Assessment on rework costs probability of housing projects in Sri Lanka

Rework or rectification is a common phenomenon as well as a norm in the construction industry. It is recognized as an unnecessary effort of redoing an activity that was incorrectly implemented at the first time. This research is motivated by the increased attention given to the significant impact that rework costs have on cost performance. Therefore, the research investigates the rework costs involved in rectifying the defects and thereby develop a rework costs probability model for housing projects in Sri Lanka. A questionnaire survey was carried out together with a detailed analysis of documents. Statistical methods for eliciting probability distributions were used to analyse the data collected from 47 housing. Results of the non-parametric test; goodness-of-fit tests, revealed that generalized exponential distribution provided the best fit for the dataset. Findings of the study indicates 36 different types of more likely to occur in housing projects in Sri Lanka. On average the total rework cost as a percentage of cumulative work done value is found to be 0.92% in housing projects. Finally, the research proposes to use the developed probability model for rework costs to enable construction practitioners a quantitative risk assessment and competitive advantage in the cost performance.