Technically Sophisticated Façade Design for Scandinavia’s Tallest Building

Rising on a former shipyard site in the heart of Gothenburg, the Karlatornet is Scandinavia’s tallest building. The 246-meter-high skyscraper has 74 floors and captivates with its dynamic, slightly twisted silhouette, which lends the structure an elegant sense of movement. The facade was constructed using Polycon elements.

The tower was designed by the renowned architectural firm Skidmore, Owings & Merrill (SOM). The building houses a total of 611 apartments as well as numerous commercial and service spaces. The use concept is complemented by a hotel with conference rooms, various restaurants, and fitness and wellness areas.

Challenges

Construction of the skyscraper began in 2018; completion was in 2024, and the opening of the observation deck is scheduled for summer 2026. However, the construction of the skyscraper presented technical challenges to the project team from the very beginning. For example, due to the soft, water-permeable soil, 58 concrete piles had to be driven up to 70 m deep into the ground to safely transfer the building’s loads. In addition, the tower’s enormous height means that wind speeds of up to 50 m/s occur on the upper floors. These can cause unwanted vibrations.

To counteract this, the engineers equipped the building with a reinforced concrete core and a 150-metric-ton pendulum. The pendulum is located at the top of the building and reduces the amplitude of the vibrations. However, it is not only the building’s structural integrity that is exposed to the enormous wind loads; the facade is as well. It must also withstand temperature fluctuations, UV radiation, moisture, and salt water. At the same time, its appearance influences how the building is perceived—one reason why the architects placed great emphasis on an appealing design.

Facade

The goal was a facade with the natural look and feel of concrete that also meets the specific requirements of tall buildings. In addition to a low dead weight, the ease of handling the elements played a central role. Furthermore, the shape and surface texture were to be customizable. The planners found the solution in Polycon, a facade system made of glass-fiber-reinforced concrete (GRC). The elements are characterized by high stability with minimal material thickness, achieved through the use of alkali-resistant fibers. Since the material does not require corrosion-prone steel reinforcement, Polycon enables the creation of delicate, lightweight components as well as complex three-dimensional geometries with custom surface textures. Conae GmbH serves as the authorized representative for the system in the DACH region and beyond.

In addition to its design and technical qualities, the compelling price-performance ratio was a decisive factor in the decision. In close coordination with the internationally active facade contractor Yuanda Europe, this system was therefore selected.

Customization

To ensure a smooth construction process and precisely implement the architects’ design vision, Conae GmbH advised the project stakeholders from an early stage. The team provided support with both structural calculations and the development of a suitable concrete mix design. Specifically, the designers wanted the concrete to have a specific color with a subtle shimmering effect in sunlight. This was achieved through targeted pigmentation combined with black, glittering aggregates. To ensure these visual elements were shown to their best advantage, the manufacturer washed the concrete surface using a specially developed, environmentally friendly process.

At the same time, the requirement was that the slender concrete slabs should create a solid, substantial appearance along their edges. The Polycon manufacturer ensured this by specifically thickening the edges to 30 mm, which were also given the characteristic surface texture. To realistically test the design and technical requirements, the supplier constructed several 1:1 scale sample elements.

Manufacturing and Installation

Once the fundamentals of the building cladding had been clarified, the facade contractor Yuanda produced the DWG drawings. Based on these, the Polycon panels were manufactured - in accordance with the progress of construction - and sent to the facade contractor. The contractor then used them - in combination with the glazing - to construct large facade elements, which were installed on the tower. In this way, a total area of 15,117 m² (equivalent to approximately two soccer fields) was gradually delivered to the construction site. All the Polycon elements together had a total weight of approximately 600 metric tons (equivalent to about 100 full-grown elephants). One aspect, however, always took top priority: safety.

Given the loads involved, the building’s height, and its exposure to wind, it stands to reason that those in charge took the utmost care to ensure the facade panels were securely fastened. They achieved this, among other things, by using an increased number of fastening points. For example, the largest element—which has an area of 8.9 m² and weighs 350 kg - was secured with 28 anchor points. Installation was carried out at the factory using M8 threaded sleeves embedded in concrete. To meet the high safety standards, the dimensional tolerance between the fastening points was set at a maximum of +/- 2 mm.

Consistent Quality

Karlatornet demonstrates that modern high-rise projects—especially those in extreme climatic and urban planning conditions - require not only technical excellence but also reliable, competent partners. Conae proved that it is just such a partner. The staff supported the project managers during the preliminary planning phase and helped identify the right concrete mix for the desired appearance and application. They ensured careful coordination and, with Polycon, supplied high-quality glass-fiber-reinforced concrete elements that maintained a consistent appearance throughout the long delivery period (2.5 years) and exhibited exceptional dimensional stability.