In the Architecture, Engineering and Construction (AEC) sector, information flow and knowledge management influence how companies organize, work and produce, which can be represented in a social network analysis (SNA). Information flows are a critical activity for the work done in architecture firms. The objective of this study is to analyse the social structure of architecture firms to determine how to address information flow and knowledge management. The study is part of benchmarking research related to SNA, management practices and Key Performance Indicators (KPI) in architectural offices. After an extensive literature review, a survey was implemented to develop the SNA. Findings show network type shown by the office depends on its organizational infrastructure. There are also behavioural patterns; it is possible to observe that as the firm's size increases, the density of the work-related connections in the network decreases and the average length of the path between the nodes within the network increases. Therefore, we can conclude that when offices have more human resources, as well as a pyramid structure and defined hierarchy, information flow is concentrated in small groups.