Four solid walls and a roof over one's head. These, from an essentialist standpoint, are the minima of homely existence. What happens then under conditions of speculation and subdivision when domestic walls are no longer stable givens, but become flimsy, mobile and contested? Drawing on a rich seam of popular British films from the late 1950s and early '60s -set in the transitional world of postwar London lodging houses -this paper examines how partition walls refashioned the interior space of the terraced house. Analysis of popular visual culture is supported by archival research centred on local valuation lists, which allow us to read the traces of these sometimes temporary, often illegal structures. The paper argues that partition walls were key to the extraction of value from a declining private rental sector by property traders and landlords. At the same time, these ubiquitous structures formed a series of highly charged thresholds between disparate individuals. Partition walls were instrumental in the 'spatialisation' of race in postwar Britain, serving to heighten an awareness of otherness while simultaneously bringing individuals into uncomfortable proximity. Finally, the paper asks how people overcame or lived between these divisions, and how this affected questions of visibility and representation.