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On Saving Our Anglican Cathedral:

Much thought about, but finally written in February 2012

On Why and How

The three questions being asked about our Anglican cathedral are should it be saved, can it be saved, and can it be made safe enough? The answer to all three is a simple yes. The cathedral at the centre of our city is a much loved building in a city where perhaps most of our most loved buildings have already been destroyed. It is arguably the most memorable of the few memorable building left in the centre of our city. It is a potent symbol of our city, one of the first images that comes to mind with the mention of Christchurch. We need only look at its location in the street grid, the prestige of its address, and its use of its image. The cathedral stands at the heart of our city, and leaving it broken is entirely the wrong symbol. We need to show to ourselves and the world that this is still Christchurch, we are still here and mean to stay. We do not want to stand forever with a broken heart, and we do not need a new heart. We will mend the one we have. If rebuilding the cathedral takes a long time, thirty or forty years is what it took the first time around, then it is no matter. A long-term cathedral building project is the act of a city that believes in its future. There is enough money, so lets build Shigeru Ban’s temporary cardboard cathedral nearby for worship and sanctuary, as he intended it, and by the time that gets too hard to maintain we should have our real cathedral back.

There is now plenty of room in this city, (including church owned land) on which new cutting edge architecture can be built. We will soon have a city of mostly new architecture, and those of us who loved this city desperately need some continuity with the city we knew before the earthquakes. With few exceptions the people of Christchurch loved this building, and most of us have lost too many places that we loved. Others have lost people too, and to add to their pain would be cruel. While the Anglican church has a responsibility to its faithful, it also has a responsibility to the city as a whole. With rights come responsibilities, and the property rights to the centre of Cathedral Square come with great responsibilities indeed.

We should bear in mind that when Dresden's Frauenkirche was destroyed in the 1945 bombardment and firestorm that razed most of their central city, the ruins of the church were not removed. The hurt of the lost city centre never went away, and after almost half a century the campaign to rebuild the great baroque church bore fruit. In 2005 the rebuilding work was complete. This act means that those of us born in the years after its destruction are able to visit Dresden and experience George Bähr's master work.

Our cathedral was designed by Gilbert Scott, one of the great architects of the mid-nineteenth century, while the project was directed and refined by Benjamin Mountfort, arguably one of our greatest architects. So much of Mountfort's work has been destroyed, and surely it would be a crime to deprive future generations of the ability to experience his work. This gothic building, in a city that was famed for its gothic buildings, also symbolised the hopes and aspirations of our forefathers for this city. While our own views may be a little different, we must still acknowledge that these were noble and worthwhile aspirations, a history to cherish.

The building is badly damaged, but there is still plenty left to repair. The walls are still there, teetering but still upright, and much of the stained glass is intact too. While the damage is considerable there is still much sculpted stonework within and without that cannot conscionably be thrown away. The roof of the nave, a glorious and irreplaceable structure of kauri and rimu, is hardly damaged. This last fact is important, for to discard that roof would be a terrible waste and a moral crime, and right now that timber could not ethically be replaced, effectively preventing a future reconstruction if the building were to be summarily demolished right away. By comparison Knox church is in an even more dire state, having lost its walls entirely, but the building still stands, and no doubt will recover, though admittedly perhaps not quite as it was. As long as the roof covers the nave, the cathedral is still standing.

So how do we repair a building where every stone has been shaken loose, and how do we make sure it is strong and safe? The simple answer is that we shore up the roof, and section by section dismantle and rebuild the walls. Again, as long as the roof remains, the building remains standing and remains our cathedral. The mediaeval stone wall generally consists of two faces of good dressed stonework with packed lime mortared rubble between. The Victorian equivalent is two faces of stonework with a core of lime mortared brickwork. Today we use a core of reinforced concrete and make sure the facing stone is well bonded to it.

Trying to strengthen an undamaged church or hall is extremely difficult, as new structure has to be fixed to the faces of the walls and columns. It must be placed where it will be effective, but at the same time it must not show. Inevitably there will be compromises. A better approach would be to replace all the heavy brick and rubble inside the thick stone walls with modern materials that strengthen the building rather than add seismic weight, but this would mean taking the building apart piece by piece and re-building it, which usually does enormous damage.

