Buildings are planned, designed and constructed to meet their functional requirements as well as to keep their occupants safe from the impacts of disasters. It has been observed in India that buildings designed and constructed by public agencies generally performed well, during previous earthquakes, cyclones and fires, although shares of such buildings among all buildings is much less (about 10%). Privately designed and constructed buildings suffered damages during previous disasters. Now, in most of the urban areas, buildings designed and constructed by public agencies are going through lots of unauthorized modifications and extensions (by cutting their structural members like beams, columns, slabs and removal of its load-bearing walls, whether they are high-rise RCC-based or low-rise load-bearing construction) by their occupants, rendering them vulnerable, as their basic structural systems are being compromised. A case study from the capital of India, Delhi, has been undertaken, and it is found that unauthorized modifications/extensions in residential buildings designed by public agencies is happening at a large-scale and in case of fires or earthquakes, these buildings will also suffer huge damages.