ABSTRACT
Construction of building projects is an endeavour that involves capital expenditure, which is either borrowed or self-financed by clients. The expected outcome of such expenditure is value for money, which is usually dictated by project objectives of cost, time and quality. Project cost, as a project objective, is a crucial determinant of project success in the prevailing economic challenges being experienced globally. Construction cost overrun has become a reoccurring phenomenon in the delivery of building projects. The major thrust of this study was to identify, analyse and model the factors that contribute to building construction cost overruns in Abuja. The study adopted a Monte-Carlo technique in simulating cost overrun using DiscoverSim version 1.1 (SigmaXL, 2013) simulation and RiskAmp Microsoft Excel add-in software to analyse data obtained from literature review, review of project documents with contract sum of over Five Million Naira executed within Abuja city in addition to interview sessions with construction professionals. The study revealed that significant cost overruns are mainly due to re-measurement and variation. The simulation result elucidated that less than 10% of building projects are completed below the initial contract sum in Abuja which could be due to the fact that projects tend to be initiated and executed without adequate project information such as client brief, design details and specifications. The study recommends the need for minimizing occurrence of re-measurement in building projects through provision of full design information prior to contract award, development of simulation model for specific project categories and establishment of a project cost overrun band that will enable a scientific measurement of project's value for money benchmarked against initial cost estimate.