Two towers, two facade systems, one sealing concept

Next to metro station Bullewijk in Amsterdam, within walking distance of Bijlmer ArenA is Amstel III. This area of more than 200 soccer fields, previously designated for office buildings, is being transformed in phases into a lively urban district combining living, working, shopping, education and facilities. Part of this development is The Ensemble, which consists of a commercial plinth topped by two sustainable and iconic towers of approximately 120 and 100 meters. A total of 592 rental apartments and various ground floor amenities will be provided here, as well as a two-level underground parking garage and 19,000 m2 of office space.

The tallest tower of The Ensemble (tower 1) is notable for its unusual curved and undulating facade, making plinth and base tower appear as one. Right across from this is being built a lower residential tower (tower 2) with a slight angular twist, creating a beautiful whole. Both towers go up simultaneously, choosing two totally different building principles. While tower 1 will be finished with timber frame facades, tower 2 will be finished with precast concrete sandwich elements. For both towers, Celdex supplies the solutions for wind and driving rainproofing.

Sealing of precast concrete sandwich elements

"The precast concrete sandwich elements are produced at Loveld nv in Belgium, where Simson Application directly also applies our sealing products," says Henny van der Heijden, Business Development Manager at Celdex. "For example, our Pre-Seal M foam tape ensures the high airtightness performance and insulation of the horizontal and vertical connections, while our EPDM Soft foam tape provides impact rain sealing on the outside. Celdex butyl tape is also used for waterproof horizontal compartmentalization. In advance, we worked out our Seal4Prefab sealing system for this in detail. Then the engineering and design were also connected to this." The precast concrete sandwich elements are produced in advance and temporarily stored on a bag field, from where they are transported just-in-time to the construction site, he says. "This allows the facade finishes to keep up with the high construction speed. In fact, a full floor is delivered every eight days."

The balconies of tower 2 will use timber frame elements made by Timmerfabriek Frank van Roij, which will be fitted with Pre-Seal M foam tape on site. The balcony elements will also be fitted with an EPDM cellular rubber strip.

Sealing of precast HSB facade elements

Tower 1 will also be closed with prefabricated HSB facade elements from Timmerfabriek Frank van Roij, with rock elements glued to the exterior. "The attachment of the balconies protrudes through the HSB facades," says Van der Heijden. "We made a custom recommendation especially for putting the balcony suspension through and tested it extensively for wind and driving rain resistance. The HSB facade elements are provided with our Pre-Seal M foam tape."

Seal4Prefab sealing system

Celdex developed Seal4Prefab as an answer to all the challenges in high-rise projects. The system includes both interior air sealing, insulating middle sealing and exterior driving rain sealing and is also suitable for prefabrication. "All of our Seal4Prefab products are suitable for the simple and fast sealing of horizontal and vertical connection seams," said Van der Heijden. "The products are produced in long lengths and equipped with a high-quality self-stick, making prefabrication even easier. In order to position the elements properly and quickly and to provide additional protection for the sealing tapes, all products are also provided with a low-friction top layer." 

Knowledge transfer and quality assurance 

An important part within Seal4Prefab are knowledge transfer and quality assurance. "This already starts with the preparation and engineering," says Van der Heijden. "We give advice on the best fitting sealing products and can test products in advance in a critical building detail for wind and driving rain tightness. We also worked according to this concept for The Ensemble. Before the assembly started, we also organized a toolbox meeting for both Timmerfabriek Frank van Roij, Simson Application and Loveld nv. During construction, we carry out random quality checks, whereby the processes are carefully recorded in partial reports that together produce a single report for private quality assurance."