Hovering 5m off the floor, the Fire pavilion is 20m by 40m in plan, 5m deep, and contains 120t of structural steel. It was, says Poyser, the most difficult pavilion to support.
Two of the shed's huge A-frame central columns, standing 12m apart, are incorporated in the pavilion's floor plate. Two short beams extending from either end of the pavilion have been welded to adjacent perimeter columns, 22m from the shed's centre line.
But load distribution is not equal.
'We assessed the stanchions to see which had spare capacity and which was weakest, ' says Poyser.
'Then we designed a lattice structure that takes loads back to the most robust points. Load distribution is biased towards the middle, where the stanchions are newest and strongest.'
As with all other pavilions at Magna, the floor of Fire is designed to carry loads of 5kN/m 2- twice the loading normal in a multi-storey car park. Poyser has been asked to accommodate some extremely high local loading. Even so, some local strengthening may be needed.
Supported on beams welded to four pairs of columns just below the enveloping dark of the shed's roof space, the Air pavilion is the least substantial of Magna's structures. Its floor plate is not solid, but a grouping of walkways.
Cladding is an inflatable fabric envelope, designed and erected by specialist aerial contractor Vector.
The impression is of a pristine zeppelin trapped amid the rafters.
Weighing 15t apiece, the four beams supporting the Air pavilion span 22m and together make up two thirds of its mass. The beams have a 300mm wide by 650mm I-section core, but are wrapped in non-structural steel bodywork, finished with filler to produce a streamlined, cigar-like form.
'The cigar beams were more like boat building than traditional civil engineering, ' comments Billington director Mike Fewster.
Perhaps the most difficult of the pavilions to design and fabricate, a tight, curvilinear geometry proved the principal challenge. In section the Water pavilion is a 20m wide asymmetric arch, curving back on itself as it meets the ground.
Over most of the pavilion's length a regular system of parallel fabricated beams could be used to provide shape and support. At either end, though, the pavilion corkscrews outwards, distorting the last three beams into ever more radical helical configurations.
Where the radii are most extreme beams were specially fabricated - webs were cut and flanges rolled to profile, and then welded together. The flatter top part of the arch was produced by bending standard universal section beams.
But the three spiralling beams at either end of the pavilion are made from 25mm thick, 300mm diameter tubular sections.
Billington used induction bending to heat the beams in 50mm lengths.
Precise alignments are achieved by rotating the tube and bending in short sections.
Beams are positioned at 2m centres to prevent deflection and are connected and braced by a corrugated steel membrane overclad with stainless steel panels.
Under Magna's exhibition spotlighting deformation of the skin 'would stand out like a sore thumb, ' Poyser comments.
The most straightforward of Magna's pavilions, Earth's composite floor is supported from beneath on three giant mass concrete piers. There is no fancy structural engineering, says Poyser: A regular system of I-section columns and beams is used, though planes on the pavilion's sheet steel cladding have been cranked to give it the appearance of emerging dramatically from the ground.
However, a careful method statement and eagle eye for safety has been called for. The Earth pavilion is positioned directly beneath Air, and construction programmes have been concurrent.