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Award-winning Stairs in SentryGlas®

BAD HOMBURG, November 2006 - Seele GmbH & Co.KG (Gersthofen/Germany) was presented with the 'Innovation Award Architecture and Glass' during Glasstec 2006 for its development of the world's largest self-supporting staircase, manufactured almost entirely from laminated glass. What impressed the adjudicators was not only the significant length of the sidewalls of the staircase - at 8.5 meters they are a good 2.5 meters longer than existing staircases of this type - but also the first-time use of a non-positive-fit connection between the steps and the sidewalls, thus waiving the need for the boreholes and bolts normally used for conventional positive-fit, bolt-fixed connections.

This pioneering development was made possible by the application of DuPont™ SentryGlas® high-strength laminated glass interlayers, which were used both for the manufacture of the glass steps and sidewalls and for the laminated-on stainless steel mountings. Seele developed this award-winning allglass staircase in collaboration with the IBK (Institute of Building Design) and the ITKE (Institute of Supporting Structures and Structural Design) of the University of Stuttgart.

Ingo Stelzer, Head of Glass Production and Composites Development at Seele, says: "By developing our self-supporting staircase of laminated glass, we just wanted to show what is technically possible today. Our ability to incorporate highly transparent DuPont™ SentryGlas® interlayers in all of the structurally important connections, allowed us to reduce the connecting elements to an absolute minimum and hence achieve a maximum impression of lightness. Thanks to the high strength and stiffness of SentryGlas® and our newly-developed laminating technique, relatively small surfaces reliably transmit the load from the steps to the sidewalls. This innovation would not have been possible with conventional laminating interlayers."

The sidewalls of the staircase each consist of three 15 mm thick layers of float glass - 'Optiwhite' from Pilkington - with 1.52 mm thick DuPont™ SentryGlas® high-performance interlayers. This combination provides the advantage of extra high clarity due to the advanced transparencies of both SentryGlas® and low iron or 'OptiWhite' type glasses. The 1,400 mm wide and 300 mm deep steps each comprise four layers of float glass of the same kind, likewise laminated with SentryGlas® interlayers to ensure particularly high flexural stiffness. The stainless steel mountings on the sidewalls - four per step - are each connected to the top layer of glass by a laminating sheet measuring only approx. 40 mm x 100 mm. The counterpieces, which engage with the aforementioned mountings, are laminated directly into one of the step interlayers.