Designertreppe im Taunusturm

Glass railing for stringer staircase

Stringer staircase with stainless steel ring in TaunusTurm

A high-gloss polished stainless steel ring surrounds the elegant stringer staircase in the Frankfurt TaunusTurm.

Project description

Stringer staircase with glass railing in the TaunusTurm in Frankfurt

In the very heart of Frankfurt’s banking district in the city centre, an amazing office tower attracts attention. The TaunusTurm, comprising a 170 m high office building and a 63 m high residential building, is currently listed as Germany’s 12th tallest building. After the architects Gruber + Kleine-Kraneburg had already won the competition in 2000, it still took another two attempts before the foundation stone for the TaunusTurm project was finally placed with the builders Tishman Speyer in 2012.
The base building accommodates beside the canteen also public lobbies and spacious office facilities as well as the service floor. Above the base is the residential tower with 50 residential units and the office tower with 40 storeys, which finds its conclusion in two opposing mono-pitch roofs.

Elliptical ring in stainless steel

In a light-flooded office unit in the 36th floor, the elegant single-flight stringer staircase swings up to the next level. With the all-glass railing contrasting with the inner balustrade stringer, the stairs take on a playful lightness. A high-gloss polished filigree stainless steel handrail provides simple elegance, which is further intensified by the smooth steel soffit cladding. However, the special eye-catcher is the elliptical stainless steel ring, also highly polished, which surrounds the stringer staircase for a sculptural character.

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Project details

Stringer staircase featuring box-type stringers

The single-flight stringer staircase is composed of a refined combination of an inner balustrade stringer in box-type design and an outer stringer, which accommodates the all-glass railing. The latter was also realised in a box-type design masking the tread steps of the stringer staircase. The steel treads were welded in between the stringers by the specialist team of MetallArt.

  • Flight width approx. 1,400 -1,700 mm
  • 22 risers, 21 steps, 1 step at the stairs’ head
  • Design according to DIN 18065 and EN1090 EXC2

The tread step construction of the stringer staircase is combined from folded and box-type steps of approx. 5-6 mm thick steel sheet.

Inner stringer as parapet-high box-type stringer

  • Stringer thickness approx. 10 -15 mm
  • Stringer width up to 60 mm (for grip security)
  • Stringer height approx. 1,120 mm topside from front edge of the tread step plus approx. 400-450 mm running downwards masking the treads and corresponding to the outer stringer

Outer stringer as box-type stringer with glass pocket

  • Stringer thickness approx. 10-12 mm
  • Stringer width up to 60 mm
  • Stringer height approx. 400-450 mm

Structurally supporting soffit lining

  • Smooth, homogenous surface made of steel sheet
  • Shaped according to the flight of the stairs
  • Flush welded in between the stringers on the underside
  • Significantly improved statics and advantages for the vibration behaviour due to the structural support

A smaller but effective feature of this stringer staircase is the so-called stringer curve at the exit. The soffit lining follows this curve with a corresponding bend that deviates from the regular gradient of the staircase.

All-glass railing of the stringer staircase

  • Laminated safety glass panes with approx. 20-24 mm thickness
  • Length of the panes up to 1,500 mm
  • Vertical glass joints approx. 10-20 mm
  • Railing height approx. 1,120 mm
  • Ascending and curved course of the glass railing, according to the flight of the stringer staircase
  • Stainless steel handrail approx. 40 x 30 mm, high-gloss polished stainless steel U-profile

The design of the gallery railing corresponds to the railing of the stairs. It was realised with panes made of laminated safety glass and a top-attached, high-gloss polished stainless steel handrail.

Stainless steel ring construction with rope suspension

  • Design in triangular cross-section (isosceles)
  • Side length of the triangle approx. 170 mm
  • Manufactured in 3 segments, welded
  • Elliptical ring layout
  • Central axis (length) approx. 6,215 mm
  • Central axis (width) approx. 4,780 mm
  • Highly polished

The ring construction was attached with three stainless steel ropes to the bearing ceiling structure covering the 37th floor.


Gruber + Kleine-Kraneburg, Frankfurt