Purpose – Buildings maintenance is a complex activity: importance of issues, scales crossing, diversity of civil engineering domains . . . The key point of this activity is the elaboration of the maintenance. This paper seeks to present a method and the associated tools to elaborate a building maintenance plan considering the complexity of the facility management. Design/methodology/approach – The risk notion can be a solution to handle the complexity. Specialists may specify each decision in terms of risk form in order to purchase (reflecting the probability and the associated consequences) a rich view about the global situation. The principle is to use a simulation logic, to compare the situation in terms of risk, with or without the realization of an action (work, equipment replacement, formation, etc.). This simulation logic must be based on efficient software tools, which enable one to manage the risk database ergonomically. Findings – The method took the form of an experiment in a leading French company. The experiment’s results and plan were highly beneficial. Although the method was based on personal choices rather than on a mathematical function, the final maintenance plan was considered sound and seemed to correspond to the expectations of all the participants. Originality/value – Most facilities management methods and tools find answering the complexity problem difficult. They ignore the complexity by focusing only on the technical aspect. The work takes place at the highest facility management level, therefore shedding new light on this domain. The risk notion enables one to consider the complexity of the maintenance and to formalize it into an understandable form for the decision-maker.