Communication is both the problem and the solution to misunderstanding. It is the human communicative ability to display understanding to resolve misunderstandings that plays an important part in the organization of the design inputs to a construction project. Ambiguity and uncertainty, as different forms of misunderstanding, are studied in this article, as they are manifest in the conversation at a design meeting. In this setting the coordination of both in situ design activities and the planning of design tasks takes place in real time, in conversation. Exhibited are several ways that design ambiguities and uncertainties can be seen in the interactional details of a multidisciplinary design team's conversation, to then report on how different design expertise featured in the raising of, and attempts at resolving, the misunderstandings that arose. In the course of this meeting, ambiguity and uncertainty were observed not as neat, discrete phenomena but were interwoven in the conversation. This characteristic poses difficulties in the disambiguation of the problem-solving response to each form of misunderstanding and further develops our understanding of design as it is communicated and conducted in social interaction. Finally, some implications from this study are put forward to inform the design of support for collaborative design.