Abstract
Contemporary public spaces suffer from over-regulation and digital displacement, reducing urban activity and spontaneity. This article introduces spatial plasticity—the capacity of environments to absorb spontaneous, user-initiated physical and programmatic modifications across scales and timeframes without losing essential functions. Unlike flexibility or adaptability, which rely on pre-scripted scenarios embedded in design, plasticity focuses on a space’s threshold to accommodate unscripted, bottom-up interventions. The study employs a dual methodology combining conceptual analysis with research-by-design, drawing on theoretical synthesis and empirical experiments conducted between 2019 and 2026 in Central Europe and Berlin, Germany. By distinguishing between natural/artificial and material/immaterial dimensions, the article links the political question of who modifies space with the design question of how an environment enables such action. Through case studies-from snow-induced transformations to residential front gardens, the argument demonstrates plasticity’s value as both an analytical tool to identify spatial limits and a design principle for calibrating urban openness. The findings suggest that enhanced plasticity fosters spatial activation and reinforces identity through visible user traces. Ultimately, the paper argues that cities can be designed to enable everyday interventions that deepen residents’ attachment to the public realm, offering a more hands-on alternative to formal participation.