Root Causes of Clashes in Building Information Models

Iris D. Tommelein1 & Sepide Gholami2

1Professor, Civil and Environmental Engineering Department, and Director of the Project Production Systems Laboratory (, 215-A McLaughlin Hall, Univ. of California, Berkeley, CA 94720-1712, USA, Phone +1 (510) 643-8678,
2Research Volunteer, Project Production Systems Laboratory, 215-A McLaughlin Hall, Univ. of California, Berkeley, CA 94720-1712,


Building Information Models (BIM) support designers and builders in creating and coordinating system designs and planning work. In practice—out of necessity—this includes checking that systems do not clash, but what constitutes a clash? How do clashes come about? Do clashes relate to design-, buildability-, or building- performance qualities? How does a clash detection process fit (or not) in lean project delivery? In this paper we describe our findings from research into clashes. Our sample is biased in that a number of the people we spoke with have been working in Integrated Project Delivery (IPD) teams, with commercial terms spelled out in an Integrated Form Of Agreement (IFOA). Many are co-located on their project site—at least some part of each week—so that they can work together closely as their thoughts on design and construction unfold. It is common practice for these teams to share their BIMs, each discipline-specific model having been developed by a specialist design- or contracting firm, and integrate them in a big-room setting. Nevertheless, this integration process invariably appears to include the identification and resolution of clashes. When viewing these BIM development practices from a ‘lean’ perspective, we found that many are far from lean. Accordingly, we present opportunities for process improvement when using of BIM in pursuit of lean ideals.


Building Information Model (BIM), BIM pathology, clash detection, root-cause analysis, design management, tolerances, constructability, contingency, waste



Tommelein, I.D. & Gholami, S. 2012, 'Root Causes of Clashes in Building Information Models' In:, Tommelein, I.D. & Pasquire, C.L., 20th Annual Conference of the International Group for Lean Construction. San Diego, USA, 18-20 Jul 2012.

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