With the roof of the cathedral shored up (this is probably the single most difficult and expensive operation in the process), the walls can be carefully dismantled from top to bottom, the damaged stonework given over to the banker masons to repair or renew as necessary, conservators and artists brought in to restore or replace sculpture as necessary. There would be no significant damage done, as the earthquakes have already weakened the mortar and loosened the stones. New foundations would be dug under that length of wall, piles bored if needed, the reinforcing cages put in place and the walls carefully rebuilt, using the original facing stone wherever possible, in lifts around the steelwork, the concrete gradually being placed as the walls rise. Larger stones would perhaps be secured with reinforcing rods epoxied into holes carefully drilled in the back, and tied into the main reinforcing cage. Some blocks might even be hollowed out, filled with the reinforced concrete that now does most of the work. Eventually, and it will take time, the walls will be complete, as strong as we choose to design them, and they can be made very strong and safe, enough that the building could be relied on in future emergencies if needed. This done, the stained glass can go back, restored where possible, and with new windows commissioned where there is too little left. Perhaps a new rose window might be commissioned too. Its future will be assured, as it will be installed in what will structurally be a modern building with a layer of stone to protect the concrete against the weather. For the first few years there may be a little efflorescence on the exterior facing stonework, but this will diminish over time and is a small price to pay for the security of casting the concrete directly against the stone. Under gravity the walls will work as they did before as load-bearing masonry, and in earthquakes the reinforcing and concrete will ensure everything is held firmly together.

We happily dismantle a car to restore it, and often enough dismantle old buildings to reassemble them elsewhere. Old stone buildings have been dismantled stone-by stone and relocated before, and there really is no novelty or technical difficulty here.

The spire too would be rebuilt much as it was, certainly to its original geometry for this is a vital part of the composition that was and again must be our cathedral. The concrete might be left exposed internally, just as the brick was in the original. The old spire was capped in copper clad timber framing where the first spire had been damaged by earthquakes early in its life. Perhaps to mark the damage done on that February day we might rebuild the spire from the bellchamber upwards framed in timber or steel and clad in copper. The copper to the top part of the spire might be a slightly different alloy that weathers to a slightly different green, to remind us that these earthquakes do happen from time to time.

The tower in the rebuilt cathedral would be an important bracing element, its lower portion being a strong closed box with few and small openings. If further stiffening structure is needed the addition of a second tower would be of great benefit, especially if located in the Southeast corner of the building. Such a tower would be able to serve as both strengthening and earthquake memorial.

None of this will be cheap, and it will take time, but a project like this will have no trouble attracting funding, and time we have in abundance. The work is technically simple. We need this to happen, so lets make a start now, before the building or our spirits deteriorate further.We need a built environment that is not only safe and functional, but makes our city a pleasant and desirable place to be in, for the sake of our day-to-day happiness, our overall well-being, and our economic survival.

A Possible Sequence of Events for Rebuilding the Cathedral

Note that I have started with the West front as it has the potential to give good safe access to the body of the building, and its reconstruction early in the project sends the most powerful message. This is not essential, and with more detailed information there may be good reasons to start elsewhere.

1. To be carried out simultaneously:

-Design the shoring system to support the cathedral roof.
-Design the movable braces to support the adjacent walls as the section to be rebuilt is dismantled.
-Design the movable staging for dismantling and rebuilding the cathedral walls (this may be something like a large partially roofed scissor-lift platform).
-Design the strengthened internal structure to the rebuilt cathedral, to bring it to the structural capacity required of our most important buildings.
-Set up yard and workshop space for work that cannot be carried out on site.
-Carry out the detailed design for Shigeru Ban’s cardboard cathedral.

2. Again simultaneously:

-Build the movable staging for dismantling and rebuilding the cathedral walls.
-Build the movable braces to support the adjacent walls as the section to be rebuilt is dismantled.
-Prefabricate the shoring system to support the cathedral roof.
-Build the cardboard cathedral on a church or council owned site nearby, ideally a site that needs more love.

3. Fit the shoring adjacent to the West front and tower.

4. Document and dismantle the West front, porch and tower.

5. Simultaneously:

-With the West wall removed the roof shoring can be installed at this end. As the shoring is installed the nave can be made safe and more shoring installed further in until the entire roof is supported and the interior temporarily braced.
-The facing stones to the West front, porch and tower can then be repaired and re-made as necessary. New sculpture can be carved as required.

6. Simultaneously:

-Excavate new foundations for the West front, porch and tower and prepare the reinforcing steel. Bored or screw piles may be needed. Driven piles would cause too much vibration.
-Salvage other fragile fittings from inside the cathedral and as much stained glass as can safely be removed.

7. Simultaneously:

Begin rebuilding the West front: Pour new foundations, position reinforcing steel and build say a metre of the stone facing on each side. Fill with concrete. A few days later lay the next metre of facing stonework. Continue until the wall is complete.
-Brace and then begin dismantling the next most damaged or fragile section of the building.
-Begin repairing and replacing damaged and destroyed fittings and stained glass offsite. Where original art has been destroyed, new works should be commissioned.

-It may be desirable to add more permanent bracing to further stiffen the structure. This could take the form of a new tower towards the Southeast corner of the building, which might double as an earthquake memorial, while being far enough from the West front to not interfere with its composition. This work may commence at this stage.

8. Continue dismantling and rebuilding the walls until the building is entirely rebuilt.

9. Reinstall the fittings and stained glass, repair the floors.

10. Re-consecrate the cathedral and open the doors.

James Carr - February 2012