How we did it ... Cathedral repairs keep conservation in balance

Ben Willis, Planning, 10 October 2008

Background: Much of the pipework used to transfer rainwater from the cathedral roof to ground level had fallen into disrepair, posing a threat to the delicate stonework of the building's south elevation.

Who is behind it? Freeland Rees Roberts Architects, contractor WS Lusher & Son, surveyor Downland Partnership, English Heritage, Friends of Norwich Cathedral.

Project aims: To repair water pipes and replace or conserve any damaged stonework or other historic fabric.

Skills involved: Surveying, architecture, conservation.

Repairing rainwater pipes may not sound like the most pressing of tasks, but when you are dealing with an 11th century Romanesque cathedral, it is of key importance. In the case of Norwich Cathedral, much of the pipework along the building's south elevation had sprung leaks that were threatening the delicate stonework on its facade.

Cathedral architect Henry Freeland was brought in to assess the damage and oversee repairs as part of a regular programme of maintenance. The initial stage of the process was a survey by the Downland Partnership, which used specialist photographic techniques to build up a detailed picture of the cathedral facade and establish those areas that had sustained the worst damage.

Freeland says most of the immediate damage was found around the pipes, although further general problems were identified when scaffolding was put up to carry out the repairs. These included cracks on the parapet, decay of facade stonework and damaged leading on several stained glass windows.

Because the overall aim of the project was to ensure that further repairs would not be required for some time, these problems all had to be dealt with at once, Freeland recounts. "It was all about cutting down maintenance requirements so no-one would have to go back for the next 30 years or so," he explains.

In the end, the job involved replacing or repairing every pipe in eight of the 14 window bays along the south aisle. A small amount of stonework also had to be replaced across the facade, while Freeland estimates that around another five per cent required lime conservation work. This involved the application of a protective render. Six windows also had to have their leading replaced.

But before any of the works could be carried out, they had to be formally approved. Although the cathedral carries a grade I listing, like other religious buildings in England it is also has an ecclesiastical exemption from listed building consent. This means that instead of going to English Heritage for approval, any repairs needed are handled through the Cathedrals Fabric Commission for England via each individual building's fabric advisory committee, which makes decisions on its behalf.

In this case, it was mainly repairs to the stonework that required consent, Freeland says. "Anything that changes the original fabric of the building needs approval. It is carefully controlled," he notes. And because the repairs were partially funded by English Heritage, one of the agency's architects was involved in overseeing the whole operation.

Freeland says the proposals were approved without difficulty. Perhaps surprisingly, the replacement pipework was made of lead, chosen because it would not need repainting. "We were obviously nervous about this, but the pipes come down on to other roofs rather than the ground, so it is a reasonably safe thing to do," Freeman explains.

Repairs to the facade were altogether more complex. Where possible, the original stonework was retained using limestone conservation techniques. Sometimes, however, the extent of damage meant that there was no other choice but to replace the fabric, Freeland says.

"It is a fine balance. What you are trying to do is to conserve the historic fabric, but sometimes you have to take the decision to replace. That is the hardest thing to do."