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Hot Topic NBR Focus: GMO
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Christchurch Three Years On: Warren & Mahoney embraces modernism while preserving heritage

Sat, 22 Feb 2014

Architectural firm Warren & Mahoney was part of the team selected to redesign central Christchurch after the earthquakes. 

Other architects and sports design specialists were included in the team, which produced a blueprint for a new city plan.

The redesign team was set up to consider 16 anchor projects identified by the government for the regeneration of the city. 

Managing director Peter Marshall says the regeneration and rebuild of the city is complicated, not least due to insurance issues. 

“The flip side is the opportunity to start again and deal with some problems the central city always had. A lot of our commercial buildings were constructed in the 1980s and 1990s and there have been significant technical advances in building materials since then.

“There are so many different attributes of design that we do differently now, so Christchurch is going to be the most modern city in the Asia Pacific region.”

Warren & Mahoney is also associated with many iconic buildings in the city, including the Town Hall, designed by Sir Miles Warren.

In 2010 a Warren & Mahoney-led refurbishment of the Town Hall was already under way before the first quakes hit in September.

The firm has been contracted to repair the damage from the earthquakes and to refurbish the building to modern safety specifications after Christchurch City Council last year unanimously voted to restore the modernist building that has served as a gathering place for performance, cultural and community events since 1972. 

The original Christchurch Town Hall commission in 1966 was a big win for Warren & Mahoney because it gave the practice a building of prominence that led to more civic and institutional work around the country. 

The restoration requires strengthening foundations and repairing damage to the original design. Damage from shaking was limited but the earthquakes destabilised the land. Most of the work will be remediating the liquefied layer of earth beneath the building.

The Town Hall will be one of the first buildings in New Zealand to be remediated using jet grouting. This requires inserting grout columns into the earth, transferring the weight of the structure to deeper ground, and creating pressure to help compact and brace the foundations. Above ground, instead of adding extra concrete to reinforce the building, a new method of applying fibre-reinforced polymer to the original walls will be used. The new material is thinner but as strong as concrete.

These solutions have been peer reviewed by international consultants and will limit any damage from further land spreading in future seismic activity.

The building will be repaired to 100% of the new earthquake building standard. Engineers will perform major repair work in the supporting structure and then hairline cracks and cosmetic damage will be fixed. 

A visible steel structure will be inserted under the Limes Room to reinforce visually that the building has been strengthened.

From a structural perspective, the new space will look very similar to capture the essence of the original building and the acoustic qualities for performances. 

Warren & Mahoney is involved with the Awly building, the largest commercial project currently being constructed in Christchurch, at 287-293 Durham St, opposite the historic Provincial Chambers on the site of the demolished Amuri Courts.

Another Warren & Mahoney project is the Arts Centre, which includes the original brick buildings of the old University of Canterbury, some dating back to 1883. Twenty-two of the original 23 buildings were so severely damaged that they remain closed for safety reasons. However, the plan is to restore the buildings over six years, with some innovative technology, such as inserting carbon rods into bricks, to bring the building up to 100% of the new earthquake building standard.

Warren & Mahoney also worked on the transitional “cardboard” Anglican cathedral at 234 Hereford St overlooking Latimer Square in association with Japanese architect, Shigeru Ban.

One of the city’s most significant heritage facades has been restored at the front of the Isaac Theatre Royal.  It is the oldest existing Edwardian theatre in New Zealand, built in 1908 and seating 1300. It was damaged in the first earthquake and, in the February 2011 earthquake, the proscenium collapsed, requiring complete rebuilding. Features that have been saved include the marble staircase, added in 1927. The poppy windows and auditorium ceiling dome were saved. Although the ceiling collapsed, craftsmen rescued examples of the plaster mouldings so they could be recreated. The roof is about to be reinstated and work is almost completed on restoring the dome which is painted canvas over plasterwork. Four conservators, under the guidance of Italian conservator Carolina Izzo, are working on he project.

The dome has been wrapped in plastic since the earthquake, and the façade had been propped up and protected behind shipping containers. The dome restoration is a $1 million project alone, and is due to be craned into place in late February. 

The theatre is due to be completed late this year. A team of four to eight, headed by Warren & Mahoney’s Vanessa Carswell, is leading the restoration.

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Christchurch Three Years On: Warren & Mahoney embraces modernism while preserving heritage