New office building attached to listed building

Special triangular shape with glass and aluminum

Vesting Bouw is currently working on a special project in Amsterdam Sloten. A new office building is being built in the "armpit" between two existing properties. The new building will be linked to the adjacent, monumental building. "The architect has made something beautiful out of it," he says.

One of the existing properties has protected status. This building was renovated ten years ago (phase 1) and the building at right angles to it four years ago (phase 2). Dennis Honkoop, director of Vesting Bouw: "We are now building the final piece of the plan: a two-story parking garage below ground level with six layers of office space on top."

Working with established parties

Vesting Bouw previously worked with the same architect, Onno Vlaanderen, on an apartment complex in Zaandam. That collaboration was so successful that this time the architect also mentioned the name of the contracting company to the client. Honkoop: "I told our story to and that appealed. We work with regular parties, such as a piling company and a plastering company. We trust our partners to charge market-based prices and to help us. They know we don't go "shopping" and are therefore happy to work with us. Eventually we got a budget and started calculating, in consultation with the architect and structural engineer. We were scheduled to start construction in 2021." Then the municipality revoked the permit, which led to discussion and even a lawsuit. In late January 2023, the judge ruled in favor of the client and construction could still begin. Unfortunately, in the intervening (corona) years, prices had risen sharply and the budget had to be increased. 

Cleaning up

The contractor began cleaning up the site, previously owned by a piling company, in March 2023. Because of that company's activities, the land was given contaminated status. "We started by putting in sheet pile walls, then we did the earthwork in two phases. We encountered many obstacles, such as piles lying horizontally under the ground. The remediation was done under remediation conditions, which means we had to measure continuously." As a result, the earthwork lasted through October. In November, construction of piers, elevator pits and concrete work in the basement began. Next time, the basement basin will be made and the ground floor is expected to be completed this spring.
ground floor poured.

Vesting Bouw is an all-round contracting company, with a preference for non-residential construction and renovations and operates extensively within Amsterdam. This construction site is easily accessible, and next to the site is a green strip that was set up as a construction site. "There will be another tower crane 55 meters high and with a boom of 73 meters. Fortunately, we have the space to unload and do not block the public road," Honkoop said.

Ingenious staircase

A special feature of this project is that the new building will be connected to the existing monumental building, because there was no elevator there. Therefore, the contractor is building the new stairwell against the old stairwell. "That doesn't quite fit together though, there are some height differences between the two buildings. It will soon look very ingenious, because the architect has managed to make something beautiful out of it. In addition, the building has an appealing shape: it is a sharp triangle of precast concrete, fitted with glass facades with aluminum facades."