TY - CONF TI - Variation management in prefabricated MEP installations: challenges and opportunities C1 - Singapore, Singapore C3 - Proceedings of the 34th Annual Conference of the International Group for Lean Construction (IGLC 34) SP - 727 EP - 738 PY - 2026 DO - 10.24928/2026/0129 AU - Valkonen, Tuomas AU - Seppänen, Olli AD - Doctoral Researcher, Department of Civil Engineering, Aalto University, Espoo, Finland, tuomas.valkonen@aalto.fi, orcid.org/0000-0002-2710-5190 AD - Associate Professor, Department of Civil Engineering, Aalto University, Espoo, Finland, olli.seppanen@aalto.fi, orcid.org/0000-0002-2008-5924 ED - Hamzeh, Farook ED - Poshdar, Mani ED - Garcia-Lopez,, Nelly P. AB - Managing variation is an essential lean principle. Tolerance management remains marginal in construction and focuses on architectural and structural trades. Especially mechanical, electrical and plumbing systems have largely been neglected in tolerance management research, despite their critical role in project delivery. This research studies variation management, its challenges and opportunities for improvement in a plumbing renovation project through semi structured interviews and thematic analysis. The interview questions addressed prefabrication practices, planning processes, production and control activities, tolerance management, accuracy, and sources of variation. Three aggregate themes emerged as key results: (1) detection and management of deviations, (2) design information and tolerance management, and (3) management of change and personnel. Together these themes highlight the multifaceted nature and difficulty of variation management. The results emphasize that both technical and human factors must be addressed simultaneously while maintaining constancy of purpose. Improving installation guidelines and accelerating issue resolution were identified as key development areas. Stabilizing the production system provides an opportunity to further enhance productivity and shorten cycle times. KW - Tolerance management KW - variability KW - variation KW - prefabrication KW - MEP. PB - T2 - Proceedings of the 34th Annual Conference of the International Group for Lean Construction (IGLC 34) DA - 2026/06/22 CY - Singapore, Singapore L1 - http://iglc.net/Papers/Details/2455/pdf L2 - http://iglc.net/Papers/Details/2455 N1 - Export Date: 19 June 2026 DB - IGLC.net DP - IGLC LA - English ER -