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Dahanayake, B, Ramachandra, T and Thurairajah, N (2016) Assessment on Rework Costs Probability of Housing Projects in Sri Lanka. In: Chan, P W and Neilson, C J (Eds.), Proceedings 32nd Annual ARCOM Conference, 5-7 September 2016, Manchester UK. Association of Researchers in Construction Management, 1265–1273.

  • Type: Conference Proceedings
  • Keywords: Construction, housing projects, probability, rework cost, Sri Lanka.
  • ISBN/ISSN: 978-0-9955463-0-1
  • URL: http://www.arcom.ac.uk/-docs/proceedings/9366565d06bae695fcf43221edd27214.pdf
  • Abstract:

    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 could have on construction cost performance and the fact that ineffective approaches are often used to determine and quantify these undesirable costs. Therefore, the research investigates the rework costs factors involved in rectifying the defects and thereby develop a rework cost 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 projects. The empirical distributions for rework costs were found to be non-Gaussian. Non-parametric tests were used to determine the goodness-of-fit of the selected probability distributions.

    The results of the goodness-of-fit tests revealed that generalized exponential distribution provided the best fit for the dataset. It was established that rework can make a significant impact on contractors’ profits. Findings of the study indicates 36 different types of defects that are pertinent to several work trades more likely to occur in building construction 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. For a mean total rework cost of 0.92%, the likelihood that a housing project exceeds is 37%. Finally, the research proposes to use the developed probability model for rework costs to enable construction practitioners a quantitative risk assessment and ultimately lead to identifying most rework pertaining trades to minimize the cost impact on contractors’ profit.