Platform on new construction, renovation, restoration and transformation
The former Aurora office building on Amsterdam's Stadhouderskade and Overtoom is undergoing a large-scale transformation and renovation. The monumental value will be preserved and the building will be expanded at the rear. Van Wijnen Amsterdam is involved as the construction contractor from the start.
According to Renovation & Transformation Project Manager Sander Kokmeijer, the collaboration started early. “We got involved in the design right away. That gave room to make architectural and structural choices together.”
The fact that it became a listed building had direct implications for the renovation. Originally, the plan was to address all the façade window frames, but they were given protected status. “We were allowed to replace the window frames, but the grid and concrete look had to remain as they were,” Kokmeijer says. The main stairwell is also monumental. That required specific attention during the job. “The natural stone stairs, railings and balustrades: we had to completely protect the stairwell,” he says.”
The biggest challenge is in the construction. The building consists of two parts from different construction periods. Records are even missing from one part. “The structural engineer had to make calculations without clear assumptions. Drilling recesses in floors, walls or columns is almost impossible, but sometimes it has to be done anyway. That was a big challenge.” On top of that, a third building section is being added at the rear. New structures come on top of existing structures for which not all the details are known. The construction site itself is also tight. Streetcar cables are literally attached to the building, so supply and removal is tightly directed.
To reduce risks, the property was scanned in 3D several times. “Right at the start and again during demolition. Our engineer Jacco Boer worked out all the parts in a model. He put a lot of time into that, and with results: everything fits to the few millimeters. That way you avoid problems in execution.”
The approach is paying off. Three executives and three work planners work with the model daily. “They get data from it and see immediately what is happening. That helps tremendously in execution.” In this project, some 60 to 70 percent of the work has been 3D modeled. “You can see that the bottlenecks are also in things we haven't modeled, in this case the installations. You want to start including that in the future.” According to Kokmeijer, here also lies the most important lesson for other inner-city renovations. “In new construction, we always work with 3D and BIM models. You also benefit greatly from this in large-scale, complex renovations of this kind. The intensive preparation pays off on the construction site.”
