Unzipping an unusual mix

The Berlin-based practice behind a mixed use project in Düsseldorf containing healthcare, hotel and residential functions, speaks to Tom Boddy about its first high rise building – and its zip-like aluminium facade

Rising 19 stories above the grounds of the historic Düsseldorf healthcare institution of Dominikus-Krankenhaus, the Zipper RKM 740 Tower stands as an impressive and innovative hybrid high-rise structure, reflecting an equally unusual mix of uses.

Designed by international practice J.MAYER.H. (JMH), the tower sits on the left bank of the Rhine, which winds through the heart of Düsseldorf. The building’s presence is enhanced by its perforated aluminium facade, which alludes to a series of horizontal zips in different stages of openness, resulting in a dynamic series of curved forms.

This stacked series of varying facades enables a “gentle arrangement” of open and closed areas, say the architects. As well as the already unique design of this building, it offers panoramic views to users, encompassing both the famous river and the vibrant cityscape.

The white, wave-like elements semi-organically delineate the building’s levels on the otherwise glazed facades. They mirror the ripples of the Rhine, creating a strong sense of movement.

The mixed use building, which was completed in 2022, stacks a range of medical facilities beneath residential levels and ‘hotel’’-style provision. According to the architects, the arrival of the Zipper Tower elevates the pre-existing hospital to a level of national significance, positioning it as the “prototype of a hospital for the future.”


The project represents a pivotal addition to the city’s urban landscape. In recent years, Düsseldorf’s increasing urban density has led to the development of new varieties of hybrid high rises to serve demand while maximising the use of land. The Zipper is part of the latest generation of these mixed-use concepts, and helps align with the local context by introducing the new medical facilities alongside residential spaces.

The opportunity to design the tower came to fruition when JMH won an international design competition for the project back in 2011. For the architects, this project holds “special significance,” as it marks their first high-rise design.

The project is an integral part of a broader vision aimed at “maintaining and modernising” the hospital on the historic grounds of the former Dominikus- Krankenhaus. Originally established in 1892 as the successor to a Dominican hospital, the healthcare institution underwent a fundamental transformation in 1972-73 with the construction of a new building and the demolition of the old hospital. The architects explain that over the past decade now, the facility has been in the process of a transformation, over a series of iterative changes under its new ownership.

Given the site’s long medical history,
it was a priority to incorporate commercially sustainable medical facilities into what could otherwise have been a purely residential development. The architects also saw it as an opportunity to revitalise the site and introduce a new generation of high-quality residential spaces. Consequently, the building was designed to accommodate medical supply shops, doctors’ offices, and even a dedicated floor for operating theatres.

Despite its bold, striking design, the project has focused on its commitment to integrating into its surroundings and harmoniously coexist with neighbouring buildings. The Zipper, in conjunction with the Vodafone Tower, a nearby high-rise structure, “takes up the traffic from the West like a city gate and serves as a counterweight to the striking existing buildings of the hospital,” says
the architects.

Facade design

The exterior of the Zipper Tower has been created to deliver a clinical yet playful impression. The wavy shell “generously” unfolds on the east, south, and west sides of the building where the various terraces offer striking views of the Rhine. In contrast, the northern side is enclosed to ensure effective noise insulation from the busy nearby traffic from that side.

To create the impression of ‘real’ zips, the facade has been designed to create “seamlessly gradual” transitions between the open and closed sections, along long curves. This also allows “flexible adaptation during the process of development over the years,” asserts the architects.

The facade comprises a fairly complex arrangement of features, including a double-skin aluminium curtain wall, all-glass balustrades, sliding glass units, and a special lattice girder structure for the pergola.

Notably, the curtain wall, glass railings, and slide-turn glazing systems all share a common substructure. The architect’s comment: “Here, therefore, was a possibility to constructively compensate for the construction tolerances,” however adding that “a high assembly accuracy was required.” The material used for the curtain wall was a “barely visible” brown powdered smooth sheet metal.

