This research reports on a sequenced co-design process to engage lived experience consumers, carers, healthcare professionals, sector advocates and government representatives in co-designing spatial and experiential inputs to a residential eating disorders facility. The stakeholder community was enabled to co-design a model of care and, building on this, shape the functional brief for the design of health spaces. The stakeholder community input provided architects and designers with a more expansive understanding of user needs regarding specific architectural qualities including psychological safety, flexibility, social connection, and sensory experiences. Our approach yields insights across three interlinked areas: capacity building in the stakeholder community to develop the design language to contribute to design discussions; co-design processes to question pre-existing design assumptions; and subsequently, the development of a more nuanced brief for health spaces. The research supports designers, architects, health organizations and health planners to meaningfully engage with future users of complex healthcare environments.