Studies of architectural design practices have shown that building projects take shape through the intricate interactions between human designers and various technological tools. In present-day’s architectural practice, these interactions are increasingly being reconfigured by two major trends that are affecting the future of construction: digitalisation and the imperative to make building processes and the built environment sustainable. Against this backdrop, the paper presents insights from an ethnographic case study on socio-digital co-design practices in the planning and preconstruction phase of an ambitious building project. This research explores how digital tools reconfigure design practices and highlights the ‘reverse salient’ that has limited the realisation of the integrative potential of socio-digital design processes. Using a practice theory approach centred on ‘socio-digital co-design’, the study shows that digital tools reorganise, but do not take over, the coordination practices in early design necessary to achieve coherent results and sustainability outcomes.