Analysis of causes of construction defects using fault trees and risk importance measures

Defects can have a significant impact on construction performance. A defect is not usually an outcome of a single cause, but rather occurs when multiple interrelated causes combine, forming a defect's pathway. Because defects may occur through numerous pathways, the risks of causes can vary in terms of the number (i.e., frequency) of pathways that they take part in and the impact (i.e., magnitude) of the contribution they provide for the formation of these pathways. Several studies have strived to identify generic defect causes; however, research on the analysis of the risk of causes in order to develop further defect management efforts is lacking. To address this deficiency, this study aims to develop a methodology to identify and quantify the risk of defect pathways. Specifically, the study uses a fault-tree approach to construct the taxonomy of the defect causes and uses risk importance measures to assess the identified defect causes in terms of frequency and magnitude. Applying the developed methodology to four residential projects in Dubai confirmed its applicability as an effective tool for analyzing the risk of defect causes in construction. An effective defect-prevention strategy is expected to be further developed by applying the methodology to a large number of defect samples in a subsequent study. This paper makes a contribution to knowledge in the area of construction engineering and management by introducing a quantitative model, which opens a gateway for researchers to address the complex nature of defect generation and to better understand the vulnerability of a construction project system to defects. In addition, this paper is of value to practitioners with respect to providing an effective tool to rank the significance of defect causes and to optimize their resources consumed for defect prevention.