This research presents the possibilities of extending the lifespan of multi-family residential buildings constructed during the mass construction period through the application of comprehensive renovation. Buildings constructed between 1946 and 1970 constitute one-quarter of Serbia's total multi-family housing stock; however, their lifespan is questioned due to their energy, spatial, and functional deficiencies. The study analyses the application of the comprehensive renovation methodology through volumetric additions, aiming to achieve energy, spatial, and functional improvements to the building to enhance residential comfort and extend its lifespan. The research includes an analysis of a selected freestanding multi-family residential building and two variants of comprehensive building renovation using different volumetric additions: continuous and partial additions. The study examines the possibilities of achieving the highest possible energy class by improving the building’s thermal envelope, increasing the usable heated area of residential units, spatial reorganisation of apartments, forming private open spaces for apartments, as well as enhancing vertical building communication by adding an elevator. The research aims to determine the advantages of implementing multi-criteria building renovations to extend the building’s lifespan.