An ever-changing modern society imposes new challenges for city development, namely how the built environment can be designed for a changing population and urban housing density. This article argues that current large-scale top-down demolition and construction strategies for densification are not the most efficient and sustainable approaches. Alternatively, a proposal for a more flexible system, consisting of small-scale interventions, is put forward, with the goal of creating resilient neighbourhoods that can adapt to different dwelling densities. This article takes the neighbourhood of Hillesluis in Rotterdam South as the research subject to explore possible densification strategies. Afterwards, a new housing model of ‘Sponge housing’ is proposed that can self-regulate the number and size of houses , creating a system capable of having flexible densities.