AKADEMIKERNES A-KASSE

Slender staircase in Ultra High Performance Concrete connects four floors in a new atrium

Build Year

2025–2026

Architect

CCO Architects

Entrepreneur

Sten Jensen Gruppen A/S

Engineer

VITA Ingeniører A/S

Builder

Akademikernes A-kasse

FROM 1930s BUILDING TO MODERN WORKPLACE

In the heart of Copenhagen, a former Danish Patent Office building from the 1930s has been transformed into a modern workplace for Akademikernes A-kasse. A key element of the transformation was the creation of an open atrium, where a large four-story accordion staircase in Ultra High Performance Concrete (UHPC) from Hi-Con connects the floors and the new office environment.

With its central location, the staircase is visible from several levels, and the architect therefore had a clear vision for its appearance. The structure needed to be as slender as possible to create a light expression, while, contrary to conventional practice, the fair-faced cast surface of the concrete was to face downwards and remain visible from the atrium.

This placed demands on the choice of material and execution. Using UHPC, Hi-Con was able to design and deliver the slender staircase solution that realized the architect's vision while creating a new connection between the floors.

"Our experience was entirely positive, and Hi-Con was professional throughout the entire process, from design and delivery to documentation."

Martin Porsgaard

Project Manager and Partner, Tømrerfirmaet Sten Jensen A/S

A SLENDER STAIRCASE WITH CONCRETE AT THE CENTRE

Hi-Con's delivery consists of staircase, landing and wall elements in Ultra High Performance Concrete. Six accordion staircase elements are connected by landings to form one continuous staircase through the new atrium. The elements are approximately 1.6 meters wide and just 110 mm thick.

The staircases and landings, together with the existing floor slabs, are supported by a 1.3-metre-wide UHPC wall panel positioned centrally within the landing area. Together, the elements form the large staircase structure that extends through the atrium and connects the office spaces across the different floors.

A distinctive detail can be found in the surface of the elements. While the fair-faced cast surface would normally face upwards, here it faces down towards the atrium, making the finished concrete surface visible from the spaces beneath the staircase. The treads have subsequently been finished with a timber surface that continues the material expression of the surrounding floors. This combination highlights the concrete when viewed from below, while from above the staircase appears as a natural extension of the floors.

Hi-Con was involved with the staircase solution throughout the design process and through to delivery and also provided the associated documentation. The contractor describes the collaboration with Hi-Con as professional throughout the entire process, from design and delivery to documentation.

THE STAIRCASE AS A FOCAL POINT

In the completed office environment, the staircase has become more than simply a connection between floors. Together with the atrium, it now forms a central element of the transformed building.

The combination of slender concrete, light-colored balustrades and timber finishes gives the staircase a light expression, while allowing the UHPC structure to remain visible as part of the architecture.

"The atrium and staircase have become the heart of the new/renovated office and connect all the floors. We have received many positive comments on the way the staircase has been executed, with the fair-faced concrete surface facing downwards and timber flooring above." – Martin Porsgaard, Project Manager and Partner, Tømrerfirmaet Sten Jensen A/S

The project demonstrates how a staircase in Ultra High Performance Concrete can do more than simply provide a practical connection between floors. By using the material's strength to reduce the dimensions of the structure, the staircase can also become an active architectural element in the transformation of existing buildings.

Curious to see how our Ultra High Performance Concrete staircases could enhance your project? Contact us. Our specialists are ready to provide advice and technical sparring. Or explore our other products.