The National Stadium roof is the world's largest free-span dome at opening — a diagrid steel shell, 312 m in diameter, spanning a bowl that seats 55,000 people. Getting it there meant building temporary works that did far less than a conventional long-span roof would normally require, and letting the permanent structure do far more of the work along the way.

To erect it, temporary trestles up to 75 m tall were positioned across the bowl — not a full forest of conventional falsework, but a targeted system of props, supporting each stage of erection while the permanent structure progressively took over.

312 m
Dome diameter
55,000
Seating capacity
75 m
Max trestle height
2014
Year completed
Phase 1 — Targeted temporary works
Props, not a forest of falsework
Temporary trestles up to 75 m tall were positioned across the bowl in a targeted system, sized to support each stage of erection rather than the entire roof at once — a deliberately leaner approach than conventional full-falsework support for a dome of this span.
Phase 2 — Perimeter-inward erection
The dome starts working before it's finished
The erection sequence worked from the perimeter inward. As each ring of the diagrid connected, it gained stiffness and began carrying load for the next stage — a different construction logic from most long-span roofs, where the structure typically stays fully propped until completion.
Phase 3 — A structure that changed its own load path
Every erection state analysed against a moving target
Every temporary erection state had to be analysed within a structure that was changing its own load distribution with each new connection. Connection sequencing, geometric control, and the transition from propped to self-supporting behaviour governed the programme in ways that don't appear on a conventional erection drawing.
Phase 4 — De-propping
Finding the dome's permanent geometry for the first time
De-propping was the point at which the roof transferred fully onto the concrete perimeter ring beam and the temporary trestles came out — removed in a controlled sequence while the dome found its permanent geometry for the first time. The order of removal, the geometric targets, and stress redistribution during de-propping were where much of the erection exposure sat.

The retractable mechanism gets the press release. The erection engineering is what made the structural concept buildable.

By the time the crown closed, the dome's own structural behaviour had been developing throughout the erection sequence, not switched on all at once at the end. Singapore Sports Hub stands as a reference case for progressive load transfer at extreme span: a targeted temporary works strategy that let the permanent structure do increasing amounts of the work as it grew, rather than carrying the entire roof on falsework until the last connection closed.

For further reading on temporary structural states, see What is Temporary Works & Erection Strategy?

Related case studies: Eiffel Tower · London Eye · FAST Telescope

The Singapore Sports Hub's retractable dome roof viewed from a distance across trees and low buildings, its ribbed steel structure visible against the city skyline
The Singapore Sports Hub's self-supporting dome, Kallang, Singapore. Resized from the original for web display.
Photo: Jnzl's Photos, via Wikimedia Commons, CC BY 2.0.

Sources: Guinness World Records — certified as the largest true (self-supporting) dome, spanning 312 m, designed by Arup and DP Architects; Dezeen — retractable ETFE roof sections and the supporting arch rigging, with project architect Clive Lewis on the dome form. The span is published as both 310 m and 312 m; Guinness certifies 312 m.

Frequently Asked Questions

The National Stadium roof is a diagrid steel shell 312 m in diameter, spanning a bowl that seats 55,000 people. It was the world's largest free-span dome at opening in 2014.

Temporary trestles up to 75 m tall were positioned across the bowl — not a full forest of conventional falsework, but a targeted system of props supporting each stage of erection while the permanent structure progressively took over.

The erection sequence worked from the perimeter inward. As each ring of the diagrid connected, it gained stiffness and began carrying load for the next stage, so by the time the crown closed, the dome's own structural behaviour had been developing throughout the erection sequence rather than switching on all at once at the end.

De-propping was the point at which the roof transferred fully onto the concrete perimeter ring beam and the temporary trestles, up to 75 m tall, were removed in a controlled sequence while the dome found its permanent geometry for the first time. The order of removal, the geometric targets, and stress redistribution during de-propping were where much of the erection risk sat.