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Frontside View 381 for an ambitious tensile facade project with multiple challenges

Located in Dortmund, Germany, TEDi’s headquarters and logistics centre employ more than 3,500 people, including many car commuters in need of a comfortable parking solution. This new development saw the construction of an impressively sized, 370-metre-long multi-storey car park in a highly desirable location, directly on Westfälischer Hellweg — a medieval route connecting the Rhine with the Elbe River. To make this uncommonly long and monolithic design more visually appealing for the residential community surrounding it, its street side was covered with an undulating, curtain-like tensile cladding using Frontside 381 membrane. But before construction could begin, a number of highly difficult technical challenges had to be addressed.

A dynamic, curtain-like design

Inspired by a 3D ‘curtain wall’ previously developed by tensile facade specialist Typico for a music school, the architects formulated another ‘curtain wall’ design featuring wave shapes of varying sizes, extending vertically along parallel rails at the top and bottom.

Feasibility with a big question mark

In spite of the concept’s appeal, the development of the textile facade raised a number of concerns, including with regard to securing approval for the solution in terms of ventilation, fire safety and especially statics. At the onset of the development process, the architects were told by many prospective contractors and professional organisations that it would simply be impossible to deliver this project. But convinced by the architects’ passion for the sophisticated design concept, the clients emboldened everyone involved in the project to keep looking for possible solutions.

In the end, steadfast commitment from project managers at Hegerath Group and Typico’s spirit of innovation were the keys to a masterful solution to the following challenges, eventually allowing the construction of this ambitious facade within budget.

All-in-one solution with a unique offer

The design’s curtain-like feel is the product of two flowing lines running parallel to each other at the top and bottom of the framework. The resulting form is organic, consisting of half-circle shapes of varying recurring radii, which from the outside provides the sense of an utterly free-form design.

Interaction between the support framework and the membrane

The key to this successful concept lay in two factors: the ability to take full advantage of tension forces and to find a novel approach to tensioning on the one hand, and a choice of membrane with a well-established stretching behaviour on the other. In this case, a fiberglass textile could not be used because of the forces involved. Conversely, Serge Ferrari’s high-resistance PVC-coated polyester membrane offered obvious advantages, not only in that it was easier to work with and shape, but also because of its stretchability, which ensured better control of the considerable tension forces it would have to sustain.

The broad palette of 17 colourways currently available for Frontside View 381 was another decisive element. In their design, the architects had envisioned a silver or light grey shade, which allowed for a wide range of possible colour options. Their choice eventually settled on Frontside 381 — 3121 Shifting Grey, which ideally complemented the concept and created a beautiful sculptural effect in combination with the undulating shape.

Another crucial step in the development process was adapting the supporting framework to a standardised construction built from prefab reinforced concrete elements, which could withstand certain loads and geared solely towards the building’s functionality. Thomas König of Typico GmbH says: ‘When a facade builder comes in with a request to attach anything solid to the frontside of reinforced concrete beams on a car park structure, the answer is understandably always the same: For Heaven’s sake, that’s out of the question! Now when it comes to such a complex shape, with two horizontal lines of tubular framework bent into organic wave shapes over a length of 370 m, you are talking about almost a full kilometre of bent steel and aluminium profiles, not to mention brackets, fastenings and all additional hardware. This would have blown the budget entirely! Our only hope was to find a way to make this concept work, where the canvas is attached only at the top and bottom, and stretched over the full 11-metre height.’

A sheer look, with extreme force absorption

The challenge was solved structurally by placing fixing brackets 2.5 m apart, following the span between each support post of this standardized multi-storey carpark. Brackets are embedded in the overhang and secured to the free-form bent steel tubes using connectors.

This was achieved with a 28% open mesh combined with the tridimensional, undulating shape of the cladding, which creates a stack effect through the half-circle openings at the top, facilitating natural ventilation. In addition, further ventilation is delivered from the courtyard side, which was left unclad, providing a generous continuous opening.

The project also delivered on fire safety, as Frontside 381 membranes are rated Euroclass B-s2,d0/EN 13501-1 and ensure high fire resistance in terms of mass, with a weight of 550 g/m2.

Project participants :

Client: TEDi GmbH & Co. KG, Dortmund
Architects: Spital-Frenking + Schwarz Architekten I Stadtplaner, Dortmund
Project management: Hegerath Unternehmensgruppe GmbH, Moers
Tensile facade detailed design & manufacturing: Typico GmbH, A-Lochau (www.typico.com)
Facade material: Serge Ferrari Frontside 381-3121 Shifting Grey
Facade dimensions: 370m in length / 11m in height.
Tensile technology: Typico K45 edge roll aluminium tensioning mechanism (anodized surface EV1)
Copyright: Philipp Kistner