Why do some projects prefabricate MEP while others do not?

Research Question: Why do some projects prefabricate mechanical, electrical, and plumbing (MEP) systems while others do not? Purpose: Most of the literature on MEP prefabrication is focused on its benefits, implying prefabrication is a rational choice, yet adoption rates remain low. The purpose of this study is to increase understanding in prefabrication decision-making. Research Method: Multiple case study research with a qualitative approach. Findings: The decision to prefabricate can result from a long lean implementation process or as an individual method to overcome a specific problem. Shortening cycle times and removing task dependencies to shorten the critical path are motivators for choosing to prefabricate. Additionally, cost savings during the project and improved productivity at the portfolio level are reasons for prefabricating. Tight schedules, late contractor involvement, and higher direct costs are reasons for not prefabricating, although cost- and schedule-related benefits are simultaneously acknowledged as benefits of prefabrication. Limitations: The study is limited by the low number of case projects and its emphasis on the Finnish market where MEP prefabrication is uncommon. Implications: The results support fact-based decision-making by highlighting reasons for prefabricating and the limitations of the evaluation methods. Additionally, required changes to production systems to realize the benefits of prefabrication are shown. Value for practitioners: The perceived benefits of prefabrication increase in certain circumstances, such as when takt production is utilized. The perceived benefits decrease when prefabrication is considered late in the process, is used instrumentally, or is isolated from other lean approaches.