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Title of the thesis: Improving quality and productivity in mechanical, electrical, and plumbing construction: the role of tolerance management, prefabrication, and detailed design.

Thesis defender: Tuomas Valkonen
Opponent: Prof. Rodrigo Herrera, Pontificia Universidad Catolica de Valparaiso, Chile
Custos: Prof. Olli Seppänen, Aalto University School of Engineering

Building services installations, including heating, ventilation, plumbing, and electrical systems, do not always end up where they were designed to be. Differences between their designed and actual locations can cause installation problems, rework, and delays, contributing to persistent quality and productivity problems in building services construction. Nevertheless, little empirical research has examined the extent and causes of these deviations or how they can be managed. This research addressed this gap by investigating dimensional variation in building services installations. Its purpose was to support improvements in construction quality and productivity by enabling installations to conform more reliably to their designs. The study connects three areas that have usually been considered separately: detailed design, tolerance management, and prefabrication. The results show that dimensional deviations can be substantial and vary considerably between projects and installation environments. They arise from interconnected factors, including building structures, incomplete design information, installation practices, and on-site problem-solving. The study provides new measured evidence of these deviations, identifies their main sources, and proposes seven principles for managing tolerances throughout a construction project. It also explains why prefabrication, as a method for improving dimensional accuracy, is adopted or rejected and what conditions support its successful use.

The main conclusion is that dimensional variation cannot be controlled through inspections or more accurate installation alone. It must be managed throughout the project, beginning with sufficiently detailed and buildable designs. Tolerance requirements must be defined, the compatibility of structures and building systems must be verified, and unavoidable variation must be accommodated in the design.

The findings can be used by designers, contractors, prefabricators, and clients. They provide practical guidance for detailed design, system coordination, tolerance specification, and quality control. Better management of dimensional variation can reduce improvisation and rework, make prefabrication more reliable, and help ensure that building systems are constructed and operate as intended.

Thesis available for public display 7 days prior to the defence at . 

Contact information: tuomas.valkonen@tuni.fi