Invisible architecture: the hidden work of the conservation architect

The conservation architect Kirstie Robbins talks to Stuart Nathan about working with engineers to preserve and enhance

A mildly disgruntled engineer once told me at length during a car journey that no engineers were well regarded in the UK apart from one group. This group, he explained, had the good sense not to call themselves engineers. They tended to dress in polo neck jumpers, wear angular glasses, and call themselves architects. This group, he argued, were universally lauded and even elevated to the House of Lords with no controversy.

But architects are not engineers, although they work closely together. Kirstie Robbins, a director with the architecture practice Ptolemy Dean Architects, points out that architects, in fact, tend to come from a very different background from engineers. “It tends to attract people from the arts side, possibly because of the way that architecture degrees are set up with their emphasis on drawing.”

Architects also need more of an awareness of history and visual arts than engineers, because their creations have to sit alongside buildings from many different eras and will naturally be compared by how they look.

Robbins and the firm she works for specialise in conservation architecture. “That is sometimes confused with, or even called, restoration architecture, but that is something completely different,” she explained. “Conservation is about preserving what is there and working in harmony with it. Restoration is making something old look like it was new, and we categorically do not do that.”

The most high-profile project Robbins has worked on recently is the creation of a new museum gallery and access tower at Westminster Abbey, which The Engineer covered in-depth on our website. Ptolemy Dean is the surveyor of the fabric at Westminster Abbey, so the project carries his name as chief architect, but like all projects of this type, this was teamwork. Robbins was project architect, responsible for the day-to-day running of the project, working on site, handling all necessary permissions to work and liaising with the building team.

Robbins admits that her route into architecture must not be typical. “A lot of architects come into the profession because they want to make a tangible mark on the world and create landmark buildings. I never wanted to do that,” she told The Engineer over coffee outside Methodist Central Hall on Parliament Square, overlooking her most recent work site (although the tower itself was not visible, being behind the bulk of the Abbey from that viewpoint). “I got on to a partial architecture degree, not the full one, but I did some work experience in an architecture office and I fell in love with the practice of architecture, so reconsidered my training.” After gaining her degree from the University of Edinburgh, Robbins completed her training at the Bartlett School of Architecture at University College London, specialising in the history and theory of the discipline.

As a conservation architect, most of Robbins’ work is in historic buildings, often returning them to a safe state after periods of neglect, rather than in making new structures. She has worked on projects at Arbroath, Glastonbury and Cleeve Abbeys, the Bishop’s Palace at Wells and Christopher Wren’s St James’s Church on Piccadilly in central London, as well as an ongoing project at Westminster School. However, the Westminster Abbey project was a novelty, in that it involved making a new structure as well as working on an existing space.

A large part of the project was converting the neglected triforium space above the nave into a gallery, displaying the Abbey’s historic treasures. However, it also involved making the Weston Tower, a steel, glass and oak construction surrounding a lift shaft directly adjacent to both the oldest part of the Abbey and its most ornately decorated exterior section: the Chapter House, dating back to the 12th century, and the Lady Chapel, built by Henry VIII in the 16th century to house the remains of his parents and grandmother. On both parts of the project, Robbins worked with specialist engineering firms whose work is also often connected with historic buildings: structural engineers Price & Myers, and multidisciplinary engineering firm Max Fordham Partnership. “They were involved right from the start of the project, so it was very much a collaborative process. It was not a case of us coming up with a design and then presenting it to the engineers and saying ‘build that’.”

This may be the situation for other engineers working with architects. In her recent book, Built, civil engineer Roma Agrawal describes the structural engineering aspects of building the Shard at London Bridge, where she received drawings from the architect Renzo Piano’s practice and her first task was drawing over their lines where she thought supporting steelwork would have to go. Steelwork is, in fact, one of the things that Robbins discusses most with engineers. “We are always saying ‘we want to have less steel there,’ and they’re always saying ‘sorry, but you need more steel or it’s going to fall down’. That can be a constant back-and-forth.”

Robbins categorically does not consider herself to be an engineer, but is fully aware of how vital the discipline is to her profession. “Over time, you do pick up at least the language of engineering and you know roughly what questions to ask and what things they are going to be concerned about, but I wouldn’t be able to do the calculations that they do to work out the point stresses and other suchlike data in the structure. Similarly, we are all using digital tools to design now but as an architect I can’t pretend I use them in the same way an engineer does.”

Working on the Weston Tower gave Robbins’ work a visibility it doesn’t often have. “Very often, the goal of conservation architecture is to be invisible. You want the space to look like it is the age that it is; you absolutely do not want it to look new. For example, in the triforium one of our jobs was to remove staining from the walls that had appeared in what was being used as a storage space; but we didn’t remove all of it because that period is part of its history and we don’t eradicate that. Similarly, all of the timber work in the space that was put there in the 17th century by Christopher Wren to support the roof when he was surveyor of the fabric had to be preserved, and if we had to shore it up that would need to be invisible. In the event, it was in very good condition, and one of the most striking aspects of the engineering that Max Fordham did in that space was on the junctions between those timbers and the new oak floor.”

The Weston Tower engineering came out of conversations between Ptolemy Dean and Price & Myers. “There was a lot of liaison with the archaeologists on site because we just didn’t know what was underneath the area where the tower would be sited,” Robbins said. “And we had long discussions about the geometry and how that could be made to work without compromising the structure of the tower.” Once again, junctions between old and new were the subject of much discussion. The tower only touches the Abbey’s fabric at two points: its entrance lobby next to Poets’ Corner and at the top, where a corridor takes visitors from the staircase or lift into the Queen’s Diamond Jubilee galleries. “It was important that it was very clear where visitors were stepping from new into old,” Robbins said.