The amount of research dealing with innovation has increased dramatically, construction management research included. This thesis focuses on innovations with inter-organizational effects, systemic innovations, which may radically change and improve the construction process. The overall aim of the thesis is to contribute understanding of diffusion of systemic innovations in the construction sector through the study of two different types of systemic innovations, Building Information Management and Multi-Story Housing in Timber (MSHT). It explores what facilitates and hinders innovation diffusion, with a special focus on knowledge integration and mechanisms used in the diffusion process and their effects on knowledge development. The studies conducted were made in a Swedish context related to two separate companies work with diffusing the innovations, using a broad approach with different data collection methods.

The research departures in the interplay between the innovation content, context and process through which diffusion take place, displaying differences in how diffusion precedes and is affected. Where organizations are situated in the construction process and their ability to control the diffusion process is influential and diffusion is affected by established traditions and work procedures. For MSHT other structural materials form obstacles, while for BIM it is established work procedures and methods. Environmental pressure drives diffusion of MSHT and both innovations are supported by active clients. Diffusion also requires financial resources depending on the size of investment and associated risks. The cases show advantages with moving activities from projects into a continuous business that delivers to projects, where simplifying implementation is central. Mainly due to complexity, developing in steps enables simplifications and adjustments towards users in a controlled manner. MSHT to a higher degree depends on performing real projects for development and diffusion than BIM, which can be tested to a larger extent before diffusing into the real environment. MSHT in particular show a difference in relation to many traditional models of innovation and innovation diffusion where tests are assumed possible.

The research relates to and has emphasized interaction and dynamics in the diffusion process and has provided additional understanding for managing complexity in the diffusion process. Projects are the most crucial knowledge integration mechanism with many underlying mechanisms, since they are a result of the development and show consequences of work performed. The applicability of codified knowledge in combination with more interactionintensive mechanisms has been shown and the introduction of the knowledge type’s domain-specific, procedural and general knowledge, complementing the current use of tacit and explicit knowledge, has provided additional understanding for diffusion and related knowledge flows. There are however differences in how knowledge types develop for the innovations. General knowledge is more influencing for BIM, while MSHT is about developing domain-specific knowledge. MSHT is about learning something new, while for BIM it is about re-learning. Findings show relevance in both using and developing the framework of innovation in organizations by Rogers (2003) for future diffusion studies in construction management research as well as the necessity of developing knowledge concerning implementation.