World’s largest free spanning dome is over 1000 feet across and has a lightweight movable EFTE roof

Singapore’s new national sports stadium (completed in 2014) is the world’s largest free-spanning dome, measuring 310-meters (1017 feet) across, and its roof can be opened or closed to suit the tropical climate.

The moving roof sections are made from translucent ETFE plastic, chosen for its strength and thermal properties.

The panels are supported on metal rigging that arches over the pitch, connecting to a framework that covers the auditorium on either side of the stadium.

The 55,000 capacity National Stadium has a 19,500 sq-meter (4.8 acres) retractable roof, which can open or close in just 20 minutes. The roof is made with a multi-layer ETFE pillow. The moving roof incorporates a matrix of LED lights, making it one of the largest addressable LED screens in the world.

The EFTE for the roof is a 0.15mm to 0.25mm-thick Fluon ETFE fluoropolymer film. Fluon ETFE Film is made of a high-performance thermoplastic fluoropolymer, and features excellent transparency, non-stick and insulation properties, and resistance to heat, chemicals and weather. ETFE film is used for electronics, solar cells, wallpaper and greenhouses, but has recently been attracting global attention as a high-performance building material.

ETFE film is self-cleaning (due to its nonstick surface) and recyclable. It is prone to punctures by sharp edges and therefore mostly used for roofs. In sheet form as commonly employed for architecture, it is able to stretch to three times its length without loss of elasticity. Employing heat welding, tears can be repaired with a patch or multiple sheets assembled into larger panels.

ETFE has an approximate tensile strength of 42 N/mm² (6100 psi), with a working temperature range of 89 K to 423 K (−185 °C to +150 °C or −300 °F to +300 °F).

SOURCES – Dezeen, Wikipedia, Chemours, Pro Audio Asia