Quantification of the cumulative impact of change orders on sheet metal labor productivity

Change on construction projects is inevitable and often the effects of change are disputed amongst owners and contractors. Change orders, the contractual method of issuing a change to a construction contract, are legal and present on every job. The complete effects that change orders have on a project are noticed by the contractor but are difficult to quantify. This difficulty lies in the fact that the total and complete costs of a change are not only the direct costs of the extra material and equipment hours that are needed to carry out the change but also the effect that the change has on the flow of work (its effect on labor) and the “ripple effect” that change orders cause through the project. This ripple effect has been defined as the cumulative impact of change orders and its sources impact both the changed and unchanged work. Some sources of change order cumulative impact are dilution of supervision, out of sequence work, rework, schedule acceleration, etc. The current research focuses on the impact of change orders on labor productivity for a different and unique section of the construction industry: sheet metal. The current research undertook the issue of cumulative impact on sheet metal construction by investigating and hypothesizing that the productive impact of change order caused inefficiencies can be reasonably estimated on an individual project basis using observed project characteristics and conditions. The hypothesis was tested by developing and rigorously cross-validating a model that can estimate the productivity loss on a project impacted by change orders. The research resulted in the formulation of a regression model that can be applied to projects to generate a percentage loss of productivity due to changes. In addition to the primary research hypothesis the research tested 23 secondary hypotheses to identify key factors that contribute to project performance. The research also created project control tools and industry benchmarks that sheet metal contractors can use to minimize the impact of changes and help improve any project's productivity.