The European project IDEA (Improving Damage assessments to Enhance cost-benefit Analyses) is a response to the limited reliability of data currently used to support cost-benefit analyses for natural hazards mitigation; in particular, an improvement of both damage data quality and procedures to collect and manage them is pursued by the project. A comprehensive understanding of (i) how disaster data are presently collected and stored, (ii) main reasons for data collection, (iii) possible uses of collected data, and (iv) stakeholders involved in data collection and management is the first step to improve the present quality, reliability and usability of data. To this aim, several case studies were analysed in the project referring to dif...