Availability and quality of cost data for detailed construction cost estimating in Ghana

In Ghana as in other countries, construction Cost Estimation and Price Analysis (CEPA) are key activities in the design and planning of construction projects as they form the basis for decision making at various phases of construction projects. In view of the above, the accuracy of the cost estimate is very important. Studies have shown that, quality and the adequacy of cost estimation data have significant influence on the accuracy of cost estimates. The aim of the current study was to investigate into the availability and quality of cost data for detailed cost estimation in the Ghanaian construction industry. In order to achieve the above, structured questionnaire was designed and self-administered to cost estimators in construction and Quantity surveying firms in the Kumasi and Accra Metropolises. A total of 50 questionnaires were self-administered to construction and Quantity surveying firms. The data obtained was analyzed into descriptive statistics such as means, frequencies and percentages. The analysis was done using the Statistical Package for Social scientist (SPSS) software. The results revealed that during detailed cost estimations, a number of cost data are used by the firms including labour outputs, All-in- labour rates, plant outputs, All- in- plant hourly rates, material prices, material utilization rates, waste factors for materials, inflation rate / Indices and taxes. Most of the firms have cost databases which they update frequently. In addition to the above, it was found that a number of factors influence the quality of cost data which include the following: the source of the data; the experience of the person handling the data; the frequency with which the data is updated; the processing/analysis of the data and the method of collecting the data. Furthermore it was revealed that the firms obtain the cost data from sources such as company database, suppliers, and GhIS publications. Some of the data are determined based on past experience. Estimating techniques such as estimating from first principle, benchmarking rates from other organizations and the use of expert advice are used in determining the detailed cost of a project. It was observed that among the factors that significantly influence the quality of cost data is the frequency with which the data is updated, it was therefore recommended that there should be frequent update of cost data ideally every month so as to enhance the quality of the data. The study also reveals that estimating from first principle is most preferred by firms in Ghana for detailed cost estimate, however availability of time greatly affects the accuracy of this method. The study recommended that enough time should be given to cost estimators to prepare detailed cost estimate. The study also shows that some of the firms do not have cost database. It is therefore recommended that such firms should improve upon their data management system by creating cost data base. This will enhance cost estimation and pricing of construction works in Ghana. Good pricing and cost estimation will benefit the industry stakeholders who rely on it for decision making

Source: KNUST