SOME ENGINEERING CHARACTERISTICS OF NIGERIAN TIMBERS

Abstract

This paper is a presentation of the results of tests on the characteristics of some common roofing materials found in the Nigerian markets as typified by the Bauchi Timber sheds. The principal roofing material investigated is timber but there is mention of types of roofing sheets and nails. The emphasis is on engineering properties such as density, equilibrium moisture contents (EMC), and flexural, compressive and tensile resistances, of timber. The tests reveal that the three top resistances in flexure, in increasing magnitude, are: Bush Mansonia (121.3N/mm²), Iroko/Loko (127.5N/mm²) and Madachi/Mahogany (131.9N/mm²). All the Timbers tested recorded compressive strengths above 25N/mm² parallel to grain (except plywood) but Mahogany and Teak recorded appreciably higher values ( 24.5N/mm² and 27.2N/mm² respectively) perpendicular to the grain. For obvious reasons, and from the public viewpoint also, the authors prefer Mahogany for overall strength superiority. It is heavy and other authors frequently recommend Iroko best for superstructures because of its relative better ability to as resist decay coupled with good strength properties and lower density.

The tests, which were conducted in the laboratories of Abubakar Tafawa Balewa University and the Federal Polytechnic Bauchi, are expected to provide data important for the structural design in timber using available species in the Nigerian market.