Orsaker till fel i byggandet: en studie om felorsaker, felkonsekvenser, samt hinder för inlärning i byggprojekt
Doctoral thesis, 1994
One means of increasing the effectiveness of building is minimisation of the numbers of de-fects and their consequences. In order to accomplish this, it is necessary to have knowledge of why defects occur, of their consequences, and of how to learn from errors. A survey of existing defect studies indicates that there is a restricted amount of knowledge about these factors avai-lable today.
The aim of this study is to increase the available knowledge within the field. The study was based on a preliminary model of the course of development of a defect. Through discussions of the concepts of defect and cause and effect, of the organisation of building projects, and of the behaviour of individuals in organisations, the study goes on to further develop this model and to root it in theory. Particular discussion is devoted to organisational learning, and is related to the abovementioned model of defects. A number of research questions are posed on the basis of the model, with a view to increasing the available knowledge about the causes of errors, about ways of restricting the consequences of errors, and about impediments to error learning.
The empirical material consists of one major case study. A construction project was followed throughout its course, by an appointed observer over a two-year period. Through direct, regular observations and interviews, 1460 defects were registered, analysed and described in detail. An overall analysis indicates that internal failure costs corresponds to approximately 6 % of produc-tion cost, that most defects originate at site management level, and that the dominant cause of errors is lack of personal motivation.
Three analyses are carried out in order to create a more thorough understanding of and to de-velop the model for defects. In order to gain insight into the complexity of defects, a longitudinal analysis of ten defects was carried out. In an in-depth analysis of 515 key elements of defects, as-pects of the model are further penetrated. Organised learning is assumed to be one means of avoi-ding repetition of errors. Impediments to learning are identified.
The analyses provide a basis for development of a refined model for studying the course of development of a defect. The study confirms that the main source of defects is individual motiva-tion, as well as conflicts between members of an organisation with regard to objectives. Short-comings in inspection procedures and neglecting to correct defects contribute to the continuation of the course of development of a defect, and of the consequences being extended. Impediments to transferring knowledge among individuals imply that learning mainly takes place in the perma-nent organisations and within roles.
consequences of defects
causes of defects
costs of defects