The building envelope serves as the interface with the external environment. Its technical elements (e.g., cornices, balconies, and finishings) are highly vulnerable to damage from external hazards due to their technological characteristics and state of preservation. Such phenomena can lead to potential detachments and falls of these elements onto surrounding areas, posing significant risks to exposed agents and transforming them from “factors at risk” to “risk factors” for urban systems. This paper seeks to formalise the concept of Building Risk, which is defined as the probability that a hazardous event, stemming from the vulnerability of the technical elements of the building envelope, can have detrimental effects on urban systems. A scientific literature survey was conducted to analyse how existing studies have addressed these issues. The results indicate strong interest in the impacts of external hazards on buildings and urban systems, revealing significant gaps in modelling the cascading effects arising from the building envelope vulnerability. Assessing this vulnerability and its impacts is crucial to ensure urban system safety and to fully understand the multi-risk dimensions to which these systems are exposed. The proposed topics aim to inform the implementation of risk reduction measures and the design of low-vulnerability technological solutions tailored to contexts’ specific hazards. Future implications include the renewal of risk management strategies to enhance urban system safety.
