© Ossip Van Duivenbode
© Ossip Van Duivenbode

The shopping mall in the city centre of Rotterdam, Netherlands, dating from 1949, has been re-developed in a special way. Rotterdam based architect IbelingsvanTilburg created the design plan that consisted of restoring the building in its original state in combination with urban densification: adding a 16-storey apartment block on top of the existing building. Royal HaskoningDHV delivered the structural design of the building.

We have made this challenging re-development plan feasible by reversing the design process: using the capacity of the existing structure as a starting point. A smart adaptation of the existing supporting strength doubled its bearing capacity. Combined with an ultra-light weight building method, we made it possible to create the desired number of apartments on top of the existing building. The weight of the light weight residential building is only one-fifth of the weight of a normal building with such volume.

Because of the low weight of the building, extra requirements for sound insulation and vibration levels were necessary. By measuring in test houses and modelling in a computer model, the comfort level of the apartments has been brought to the desired standard. This result matches the expectations of new top class apartments. The sound insulation (a very important comfort factor), even exceeded the appointed minimum requirements..

The light weight construction (a steel frame with wooden floors and facades) created high flexibility. Separation and combination of apartments was possible even during the completion of the building, and with relatively simple interventions. Therefore it was possible to quickly respond to the specific demands of the inhabitants, and a bigger target group was reached.

By preserving the existing building, the demolition and transport of 15.000 tons of concrete from the city centre was prevented, as well as bringing back new materials of the same volume. Three months of demolition work, lots of noise and dust, and a minimum of 750 lorry rides was spared the city centre.

The Karel Doorman shows that innovation and sustainability in the building sector are economically feasible, even in difficult times.