Katerina Dionysopoulou and Billy Mavropoulos discuss the importance of material research and establishing close working relationships with specialist suppliers and subcontractors
Katerina Dionysopoulou and Billy Mavropoulos pictured in Bureau de Change’s meeting space, with bespoke furniture designed by the architects.
Established in 2012, Bureau de Change is a London-based practice that operates across a range of different typologies and scales, from product and furniture design to major refurbishment and new-build projects. The architect’s work frequently combines pragmatism and formality with playfulness, innovation and beauty. Traditional materials, such as brick, timber and metal, are routinely reimagined and reworked to produce visually striking designs that nevertheless embed themselves in their context and place. Notable examples include the twisting, cog-like masonry façade of The Interlock in London’s Fitzrovia; the charred and vertically-laid larch cladding employed on the Long House in the Cotswolds, and the patterned, laser-cut bronze panels that articulate the lift and stair cores of the refurbished 1920s Gaslight building, also in Fitzrovia.
The ten-strong studio places a great deal of importance on rigorous thinking and analysis, with designs brought to life through a combination of making, prototyping and testing. Much of this process occurs in the architect’s Hoxton Square office. The materials library is located in the main studio space, but key samples and prototypes adorn the walls of both the studio and meeting space – evidence in many cases of the benefits of working hand in glove with specialist suppliers and subcontractors. This collaborative approach has been central to the architect’s success and continues to be a driving force, as practice founders Katerina Dionysopoulou and Billy Mavropoulos explain.
Staffordshire Blue brick specials by Forterra. “Made for The Interlock project in London, these brick specials are part of a larger ‘family’ of bespoke handcrafted bricks derived from 14 different moulds. We chose Staffordshire blue clay to contrast with the London stock brick of the surrounding buildings. The undulating form of the façade meant that the position of the brick expansion holes had to be carefully considered and mathematically calculated to ensure they remained hidden from view at all times.”
How do you organise the materials library and who is in charge of running it?
Katerina Dionysopoulou The main archive is in the studio space and comprises a series of drawers organised by material type. There are also project-specific drawers, which contain all the samples relating to ‘live’ schemes. There is nobody specifically in charge, but we have an Excel spreadsheet that lists all the materials that we have, who supplied them, where we’ve used them, etc, and everyone is expected to feed into this.
What happens when projects complete? Are the materials returned to the main archive?
Katerina Dionysopoulou The project-specific draws are a recent development for us, and we want to find a way of preserving them even when projects are completed – perhaps by mounting them on the wall. In this way the material palettes will serve as ‘memories’, which will help inform and develop succeeding projects.
Billy Mavropoulos It is also potentially easier to locate specific materials by thinking back to individual projects, rather than sorting through the main library. Added to this, it’s more sustainable if we don’t have to re-order samples; we know exactly what the sample is and where to find it.
Materials are clearly a focus from the outset, so how does this manifest itself within the design process?
Billy Mavropoulos One of the first things that we do – alongside 3D studies – is to think what the building will be made of both inside and out. For us, there has to be a narrative or story with the materials, as much as with the architecture itself.
Katerina Dionysopoulou This is driven by extensive research into the project’s context. What comes out of this process forms an understanding and driver for the material, or the form, or the diagram, or whatever it is we are trying to do, depending on the scale of the project. Material choice is always reliant on this type of investigation rather than preselection.
Site history is also important, and we often like to counterpoint the old with the new. This is what happened with the Gaslight refurbishment scheme, where we chose an art deco palette – in homage to the original building – but expressed it using contemporary materials and fabrication techniques. These included PVD (physical vapour deposition) coated stainless steel, which provides a much deeper and richer finish than powder coating. It gives the material a certain life and patina, as well as durability, which is important in a commercial setting. We enjoy this ‘marriage’ of history and modernity
Tiles from repurposed brick by Vico. “We are working on a refurbishment scheme in Euston, which will include recladding the façade. Instead of going to landfill, the existing brickwork will be removed, crushed and remade into these reconstituted masonry cladding panels. The test sample incorporates material from the whole demolition – not just the façade.
How much emphasis do you place on sustainability?
Billy Mavropoulos This is becoming increasingly important to us. We are currently working on a large-scale commercial project and our aim is to make all the interior finishes sustainable. To this end, we’ve undertaken in-depth research to find the requisite materials and make sure that they are commercially available. We came across some super-interesting products and this has inspired us to do the same for all of our projects. When people talk about sustainability, they usually think about concrete and steel – all the ‘big’ stuff. But actually it’s also about everything that goes inside the building; all your materials and finishes. There’s a wealth of products out there that do tick all the sustainable boxes; it’s just about finding them. Again, it’s about research.
