Stabilising Christ Church Cathedral
What?
Stabilisation is the first physical step to reinstating the Cathedral. It will address severe structural damage and prevent further damage until the Cathedral has been reinstated. It will also ensure the building is safe for workers and enable access to parts of the Cathedral. Watch Project Director Keith Paterson explain progress as at September 2020.
How?
It involves:
- Installing support frames to support and secure the Cathedral
- Deconstructing some badly-damaged sections to manage collapse hazards, and allow access to other areas. These parts will later be reinstated.
- Removing more recent additions to the Cathedral to give safer and faster access to stabilise the older parts
- Accessing the interior of the building for salvage and investigation works
- Retrieving heritage items, including the remaining stained glass windows and organ
- Temporary weather-proofing.
When?
In the latter part of 2020 people will see steel framing and scaffolding progressively being erected. We estimate stabilisation will take between 18 and 24 months.
Where? The areas of work
Nine areas of work are planned. The order is indicative only and may change or overlap, and each area of work has its own methodology.
North and South Transepts
Damaged masonry for both the transepts will be deconstructed. Temporary steel support frames will be installed, and temporary wall cladding will be needed.
September 2020 – The large concrete foundation needed for the steel support frame that will be used to stabilise the transept was poured.
October 2020 – The 32 tonne steel support frame is now in place (see the photo at the top of the page).
November 2020 – Extensive scaffolding is now in place (see image bottom right).
West end works (including porch, wall and gable)
The upper section of the west wall collapsed taking with it the iconic Rose Window, leaving a large hole. The porch has moved and broken away from what remains of the wall.
We will install a supporting frame similar to the one below in the upper part of the west wall and deconstruct the lower part, including the porch, to allow machine access into the Cathedral.
Stone masons will carefully remove the damaged and loose sections of stone. A prefabricated steel frame will be lifted into place. This frame provides the underlying structure within which the reinstated Rose Window will once again sit, and it gives the building strength.
This frame will be covered to give weather-proof and help protect the Cathedral.
September 2020 – Work to remove loose slate and secure some of the roofing timber was carried out. Areas of the roof have been reinforced on both sides to prevent further damage and to ensure loose roofing slate isn’t dislodged during works.
November 2020 – In the past few weeks we’ve been carefully deconstructing the remaining areas of the Rose Window (see photo above) in preparation for the installation of the steel frame in early December.
December 2020 – The steel frame has been installed including a weather-tight cover that has an image of what the reinstated Cathedral will look like.
Vestries
The north and south vestries, built in 1964, will be removed to enable safe access to stabilise the main Cathedral.
More information will become available when work begins in these areas.
North Porch (including north aisle roof works)
The north porch walls and adjacent roof were badly damaged when the tower collapsed. We will be installing a temporary steel support frame and adding a temporary roof.
August 2020 – A concrete foundation was poured ready for the temporary steel support frame. Around 5 truckloads of concrete were used, poured into a prefabricated steel reinforcing cage. Watch the drone footage of the concrete pour.
October 2020 – The 6 tonne temporary steel frame has been installed. Watch the video.
Apse
We will be installing a steel support frame for the Apse.
More information will become available as work begins.
Further areas
Methodology for the remaining areas — Visitors’ Centre, Tower, Interior works – nave and crossing, North and south aisle wall and roof areas — will be published as those stages are planned.
Heritage
Christ Church Cathedral is a listed as a Category 1 Historic Place under the Heritage New Zealand Pouhere Taonga Act 2014 and is also an archaeological site under that Act. Category 1 places are defined as places of special or outstanding historical or cultural heritage significance or value . The scope of the stabilisation work includes protecting heritage elements and materials for later reinstatement.
Design
Christ Church Cathedral Reinstatement Limited appointed Holmes Consulting as structural engineers to lead the stabilisation design, and Naylor Love as consultant contractor. Early contractor involvement is highly advantageous in achieving the best methodology and constructability. This is a strong focus on the health and safety of workers, along with an emphasis on heritage, cost, and time management.
