This project, located in the dense urban fabric of Observatory, transformed an ordinary single-storey, free-standing house into two multi-level row houses, reinterpreting the existing Victorian semi-detached walk-ups that characterise much of the neighbourhood. Mirror images of each other, the compact planning of each unit is anchored around a stairway/ circulation zone against the party wall. A lightweight steel structure spans between party and gable walls, generating three floor levels linked vertically by interconnecting volumes, and enclosed by a steeply sloping roof that defines the essential character of the building. This roof formation creates an appropriately limited south-facing street interface whereas to the north side, it opens up to the sunlight and private garden. The gable walls are punctured with portholes that restrict light and heat admission from the east and west.