Isaac Theatre Royal: Despair to repair

Wednesday, 5 November 2014

**History will judge the rebuilding of the Isaac Theatre Royal as one of Christchurch's great engineering achievements. Here is an edited extract of how it played out - sourced from the theatre's new updated history book.

**

After the February 22, 2011 earthquake, the Isaac Theatre Royal was left shattered and broken. For three months it sat closed while Christchurch tried to come to terms with what had happened.

Theatre chief executive Neil Cox and his staff  were unable see the full extent of the damage inside the building.

Brickwork in many areas had been compromised. There was a gap between the proscenium arch and the auditorium, and the dress circle had slumped. The theatre was filled with cracked plasterwork, broken joinery and glass.

In August 2011, an engineering report showed the main structural damage appeared to be confined to the auditorium, the adjoining poster room and office spaces. The offices had not been previously strengthened. Sand boils - earthquake-induced liquefaction - had revealed itself beneath the auditorium and on the side nearest New Regent Street.

The ITR board had two options: demolish and eventually rebuild a completely new Theatre Royal, or carefully repair the century-old masonry walls and marry the old with updated and more stringent building technologies.

Two significant aftershocks on June 13 and December 23, 2011 exacerbated the existing structural problems. Floor slabs in the foyer moved on construction joints and the floor of the main auditorium appeared convex in shape and sloped towards the eastern and western sides of the building.

Foundation beams running from the rear of the auditorium towards the stage were lifting at the edges, while the auditorium's walls had noticeably sunk and settled a few centimetres lower than before.

Inspections also revealed the east and west side walls had sunk further - the western wall was about 10 to 20 millimetres lower than the east.

Warren and Mahoney were the consulting architects engaged by the ITR to design and draw the plans for earthquake repairs.

Associate architect Vanessa Carswell says the first major task was locating original plans for the building, some of which had been lost among waterlogged files and boxes in the damaged theatre's storage cupboards.

A stocktaking exercise was used to define whether the theatre should be rebuilt in an efficient, modern form or restored, strengthened and improved. ''It was a question of gauging what was important both for the theatre and for the people of Christchurch,'' she says. ''In the wider context, there was the element of history and continuity which obviously touched people's emotions at a time when they had lost so much.

''We wanted to retain everything that people loved about the theatre. It would be cheaper and easier to build a new theatre on the site, but it would be good for the rebuilding of Christchurch that we have a physical representation of what was here before the earthquakes.

''We did not simply want a clean slate,'' she says.

The Isaac Theatre Royal was too grand to lose forever.

The board announced  in late January 2012 that the existing theatre would be saved, and deconstructed before being rebuilt and restored.

By February 2012, a project outline was completed. It indicated that when completed, the repairs would provide a level of earthquake resistance significantly in excess of the building code requirements.

It was a unique goal for any New Zealand heritage-listed building, but one which would ensure the long-term safety of the building and its audiences.

The auditorium's brick walls would be replaced by strengthened steel and concrete walls and a lightweight reinforced steel-beam roof.

The new materials would be beneath reinstated plaster work and other original details which preserved the essential character of the original auditorium.

The early 20th century would be gently fused with 21st-century technology.

In a major enhancement, a hydraulic pit-lift would provide an extendable stage, while a new foyer space would be built in the upper-level gallery by adjusting the pitch of the roof.

The gallery had always been known as ''the Gods'' or the ''cheap seats'' for good reason: it had no foyer and was accessible only by climbing a 96-step staircase.

An upgrade to this level had been considered for years, but had never been affordable. With a chance to rebuild, the old gallery would fully deserve its eventual new name - the Grand Circle.

A multi-purpose performance and function space would also be constructed adjoining the dress circle foyer together with new ticketing sales facilities and relocated office space for theatre management.

The first stage of the overall project began  in May 2012 and focused on structural repairs and strengthening to protect the building's fabric.  At that stage, Cox was hopeful work would be completed by the first half of 2013, but as the extent and complexity of the project became apparent, the date was pushed back to the second half of 2014.

While discussions continued on the challenging task of saving it, work was moving ahead to preserve and catalogue the architectural and decorative features still housed throughout the building.

Everything that could be saved was carefully collected, packed into shipping containers and safely stored.

A growing army of builders, engineers, heritage experts and electricians slowly filled the building. The theatre's dressing rooms were transformed into the contractor's offices.

A towering mesh of scaffolding started to twine its way through the building.

Among the team was Gary Watson, the founder of the Christchurch company Plaster Services. He had worked on the theatre's 2005 refurbishment and was  called in after February 2011 to provide an expert overview of the  damage to the theatre's expanse of early 20th-century decorative plasterwork. In Watson's opinion, recovering most of the plaster decoration was impractical. Reinforced by horsehair and vegetable fibres, the ornate decoration was in a bad state.

