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The Nieuw Bergen neighborhood in Eindhoven is taking on a striking profile. The sloping roofs immediately catch the eye. These roofs are covered with a green layer that requires more than standard roof vegetation. For Van Kessel Sport en Cultuurtechniek, a division of Gebr van Kessel, this was literally breaking new ground, involving technical decisions and construction at great heights. Project manager Jaap Hennevanger looks back on an intensive process.
Van Kessel became involved in this project as early as the design phase, Hennevanger explains. Commissioned by Stam + De Koning Bouw, the team developed a proposal for the green roofs. “Together, we looked at how we could solve this from a technical standpoint and translated that into a feasible plan.” The roofs are anything but standard. “The slope angle varies from 42 to 52 degrees. We often build rooftop gardens, but the combination of slope angle and height made this project challenging.”
Six green roofs were designed for five buildings, each with its own specific features, such as window arrangements and installations. This called for a carefully chosen solution to prevent slippage, as well as close coordination with the builder. With the help of various suppliers, the Van Kessel team devised a system consisting of profiles secured to a wooden structure beneath the roof covering. A special protective, draining, and water-retaining fabric and mesh are clamped into the profiles. Elements with steel pins are attached to the mesh to hold the substrate and the vegetation mat in place. “So we had to calculate exactly where and at what distance from each other the profiles needed to be installed.”
A computer-controlled irrigation system was also installed, with pipes running from the utility room. “The structure is only 6 centimeters thick. You can’t store much water in that. So you have to ensure proper irrigation.”
The roofs are covered with a mix of sedum, herbs, and grasses. Together, they create a scene reminiscent of an alpine meadow. “You want the roof to look good all year round. That’s why we combine about 25 different species. Sedum stays green in the winter. Because these succulents don’t die off in the winter, they provide structure. Herbs and grasses add variety.” This makes the final look rich and varied.
Installing the roof structure and the mats required a special approach. Working at heights of up to sixty meters, the team employed certified climbers.
The dead materials and vegetation mats were placed on special pallets, and the substrate was loaded into buckets and transported upstairs to be processed under controlled conditions. “You’re tied to a line, so the work goes more slowly. At the same time, everything has to be done safely. Nothing is allowed to fall down.”
After completing the first few roofs, the work process was evaluated and refined. Materials were pre-assembled on the ground, which, combined with more streamlined logistics, led to faster progress.
Now that the first winter is behind them, the team is watching with interest to see how the roofs continue to develop. “The combination of height, sloping roof surfaces, and various plant species makes this project unique—and that is precisely why it is so valuable.” For Van Kessel, Nieuw Bergen is a special project to look back on and an inspiring example for future green roofs on sloped surfaces. It’s a wonderful showcase of what technical expertise and green ambitions can achieve together.”
