Abstract. Given the current challenges in flood risk management and vulnerability assessment of buildings exposed to flood hazards, three-dimensional numerical modelling of torrential floods and its interaction with buildings are presented. By means of a case study application, the FLOW-3D software is applied to the lower reach of the Rio Vallarsa torrent in the village of Laives (Italy). A single-family house on the flood plain is thereby considered very detailed and exposed to a 300 yr flood hydrograph. Different building representation scenarios, amongst an entire impervious building envelope and the assumption of fully permeable doors, windows and cellar shafts, are analysed. The modelling results give insight into the flooding process of the building’s interior, the impacting hydrodynamic forces on the exterior and interior walls and, further, quantify the impact of flooding a building on the flow field on the adjacent flood plain. The presented study means a step towards the development of a comprehensive physical vulnerability assessment framework. For pure water floods, it shows possibilities and limits of advanced numerical modelling techniques within flood risk management and, thereby, the planning of local structural protection measures.