Drawn into nature

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Richard Rogers’ final project is the latest addition to an array of modern architecture at Château La Coste, near Aix-en-Provence. Jack Wooler reports on a gravity-defying cantilevered design that soars over its woodland setting

Along a historic Roman road that leads past Château La Coste in southern France, The Richard Rogers Drawing Gallery’s cantilevered form projects through the woodlands. It’s an architectural gesture that’s both striking, featuring a bold orange steel structure, and delicate – barely impacting on the landscape around it in terms of its footprint.

The Rogers Stirk Harbour + Partners (RSHP)-designed project provides a 120 m² gallery space for the Château. It sits in a 500-acre area of outstanding natural beauty and already includes an art and architecture centre, wine estate, restaurants, and luxury hotel. The new gallery will host a variety of exhibitions within its unique housing.

The project takes the form of a timber panelled and steel-clad box inside an orange-painted, tubular steel ‘cage,’ cantilevering out 27 metres to a point 18 metres above the heavily wooded site. The structure proudly displays hand-finished welded joints, showing how they support the lightweight, ‘extruded’ gallery.

The project is the fruit of over a decade of conversations between the practice and client – and friend of Richard Rogers – Irish developer and hotelier Paddy McKillen, who owns the Château. This building is the renowned architect’s last before his retirement, and joins the ‘architectural walk’ on McKillen’s estate that features projects by other major architects including a gallery by Renzo Piano, a restaurant by Tadao Ando, and a ‘wine cellar’ by Jean Nouvel.

With a design aiming for minimum impact on its environment, the gallery barely connects to the ground, with just four modest steel footings touching the earth – two pivot points at the edge of the hillside and two sets of four tension rods tying the building to the ground. The foundations are concrete, but the steel exoskeleton provides a flexible form responding to the forces as required.

The building envelope is both heavily insulated and projects beyond the glazed end facades to ensure that the internal environment can be sufficiently controlled to ensure flexibility for the likely range of artworks to be displayed.

The gallery itself forms an industrial sculpture in its own right.

A gap among the trees
The architects say that it was immediately clear to them where the project should sit, on their first visit to the site. Located off a dirt track, with limited vehicular access, the steep uncultivated woodland site offered a naturally formed gap among the trees through which the building could be ‘launched.’

“As if by nature, here was this idyllic spot for a gallery,” says Stephen Spence, lead architect, of his first impressions of the site. “All we had to do then was to design the most appropriate form for the location.”

According to the architect, in the early stages the team looked at various options, largely focused on how to deal with the steeply sloping site in order to minimise any visual disruption. The other key constraint was avoiding the ancient Roman road, which the client and architects wanted to leave untouched.

“We looked at elevating the gallery above the road, but finally gravitated towards a design in which users would come along the track, and then step off solid ground across a bridge into a building that floats among the trees, leaping off the side of the hill,” he explains.

The design intention then necessitated a structural solution that would connect the gallery in as minimal a way as possible to the ground, avoiding a series of extended columns connecting it to the ground.

“There was a step by step analysis through a series of concept sketches, which was then presented to McKillen, who immediately bought into it,” says Spence. He says that McKillen would not entertain even a single column – “‘why compromise the design’ was the client’s clear steer.”

He adds: “By supporting the purity of the design, this allowed us to keep the magic of the site.”

Collaboration & unity
Through the high level of collaboration and unity with the client – the architects had his “full support from day one,” enthuses Spence – the team were given “total freedom” to design whatever they deemed best for the site and the building’s function.

Other than small requests, such as the stipulation that the gallery be able to cater for changing, temporary exhibitions, and offer a certain size necessary to host them, the architect tells me that what the client sought most dearly – in order to match the multiple architectural works on the estate – was a building that was “a beautiful object in its own right.”

According to Spence, the biggest discussions with the client during this process were to do with the size and colour. Remembering an early conversation between himself, the client and Richard Rogers, he says: “We sat in Richard’s house one day, which is made up of two houses knocked together, and we measured the space – 12 metres.”

“McKillen decided on the size he wanted in a very simple way; for it to be twice the size of that room. That is how we came up with the 24 metres; we thought the 5 metre width and 4 metre height were appropriate for the overall proportions.”

When it came to the colour, the architects searched for a tone that would work with the changes the seasons bring to the site’s landscapes, along with the variations of grapes in the wineries, and the overall wooded backdrop.

When shown what it would look like in the setting, the client agreed to the strong shade of orange for the structural steelwork. The practice has used it before, and was deemed to be sympathetic to the green landscape, while “bright and beautiful; a vibrant colour that’s noticeable.”

