'Scaffoldless residential tower is feat'

On the former site of the ROC in Leiderdorp lies the brand new district Bij de Zijl: a lively, varied residential area with 182 houses and apartments surrounding a green park. The new construction project was completed in a very short time. This is due to the innovative construction method, but also to the good atmosphere and connection on the work floor.

Text | Patricia van der Beek Image | Finch Construction

Bij de Zijl is a development by Vink Bouw and Did Vastgoedontwikkeling. The new housing development consists of 36 social rental apartments, a residential tower with 104 free sector rental apartments and 42 ground-level single-family homes. "The social rental apartments and the residential tower have now been taken over by Rijnhart Wonen and Amvest," says project manager Joost Stolwijk of Vink Bouw. "Together with Did Vastgoedontwikkeling, we sold the ground-level homes to private individuals. We also provided buyer guidance and for those buyers who wanted it, we offered Start Smart. With this service, we make the home, completely ready according to the buyer's wishes."

Construction work at the Zijl.

Small piece of city

KAW Architecten designed Bij de Zijl as a self-contained residential area with different housing types in one cohesive, urban architectural style. Characteristic features are the high buildings with flat roofs, the unambiguous facade rhythm and the brickwork in light colors. "It has become a small piece of city in which different places have been subtly created," explains architect Mathieu Kastelijn. "A clear cohesion between the different subplans is perceptible, without being monotonous. This was achieved by applying a palette of materials and detailing that emphasizes the differences and creates a beautiful image both from afar and up close."

High-rise buildings without scaffolding

Vink Bouw, which also built the ROC, demolished the old school building during the 2018 construction season. New construction work then began. Stolwijk: "The single-family houses and apartments are traditionally built with in-situ concrete, wide slab floors and masonry in the facades. The tour de force is the 70-meter-high residential tower, which we built scaffold-free. We made this possible by tunneling the shell, directly integrating the complete facade. We manufactured the facade elements from complete precast concrete sandwich elements. Thereby, the inner leaf functioned as the load-bearing building wall. The outer leaf - including stone strips, concrete bands and window frames - made the building immediately wind and watertight. Provisions for safe working were also integrated into the elements."

High construction speed

The construction speed of the residential tower was tremendous. Three building layers below the shell, the complete facade, including balconies, was completely closed. Thanks to special rubber seals between the facade elements, Vink Bouw was able to work completely dry one layer below. This meant that the interior walls, which had already been laid in the apartments during the shell construction phase, could be placed only four building layers below the shell construction. The building layer below that, the floor heating was installed, one layer below that again the screeds, etc.. In this way, the apartments were progressively completed behind the shell construction. Stolwijk: "The second floor was already finished while at the top the structural work was still in full swing."

The 70-meter-high residential tower.

Atmosphere and connection

Stolwijk continues: "High construction speeds are a hot topic in construction. Shortening intervals and prefabricating parts contribute significantly to this. But to really make a difference, a good working atmosphere is important. The trick here is to connect all parties and people on the shop floor. We need each other and every part and every professional is equally important. If everyone walks in the same pace, you work more efficiently and therefore faster. That has worked extremely well on this job. A team performance we can be proud of."

Construction Info

Development Vink Bouw B.V., Nieuwkoop and Did Vastgoedontwikkeling, Utrecht
Architect KAW architects, Eindhoven
Contractor Vink Bouw B.V., Nieuwkoop
Installations HEK Installations