ATLANTA—The downward trend in U.S. construction productivity is largely the result of mis-categorization by the Census of Business, according to a paper in July’s Journal of Construction Engineering and Management. Much of the construction industry fabricates made-to-order components for construction that the Census of Business wrongly considers part of the manufacturing industry, the authors say. The off-site operations that produce steel, precast concrete, and curtainwalls have consistently higher productivity than on-site construction operations.

The study, authored by researchers Charles Eastman at the Georgia Tech College of Architecture and Rafael Sacks at Technion, looks at production activities for industries with both off-site and on-site components, and compares their productivity with productivity changes over 10 years.

According to Eastman and Sacks, the news is significant to analysts, planners, and other decision makers in the building industry who have struggled to understand apparent declines in productivity in stark contrast to increasing productivity in manufacturing. With the advent of building information modeling in the last six years, where the design process involves one or more digital models for architects, engineers, contractors, and owners to coordinate the construction together, building components can be more easily pre-fabricated to reduce waste, enhance safety, and avoid delays.