The building’s name is drawn from its impressive atrium entrance hall, designed by architect firm, Oded Halaf, which came up with the radical idea to construct a tornado-shaped staircase; a sculptural piece that would provide both movement and interest into the orthogonal, glass-encased, four-storey-high lobby. Halaf wanted the staircase to be free of all visible support – a complex and seemingly impossible assignment which had to be contracted out to an expert.

Given the complexity of the project, Halaf commissioned Tomer Gelfand, a master Craftsman who specialises in providing architectural solutions to engineering problems. Over the course of an 18-month period, he managed to execute, supervise and finalise all stages of construction, turning Halaf’s dream into a reality.

The stair structure is composed of two interlocking parts; a skeletal metal staircase and a sculptural wooden envelope. Together, they rise as an expressive tornado from the reception desk, conceived from the ground and rising up 14m above to the first floor mezzanine. The reception desk was envisioned as the starting point for the spiralling wooden sculpture and is made from the same tulipwood as the stair’s railings. To enable this, Gelfand devised a system of continuous wooden profiles, which look fluid and flexible but are extremely stiff and stable.

“The entire structure includes the spiralling stairs and a tornado-like element, which seems to emerge from the reflecting walls of the entrance lobby. The stairs and the tornado elements merge at the top of the first floor, and the round top acts as a viewing balcony to the impressive hall below,” said Gelfand.

Gelfand began by implementing an MRI-type scan to the skeleton, cutting vertically through the structure and generating sections in the width of the given wooden profile. The resulting number of cross sections, each exported with a different radius requirement, produced a seemingly endless amount of arches. In order to deal with this, Gelfand narrowed it down to ‘master-arches’ – devised by calculating the wooden profile’s average bending tolerance which dictated the radius and angle of the ‘master-arches’.

Next was the task of creating the radial profiles from the material itself. A total of 9000 linear meters of tulipwood was cut by a CNC machine to create the stock for the master-arches, each coded and marked to fit precisely in the grand scheme. As no single piece was interchangeable, every measurement had to be taken in advance to ensure the success of the final installation. For example, each of the connecting points between the modules was completed with a reverse radius; together, they form a sinuous wave, thus creating a seamless transition.

American tulipwood was selected for the project by both Halaf and Gelfand, as it fulfilled the requirements in terms of colour. Sourced from local suppliers, a total of 120 cubic metres of tulipwood was used in this project. According to Gelfand, freshly-cut tulipwood showed a variety of natural colours, which would have hindered the seamless quality of the structure. In order to unify the design, a palette of 12 average shades was selected from the tulipwood pieces and then applied to the modules.