The increasing complexity of building projects, with high quality standards, integrated technologies and strong management restrictions, demands the intervention of numerous and diverse specialists. This requires an intense leadership, organization and coordination effort. However, building regulations, such as the Spanish Law on Building Management (LOE) 38/1999, only formally consider developers, project designers, project and work supervisors, quality control entities, construction companies, owners and final users as building agents. However, these categories are insufficient to represent the interests of all the stakeholders. The purpose of this paper is to carry out an analysis of the agents that are currently part of the entire building process. If their relationship of influence and dependence, as well as their alignment with the overall objectives of the project are studied, potential convergences, divergences, agreements and disagreements can be established. To do this, the authors conducted a prospective analysis through the MACTOR (Matrix of Alliances and Conflicts: Tactics, Objectives and Recommendations) strategic planning simulation tool, for which the rules of the Delphi technique were applied and a consultation with technical experts, both professionals and academics, was held. The research provides insight to assess the power relationships between the building agents, as well as to measure the alignment of objectives with their interests. Results show that, in the context of integrated project management (IPM), the influence of technical agents is reduced by limiting their functions to those marked by their regulatory framework, allowing them to focus on their legal powers, and the room for manoeuvre of the professional agents, who are subject to systematized monitoring and control, is also reduced. The prospective analysis also highlights the importance of defining the scope from its early stages, as well as the need to reach multilateral agreements based on the other two main constraints: time and cost.