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Refurbishment and extension to 133 Molesworth Street, Wellington

30 Nov 2016

Studio Pacific Architecture & Beca Group Ltd have taken home the 2016 Supreme Award for the refurbishment and extension to 133 Molesworth Street, Wellington. The award celebrated concrete’s role in the significant upgrade and extension to one of the world’s first base-isolated buildings with lead-rubber bearings.

Known as the William Clayton Building and designed by the Ministry of Works as their Wellington District Office and as a Civil Defence Hub, it originally opened in 1982. Subsequently it was occupied by the Ministry of Health. The Ministry will be moving back in late October following completion of the building upgrade and a new interior fit-out.

The building extensions have doubled the lettable floor area from approximately 8000m2 to 16,000m2, enabling the Ministry to consolidate its entire staff into the one location, leading to significant operational improvements.

A decision was made to upgrade the building for both seismic and wind considerations. This has been achieved by the replacement of 39 of the original 79 lead-rubber bearings, and an increase in the perimeter seismic “rattle space” from 150mm to 400mm.

To reduce energy use, it is important to minimise afternoon heat gains along the west elevation of the building. To help achieve this, the proven longevity of precast concrete made it a natural choice. The deeply profiled concrete spandrel cladding panels not only act as sunshades but also considerably modernise the overall look, creating a dynamic “gateway building” alongside Wellington’s motorway into the city.

Despite the radically changed appearance of the building, the owner and design team were committed to re-using as much of the existing building fabric as possible. The design was developed so that all existing main precast cladding panels were able to be re-used — a total of 58 were relocated, with only two new ones required.

The fire egress stairs were also reconfigured to maximise the reuse of precast concrete stair flights. A new main interconnecting stair incorporates precast concrete treads, using white cement to contrast with an adjacent dark feature wall.

The original William Clayton Building received a New Zealand Institute of Architecture Award in 1983. While generally positive, the 1983 citation commented on the main entry’s lack of finesse. The new design widens the entry to create a dramatic in-situ entry portal. This celebrates the plasticity of concrete by looking like one of the spandrel panels has been stretched to create a striking canopy.


The refurbishment and extension to 133 Molesworth Street in Wellington ticked an array of sustainability boxes with the judges. Not only did the project team re-purpose an existing concrete structure, placing an emphasis on the re-use of virtually all precast concrete exterior panels, but they were dealing with the incredibly important William Clayton Building — New Zealand’s first base-isolated building. The enhancement of the base isolation system (and consideration of wind), use of concrete to reduce heat gain, and doubling of the floor, were all skilfully achieved while simultaneously revitalising the building inside and out to create a striking structure at the capital city’s entrance.

SUBMITTED BY Studio Pacific Architecture & Beca Group Ltd

CLIENT Balanced Investments Ltd

ARCHITECT Studio Pacific Architecture Ltd


CONTRACTOR Fletcher Construction Ltd

William Clayton Building prior to refurbishment and extension.