This article focuses on the role of subjective meanings in the production of informal housing. It argues that, although individual and family meanings, aspirations, perceptions, and expectations have usually been overlooked in studies on urban informality, their analysis is fundamental for a sophisticated understanding of the genesis, features, and developing trajectories of informal housing. To this end, the article investigates the informalization process of temporary self-promoted housing units (the so-called casette, i.e. “little houses”) built in the aftermath of the 2009 earthquake in the city of L’Aquila, Italy. Although it is exceptional, the phenomenon of the casette illuminates several traits of other informal housing practices. Thus, it offers two interrelated conceptual insights for a deeper, fine-grained understanding of the varied ontologies of housing informality. First, it illustrates the concurrence of simultaneous drivers, differing in nature (e.g. subjective and objective, structural and agency-related, micro and macro) at the root of the production of informal space, where a key role is also played by inhabitants’ meanings, aspirations, perceptions, and expectations. Second, it shows that informality is not a fixed and unambiguous state. On the contrary, it is a field traversed by intertwined forces in a perpetual state of tension, so that a housing unit can move through different shades of (il)legality entailing varied combinations of subjective and objective drivers.