Katerina Dionysopoulou We are talking hours and days of research. Some products are sold or marketed as sustainable, but when you investigate further you discover that this is not completely true. It’s a process of elimination where you keep only the products and materials that matter or really do make a difference.
You mentioned how you consider both the interior and exterior materials at the outset of a project. Do you also explore how these interact with each other?
Katerina Dionysopoulou Yes always. Whether it’s related directly to the materials or the building geometry, there is something really interesting about the progression from outside to inside and vice versa. So, in a lot of our projects we’ve run the exterior façade inside the building, and, in the case of Step House, turned it into a roof. It’s about being inside a structure that feels somehow as if its external.
Billy Mavropoulos It’s also about the journey; from the moment you see the building to holding the door handle, to being inside. We feel that everything needs to be coherent in terms of materials and finishes. It’s a shame when you go to places where the architect designed the outside, but either didn’t do or didn’t care about the inside. You can pretty much always tell when this has happened.
Cast flint on GRC panel from Armourcoat. “These unusual and highly textured GRC panels are being used for the interior of a commercial project in Henley-on-Thames. The deep, organic pattern has been achieved by using flint in the casting process – the aim being to subtly highlight this prevalent local material.”
Katerina Dionysopoulou But care doesn’t mean cost. You don’t have to ‘over’ design every room or choose expensive materials. It’s about thinking about the experience or journey coherently, and making decisions that will highlight the design and its influences to building users as they move through the space.
So what materials tend to interest the practice?
Katerina Dionysopoulou In a way, it’s quite enjoyable to find materials that are super humble and then give them a new life.
Billy Mavropoulos Yes. We generally like materials that we can play with – meaning that we can affect them, remould them, or change them. This is when those modern construction techniques come in; you take something that is standard and repurpose it. Beyond that, there are existing commercial materials that you can’t really effect, from which we don’t have favourites as such. It’s about whatever’s relevant or right for the project each time.
With The Interlock, for example, we came to the conclusion that it had to be a brick building. It was then a case of seeing how far we could push brick as a material, and [laughs] how could we make this the worst possible experience for the brick fabricator!
Joking aside, how did you and the brick fabricator find the experience of realising such a complex façade?
Katerina Dionysopoulou The brick fabricator, Forterra, was amazing and we could not have done the project without their input.
Billy Mavropoulos That’s very true. But actually on every project where we have pushed a material to the limit there has had to be close alignment between us, the client, and the specialist contractor or fabricator in order to reach the end goal. It’s like a quest, and if one of the three parties is not fully committed, then the project will not happen. I think that a big part of our job is to inspire the other two parties so that they want to become part of the journey. And that’s where we direct a lot of our energy.
Concrete cladding panels from Vico. “This material has been chosen for the façade of a new-build house in north London, which is currently on site. By varying the aggregates in the panels, the cladding will go from a rough, Barbican-style bush-hammered effect to a smooth, polished finish the nearer it is to the windows. The manufacturer has been very supportive and patient in terms of achieving the right mixes, and the end result is exactly what we wanted.”
Katerina Dionysopoulou In terms of working with specialist suppliers and fabricators, it is important to meet with them, visit the factory, and to listen and understand exactly what they do. For us, as an architect, to manipulate a material or product, first we have to understand where it comes from and at what stage of the manufacturing process we can intervene.
A good example is The Interlock, which initially appeared cost prohibitive in terms of the number of brick specials needed. However, we realised – by visiting the brick factory – that it was actually possible to cut the bricks when they were ‘wet’ at no extra cost. As a result, we were able to create 44 different types of brick from eleven dies.
Of course, this isn’t the case with all specialists. Some companies are simply not interested in projects of this type, or do not have the R&D capabilities available to them. When this happens you have to stop pushing them, because it’s not going to go anywhere, and you are just wasting your time and their time.
Billy Mavropoulos Generally, we’ve been very lucky, and we’ve come across some amazing people and companies who have brought our projects to life. We find that you can have an idea, but you need to find the right people to make that idea happen. What’s more, the design concept always gets better through the influence and input of specialists.
Charred larch block by Eco Design Wood. “We used lightweight larch cladding for the Long House in the Cotswolds. The charring was carefully graded to create a striking ombré effect that highlights the rhythm of the window openings across the façade. In total, there was 7,200 metres of cladding and we produced a detailed diagram for the contractor showing where each length of timber should go.”
What about client involvement and commitment to the cause?
Billy Mavropoulos Thanks to good clients, we’ve managed to build a reputation for materially rich, and at times, challenging projects. This has helped us to attract new clients who are committed to creating unique, boundary-pushing buildings.
