Estimating Contingency Sum for Building Works in Ghana

2013

English

It is a common practice in the construction industry in Ghana to allow for contingencies to cater for any unforeseen events. This study was to identify existing methods of determining contingency sum, factors influencing contingency sum and develop a new system of determining contingency sum. The study employed a case study of some 38 completed building projects in Ashanti and Brong Ahafo regions of Ghana to compare the accuracy of both the existing and the new method. Questionnaires were distributed to the selected professionals. Relative Importance Indices Ranking and the Kendall coefficient of concordance were used to rank factors and the agreement of factors ranking among building professions. It was established that the most commonly used method is the Percentage Approach method. The study revealed that 77% of the building professionals have been using the Percentage Approach and 23% have been using the Probabilistic Estimation Methods. These methods were based on subjective approach. Economic, Environmental and Technical factors were identified as the most influential factors. The study concludes by developing a new software system of determining contingency sum and new method was found to be 45% more accurate than the Percentage Approach.

Asamoah, R. O.; Danku, J. C.; Amissah, P. B.