Characterization And Grading Of Timber Species Available In Nigeria For Structural Applications – A Systematic Review

Abstract

In Nigeria, a diverse range of timber species is available across different regions, many of which hold significant potential for structural applications in construction. However, the overdependence on a limited number of commercial timber species has led to overexploitation and market saturation, prompting a critical need to explore and characterize lesser-known species. This study presents a systematic literature review on the characterization and grading of Nigerian timber species for structural applications. The review assessed physical properties, including moisture content and density, as well as key mechanical parameters such as compressive strength, tensile strength, shear strength, modulus of elasticity (MOE), and modulus of rupture (MOR). The timber species reviewed were graded following the grading methodologies outlined in BS 5268-2 (2002), EN 384, and NCP 2 (1973). The results revealed significant variation in properties across species, with some lesser-used hardwoods like Irvingia gabonensis, Newbouldia laevis, and Brachystegia eurycoma demonstrating mechanical performance comparable to internationally accepted standards. While some indigenous species remain unclassified under existing standards, findings suggest the adoption of performance-based grading frameworks such as EN 338 to facilitate broader utilization. The study concludes that integrating international grading systems with indigenous practices will enhance the acceptance and structural use of underutilized timber species, promoting both economic development and environmental sustainability. Future research should focus on experimental testing and standardization of additional species to expand Nigeria’s structural timber compilation.