Engineering & logistics
Once the size, colour and location had been chosen, the next challenge for the team was to design a building that not only lightly touched the ground, but which only used elements of a certain length, due to the site’s constraints.

The cantilever itself required complex physics; the 27 metre projection was itself no small task, with the added constraint of the region’s seismic activity. The building required “bridge type” engineering and construction techniques to accommodate both of these factors, with flexible materials and cables at the entrance which allow the structure to contract and expand with the local climatic conditions.

Early on, because of these complexities, the team had hoped that the entire building could be prefabricated offsite, and lifted in as a complete element. The limited vehicle access meant that this was impossible, however.

Steel beams of six and eight metres were loaded onto a trailer and were brought to site by a tractor. Once on site, the team employed a spider crane at the bottom of the slope which lifted elements into place.

This construction process proved complex, with the team having to be very careful to avoid disturbing the trees on site, as well as overcoming the task of getting materials up the slope and working with them at a challenging angle.

To counteract this awkward location, the building was designed to be joined together on site by hand, and as such the team produced a “handcrafted” piece of architecture. All the nuts and bolts for example were sized specifically for individual locations with access for fixing kept to a minimum.

To ensure this process was achieved as smoothly as possible, the team employed Bysteel in Portugal – who both the client and RSHP had worked with previously. Having fabricated the steelwork, to ensure no issues on site, they constructed a full scale mock up. Having been successfully erected, it was then dismantled, painted, packaged and transported to the Château. Construction was reportedly “fairly seamless,” which the architect attributes to the high level of preparation, and the hard work of Bysteel and the local construction team.

Environment for art
With the structural designs proving successful, the team moved onto the interior art space, which was optimised to be as flexible as possible – in part due to the changing nature of exhibitions.

The architects specified “standard” white walls, a simple white ceiling, and a uniform lighting grid which could be adapted to “accommodate just about any potential exhibition configuration.”

Spence says the lighting can alter “significantly” to suit the installation; “the art may be on the walls, or it may be housed in the centre, so we ensured the lighting would be flexible enough to adapt and accommodate any scenario.”

One challenge here, however, according to Spence, was the difference in the lux levels between what was required internally and the natural daylight penetrating through the two end walls. To assuage this somewhat, the team incorporated a “buffer zone” overhang in the building envelope, which forms a transition between inside and out. This was the only real measure needed to control daylighting, says the architect. There are normal internal blinds, but no special devices on the exterior – “we didn’t want anything on the outside, given the exposed location,” he adds.

At the far end of this box, a terrace allows users to gain the views produced by the long cantilever. The fully-glazed opening doors leading to this terrace allow fresh air in where the art displayed allows for it. When this is not possible – due to changes in weather or restraints introduced by precious art pieces – the team designed a controlled environment for the works on show. This is serviced by a dedicated air system from a small plant room, which feeds air through at a low level, to then be extracted at high level.

Covid triumphs & tribulations
Despite the building now being completed, at the time of this interview the design team had been unable to see the finished result, with Spence only able to make it onto the building site once during the entire process because of Covid restrictions. Also sadly due to Covid, there would be no chance of an opening event either for the design team.

Where once not visiting the site might have been a significant barrier, however, the in-depth modelling of the project beforehand by the specialist engineer, Hasson Engineering Solutions (who produced the 3D Tekla model), and what Spence calls the “diligence of the Bysteel fabrication and construction teams” enabled the project to be completed smoothly and “under careful watch” throughout.

“The modelling was a very good device for us to be able to control exactly both the production and construction onsite without the usual visits,” explains Spence. “We were getting updated photographs throughout, but there were very few surprises due to the level of thought and refinement that had gone into this model.”

“This worked heavily to our advantage in terms of Covid and the lockdown circumstances since,” he adds. “And this success is shown in the outcome – since completion, the response has been really positive, so the whole team are proud of what we have been able to produce.”

While lamenting his inability to see the completed building, Spence is eagerly looking forward to a future visit: “I’m most excited to see the gallery when it is further ‘bedded’ into the landscape,” he concludes. “With social media, it’s also fascinating to see other people’s take on a project, and there’s always something in the views of others that makes you see a building in a new light.”

Project FactFile

  • Architect: Rogers Stirk Harbour + Partners
  • Local architect: Demaria Architecture
  • Client: Château La Coste/Paddy McKillen
  • Structural engineer: Lang Engineering Consultancy
  • Project manager: Rainey + Best
  • Steel Works: Bysteel
  • Building enclosure: Setanta Construction
  • Specialist engineering: Hasson Engineering Solutions
  • Local engineer: ATES
  • Internal fit out: SCEA Château La Coste, IDME France & ACM France
  • Completion date: November 2020
  • Gross internal floor area: 120 m²