Katerina Dionysopoulou You have to work hard, because the point isn’t to create something that is unaffordable; it’s to create something that is unique, but complies with the budget and other restrictions that we have. The project budgets are not unlimited, in fact it’s quite the opposite, but we don’t go over cost. This requires an extra level of research and work.
Returning to the materials, have you come across anything new and interesting lately?
Billy Mavropoulos We recently collaborated with Lulu Harrison, a Material Futures student from Central St Martins, on an exhibition for London Craft Week curated by Here Design. Lulu has invented Thames Glass, an innovative biomaterial made from the crushed shells of mussels, which clog up and have to be removed from London’s water pipes. The process not only utilises the shells, which usually go to landfill, but also requires less sand than conventional glass making. We worked with her to develop a range of patterned, cast glass façade tiles, which draw on London’s architectural history – specifically Royal Doulton, who manufactured the city’s water pipes in the mid-19th century, as well as ornamental terracotta chimney pots. As part of the exhibition, we produced designs for three ‘lost’ Thameside pubs and inns, each of which are clad and illuminated with the glass tiles.
Katerina Dionysopoulou Another interesting product that we’ve come across is a roof tile made from recycled plastic. It’s manufactured by Smile Plastics, and we proposed it for the multiple gabled roofs on our Brent Cross Pavilion competition entry. In addition to being environmentally friendly, the tiles also provide a beautiful ombré effect caused by compression of the recycled content. The sloping site would have showcased the dynamic form and rich colouration of the pavilion roof.
We’ve also found gorgeous ceramic tiles manufactured by Silicastone. They are made from 99.9 per cent recycled materials, and we would favour them over many traditional tiles for aesthetic reasons alone.
Handcrafted timber door samples by Edsons. “Complementing the moulded GRC panels on the Henley project are timber doors that employ a handcrafted, flint-like motif created by a bespoke joinery specialist. It was important that the pattern was not too subtle or overbearing, so we experimented with the size of the indentations. We’ve also specified a charred version for the front door to give the entrance sequence more gravitas.
Does the practice periodically return to certain materials?
Billy Mavropoulos We generally try to avoid repeating ourselves and avoid using the same material again and again. I think subconsciously that we’re always on the lookout for what’s new and interesting.
Katerina Dionysopoulou It’s more that we find ourselves returning to specific suppliers and fabricators that have been amazing to us; what comes from this often has the potential to be really interesting. In some ways it’s more about the people than the materials.
Billy Mavropoulos Yes, a lot of these companies seem to know what we like and what we’re after as a result of having worked with them for so long. As a result, they will show us new materials and products when we see them, or email us when something of interest comes up.
Is there a material you would like to use but haven’t been able to yet?
Katerina Dionysopoulou Recycled plastic, such as the roof tiles we touched on earlier, is one that springs to mind.
Billy Mavropoulos Structural glass is something we are exploring at the moment through a live project. Again, we want to test the limits of what’s possible with the material and it’s proving to be a quite a challenge.
Can you reveal anything more about the scheme?
Katerina Dionysopoulou It’s actually a very small project; we are designing travelling jewellery cases for a jewellery designer to use at exhibitions. The design concept is to make the case an object in itself, rather than simply a transportation vessel that hides the jewellery inside. Structural glass will be key to realising this.
How important are making, prototyping and testing in terms of material innovation and new construction techniques?
Billy Mavropoulos It’s incredibly important, as is informing our clients that prototypes will be made on their projects. This means that they are aware of the costs of this activity from the outset. I can think of critical elements within several projects that would not have happened had it not been for prototyping and close involvement with the client on this aspect of the design. The process not only reveals what works and what fails, but also what the cost will be. This means that we can value engineer the design if the costs prove to be too high. It also practically eliminates risk further down the line.
What role if any do clients play in the prototyping process?
Billy Mavropoulos It depends; the client on the Gaslight project was particularly passionate about the design and was involved in the whole process. Prototyping helps clients visually understand key aspects of the design, which may not be possible with drawings alone – however good these may be. Perhaps most important of all, it enables them to buy into the overall design process.
Finally, how do you reduce waste, and do you review the library regularly?
Katerina Dionysopoulou We are very selective when we order samples; we don’t order 99 different versions of something and then pick one. It’s better to spend more time thinking about what you actually want or need before ordering. Otherwise it’s over saturation, which can make design decisions even harder to make.
Billy Mavropoulos We try to keep anything that might be useable in the future and we try to throw away as little as possible. The library is reviewed every six months, and we like to check that key items are still being produced and are available to specify. Some suppliers that we know well will update us with this type of information unasked for.
