An analysis of material waste generated on construction sites within Kampala

Abstract

Materials are essential components of construction projects for buildings, and the failure to determine adequate allowances for their wastage throughout the estimating process usually ends in financial loss for the client and unpermitted profits for the contractor. To compare them to the percentage waste allowance in estimating books and advance for a more realistic allowance for waste in construction estimating, thus the study was designed to analyse the material waste generated on different construction sites and to determine the actual percentage quantities of building materials currently wasted on construction sites within Kampala. Seven building materials that make up the majority of building material waste were employed: blocks/ bricks, concrete, cement, sand, aggregates, timber and steel. A total of 60 questionnaires were administered to different construction professionals to ascertain the most wasted materials, the factors influencing material wastage and the adopted measures to minimise material wastage. The study adopted a percentage frequency table, and a relative relevance score to analyse data from the questionnaires. The results revealed that timber is the most wasted material, storage being the most influential factor among the causes, and re-use being the most adopted waste minimisation practice. The materials selected were observed, recorded, and measured and the exact quantities were incorporated into the works. Based on this, it was possible to calculate the average waste of materials across all sites and determine the percentages wasted at each site. Timber has the most significant average percentage of waste, with 4.98%, followed by cement (2.38%), and (2.36%), concrete (1.96%), blocks/bricks (1.70%), aggregates (1.41%), and steel (1.14%). The percentage waste allowances calculated from site measurement were far lower than those reported in estimate literature. The analysis suggests that this could be attributable to improved workmanship and site management due to recent measures implemented. The research's final result, a percentage of building materials waste allowance, of 3% is also recommended for adoption by quantity surveyors and construction estimators to minimise pre-tender cost estimates for building projects and eventually save clients’ budgets or finances.