Where past and future meet

Combining old and new in a unique composition created from two dramatically reimagined Victorian roofs, Heatherwick Studio’s Coal Drops Yard retail scheme forms the heart of the King’s Cross regeneration. Roseanne Field reports

Formerly a gritty part of London, King’s Cross has undergone a total transformation over the last 20 years. One of the key final parts of the overall regeneration has recently completed – a striking high-end retail development nestled down next to Regent’s Canal. The project takes its name from the two Victorian ‘coal drops’ (essentially covered rail viaducts) which were built in 1851 in 1860, which had a colourful history but had fallen into disrepair in recent years. They were the city’s entry point for coal for heating (and lighting, in the form of coal gas) arriving by train from northern mines. These would enter the buildings at the upper level and drop coals into hoppers on the middle level, this was then shovelled into sacks and loaded onto horses and carts at a lower level. It was only 27 years however before electrification took place and the coal drops were suddenly no longer required. The buildings were then used for warehousing and industrial use for around a century, before London’s club/rave scene – which rapidly colonised disused warehouses across the city in the late 1980s and 90s – made its way into part of the eastern of the two coal drops, in the form of the infamous Bagley’s nightclub. The parts of the buildings not repurposed to serve the nightlife trade were abandoned, and fell into disrepair. In the 2000s the site was eventually earmarked to form part of the mammoth King’s Cross redevelopment, and Bagley’s, as well as two further clubs opened in the eastern building, were closed. The still-ongoing regeneration is being led by the King’s Cross Central Limited Partnership, formed of property developer Argent and investor AustralianSuper. The project includes a total of 36 architecture practices, each working on a different element. The 67 acres was previously “underused industrial wasteland.” Once completed, the site will hold 50 new buildings, 2,000 new homes, 20 new streets, 10 new public squares, 3.4 million ft2 of workspace, 500,000 ft2 of retail space and 26 acres of public space. Coal Drops Yard sits at the centre of this development, adjacent to another reinvention of Victorian structures, Wilkinson Eyre’s residential Gasholders scheme. This eye-catching new retail project has been designed by Heatherwick Studio; the practice also responsible (with BIG) for Google’s new HQ, under construction on the other side the canal within the King’s Cross scheme. The newly-conjoined former industrial buildings now housing high-end retail are a key part of the new district. The project is significant for both Heatherwick Studio and Argent, but especially so for the architects. The studio’s office is just down the road, which made it special to them. “It will become part of our neighbourhood,” says project leader Tamsin Green.

Creating a heart

The original brief provided by Argent was to somehow link the long, two-storey and arch-filled brick buildings. They sit at a slight angle to each other, the western one being shorter due to the canal bending northwards alongside it. Green explains the designers’ thought processes in addressing the brief: “The original scheme that we designed effectively had two bridges connecting the buildings.” However, the more the studio examined the two buildings, the more they realised that this project required a more transformative response. Thomas Heatherwick, founder of the studio, commented: “The challenge to us was to create a heart that would hold and glue everything together.” Adding a third level seemed a natural way to unite the two buildings. However, the studio were keen not to just “drop a box on top.” It was thanks to the fact the roofs needed rebuilding – their state of disrepair combined with a large section of the eastern coal drop’s roof having been burned out made this a given – that the designers’ ideas started to evolve and they examined the possibility of “stitching” the roofs together instead. When the proposals were first put forward to Camden’s planners, there was, says Green, “an element of surprise. We were very much deviating from what we had outline planning for.” However, this was contrasted by the project team’s excitement at the prospect of doing something more and “being bold,” Green explains. As well as the planners, meetings were also attended by Historic England, who officiated on heritage matters. Workshop upon workshop took place with ideas discussed and sketched out, the studio “very much making them a part of the process of coming up with the idea,” Green explains. Although these discussions were characterised by lots of questioning from the two groups, ultimately, according to Thomas Heatherwick, it “made the project better.” In particular, he said he found it “thrilling” how ambitious Historic England were. “Britain has so many historic buildings and we can’t just have single formulas for how we handle them,” he added. Heatherwick Studio group leader Lisa Finlay credits the planners’ cooperation to the dilapidated state of the buildings. “They were in really bad repair, so anybody who’s prepared to invest in them, obviously the planners want to work with them,” she says. The first designs had just one of the roofs “peeling” out to meet the other, which left a hole in the middle. But this idea was challenged, on the basis that while the aim was to connect them, the buildings also needed to retain their own identity. The next iteration, therefore, was to bring both roofs out and up so that the buildings met in the middle, simultaneously creating a third level. This also raised the height of the building, which sits in a low-lying part of the King’s Cross site and, as Finlay says, “announced it” to the public. “It was totally off people’s radar, because it’s sunken.”

