This building, Royal Vopak’s former head office, has been renovated into an office and residential building: the Westerlaan tower. Ector Hoogstad Architects from Rotterdam drew the design for the
renovation and the five levels that have been placed on top of the existing tower, which contains apartments and offices. On the ground level, apart from the 250m2 main entrance, commercial room has been realised.

Project information


Building structures




Maarsen Bouw en Ontwikkeling (MBO) / Westerlaan CV


Ector Hoogstad Architects

Project size

44.600 m2 GFA

Start of project




Consulting services

Structural design and engineering renovation and new construction
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Aronsohn has designed the structure of the original office buildings in 1959 for Rotterdam shipping line Royal Van Ommeren. The fusion of Royal Van Ommeren with Royal Pakhoed—which resulted in Royal Vopak—necessitated an upgrade of the original buildings. The lower floors make up Vopak’s corporate office, meeting high utility and presentation standards. The higher floors are partly designated for rental apartments and office spaces. The building’s exploitation raised the need for a greater office volume by enlarging the building. Aronsohn has first researched whether or not additional floors can be constructed on the tower, and whether or not the existing lower floor structure could be reused. To this end, the concrete structure’s and the foundation’s capacity have been extensively analysed based on modern insights.

An analysis has also been made of the financial pros and cons of maintaining the structures versus demolishing them and constructing new structures. It appeared that the high-rise construction could be enlarged in a financially responsible way, up to a height of approximately 70 metres. However, this did require stability cores. For the lower building part, it appeared economic to construct a new building on the existing basement. A special feature of the lower building part is that it is provided with concrete core temperature control. It was decided to use ‘Wing’ plates with integrated steel beams. All horizontal cabling and pipes are consolidated in the ingenious flooring. To create this, it was necessary to design integrally from the first design stages and onwards. For the parking facilities, it was decided to realise a three-level underground parking garage with underwater concrete.