DuPont Home
Safety Glass

Stairs, bridges and floors showcase the structural strength of laminated glass

Laminated Glass News showcases state-of-the-art developments that leverage the structural strength and design freedom of laminated glass as a 21st century material for bridges, stairs and floors.

Apple Computer Inc.’s new store in SoHo, New York (completion: July 2002) uses laminated glass with DuPont™ SentryGlas® ionoplast interlayer for a glass staircase, bridge and mezzanine ensemble that look levitating, weightless, gravity-defying – and simply amazing, architecturally.

While the outstanding structural strength and clarity of DuPont SentryGlas® ionoplast interlayer is used for the stunning, ‘free-floating’ glass staircase, bridge and landing, laminated glass with Butacite® PVB is also used in Apple’s SoHo store for a skylight, vertical walls and handrails that complete the new-age glass and steel look of the store.

Architectural and structural engineering experts have said that the staircase, bridge and mezzanine represent a quantum leap forward in using the strength of glass for a self-supporting structure while demonstrating the aesthetic lightness of glass with a new minimalism.

The splendor of the stair structure is emphasized by the highly-polished, exposed edges of the stair treads which, although they contain a 1.5 mm interlayer of SentryGlas® for phenomenal structural strength, give the appearance of one solid piece of transparent glass per stair thanks to the dedicated craftsmanship of laminator Depp Glass of Long Island, New York.

Client: Apple Inc.
Architect: Bohlin Cywinski Jackson Architects Planning Interior Design, Berkeley, CA, USA.
Engineering: Dewhurst Macfarlane and Partners Inc, New York City, USA.
SentryGlas® ionoplast and Butacite® PVB interlayers for the laminated glass: DuPont
Backup structural testing and calculations: DuPont Central Research and Development
Fabrication, installation and safety tests: Seele GmbH & Co, Gerthofen, Germany
Consultant: Veroplan Entwicklungs GmbH, Bretten, Germany
Laminated glass lites for stairwalls, guardrails and skylight: BGT Bischoff Glasstechnik GmbH of Bretten, Germany
Glass stair treads, bridges and landing: Depp Glass Inc. Long Island, New York City, USA.
Point fixtures: Tripyramid Structures Inc. Westford, MA, USA.

The staircase appears to be free-floating but in reality is held to the vertical, laminated glass sidewalls (supplied by Bischoff of Germany) on each side of it by tiny titanium inserts. This is the first time worldwide that glass has been laminated to metal on a large-scale design. The glass-titantium-glass construction around the inserts was made possible by the excellent flow and processing properties of SentryGlas®. The ionoplast flows far better around the metal inserts than PVB would have done.

The outstanding stiffness of DuPont’s ionoplast interlayer means that the stair treads could be made 50 percent thinner than if PVB had been used and twenty times stronger, according to the rigorous load-bearing testing that took place in Germany.

New Bystronic HQ showcases state-of-the-art glass concepts

Bystronic, a leading equipment supplier to the worldwide architectural and automotive glass industry, wanted to showcase state-of-the-art applications for architectural glass when it planned its new North American headquarters in Hauppauge (NY) USA. The building features an ethereal looking yet load-bearing, self-supporting staircase of laminated glass with SentryGlas® ionoplast interlayer in the entrance hall and a laminated glass curtainwall incorporating Butacite® PVB interlayer.

Architect Hans Rudolf Kaeser of Interior Concepts, New York City, said: “Bystronic wanted the entrance hall to be as light and airy as possible; we achieved this by designing glass stairs, mezzanine floor, handrails and a large skylight all in a low-iron, bluish- coloured laminated safety glass that matches Bystronic’s corporate colour. The stairs were finished with exposed edges using Bystronic waterjet machinery; even the metal stringers for the stairs were made with the company’s laser cutting machines. The use of DuPont’s ionoplast interlayer added stiffness to the stairs and meant that the tread could be thinner than usual. This added to the visual effect of lightness.”

Laminator Wesley Depp said: “Normally, the handrails would have needed to be made of laminated heat tempered glass for extra strength. The use of SentryGlas®, which provides five times the tensile strength and 100 times the rigidity of PVB, obviated the need for tempering. In addition, using a triple interlayer of the ionoplast on the stairs meant that we could make the 6 foot wide stairs self-supporting with a tread that is just 2 inches thick.”

Bystronic president Rick Troesch said: “We are very pleased; the stairway is absolutely beautiful and has generated a lot of interest from visiting customers who always ask how it was made. Our aim is to show that laminated glass is an unbelievable material for interior concepts as well as exterior applications.”