Uncertainty is a parameter used to define safety factors but, in the case of evaluating existing buildings, uncertainty could influence the definition of how we want to renovate our buildings and how much we need to invest in structural adaptation. This article aims to stimulate the debate on technical regulations which – starting from the shared need for in-depth knowledge of existing structures – allows the inclusion in the regulations of parameters related to the investigated or neglected elements and structural mechanisms, in order to highlight to the designer how large, or limited, the uncertainty is in evaluating the safety of the structural unit. The evidence of this uncertainty is becoming increasingly important to balance the growing speed of calculation that gives professionals an illusory ease of modeling that risks becoming a "game"1 dangerous for public safety.