Victorian industrial to 21st century retail

One of the biggest challenges presented by the coal drops was making them suitable for high-end retail, says Green: “They were never envisaged to be that, so there’s a lot that goes into how to get those kind of buildings to work.” For example, the architects were very conscious that the width across a typical shopping environment would usually be 10 to 13 metres – a distance based on how people will interact with the environment and at what distance they’re likely to be drawn into shops. The distance between the coal drops ranges from 26 metres at the northern end to 39 metres at the southern end. This was a contributing factor to the studio’s notion that the development needed a heart, and that making bridges between the two wasn’t going to cut it. The brief’s aim to create a ‘destination’, was key to their thinking. “We thought if you just refurbish these buildings and put bridges in, you’re not going to get what you want,” explains Finlay. Naturally with a part-heritage project such as this, the studio were conscious to do as little alternation as possible to these historic structures – especially given the eastern one is Grade II listed. For the most part, the original brickwork remains intact, complete with soot stains and old paintwork. “We’ve tried to keep the slight moodiness,” Finlay summarises. However, various uses and alterations over time meant floor levels were all over the place, and so adjusting those became the biggest change at lower levels. “We had to be able to get the inside level to meet with the outside,” Green explains. As well as the floor level, in some places the sills had to be dropped. Every bay was closely examined by the heritage consultants, not only to assess the structural integrity, but also to see where it would or wouldn’t be appropriate to alter it. “There was a lot of going back and forward,” Finlay says. At the end of each building is a large “anchor” unit, where much of the original structure could be left intact, the retail tenants installing stairs and lifts where necessary.

Meeting the challenge

With various teams and consultants working on the project, 3D BIM modelling formed a key part of the design process. The basis for these models was formed from a point cloud scan of the building, which was conducted early on. However, with a conscious desire “not to stay in the digital environment”, the studio also produced many physical models to “check scale and materiality”. Adding an additional level to the buildings presented myriad challenges. Green says that a key aim was the “illusion of the roof being peeled out, and that there wouldn’t be any columns underneath.” She adds however: “The structural gymnastics of achieving that were incredibly complicated.” The coal drops themselves couldn’t support the new level, so they had to find a way to “stitch it through the existing structure onto new foundations.” In total, 52 pairs of steel columns – which sit on either side of the walls separating each bay – have been “threaded” through the existing buildings. This in itself presented a headache for the studio, as Finlay explains. They couldn’t get a standard piling rig in the space so they used mini piles for each pair of columns. “You just couldn’t do things in a conventional way.” The new roof “ribbons” themselves are made up of 20 steel sections bolted onto trusses at either end and tied back to the columns. The structure is also shored up by concrete walls and cores, and the new floor is hung via a series of high tension cables tucked in the corners created by the concertina-style glass. Although this steel and glass contrasts with the historic buildings below, it was part of Argent’s brief that the additional level should be “as transparent as possible,” says Finlay. “There was this feeling that you could look through, up into it and out of it, and it all felt connected together,” adds Green. Specifying the glass wasn’t a simple task. There was a fixed budget that didn’t allow for curved glass, which is how the concertina shape evolved. The designers see this design as a contemporary way of echoing how the buildings below are broken up into sections by the arches. As well as the overall design, the thermal properties, and ensuring the views in and out worked for retail clients, also had to be considered. “There was a lot of testing on samples of glass to make sure it would work,” Finlay says. Originally, a third viaduct ran through the middle of the coal drops, and the design of the cobbles follow its footprint, by way of recognition of this vanished edifice. Despite the removal of this substantial structure, the site was still incredibly tight. “When the four sections of steel came, they were lying in the yard taking up all of the operational space,” explains Finlay. Many of the utilities for the surrounding area also run through the site: “Underneath the yard every inch is taken up,” she says. “We were coordinating facilities at the same time as coming up with our very early concept design,” adds Green. With this being one of the final projects to complete in this smartly regenerated area, a certain amount of inspiration was drawn from new buildings emerging in the development. “Our job was stitching all this together,” says Green. “We took some details from the wider scheme but also needed to make it a distinct place.” Timber infills have been used throughout to bring warmth – and can also be seen on the restored granary building next door, now the new home of Central Saint Martins. “Things like that were inspired by the tones and colours the original railway company used,” explains Finlay. The reuse of existing cobbles can also be seen elsewhere across King’s Cross. Some of the original roof trusses have also been retained where possible. In the sections that were burnt out, trusses were relocated from the middle of the building where the new structure sits. The new roof has been clad in over 80,000 slates – some individually hand-cut to fit the curve – and they come from the same Welsh quarry as the originals. This traditional craftsmanship paired with the use of 3D modelling embodies how the project brings together two worlds, says Finlay, “pulling out this modern space from within these existing buildings.”

The finished product

The retail units are now home to a mix of established higher-end brands as well as new entrants, some of whom have opened their first shop here. Samsung has taken the entire unusually-shaped space which occupies the new third level created under the ‘kissing’ roof. The dramatically glazed and timber finished interior is sure to prov a dramatic location for its promised “digital playground.” The central cobbled space is to host events, enabled by the copious amount of space between the buildings. The area has also allowed for seating which will not impede passers by. “It’s a place where people will gather and spend time,” Green explains. Despite some initial concerns over this larger-than-usual gap between buildings, in the end, says Finlay, it “works really well.” Having handed the majority of the King’s Cross redevelopment over to various tenants and agencies, Argent will be retaining and managing Coal Drops Yard themselves. As this massive overall transformation of an area approaches the end of its 20 year tenure, this particular project is a very important architectural centrepiece – “it’s a bit like its gem,” says Heatherwick’s Finlay.

  • Client: Argent
  • Developer: KCCLP / Argent
  • Lead architect: Heatherwick Studio
  • Heritage consultant: Giles Quarme & Associates
  • Structural/facade engineer: Arup
  • M+E/sustainability: Hoare Lea
  • Lighting designers: Speirs and Major
  • Cost consultant: Gardiner and Theobald
  • Delivery architect: BAM
  • Design Slate supplier: Welsh Slate