material in Kirinyaga County

Abstract

Kenyan population has been steadily rising over the years which has in turn exerted pressure on available natural resources. As a result of increase, the demand of quality construction timber has outstripped supply. This shortage of quality construction timber constituted the problem to be addressed. The objective of this study was therefore to determine the extent of usage and assess the physical and structural strength of timber as a building material in Kirinyaga County. Descriptive cross-sectional design and experimental research designs were used to carry out this study. Under descriptive cros-sectional design, open ended questionaires were administerd to contractors, county forest officers, saw millers and timber yard owners to collect the desired information. Data was also collected through direct observation and interviews. Under experimental research design, tests on timber derived from selected tree species i.e cordia Africana, Eucalyptus, Cypress, Grevilea robusta and Pine were done so as to determine their mechanical properties. Non-probabilistic sampling methods were used. Results from this study show that 15% of land mass of the county is covered with trees. Unfortunately, the 15% tree cover does not translate to timber sufficiency as most of it is sold to neighbouring counties and other major towns. Apart from construction, wood is also extensively used as electricity transmission poles and wood fuel. The high moisture content percentage contained by timber in this region contributes significantly to lower mechanical strengths. Sixty-eight (68) percent of the sampled species had a moisture content of more than 20%. The findings show that there exists a correlation between increase in population and higher demand of timber. Exploration on use of bamboo, use of alternatives such as steel and composites and prudent use of available timber are some of the recommended measures to counter shortage of timber. For further research, it is recommended that a research on timber with moisture content of 12% and below be done. The scope should also be widened to cover species not done.