PurposeHow organisations interact with and respond to environmental pressures has been a long-term interest of organisational scholars. Still, it remains an under-theorised phenomenon from a project perspective. So far, there is limited understanding of how projects, which are composed by a constellation of organisations, “respond” to institutional pressures that are exerted on them. This research takes the perspective of projects as adopters/implementers of institutional pressures and analyses how they interact with, and respond to, such pressures. More specifically, this research explores how construction projects respond to the pressure of a Building Information Modelling (BIM) mandate.Design/methodology/approachMultiple in-depth case studies were conducted to explore the practical implementation of a BIM mandate in the UK and understand how the construction projects responded to the coercive pressures to implement a new policy mandate for process digitalisation. Multiple sources were employed for data collection and the data were analysed inductively. The findings identify a hybrid response comprising four distinct ways that projects might respond to an institutional pressure.FindingsWe find that projects decouple both from the content and from the intended purpose of a policy, i.e. there are two variance of a policy-practice decoupling phenomenon in projects. The findings also reveal the underlying conditions leading to decoupling.Originality/valueWe advance decoupling literature so that it better applies to the temporary, distributed and interdependent work conducted via projects. Second, we define decoupling in projects as a provisional and fragmented process of wayfinding through heterogeneous institutional spaces, and discuss the potential policy-practice assemblages in projects, influenced by how, if and when project members' activities decouple from the many and often contradicting institutional pressures they face. Third, we discuss how the qualitatively different forms of decoupling that we identified in our work may act as part of a legitimation process in ambiguous situations whereby projects might share a resemblance of conformity with institutional pressures when they are de facto only partially conforming to them.