We studied the organizational practices around Building Information Modeling, or BIM, in inter-organizational collaborations among architects, engineers and construction professionals in order to theorize how communication supports technology adoption. Using ethnographic observation and one-on-one interviews with project participants, we observed five teams on three different commercial and institutional building projects that each collaborated over periods of 8–10 months. In this paper, we argue that the dynamic complexity of design and construction processes requires what we call ‘messy talk’—conversations neither about topics on meeting agendas, nor on specified problems or specific queries for expertise. In messy talk interactions, AEC professionals contributed to innovation and project cohesion by raising and addressing issues not known by others. The communicative ‘affordances and constraints’ of BIM structured meeting conversations away from less structured, open-ending problem-solving and towards agenda-driven problem-solving around already identified problems. In other words, using BIM to make information exchange more efficient and effective worked only for certain tasks. We found BIM supports the exchange of explicit knowledge, but not necessarily informal, active and flexible conversations and exchange of tacit knowledge through messy talk. Although messy talk is perceived as more inefficient, it ultimately makes inter-organizational teams more effective.