Building contractors Naylor Love subsequently invited Watson to join the rebuilding team.  The next step was to take moulds of each section of the existing plasterwork to work out how the new sections could be grafted on to the older details.

The team also faced the reality of complying with new building codes designed to meet upgraded seismic strengthening.

Vero Insurance partnered with the ITR in facilitating the repairs. These were in the hands of a dedicated group, including project managers RCP, Holmes Consulting Group, building contractors Naylor Love, geotechnical engineers Tonkin and Taylor, hydraulic and mechanical engineers Powell Fenwick, architects Warren And Mahoney, electrical engineer Neil Pritchard, Andre Goldsmith the ITR's technical contractor and designated heritage architect  Tony Ussher.

Richard McGowan of Warren And Mahoney Architects remembers how decisions with Vero were reached incrementally.

''During those first months, we were doing an enormous amount of work: diagnosing and establishing how we would repair what was a large brick structure and going down the track of how an increasingly badly damaged building could be stabilised and re-enforced. 'Throughout that process, the insurers were listening and involved in the continuing conversation to ensure that it was possible in their eyes.

''At any stage they could have pulled the plug because it was not cost-effective, but they stayed the course.'' By December 2012, the theatre's familiar shape was changing radically.

Behind the 1908 facade, now protected behind a temporary wall of 22 shipping containers stacked four high, the foyer and the auditorium were  deconstructed completely.

The grand marble staircase was hidden under wooden boxing while other major architectural features were either protected or placed in storage pending  reinstallation.

The dramatic and surreal sight of a large building seemingly slit in half became the focus for many tourist photos - and occasional rumours that the theatre was being clandestinely demolished.

For the architects, the theatre's external and internal appearances had to remain the same, while the building's bones were to be made bigger and stronger, ''adding muscle and new heart'', as Carswell says.

Throughout 2013 the work continued. By November, reconstruction and strengthening work on the western and eastern auditorium walls had been completed, while work on the remaining two walls was nearing completion.

The building team was now on schedule to begin one of the project's major challenges - lifting the two main sections of the new auditorium roof into place.  The installation involving the roof trusses and secondary steel supports was a complex and testing procedure. But it  was crucial to the overall programme.

The entire operation, conducted with surgical precision, had been preceded by days of detailed planning to ensure that the sections fitted exactly in what was essentially a giant jigsaw puzzle.

By March this year, the theatre was completely roofed. The watertable levels under the theatre and surrounding areas had always been a flooding threat, but the earthquakes had reconfigured the land and the stormwater system below the city was struggling to cope with occasional heavy deluges. A future-proofing decision in July 2014 was made by  drilling a permanent borehole in the theatre's loading alleyway. It  provides a dewatering system to keep rising water-table at manageable levels.

The well has an automatic trigger 15 metres underground that starts the dewatering process when the underground water levels rise past the switch.

Extra safeguards are two  pumps below the new hydraulic stage extension  that will ensure the auditorium remains dry when it is very wet outside.

THE REBUILD IN NUMBERS

1908 The year the theatre was first opened and the year the lead-glass poppy window which has been included in the new rebuild.

1290 seats. If the new extension is not being used to help project music from the orchestra pit then the theatre can add another row of seats, lifting the capacity from 1255 to 1290. Pre-rebuild it could seat 1266.

40 million dollars for rebuild. $22.096 million in insurance and the rest has been raised or loaned or granted.

100 per cent. Every area of the theatre is built to 100% of the new building code or more. It's the place to be in an earthquake. That's where the theatre's structural engineers said they would want to be.

120  workers would have been on site on the busiest days over the last three months. That would be when the plaster work was in full flight.

153 doors. There are 153 doors in the whole theatre, counting double doors as 2 and excluding cupboard doors.

8 individual and separate artwork panels comprise the famous ceiling dome

22 ladies loos can be found in the theatre (including unisex and accessible options). This is 4 more than the pre-quake theatre.

1 lift that goes up 3 floors. this is the first time the theatre has had a lift. once we deconstructed the auditorium, we realise we had to deconstruct the foyers and so it became a new build, so facade to procenium arch was a rebuild. for the first time we can have wheelchair seating in the dress circle.

4  fulltime staff run the theatre. It's 1 more than before. But up to 40 casual staff can be called in for  various events.

280,000   the dollars it cost for the new film projection system. The money was raised the NZ Film Festival Trust. The trust owns the gear and screen, it lives at the theatre and the theatre is used to host the annual film festival.

9 per cent. The part  of the overall cost of the rebuild that was spent on reproducing and replicating  the theatre's plaster.

Source: The book Theatre Royal Christchurch. Revised version with new chapter by Christopher Moore.