The Filter buildings belong to Rotterdam’s most remarkable buildings. It is an ensemble of three buildings, designed by Van der Steur, that was transformed to cheap apartments in the early 80’s. De apartments are organised around monumental halls. For a long period the buildings are subject to social problems, such as vandalism, graffiti, violence and even murder. Reason for the client to take action and ask Krill to design new entries. We proposed to investigate the social logic of the whole internal fysical organisation. Using a method we developed earlier we created a script showing the weak points in the infrastructure of the buildings.