Sky Tower | Moller Architects

The Sky Tower took two years and nine months to construct and opened on 3 August 1997, six months ahead of schedule.

Fletcher Construction was the contracted builder for the project while Beca provided engineering and structural services for construction of the Sky Tower. The Sky Tower was designed by Gordon Moller of Moller Architects and has received a New Zealand Institute of Architects National Award as well as regional awards.

The Sky Tower is constructed of reinforced, high-performance concrete. Its 12-metre (39 ft) diameter shaft (containing three public lifts, one service lift and two emergency stairwells) is supported by eight 'legs' based on 16 foundation piles drilled more than 15 metres deep into sandstone. The main shaft was built using climbing formwork.

The upper levels were constructed from composite materials, structural steel, precast concrete and reinforced concrete, and the observation decks clad in aluminium with blue/green reflective glass. A structural steel framework supports the upper structure.

During construction 15,000 cubic metres (20,000 cu yd) of concrete, 2,000 tonnes of reinforcing steel, 660 tonnes of structural steel and 260 panes of glass were used.

The mast weighs over 170 tonnes. It was too heavy for a helicopter to lift so was put in place by a crane attached to the structure. To remove that crane, another crane was constructed and attached to the upper part of the Sky Tower. After dismantling the first crane it was in turn dismantled into pieces small enough to fit into the elevator.

The Sky Tower is designed to withstand wind in excess of 200 km/h (120 mph), and designed to sway up to one metre (39 in) in excessively high winds. As a safety precaution the Sky Tower’s lifts have special technology installed to detect movement (such as swaying due to high wind) and will automatically slow down. If the building sway exceeds predetermined safety levels the lifts will return to the ground floor and remain there until the high winds and building sway have abated.

The Sky Tower is built to withstand an 8.0 magnitude earthquake located within a 20km radius.  There are three fireproof on levels 44, 45 and 46 to provide refuge in the event of an emergency, while the central service lift shaft and stairwells are also fire-safety rated.