With the predicted growth in the number of people with dementia living at home across the globe, the need for home-based care is expected to increase. As such, it will be primarily family carers who will provide this crucial support to family members. Designing appropriate support for family carers is thus essential to minimise risks to their health, to prevent premature institutionalisation or poor care for persons with dementia, as well as to sustain the effective functioning of health and social care systems. To date, the high volume of research related to care at home and acknowledged low impact of interventions suggests that a re-examination of the nature of care at home, and how we come to know about it, is necessary if we are to advance strategies that will contribute to better outcomes for families. This paper describes findings from an ethnographic study that was designed to support an analysis of the complexity and materiality of family care arrangements – that is, the significance of the actual physical, technological and institutional elements shaping care-giving situations. In this paper, we describe the arrangements made by one family to show the necessary collectivity of these arrangements, and the consequences of the formal care system's failure to respond to these.