The BZO draws a clear distinction between preservation zones and transformation zones across the City of Zurich. While former peripheral areas and Gartenstadt structures are largely exposed to the volatility of the real estate market, historic central areas are specifically protected.
The prevalence of demolition in Zurich further reinforces this distinction. However, if greater attention were given to conversion practices, such as vertical extensions, this distinction could become less clear.
The vertical extension of the city has repeatedly been proposed as a response within urban planning discourse. Such proposals can be traced to a broader historical lineage that emerged during periods of crisis or in anticipation of societal change. In moments of transformation, artists and architects have searched for constructive images of the future by looking upward.
Extending structures superimposed new interpretive layers onto the city. Vacant, sometimes derelict, neighbourhoods were reappropriated through formal or informal means of extension, and voids were redefined.
Today, voids have become rare. The city has changed. And so have proposals for vertical extensions. They are increasingly proposed as a sustainable alternative to demolition and a solution to the housing shortage. The local liberal party (FDP Stadt Zürich) launched an initiative calling for a “1-storey-raised” Zurich in 2024. Or, already in 2008, the Loi 10088 sur la Surélévation in Geneva attempted to establish upward extensions as a strategic planning instrument. Both emphasize the pragmatism of a simple solution.
While extending buildings can offer responses to multiple crises, this very characteristic also creates room for politicization and commodification. The vertical extension becomes a reconciliatory answer to a multitude of crises within a political debate that places considerable emphasis on economic reasoning: increasing supply reduces excess demand and consequently stabilises or lowers rents.
Our proposals for vertical extensions in Zurich do not seek to provide a comprehensive solution to the housing shortage. Instead, they focus on strengthening specific local conditions and on questioning and blurring the rigid distinction between development and preservation areas, where demolition has become the default logic. Instead, we imagine scenarios in which the extension of buildings becomes a common practice of city's development.
