An Assessment of Risk Factors Impacting the Cost of Contractor-Led Design and Build Projects

Procurement in use surveys have confirmed a steady increase in the use of design and build procurement method. However, there was also a criticism that the out turn cost of design and build procurement method makes it more expensive than the traditional procurement method. The conjecture in this study is that risk factors inherent in design and build projects are responsible for the observed variance between the contract sum and the out turn cost. Using a set of 37 risk factors, the study utilized an online survey of UK-based construction professionals to evaluate risk impacts on the variance between contract sum and final account in contractor-led design and build projects. Survey responses were analyzed using mean ranking analysis and oneway analysis of variance (ANOVA). Result showed that ‘scope changes’, ‘ambiguous client brief’, ‘scope creep’, ‘insufficient design completion during tender’, and ‘change in employer’s requirement’ are top risk factors impacting the variance between contract sum and final account. The implication of this finding is that it alerts the design and build contractors to specific risk factors they need to pay attention to in their delivery of design and build projects and to devise a proactive approach to their management so as to avoid significant cost overrun.