Architect Plus Minus Design engaged Partridge to provide structural engineering for the replacement of an existing dwelling with a two-storey semi-detached home and a separate two-storey garage and granny flat on the rear laneway. The structural scheme features a reinforced concrete ground floor slab on screw piles, stepped over four levels to follow the site’s natural slope and reduce excavation. The superstructure uses lightweight steel framing with timber joist floors and roof, with the first floor also stepping across six levels. Cranked beams were introduced to replace a line of internal columns, opening up the floor plan. Lateral stability is achieved through steel portal and braced frames, and blockwork shear walls around the stair cores. To resolve wind load transfer across the stepped floors, a horizontally spanning steel truss within the lean-to roof connects into the bracing system. Architectural detailing integrates the exposed steel structure with design elements including paired steel posts, flat-plate awnings, and custom steel framing around openings.
