Postjesweg residential towers shoot up from the ground

Office makes way for 221 apartments

This is a new construction project, which first required the demolition of an existing office building. That building was owned for many years by the Maarsen Group family business, which took the initiative to redevelop it. This family company will keep the 67 rental apartments in Fortitudo in its own exploitation portfolio after completion. Caritas, with 19 floors the tallest tower, has been sold to Invesco Real Estate. Both buildings will feature a mix of two- and three-bedroom apartments with living space between 40 and 60 sq. m. The residential towers, named after 2 of the 7 virtues, fit into the transformation of the Ringzone A10 and Overtoomse Veld.

Saddle roofs

The complex with its characteristic pitched roofs was designed by Geurst & Schulze Architects. The roofs provide cohesion within the ensemble and are also a reference to the reconstruction architecture of the Western Garden Cities. The Maarsen Group and Van Wijnen developed the project in a construction team starting in mid-2019, and the buildings will be delivered turnkey by Van Wijnen. "The residential towers have been developed and elaborated in an industrialized construction methodology," said Rick Leusink, project manager at Van Wijnen. "Both the shell and the facades were worked out in prefabricated form. Because of this innovative and scaffold-less method, the construction pace is high. Every week we were able to realize one floor. As a result, the residential towers are also quickly wind and watertight, which also allowed us to start the finishing work faster. The total construction time was accelerated by over 40% compared to a traditional execution with in-situ concrete and masonry from a scaffold." The concrete work for the bicycle basement and first floor did get poured because of the structural transfer of forces to the piles.

Just-in-time

The (partly structural) facade elements were prefabricated and assembled at Loveld, a facade builder in Belgium. "The facade elements had already been fitted with frames and glass there by other parties," says Remco Kooiman, senior work planner at Van Wijnen. "They were transported just-in-time to the construction site in Amsterdam and lifted directly into place there, also because the construction site is limited in size." The structural walls and floors come from MBS Cascobouw. The roof is made up of a separate steel structure with separate prefabricated trusses and steel frames, fitted with solar panels.

"Important in a fast construction process is that utilities are also installed on time," assures construction site manager Ralph Esschendal. "Unfortunately we sometimes see that go differently, but here good agreements were made in advance that were also met. Good agreements were also made with the adjacent city monastery. That lies in the construction safety zone and had to be partially evacuated when the facade elements were hoisted." To achieve the desired high construction speed, a longer preparation time than in traditional construction is necessary, Leusink said. "You have to synthesize the input of all the partners involved into a makeable design. That means tuning, modeling and then producing. Then a schedule of one floor per week is feasible."