Symbiotic architecture: rooftop additions on existing buildings

The paper discusses socio-economic and cultural conditions and technological and formal aspects which attests rooftop additions on existing buildings as a model for increasing built density of residential area. In Italy most of the residential buildings constructed in postwar period have today low architectural quality and are degraded. The need for upgrade of this real estate gives the opportunity to implement strategies to reduce land consumption through rooftop additions. In a conservative approach to built heritage, the dismantling of roofs implies a loss of material culture; otherwise, the construction of the same volumes in new areas would cause an irreversible land consumption. A conflict rises between the needs for conservation of built heritage and of territory; in accordance with Amedeo Bellini, the resolution of this conflict must be based on ethical judgments. Thus the addition shouldn’t be a parasite, but it must achieve a symbiotic architecture in which both host and symbiont derive benefit from the interaction.