The architectural starting point for the structure was the idea of a 'heavy' ceiling connecting internal and external teaching spaces.
A series of inverted valleys run above the new classroom infill and externally beyond, as far as the school's boundary wall. A second roof plane, a lightweight GRP canopy, projects perpendicular from the first. For reasons both visual and practical - this being a playground - support for these structures was minimal, with no interfering cross-bracing. A significant factor in the structural design was the ground condition: deep made ground. The existing school building is founded on piles, a strategy we continued in the new internal infill with a raft slab supported by four new mini-piles. To avoid unnecessary costs the external canopies were founded off the ground using much cheaper pad foundations, sized primarily to prevent uplift of the canopy. Any difference in settlements between exterior and interior was then dealt with in the details linking the two structures. All the structures are steel frames, supplemented with timber restraint beams to stiffen disparate elements. The external canopy was braced longitudinally, and in part laterally, by tying it back to the new internal structure via connections that permit vertical movement. The internal structure was, in turn, tied back to the existing concrete framed school building. The canopy's free end was braced laterally using diagonal struts. These meet the columns halfway up and are hidden inside the tricycle store. This strategy ensured that support for the canopy could be reduced to 80 x 80mm posts and, with only vertical shear to be accommodated, the visible post/beam connections were free to be detailed as the architects required.