8 Willis Street Stewart Dawson's

Argosy Property Limited, the owners of the Stewart Dawson’s Building acted quickly to strengthen the building facade in response to the MBIE Unreinforced Masonry (URM) programme. The initial project scale was for a 5-storey building to be inserted behind the newly reinforced façade to accommodate a significant retailer. However, it quickly became obvious that following the 2016 Kaikoura earthquake that there was strong market demand for a more significant development on this prime central city site. This led to the design of a much larger building which included the neighbouring existing building at 8 Willis St, also owner by Argosy.

The developer recognised demands in the commercial property market for more sustainable buildings. The fully electric building has achieved a ‘World Excellence’ 6 Green Star rating including all ten available innovation points.

Minimising energy use in a fully glazed building posed significant challenges to the design team. This required careful glass selection using Low-E glass Argon filled double glazed units structurally glazed into a thermally broken curtain wall system. Maximising energy efficiency was achieved by increasing the thermal insulation of the building fabric and using photovoltaic solar panels to generate 5% of the total building electricity demand and thermodynamic solar water heating to supply hot water. LED lighting was used throughout the building. The office areas feature exposed ceilings improving spatial volume and utilise chilled beam technology to condition the air.

The building is designed to 130% NBS and comprises two towers, one new structural steel frame on the Stewart Dawson’s site and the other an extension both vertically and horizontally to the existing concrete structure at 8 Willis separated with a trafficable seismic joint allowing both towers to move independently of one another during a seismic event.

The Stewart Dawsons Corner (SDC) is a collective description for three adjacent, three storied buildings, namely the City Meats, Stewart Dawsons and United Fruit Company. The SDC site links two major city streets - Willis Street and Lambton Quay - and is a much-loved Wellington landmark. The three facades of SDC are category II listed in the Historic Places Trust register. These buildings had been amalgamated into a single commercial building above the ground floor but with their individual retail identities retained at ground floor. The roofs were articulated as three individual roof forms behind their respective façade parapets, each facade being painted in different colours.

Initial redevelopment options involved rebuilding behind the façades and increasing the height of the building to match the level of the existing service lane off Boulcott St. This offered a potentially attractive opportunity to large scale international retailers on the most prominent corner on the golden mile. Strong interest followed, however, it soon became clear that the rental return from this strategy was not going to meet the necessary financial return. The design scope then expanded to maximise the site potential, after initial commercial market investigation suggested that any potential tenant required a significantly larger floor area than could be provided with a building on the SDC site alone.

Owing to its unreinforced brick façade, the heritage-listed SDC site was identified as requiring earthquake strengthening and the building’s owners Argosy Property Limited responded swiftly to MBIE’s requirements – doubling down on the opportunity to maximise this prime central city site.

The approach to heritage was two-fold: to restore the heritage façade to the SDC site; and for the new surrounding architecture to contrast and compliment these buildings. This site was always going to attract interest and provoke a strong response from city planners, and architecture+ worked with a heritage consultant to make carefully considered decisions about the façade treatment, refurbishment of the timber windows, paint colour selections, and material selections. Photographs circa 1920’s helped to inform the design of some of the heritage features which had been lost over the years, including details around the pediments, cornices, and pilasters. The original timber trussed roof structures were carefully dismantled and stored during the demolition staged, before being restored and reinstated.

The design for the street façade at 8 Willis responds in a very contemporary way to its Victorian neighbour. The street frontage was bought forward to align with the SDC buildings and the articulation of the glazed wall changes at the horizontal level of SDC’s heritage pediments. From below this datum to the street level, the scale of the glazed panels is broken down into smaller modules by the way of Poutama tukutuku screens, which sit comfortably next to the scale and detail of the heritage façade.

The SDC façade restoration required significant refurbishment and repair to the Oamaru stone and plastered surfaces. Façade windows are a combination of timber double hung sashes and steel windows and these all were refurbished and sealed shut to maintain tempered air quality. The paint colour selections for window and canopy elements were made from a historic colour palette and individual colour schemes were developed for each of the three buildings.

The heavily articulated parapet elements on the City Meat Building, which reflected its original use as a chemist shop, had been removed some years ago. These lost apothecary symbols were laboriously reproduced digitally in 3D, based on historic early 20th century photographs. The original external rooftop chimney and ventilator elements were also replicated.

The original retail shopfronts comprised fine circular timber members that would not meet current seismic and safety requirements. With the advice of the structural engineer a new system was developed that comprised steel flats and round timber glazing beads that were slightly oversized when compared to the original bit otherwise were an accurate visual representation of the original and met current structural loading requirements. The original trussed roof structure of the three SDC buildings was painstakingly removed and placed into safe storage and then reinstated.

We worked closely with heritage consultant Ian Bowman on the SDC buildings, who provided guidance on appropriate materials, colours, and refurbishment processes for the heritage fabric.

Design team: Stephen Poulopoulos, Kirsty Chamberlain, Stuart Gardyne, Belinda Tuohy, Michael Bennett, Andrew Camberis, Jesse Ewart, Terese Fitzgerald, Jeff Lummis, Arnie Makan, Guy Newton, Ross Tredget, Sam Wilson

Project team; McKee Fehl Constructors, Beca, Cora Consulting Engineers, Blackyard Engineers, Michael Stretton, Cognition, Ian Bowman, Spencer Holmes, ECubed, Marshall Day Acoustics