An Investigation into Factors Causing Material Waste and their Influence on Residential Construction Cost in Northern Nairobi.

Abstract

Large amounts of material waste are generated in residential building construction in Northern Nairobi, where conventional construction methods are predominant. This may be attributed to lack of cost effective building materials, technologies and material waste management systems in the region. The main objective of this study was to recommend an alternative approach to construction of residential buildings in Northern Nairobi, whose utilization results in material waste minimization. Reduction of material waste in residential construction results in cost saving to the client and to the contractor. The study investigates factors causing material waste, and establishes the extent to which these factors explain the cost of residential building construction in Northern Nairobi. The research was designed as a case study and survey. Purposive sampling was used in selection of the Northern Nairobi because of its high concentration of residential housing projects. Convenience sampling was used to select project consultants in the research area. Primary data was collected through interviews and observations. Descriptive statistics, correlation and multiple regression aided by the Statistical Package for Social Sciences (SPSS) was used for data analysis. The results show poor or complex designs, lack of security, poor work conditions and topography as the factors causing material waste which can significantly predict the cost of residential building frame construction in this region. The study noted that, 69% of building developers prefer labour contracting option despite its high contribution to material wastage. Significant factors to be addressed in minimization of materials waste during construction include: quality purchases, experienced artisans/materials handlers, adequate supervision on material handling, scheduled material delivery and good material storage practices. There is also need to adopt new technologies in construction of residential buildings in this region.