In most of city centres in the Netherlands, there is a growing demand for residential housing. However, as most of the land is occupied by existing buildings, developers recur to demolish and build higher buildings, in order to fulfil the urban need. Even though demolition, may be the simplest option in technical and economic terms, it can also destroy architectural heritage, cause noise disturbances and damage the environment.
On the other hand, refurbishment can be a sustainable option in building scale, but does not provide extra capacity for the densification demands of the city.

Structural extensions can be an attractive alternative that combines the benefits of the last two options, gaining more residential capacity in city centres and respecting the architectural heritage, and at the same time, reduce environmental impact by re-using old structures.
Although, an ambitious extension can pose important technical constraints, many successful precedents have been realized. This can be an indicator that some of the complexities will partly overcome in the near future. This work aims at increasing the awareness of structural extension possibilities in existing buildings, as an alternative for ambitious architectural and structural projects, with sustainable considerations.