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Auckland's Sky Tower's spectacular views made possible through the widespread and daring use of laminated glass

Auckland's Sky Tower – the tallest building in the southern hemisphere (328 m)

Auckland's Sky Tower, completed in September 1997, is the tallest structure in the southern hemisphere at 328 m and puts New Zealand firmly on the global architectural map. The tower, which contains the region's main broadcasting and telecommunications facility, has already become a major tourist attraction and is expected to draw more than a million visitors per year for its spectacular views which are made possible through the widespread and daring use of laminated glass. DuPont^™ Butacite^® PVB was used extensively in a variety of laminated glass applications throughout the project.

Gordon Moller, Principal at Architects Craig Moller of Auckland, told LGN: "We wanted to give a strong identity to the central business district of Auckland and allow visitors to the tower an appreciation of the orientation of the site which dominates the isthmus where the city stands, surrounded by water. Safety was the other major consideration; the tower needs to handle up to 800 people at any one time and had to pass rigorous seismic testing since New Zealand is situated on the Pacific plate faultline."

360 Degree Views

Mr. Moller continued: "All the glass used in Sky Tower is laminated for superior viewing quality. We used laminated glass for the floor-to-ceiling windows on the Observation and Sky Decks and for the revolving restaurant because of the product's unparalleled 'trueness'. Laminated glass is distortion-free and gives a much flatter finish than toughened glass."

The external façade of Auckland's Sky Tower, including the glass, was supplied by G. James Glass of Brisbane, Australia. Operations Manager, Paul Dawson told LGN: "Huge (4 m x 1.3 m) panes of laminated glass are used for the main observation level incorporating a green-colored PVB interlayer which cuts out glare and reduces solar gain. Laminated clear glass was also used in the outdoor observation deck. The glass for the Sky Tower was all manufactured and installed into frames in our Brisbane factory."

Transmitter-Friendly Façade

He continued: "We fabricated curved laminated glass incorporating a 0.76 mm PVB interlayer for a 'radio transparent' façade to the communications levels, half way up the tower, which contains the microwave, digital and transmitter radio communications equipment. This curved glass was structurally glazed to a curved frame. The glass underwent significant physical testing to ensure that it would be transparent to current radio frequencies and to the high radio frequencies required for the future."

Laminated glass is also used in the three passenger lifts serving the tower, which have glass doors looking down into the elevator shaft and ribbon windows with panoramic views across Auckland. It was also used for an impressive, 100 m² flat roof atrium to the Sky City casino and hotel complex situated at the foot of the tower.

Glass Floor Gives Dramatic Views Down

The most dramatic viewing facility in Sky Tower comes in the form of laminated glass 'viewports' (1,800 cm x 1,200 cm) located at each of the four compass points on the Observation Deck which allow people to look straight down to the ground, 200 m below.

Paul Dawson explained: "The glass viewpoint floor uses PPG Starphire, an ultra-transparent, low iron lime float glass providing excellent clarity. The floor has a total thickness of 44 mm consisting of 38 mm laminated glass for strength and safety and a 6 mm 'sacrificial' layer of clear float glass which allows for wear and tear and which, since it is loosely applied, can be more cost-effectively replaced every three months than the 38 mm glass. The panes are glazed into the rest of the deck on all four sides."

Gordon Moller said: "From the eyrie which is the Sky Tower's observation deck, people can walk on a glass floor and look down to see the tower curving down to the ground, 200 m below." Paul Dawson concluded: "Many people were originally astonished by the concept of a glass floor so far above the ground but Gordon Moller insisted on it, and in fact the viewpoints have become a key attraction for people visiting the tower!"