The Qualisurv-Habitat study of households living in substandard housing aims to describe the direct and indirect interactions between substandard housing conditions and individuals’ perceived health status in order to establish an action-oriented typology of substandard housing situations. Semi-structured interviews were conducted with 32 households in Île-de-France, Nord-Pas-de-Calais, and Provence-Alpes-Côte-d'Azur in the participants’ homes. Homeowners, tenants in the private and public housing sectors, residents without legal rights or tenancy agreements, households in rural and urban areas, couples with and without children, and single individuals were interviewed, across all age groups. The study’s results show that residents observe effects on their health and quality of life. From the residents’ perspective, respiratory health and mental health are the two areas most affected by poor housing conditions. Dampness and mold, energy poverty, and overcrowding are the most common issues, along with outdated electrical systems and structural instability. These housing conditions contribute to isolating households that already face numerous social challenges. When housing is substandard, it fails to fulfill its social and individual functions. This leads to health issues, a lack of stability, and a lack of privacy. It becomes a source of shame. Everyday activities—eating, sleeping, maintaining personal hygiene, tidying up, growing and developing, and feeling safe—which contribute to maintaining good health, cannot take place naturally. The actions taken by households to remedy their situation were linked to the length of their tenure in the housing and the presence of a supportive family and social network. These actions include repair and maintenance work, as well as taking steps with the landlord and government agencies to assert the right to healthy housing. The longer they had lived in the dwelling, the more difficult it was for households to take action. Children are particularly vulnerable to the effects of substandard housing, for both physiological (exposure to pollutants) and behavioral reasons. Substandard housing conditions hinder their chances of academic success and personal development. Finding ways to intervene with households living in substandard housing to reduce the impact of these housing conditions on their health requires taking four factors into account: -the condition of the building (unsanitary, unfit for habitation); -occupancy rate (alignment between family composition and the number of rooms in the dwelling); -the initial health status of individuals upon moving into the dwelling or the onset of medical conditions unrelated to housing conditions (cancer, organ transplant, HIV, etc.) ; -the individual’s perception of their housing history and the suitability of their home for their circumstances, a factor that shapes how they view their home and the steps they take. Prevention and remediation efforts should incorporate these four dimensions in order to be effective and accepted.