Construction Deficits in Swiss Housing

Despite technical progress the construction of a building is a highly labor-intensive process. The possible construction defects that occur are mostly the result of mistakes in the design and construction phases. Thus the construction industry suffers a loss of image. The costs of rectifying construction defects amount to approximately 8% of the monetary expenditure in new housing construction.

The aim of this dissertation is the development of an overview of the causes of construction defects, which reveals chains of causes on the level of the decision maker as well as the var- ious mutual interactions during the design and construction phases. Furthermore, the quanti- tative distribution of construction defects, building elements and responsible parties is deter- mined on the basis of different data sources. The dissertation is restricted to Swiss housing, with a focus on new building. The central emphasis lies in construction defects that result from mistakes in design, construction management or realization. The legal view, the public procurement department and private persons are excluded in this dissertation.

Quantitative and qualitative research approaches were methodically linked. In the quantita- tive research approach the analysis predominantly used defect reports and expertise reports, and in the qualitative research approach, interviews were conducted.

The conclusion of the quantitative research approaches is that the cause of construction de- fects lies primarily in human failure, particularly on the part of the employer, the planners and the construction management. Material defects, errors in use and natural wear are of minimal importance. Sorted by building elements, construction defects noted in defect reports are predominantly located on the surfaces of the interior fittings. In expertise reports it is shown that about 60% of construction defects occur in connection with water and the building enve- lope. The building elements concerned are the external wall, the balcony/terrace, the ceil- ing/floor, items in contact with the earth and the roof as well as the windows. In the qualita- tive research approach, the design and building process was analysed to determine the causes and their mutual interactions that lead to construction defects. The result of the qualitative research approach is the identification of root causes of construction defects: investment target, decision of the client, construction management, bidding, award of contract, professional expertise of the employer, construction plans/detailed plans as well as key dates. The determined causes are in various ways and to varying degrees dependent on one another.