Continuity and Parity: Purcell's approach to the conservation of modern buildings

David Hills: Our message has always been that it doesn’t differ and shouldn’t. Although different periods can involve different materials and techniques the applied process and sensitivity shouldn’t change when working with modern buildings in comparison to older ones.

At Purcell, we have tried and tested conservation principles. With Modern buildings, issues usually start when people have deviated from the basic tenets. There is a misconception that because it's a modern building the fabric isn’t as important, and can be changed or replaced more readily, which is something you wouldn’t necessarily contemplate when conserving or adapting an older building.

Jon Wright: It’s important that we set this in the context of how we’ve cared for listed buildings of the 20th Century so far. At best, the conservation track record is mixed; many interventions, well-meaning or otherwise, have resulted in detrimental impacts on listed buildings.

There have been many unfortunate schemes that have not delivered anything approaching conservation and the primary motivations for those have been: “we can treat these buildings differently because they are Post-War or because they’re made of concrete, or ugly.” At Purcell, we give considerable intellectual and practical effort to balance that. With listed buildings, it doesn't matter which period it is from, you have to look at what is important about a building or a site, and respond accordingly.

David Hills: Because Modern buildings are more recent, there is the opportunity to research and learn more about them, including the intentions of the architect. However, quite often, one of the justifications for making wholesale change to Modern architecture is that the intentions of the architect are more important than the actual existing building fabric.

One example is Park Hill — the intention there was that the original brick was an infill within the concrete frame. The architects boasted that there were never any proper elevations done to the building and the infills were done on a random basis in terms of the colour of the brick. Part of the argument was that the fabric wasn’t actually that important. The intention of the architect is something that is used as a justification for getting away with all sorts, which is an argument that wouldn’t happen when discussing the conservation of older buildings from other eras. Fabric does matter, whether it is listed in the 1860s or 1970s.

Jon Wright: An important discussion to have is about the decoration of buildings — there's almost a sort of ‘fetishistic’ view about the qualities of earlier periods of building and how you restore decorative elements of architecture, which are the ‘easy wins’ for the heritage lobby to claim that they've done the ‘right’ thing. Almost every period of architecture, even the fairly stripped back Georgian townhouses, have a lot of decoration as opposed to anything post-1930. If you're dealing with the buildings of the 20th Century, the decorative elements are the structural components of the building itself.

If you look at Balfron Tower for example, the way in which Goldfinger laid out the windows, timber panels and concrete — as one big ensemble — the architectural importance of it rests on those ‘sculptural’ elements as much as it would on the decorative elements of an earlier period of building. If you mess with those structures, you mess with the fundamentals of its architecture, and aesthetic.

The components of modern buildings are where the architecture ‘lives’. Within a Victorian terraced house, that would be in the brickwork and the decorative guttering and the bay window. What makes a Park Hill flat important is the composition of the various structural elements and the manner in which the repeating patterns of the individual dwelling contribute to the composition and rhythm of the whole.

David Hills: The argument about the importance of the original fabric is obviously a vital factor in sustainability strategy too, because you're keeping as much of the original building as possible. But there’s been a worrying formula: strip off all the cladding, keep the concrete frame — and there's a lot more to it than that!

Jon Wright: There are lessons to be learnt from looking more intensely at the fabric of listed, Post-War structures in particular as these buildings may have important ramifications for how you treat or deal with non-listed structures as well. There's an important role for what's been learnt in conservation terms (e.g. looking after the high points of Post-War architecture) that needs to filter down through experts like Purcell. We need to share that kind of information, so that the lesser buildings of the period that still face those problems, can be adapted and reused successfully without knocking them down, and building something new.

David Hills: The construction industry really needs to think before the wrecking ball comes out. Ask questions like: is it significant in the first instance? Is it actually performing better than you think it is? How far have we delved into the question of whether this piece of fabric needs to be removed? Is it important in terms of the significance of the asset? And is it actually performing so poorly that you need to remove it? Or is there an opportunity to hang on to it, to adapt it more sensitively, like we would with earlier fabric? When it comes to Modern fabric there isn't that ‘value’ placed on it, and it’s important to change attitudes.

Jon Wright: In almost all the cases where we're proposing change to Modern architecture, I've encountered various planning responses: “we’re going to protect everything”, “or “we cannot see why it is important to protect this structure”. At Purcell we’re trying to open up the debate about change to Modern architecture that is proportionate, and it does bring into play the educational role of analysis and knowledge. But this is a natural process, and I’m sure not everybody in the 60s (for example) appreciated Victorian architecture, and it took some time for organisations like the Victorian Society to get up and running to educate people.

Modern buildings are potentially much more adaptable, because of the way that they were designed: future proofed, designed to change. For example, The Finsbury Health Centre, which is a grade-1 listed, Modernist building where its interior was meant to be moved around as teaching practice changed. Another example is the University of East Anglia’s Lasdun Teaching Wall, where the university anticipated a certain amount of expansion, and didn't finish certain areas of the building externally, to allow them to be extended in the future.

Purcell’s work at Liverpool Metropolitan Cathedral is an ideal case study in our approach. A technically daring building in many ways, the cathedral lantern — which is a large Dalle-de Verre structure that forms the central component of the roof, is an artwork in it’s own right. Almost since day one, it leaked, with water coming in through literally millions of tiny holes in the epoxy resin matrix that holds the glass pieces in place. Various attempts had been made to fix the problem by stopping the water: flashings, a silicone wash that covered the glass in a dark film and applied mastic. These things not only failed to address the problem, they impacted the significance of the building. Purcell’s approach accepted the flaw in the design and valued the artwork and its external appearance, and we are now trialling a discreet guttering system that channels the incoming water safely away, instead of trying to stop it getting in.

David Hills: As a whole, the built environment needs to consider the ideas behind the building, but also the fabric, while ensuring a building’s sustainability strategy doesn’t get used as a ‘tool’ to sweep away what’s important about a building, and its heritage. It involves digging down and really critiquing whether removing certain original elements of its design is actually needed to improve the building’s performance.

Jon Wright: We are facing an existential climate crisis and architecture has an important role to play in it. I think Post-War architecture, often by virtue of being very heavy on the embodied energy, needs to have a high profile in collective conservation strategy. Conservation proves that buildings can be retrofitted successfully and sustainably, and Purcell has an important role to play in that.