John Meiling

Defects in offsite construction: timber module prefabrication

The construction industry is based on craftsmanship. Quality control and assurance procedures applied in manufacturing cannot usually be readily applied in construction, where there are higher degrees of uniqueness in each project. One category of companies, industrialized housebuilders, is attempting to bridge some of the gaps between construction and manufacturing. These companies prefabricate building modules for later assembly at the building site. Since they are wholly responsible for large parts of the building process, these companies have greater opportunities to control and improve quality in a more consistent way than ordinary construction companies. Thus, it could be hypothesized that the frequency and severity of defects should be lower in industrialized housing than in ordinary construction. The aim of the study presented here is to examine this hypothesis by measuring and characterizing defects in industrialized housing. The design and manufacturing processes at two Swedish timber module prefabrication firms has been analysed through interviews, site visits and document reviews. Quality audits from three phases of the building process were compiled, analysed and categorized to provide statistical measures of defects in industrialized housing. The results show that the case study companies are better in terms of product quality than conventional housing.

A study of a plan-do-check-act method used in less industrialized activities : two cases from industrialized housebuilding

In construction projects, a large number of deviations are usually found during inspections and adjusted in a reactive manner. For projects to become proactive, root causes need to be identified and eliminated as a part of a process of continuous improvement (CI). Plan-do-check-act (PDCA) methods are part of CI and have been used with success within the manufacturing industry for decades. Research studies of PDCA in construction are less common, which could be explained by the past dominance of the project-based nature of construction compared to the process-based nature of manufacture. Industrialized construction, however, has changed this picture somewhat, and it is of interest to find out how well it works for less industrialized activities in construction. A PDCA method was tested in two cases selected from one medium-sized Swedish industrialized housebuilder, which uses a building system based on offsite manufactured modules. Empirical results are based on systematic data gathered through interviews and participant observations. Results from the two cases show that the PDCA method worked even when processes were divided into industrialized parts within a factory and non-industrial parts at the construction site although this might lead to temporary corrective actions rather than permanent process actions.

A proactive plan-do-check-act approach to defect management based on a Swedish construction project

In order to continuously improve quality and avoid reoccurrence of defects, defect management (DM) in construction needs to take a more proactive approach. The classification of construction information is important for the efficient exchange and integration of data between the many roles and phases of construction and facility management, but it also provides a framework for standardization, which in turn is paramount for improvement. In order to better understand how defects can be managed proactively we conducted a case study on inspection practices at a large construction project in Sweden, using observation and analysis of inspection reports. We identified opportunities and obstacles in the classification of defect data. The project’s defect descriptions were often ambiguous and the records lacked important contextual information. We believe that this was because current practice is not designed with proactivity in mind, and there are only regulatory requirements on the data, making classification difficult. In addition, by viewing the project’s practices through the lenses of continuous improvement and plan-do-check-act theory to identify missing or inadequate steps, we propose a framework for a proactive version of the current defect management process that could potentially help to prioritize improvement work and reduce the incidence of defects.