Vertical Densification for Student Housing in Helsinki: Roof Extension in the Arabia Factory Block

Abstract

As rent prices soar and subsidies are cut, Helsinki is under continued pressure to provide affordable housing for its growing university student population. This pressure has been associated with financial barriers and well-being, as well as lower educational outcomes. As the city struggles to implement long-term, sustainable interventions in housing supply, vertical densification has been shown to offer a way to reinvigorate housing supply while also helping preserve green spaces and supporting the objectives of the Helsinki City Plan 2016. Roof extensions have arisen as a possible solution to the housing supply challenge in Helsinki, as they promise to make use of existing infrastructure while using less land than greenfield development, and therefore have a lower environmental impact than other kinds of new development. There has been, though, a relative lack of research on the applicability of roof extension in medium-sized buildings from four to twelve storeys in height under all circumstances and, furthermore, when timber construction is involved. As timber construction is a relatively lightweight material with low carbon output, fire safety, condensation, acoustics, and structural performance issues have so far limited its use in large-scale development. However, numerous buildings from the mid-twentieth and early twenty-first centuries possess structural capacity and urban significance that justify vertical additions. This research explores roof extensions as an approach to increasing housing supply for students in Helsinki. The case area for this study is a single building in the Arabia Factory Block. It combines an interdisciplinary analysis that uses stakeholder mapping, reviews of technical frameworks for timber construction, and lessons from international cases to examine how roof extensions can become feasible, viable, and context-responsive in Helsinki. The research explores how medium-sized buildings can accommodate additional residential units while supporting the adaptive reuse of their existing elements. This research ultimately provides a loose framework for vertical density in Helsinki and positions roof extensions as a method to alleviate student housing pressures and enable the city to move towards more resilient, sustainable urban development.