The ridge piece is first post-tensioned into the ribs by means of three cables. The last step is to locate a precast keying ridge continuous. As the segments for a rib are positioned they are jointed with an epoxy resin to transfer shear and stressing loads.

The main shells are built out rib by rib, from the side shells. In addition, there is a main brace between the arches parallel the auditorium axis. The arches braced in pairs either side of the auditorium center line by precast members that act as beam columns. When all four arches of a unit were competed and post-tensioned, a precast crown piece was inserted and site-cast in place. Further segments were then placed until the arches meet at the central plane of the shell between 70 to 150 feet above the tops of the foundation columns. The sides shells were erected first by locating precast segments on top of each arch pedestal and stressed to it permanently. The slab is surfaced with 6 by 4 foot panels of artificial granite with open joints between them to carry away rainwater. The slab and steps of the concourse cover some 75,000 square feet with varying spans up to 164 feet. The presence of the sea water also meant that the whole structure below ground level had to be built as a number of waterproof reinforced-concrete compartments. A large part of the building is supported on some 700, 3 foot diameter, cased bored piers. Stage 1 covered the terraced base stage 2 is the shell construction and stage 3 will be the finishing and fitting operations. Construction was planned in three stages. The assessing committee, however, recognized the originality of the concept expressed, and also its perfect suitability for the site. Designed by a young Danish architect, Jorn Utzon, the drawings were almost never submitted because he thought it would be useless. Construction of Australia's 'billowing sails' Opera House has followed an entirely unorthodox pattern.

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