Tolerance management in prefabrication of mechanical, electrical, and plumbing installations

Prefabrication in construction has advanced. However, mechanical, electrical, and plumbing (MEP) works still lag behind structural and interior applications. Inaccuracies in design and installation can undermine the benefits of prefabrication, making dimensional accuracy critical. Despite this, the literature lacks clear, unified methods for managing tolerances in MEP prefabrication. This research aims to advance tolerance management in MEP prefabrication by formulating prescriptive principles based on best practices. A multiple case study approach with five projects was adopted. Four cases with advanced prefabrication and/or tolerance management approaches and one with tolerance issues were studied. The cases included two hospitals, two apartment buildings, and one laboratory, representing projects with differing functional requirements and tolerance environments. Thematic analysis was applied to interviews, documents, and site visits. Seven prescriptive principles for tolerance management in MEP prefabrication are the primary contribution of the study. Among these, the role of communication, detailed design, and quality control are emphasized, while buffer assembly is identified as a distinctive MEP tolerance management method. The novelty and industry impact of the principles are underscored by the lack of systematic research on tolerance management in MEP prefabrication and by the fact that none of the case projects applied all the principles. Adoption of these principles is recommended to guide design, manufacturing, and installation to improve productivity, reduce lead times, and enhance quality.