Complex air sealing requires customization at Big Bear

In Rotterdam, construction of Grote Beer is nearing completion. The stepped and 68-meter-high residential tower is being built right next to Alexandrium shopping center and consists largely of prefabricated elements. From the facades to the construction walls, floors, balconies, bathrooms and toilet rooms, which made fast and scaffold-free construction possible. "Due to the scaffold-free construction and the fact that the balcony floors are already attached to the floor elements in a coldbridge-free manner, air sealing was complex," says Henny van der Heijden, Business Development Manager at Celdex. "But thanks to our extensive expertise, careful detailing and the Seal4Prefab sealing system, we were able to successfully complete this challenge as well."

Celdex was involved at a very early stage by contractor Dura Vermeer and facade manufacturer Byldis to discuss the (technical) possibilities of its sealing products. "Then, together with Zwapex Afdichtingstechnieken, we realized the seals on the outside of the new building," says Van der Heijden. "Because the balcony slabs protrude above shopping center Alexandrium, mounting options were limited. It was therefore decided to attach the balcony slabs to the floor elements already in the factory. In order to guarantee a good air- and impact-resistant connection between the two elements, a lot of attention was paid to the detailing. For example, to avoid thermal bridges. In high-rise projects such as Grote Beer, an air and water tightness of at least 450 Pa is required. To make our precast solution insightful for this, we used 3D/BIM, for example."

The Seal4Prefab sealing system for Grote Beer includes EPDM Soft foam tape as a driving rain seal on the exterior, Van der Heijden says. "In addition, a combination of Butyl tape and EPDM slab was used for the waterproof horizontal compartmentalization, while a Pre-Seal M LF foam tape provides the desired air seal and insulation of the horizontal and vertical connections. Specifically for the seals of the balconies, an EPDM cellular rubber strip was used, eliminating the need for separate caulking joints on site. With this, we have implemented the 'prefab-all-the-way' ambition of the architect in as many connection details as possible."

To support Zwapex's mechanics in the application of Seal4Prefab sealing products, Celdex processed the work instructions in 3D, supplemented by periodic digital construction checks to ensure proper final quality.