The overall facade amounts to an array of 4,500 distinct waves, each characterised by varying heights, protrusions, and recess sizes. Behind the wave-shaped curved and perforated aluminium elements, sits a further facade with integrated aluminium window elements forming the thermal building envelope.

The facade has been carefully designed to respond to the site conditions. The southern window fronts are shaded by the terraces in front, and are fitted with glass railings across the whole facade. These windows can be fully closed by sliding and rotating all-glass elements. As a result, the terraces act as a buffer against the wind on all floors, providing optimal climate control for the apartments.

All rooms on the south, east, and west facades are equipped with highly reflective interior solar shading. The surrounding wave elements offer sun, wind, and noise protection.

Every component of the facade, from the aluminium shafts to other elements, was carefully affixed to the structure, like the facade construction itself, with “high precision.” This was helped by the application of the same universal steel brackets throughout. “This innovative approach not only ensured a high level of accuracy but also simplified both the planning and assembly processes,” say
the architects.

To achieve the desired aesthetic impact of the metal exterior, similarly precise design techniques were employed. The rotating shaft elements were generated “parametrically,” and standardised in order to ensure cost-effective production. This involved the use of a three-dimensional virtual model, which was processed parametrically for integration into the data-controlled prefabrication process at the cladding supplier’s factory.


The tower’s internal programme encompasses what the architects call a “well-thought-out blend of functions” to cater to both the healthcare and residential needs of its occupants. Spanning the first six floors of the building, a diverse mix of group practices, specialists, and therapists collaborates with the existing hospital, to support a “medical health centre of regional significance,” say the architects, the integration also “extends the institution’s influence beyond the local region.”

Given the site heritage, having hosted a hospital since 1892, the project was a deliberate effort to introduce commercial medical facilities into what was previously essentially a “residential space.” The building also houses a dedicated floor for operating theatres, doctor’s practices, and medical supplies retail outlets.

The 14 upper floors feature various residential layouts, resulting in light-filled living spaces with spacious terraces, balconies, loggias, and a rooftop garden. The green spaces and vertical gardens are integrated into the design, enhancing the tower’s aesthetic appeal.

The residential section was originally planned to incorporate around 60 spacious apartments on 12 floors for sale or rent. However, shortly before completion, the private developer decided to convert the residential use into a hotel-like boarding house use with around 180 units. Among other things, the smaller apartments will serve to accommodate international patients of the medical centre and participants in international medical training courses.

The tower incorporates advanced building management systems that optimise energy usage, lighting, and climate control, making it an “environmentally-conscious structure.”

Structural challenges

Achieving structural stability on the building’s upper floors from challenging wind conditions posed a significant design challenge to the project team. Using a highly “tailored” approach, the team successfully anchored the aluminium waves, installed floor-to-ceiling balcony glazing, and added a glass balustrade – on a stainless steel platform.

For AWD Engineering Company, tasked with the structural planning of the project, the incorporation of loggias and balconies presented a unique challenge. This was because they each had folding and sliding glass doors, serving as wind protection, while offering residents the flexibility to transform their loggias into winter gardens. However, incorporating these features introduced a substantial ‘dead weight,’ meaning they were included as special loads in the structural calculations.

Beyond these features, the challenges posed by the project structurally were further heightened by its diverse functions, spanning from the technical facilities in the basement to the medical areas and residential spaces, particularly on the top two floors. Here, the design incorporated soaring rooms exceeding eight metres in height, tailored for luxurious penthouse use, complete with expansive roof terraces that imposed specific static requirements.

Additionally, AWD faced the intricate task of calculating for a distinctive architectural geometry on the building’s lower levels, where the structure recesses like the bow of a ship.

The Zipper RKM 740 Tower represents an unusual fusion of innovative architecture and practical functionality, as an addition to healthcare but also residential provision in Düsseldorf. The unique combination of functions showcases how such hybrid high rises can integrate into its context, and use facade innovation to contribute significantly to the wider urban landscape.