Abstract “Gaioleiro” buildings are unreinforced masonry buildings with flexible timber floors associated with the urban expansion of Lisbon at the end of the nineteenth century and beginning of the twentieth century. This paper presents the results from the seismic performance-based assessment of a “Gaioleiro” building case study, assumed as a prototype representative of wide number of buildings. The assessment was addressed to the global seismic response of the building, mainly governed by the in-plane capacity of the masonry walls, and to the local response, related to the activation of out-of-plane mechanisms of parts of the building. The global behaviour was determined by non-linear static analyses and the effects of some relevant modelling options were considered; in particular, parametric analyses were carried out taking into account the strength capacity of spandrel beams and the influence of the degree of connection between walls. The local behaviour was determined with limit non-linear kinematic analysis. The seismic performance-based assessment was set by the comparison of the structural capacity, with reference to various limit states (as proposed in Eurocode 8), with the seismic demand for Lisbon, related to different return periods. Different approaches to define such limits on the capacity curve were assumed in order to discuss the reliability of criteria proposed in codes for the case of structures characterized by flexible floors.