To address the current housing shortage, new houses must be added, but at the same time many existing houses need to be made more sustainable to meet climate goals. This project explores the potential for densifying and revitalizing post-war neighborhoods. It builds upon the original design principles of these neighborhoods light, air, space, and living in green environments, reinterpreting them for modern needs. The balance between private and public spaces is subtly reshaped, enhancing social control within the community. The monotonous neighborhood is densified by adding smaller, more diverse housing units on top of existing houses. This is made possible by removing the heavy exterior of the existing buildings and renovate with lightweight biobased materials, which at the same time ensure better insulation of the existing home. These materials offer a sustainable alternative for current construction materials and are gaining popularity. Designers must understand their properties and how to effectively use them, the research focuses on gaining more insight in these materials. The results of the study include schemes that allow the different alternatives to be compared using various criteria. The top-ups accommodate diverse household types, connected by a second-floor gallery that links the different rows of houses. On the south side, this gallery is designed wider to provide an outdoor space for residents, encouraging neighborly interactions. Transitions between private outdoor areas and collective gardens and streets are subtly defined, ensuring privacy while promoting interaction and social control. Ultimately, the design offers a sustainable solution to the housing crisis by densifying and upgrading existing homes, while revitalizing post-war neighborhoods.