Product quality through experience feedback in industrialised housing

Sammanfattning: This thesis is based on four appended papers and an introductory section. The work has been conducted with a focus on product quality and feedback. Hypothetically, industrialised housing gives better product quality and improved control in production. Industrialised house builders work with the prefabrication of building parts for later assembly at the building site. Timber framed volume production represents one form of industrialised housing. These house builders strive to control their products as they develop from conventional building firms into industries where quality control is a major concern. This effort becomes evident, e.g., in supply chain relations, which are long-term and well-defined in industrialised housing. The overall aim of this thesis is to investigate product quality through experience feedback at an aggregated product level in industrialised construction. It is suggested that houses be viewed as products instead of projects, based on the understanding and view of how industrialised housing can benefit from Lean and quality management theories. Quantitative and qualitative data concerning wooden stairs and timber framed volume production were collected. Results are based on data gathered through a single and a multiple case study. The single case study presented in paper I involves one industrialised house builder and one staircase producer, plus a complementary study presented in the introductory part of the thesis. Three focus group meetings and a series of interviews were conducted. A questionnaire was distributed to 700 tenants at 13 different habitats. One multiple case study employing four timber framed volume producers was presented in papers II-IV. Results are based on data gathered through semi-structured interviews, and statistical analysis of quality audits from three phases in the building process were studied. Defects from quality audits were coded, sorted and analysed regarding origin, cause and action required for correction. The single case study shows that efforts are being made to develop new industrialised housing products, though a lack of appropriate management structures hinders the quality assurance of product development. The study also reveals a shortage of available data to execute service life planning. Results from the multiple case study reveal a company focus to streamlining the production process, even though experience feedback between departments at the company was minor or absent. Organisations within the companies offer the possibility for experience feedback, which is not currently functioning. Experience feedback is essential when gradually enhancing an industrially manufactured product. In addition, 21% of all recorded defects can be directly linked to the structural design phase, building system or both. Based on the aim and by exploring the theoretical framework of quality management, service-life planning and Lean theories, it is concluded that industrialised house builders refrain from using established quality frameworks to improve their product and that product quality is currently the same as elsewhere in construction. However, the possibility to implement product quality management is large, since the prerequisites for success are present, namely production control, ownership of the building process and established supply chain relations. Feedback is not functioning due to a lack of decision of overall improvement and no allocated resources for product development and quality engineering. So far, the transformation of collected information is non-existent.