This paper presents changes in the vertical circulation and organisation of merchant palaces, and their influence on multi-family architecture in Venice from 1450 to 1600. Just prior to this period buildings underwent a substantial change in the vertical distribution of floors; this marked the transfer of the commercial-residence casa fondaco prototype into a more complex multi-level building with two semi-autonomous piani nobili palatial apartments. The resulting vertical expansion led to a departure away from the external courtyard staircase as the primary means of vertical circulation. Many Late Gothic palatial buildings incorporated double courtyard staircases that provided individual access to each palatial apartment. However, this scheme consumed a great deal of developable land resulting in the widespread utilisation of interior monumental dog-leg staircases by the Early Renaissance. This simplified internal staircase fitted cleanly into the existing structural logic of both new and remodelled palace buildings.