Kirribilli, beneath the terrace.

The engineering behind the design.

Originally approved as a modest three-level extension, this build evolved into a transformative full-scale redevelopment. Along the way, two Development Applications were approved mid-project, enabling a complete reinvention of the property without halting construction.

[PLACEHOLDER paragraph — studio voice on Kirribilli's geotechnical context. ~3 sentences on the heritage peninsula, party-wall constraints, and why the basement carve was the structural problem.]

The plan.

We coordinated the excavation of a 50 m² basement beneath an existing terrace home while simultaneously constructing the second and third floors above. The structure required a 20 m long, 1.2 m high, 500 mm deep concrete capping beam, as well as underpinning the neighbouring property. On the other side, a steel-framed cantilevered living space was erected above a shared accessway, supported by 700 mm diameter piers drilled 3.5 m into sandstone. A suspended slab was poured over an old well, and 172 m³ of rock was removed during excavation.

The standout feature: a 10 m² western red cedar sauna with microcement walls and a full-height glass face divided by grass, sitting within the basement alongside the custom steel staircase, also designed in-house.

[PLACEHOLDER paragraph — narrate the *why* behind the cantilever. Architect's brief, load path, transfer frame. ~3-4 sentences.]

Notes on the sequence.

[PLACEHOLDER section — week-by-week sequencing notes. The "sequence is the design" voice. Cover the underpinning bays, the two-stage capping pour, top-down/bottom-up framing, and certifier dependencies. ~2 short paragraphs.]