The in-built insulation provided by the pumice aggregate of the panels complies with NZBC requirements, enabling both panel faces to be exposed.
This Ponsonby house, designed by architect Ross Brown, positions itself comfortably besides neighbouring villas, characterised by welcoming entrances and open verandahs. The owners' brief was for a house on a flat inner-city site facing north, the concept for which was based on a 75mm high pounamu (greenstone) sculpture, celebrated for its rich interior life and its capacity to hold light.
Litecrete lightweight precast walls allow the 'fair-faced' concrete finish to be visible externally and internally. Double-glazed steel windows were to be employed to frame and screen openings in the concrete walls; gridded fenestration — combined with the concrete finishes — would provide a gritty aesthetic of a more European flavour, which both owners liked. The concept was for a pair of solid gable-roofed building blocks, which occupy the middle of the site, spliced and slid along the central axis to give a larger plan width in the middle. Larger outside courts were then possible in both the sunny north-west (outdoor living/swimming pool) — connecting through the glazed screens to indoors, and south-east (laundry court/garages — adjacent to the street frontage) re-entrant corners. This fitted with the sloping roof forms and vernacular of the older buildings around.
The front porch was modified from those nearby, not fully open to the street and allowing the front door to be accessed indirectly. The flat site was excavated at the rear to have the living spaces on a lower level to the street. To achieve a contrast, the pool was then elevated.
220mm thick Litecrete lightweight precast concrete was chosen for the external and internal walls because of its in-built insulation. This meant that the Building Code insulation requirements were met and both faces of the panels could be exposed. The smooth finish to the exterior of the panels, complete with a subtle custom-made 'in-situ' square pattern, is contrasted with the more rustic rough-sawn timber finish of the in-situ concrete for the stairwell. This contrast comes into relief where the smooth curve of the solid oak handrail wends its way up the stairs. To ensure continuity of the 'in-situ' appearance to the precast the owner was adamant that lifting eyes in the panels were to be hidden from view.
The owners have succeeded in creating a piece of architecture that, like the small precious object that was the catalyst for the design, manipulates light to enhance interior experience. The house was featured on TV3’s Grand Designs NZ programme and has recently received an NZIA Residential Architecture award.