It will have been a long eight years of anticipation, but in 2023 art enthusiasts in New Zealand and around the world will welcome the re-opening of one of the country’s foremost art galleries and an iconic heritage building to boot – finally restored and ready for another 100 years of performance, with a lot of help from the Contech team.

The Sarjeant Gallery/Te Whare o Rehua Whanganui (‘House of Inspiration’) is located in the city of Whanganui on the North Island’s west coast. It first opened its doors in 1919 thanks to the generosity of local farmer and landowner Henry Sarjeant, who bequeathed £32,000 – more than NZ$70 million in today’s terms – “as a means of inspiration for ourselves and those who come after us”.

The gallery was built in a neo-classical Greek-cross style and clad in Oamaru stone. The building remains the most prominent and elegant sculptural feature on the city’s skyline. It’s also one of the country’s oldest purpose-built galleries and is identified on the New Zealand Heritage List/Ra¯rangi Ko¯rero as ‘of special or outstanding historical or cultural significance or value’.

There’s value too in the gallery’s collection, which is the largest of all the regional art galleries in New Zealand. It comprises about 8,300 pieces spanning 400 years of international and New Zealand art history – and was valued at NZ$30 million in 2019. The collection includes a wide range of media, from paintings and works on paper to photographs, sculptures, installations, ceramics and glass, which can be viewed at www.sarjeant.org.nz.

Time for (urgent) change

Sadly, the building had to be mothballed in 2014 when it was discovered that its structure met just 5% of the new NZ Building Code and therefore posed a severe earthquake risk.

The situation was compounded by the fact that its basement, where most of the collection was held, lacked the environmental and temperature controls needed to protect the collection from cracking, flaking and warping – and that the lack of similar controls in the gallery spaces meant it didn’t meet the stringent requirements for attracting national and international touring exhibitions.

As a result of these findings the gallery’s staff, operations and collection were relocated to suitable temporary premises pending a resolution to the problems and, of course, an assessment of the associated costs.

After much debate and some delay, the redevelopment commenced in 2019. The Warren & Mahoney design will ultimately double the gallery’s size by building a brand-new wing to provide a state-of-the-art storage facility for the Sarjeant collection, additional exhibition spaces, education facilities, an auditorium and events space, a café, retail space and staff offices. In addition, and with the blessing of Te Ra¯nanga o Tu¯poho (the collective hapu¯ [sub-tribe] of the Whanganui iwi [tribe]), the existing building would be restored through strengthening and restoration work. The total cost of the project would be about NZ$50m.

Strengthening & restoration

Contech became involved early in the project, assisting structural engineers to develop the design for the work on the existing building, then working with main contractor McMillan & Lockwood to implement the chosen solution.

After undertaking pre-construction tests and trials, the team elected to drill down from the roof level into the core of the double-brick cavity walls in the building’s interior, then install 300 stainless-steel stress bars through the core to create a virtual cage. The bars would be anchored in a new reinforced-concrete capping beam at roof level and secured at basement level within the existing concrete foundations.

They would then be grouted in place and, when further work on the building was complete, stressed to the design load to ensure a 100-year design life.

The job was not without its challenges, as the original ‘concrete’ comprised boulders and small amounts of cement paste, so mostly just sand and stones remained. However, all team members enjoyed their role in contributing to a piece of New Zealand’s history – and helping a grand old art gallery to be restored to its place as a national and architectural treasure and a must-see cultural attraction.