Submitted in fulfillment of the academic requirements for the degree of Master of Technology in Construction Management, Durban University of Technology, Durban, South Africa, 2015. / On-time completion and conformity with assigned cost of every project are the most important factors in the success of project plans. Cost overruns and time overrun (delays) have been critical problems of many projects around the world in general and in South Africa in particular. The main objectives of this research are to assess the dominant causes of cost and time overruns, identifying possible and practical measures that can minimize overruns in office building construction projects around eThekwini Municipal area of Kwazulu-Natal. These objectives are achieved through the implementation of the research methodologies that are mainly literature review and questionnaire survey conducted to identify and evaluate the significant factors contributing to delay and cost overruns within the projects of interest. A review of literature identified eighty-five variables for delay, grouped in nine major categories and nine variables for cost overruns ranked in their order of importance in three sets based on the responses from the professionals working for the client, consultants and contractors. The agreement among the sets of rankings for delay and cost overruns has also been tested using statistical methods. The result indicates that there is strong agreement on ranking the importance of the individual variables of delay and cost overruns between parties. From each of the three sets of rankings, the twenty most important variables of delay and the three most important variables of cost overrun are identified as critical. Based on overall results, the top five most important causes are contractor’s cash flow problems, delay in progress payments by the client, poor site supervision and management by contractor, inefficient quality control by the contractor during construction leading to rework due to errors, and contractor’s difficulties in financing the project. Out of the 20 most important delay causing variables, three are found to be common between all parties. These are delay in progress payments by the client, delay in delivery and late ordering of material, and insufficient skill of labour. Furthermore, the study reveals that all stakeholders of construction parties are deeply involved in contributing to the causes of the problems. Thus, in order to eliminate or minimize cost and time extension of office construction projects in the eThekwini Municipal area, a joint effort based on teamwork is essential through effective project planning, controlling and monitoring which boils down to putting in place best practice construction project management.