The growing awareness of the importance to limit the soil sealing process has prompted a shift of building activity towards modification of the existent stock rather than construction of non-urbanized soils. Approximately a third of the European housing stock was built during the thirty years after WW-II and a huge part of it presents different kinds of obsolescence. This declining performance process makes it necessary to take action in order to meet today’s requirements. A decision must be made in order to choose the preferable intervention in a sustainable and lifespan conscious perspective. This paper focuses on multi-storey apartment buildings, which do not present historical or testimonial quality, and seeks to inform the choice between reconstruction or renovation. Focusing on physical conditions and recurrent obsolescence process, this paper highlights which parameters are most instrumental in the decision-making process and proposes an assessment method that can serve the purpose of establishing the limits of a renovation project.