Norwich Guildhall
Work to restore and strengthen the Guildhall clock tower started on schedule on 1 July 2010.
Summer 2011
Over the winter a significant amount of work was carried out at the stonemason’s yard, repairing some of the stone and forming new pieces where the old stone was beyond repair. This included some intricate carving to ensure the new pieces match in with the existing. The stonemason then built the clock tower at his yard in order to ensure that all the pieces fitted together perfectly prior to lifting onto the roof of the Guildhall.
Some of the pieces of stone are very large and therefore very heavy. All deliveries and lifting are restricted to early morning to avoid disruption. In addition to this the scaffolding is netted, so it looks as if there is not a lot going on but work is now ongoing to rebuild the clock tower. The clock face and mechanism are due to be installed in the middle of September after which the scaffolding will start to be removed.
Whilst the lower scaffolding is still in place we will take the opportunity to repair some of the flint and stonework on the east elevation. The remainder of the scaffolding will then be removed by mid-autumn.
February 2011
Highlights:
Stonework will be delivered to site and the rebuilding of the clock tower begins again.
The repairs are not estimated to be fully completed until late spring or early summer.
January 2011
The cold weather on site continued to have a major impact on the work. The lime mortars used in the restoration process were temperature sensitive and prevented the return of some of the recently refurbished stone. Fortunately, through this coldest period, the majority of the work on this project was being carried out within the confines of the stone mason’s yard and factory.
As the last sections of stone removed in November are the first that need to be returned to site, work on site was limited until these large sections of stone are fully repaired.The fact that they were also some of the most heavily damaged pieces of stone, as they were closest to the corroding iron work, is of little help. By the end of this month the majority of stone work was repaired. However as the temperatures were constantly varying , the contractor decided to wait until all the stone sections in the lower section were fully repaired before bringing them to site as it was feared a cold snap could impact on the repairs carried out.
December 2010
The structural engineer’s proposals are now agreed and some new sections of iron work are brought into the site. The original iron work is cleaned and treated to improve its corrosion resistance.
The snow and very cold weather makes working at height a very cold and miserable affair, especially as it is not possible to wear bulky protective clothing as the work is carried out in a very confined space.
November 2010
Having removed all the stone work, the existing iron work can now be inspected. Some additional new sections will need to be introduced to improve the foundation points. Examinations are also undertaken to ensure the iron work is securely fastened to the existing fabric and roof. A structural engineer is brought in to assess the iron work and submit proposals to give the necessary support.
All the façade stonework is now at the stone mason’s yard to be renovated. It has been possible to retain all the exiting front façade stonework, although much of it has to undergo extensive renovation and repair.
October 2010
It is now possible to see the iron work the Guildhall clock was founded on as all the rear stonework to the clock housing has been removed. The front façade is at the half way point and we are still finding damaged stone sections.
It was agreed to remove the clock tower to the foundation stones in consultation with conservation officers and English Heritage.
September 2010
As the damaged sections were removed, more damage was also found on the front façade of the clock. Agreement was reached that the front section of the clock had to be partially removed as well. This is a major blow to the project as the front façade is heavily detailed; even greater care is needed to separate the stone to ensure no additional damage is done. This work is very labour intensive and highly skilled, and requires the masons to be at the top of their game as they lift very heavy damaged sections of intricate stonework.
Universal Stone had expected to be starting on the rebuilding work at this stage and concerns are raised on how the work will progress over the winter as much of the restoration work requires the use of materials that are temperature sensitive. It is not possible to predict when the works will be completed, as further damage is discovered with each lift.
August 2010
Agreement was obtained to remove the clock tower down to the clock housing roof.
Once the roof of the clock assembly had been removed, it was possible to see the extent of damage caused by the rusting iron clamps, used in the past to pin the various sections of masonry together. Usually the pins are located deep in the stonework, which prevents moisture getting to them. However in clock towers the stone is generally a lot thinner as access is needed for steps or mechanical equipment. Therefore the stone work is usually slotted and stepped to provide robust connections. Unfortunately this was not the case at this location and the high use of these pinned connections, on thin sections of stone, has resulted in moisture reaching the pins and causing them to rust.
The expansive properties of rust are well documented and it is quite normal to find rusty objects expanding to four times their original size.
From within the clock chamber previous repairs are also visible together with the rusting iron work.
Due to the extent of damage we had to assess how much of the original stone can be retained or whether we can source some replacements. Moving large pieces of damaged stone is very dangerous, as it is difficult to predict whether the stone will crumble as it is removed. Great care has to be taken to manoeuvre the stone work through the supporting scaffold. Having half a tonne of stone collapse while it is being lowered is also a major concern for the site staff. Every stone is carefully assessed and wrapped prior to lowering.
The large panel size of the damaged stone makes finding new stone unlikely, as stone quarried today is cut in much smaller sizes. However, Universal Stone managed to source some compatible stone which meant more options could be considered and works could progress.
July 2010
On 1 July 2010 contractor Universal Stone set up the site for the refurbishment works. One of the first jobs was to extend the scaffold, set up the hoists and clad the support scaffold. Due to the constricted nature of the site being near the main city centre taxi rank and a supermarket it was a major logistical exercise to get everything on and off the site without impacting on the day to day work done.
While works were carried out on raising the scaffold, the clock tower stonework was cleaned to remove several years of pigeon guano that had caked on the surface.
Due to the historical significance of the Guildhall, Universal Stone was only permitted to remove those sections of stonework that showed visual damage.
However as soon as the clock assembly was removed to be sent away to be repaired, more extensive damage was found at a much lower level than we had permission to resolve.
Discussions began with the council’s conservation officers and English Heritage and Universal Stone progressed with the partial dismantling of the top section.
Each section was carefully removed, marked and wrapped.
The stonework was taken off site to the stonemasons yard, were it could be repaired in factory conditions
Gary Thompson
January 2011