The focus of this article is the open building concept in multi-family residential architecture. The article analyzes and examines two specific projects: the Solid Oud West in Amsterdam (2010) and the Plus Home experience in Helsinki (2005). By the analysis of these projects, the article seeks to define the state-of-the-art in open building practice, and aims to expose the possibilities and limitations that this kind of architecture offers. The research focuses on the three main topics related to open building implementation: the possibilities of user involvement in the design process, the opportunities for an open and time-based housing design, and the benefits of an adaptable and industrialized construction. The outcome of this research seeks to inform about this trend in residential architecture and how this could affect the building industry as a whole, and architectural practice in particular.