Top-down construction is one of the best solutions for buildings with multiple underground levels, that require large excavations. This construction method was adopted at the beginning of the ’60s and it is currently used, in general, for the construction of buildings located in crowded urban areas.
Advantages and challenges of top-down construction method:
An advantage of this construction method consists in the fact that the infrastructure and the superstructure can be built simultaneously, the delivery term being reduced significantly. The excavation is supported by the underground floors instead of by temporary retaining elements, which saves the cost for retaining system.
Due to increased stiffness of the slabs, compared with the stiffnes of temporary support elements, the strains of retaining walls are smaller, so the excavation is safer.
The top- down construction can also be challenging for constructors, as it is difficult to excavate under the floor.