1st Sep 2013
While cantilevered stone stairs are proving popular in domestic properties, in the commercial world, feature walls of stone are adding instant impact to reception areas and atria.
The pictures here show two such walls, one in Portland limestone at Finsbury Circus (on the right) and the other in white onyx at 199 Bishopsgate (below), both projects in London on which Putney & Wood was the specialist stone contractor.
The architect at Finsbury Circus was Damian Howkins of Fletcher Priest Architects, who used Belgium blue limestone for the reception floor, black granite flooring to lift lobbies and Portland Basebed for the lift lobby walls, as well as the Portland Whitbed for the feature wall. The architects had originally intended to use Basebed for the wall but, in consultation with Putney & Wood and Albion Stone, which supplied the Portland stone, decided the slightly livelier Whitbed would be preferable. The leaf motif was milled by APS Masonry on its Brembana G-Mex CNC workcentre.
The architects had worked with Putney & Wood before and had confidence in them, although Skanska, as main contractor, still went to tender for the specialist. ”You would look to someone like the team from Putney & Wood to supply answers, certainly at the site stages,” says Damian Howkins.
The alterations to the building gave the architect a 36m long wall connecting the two sides of the building and the spaces beyond by bringing aspects of the exterior inside.
Damian told NSS that because of the dimensions, it was important to avoid simply producing a long, plain wall. He worked with Putney & Wood and APS on deciding how the motif could be transferred to the stone. ”There was a great learning curve for us: How far you can push the material. Milling was new to us.”
The leaf artwork was commissioned and the architects experimented with the design, creating an interesting shape across the wall and making a big play of the contrasts.
How the design would be transferred to the stone went through a number of iterations, each being produced on 3 x 4m panels to show the architects the result.
They started with the idea of building up the picture from dots, like a printed picture, but in this case created by drilling holes of different depths into the stone to create the tone. Unhappy with the result, they moved on to the idea of intaglio carving of the designs using CNC milling, experimenting with different variations of the depths of cut with, again, the variations creating tone. Some are particularly lightly etched to give the impression of fossilisation. The wall is made of 150, 1000 x 600mm panels.
”The big thing is how you light it,” says Damian, and lighting specialist Watermans Lighting Design worked closely with the architects to provide the solution. Damian: ”It’s quite surreal. When you’re there you wonder if it’s just screened on to the wall.”
At 199 Bishopsgate, another retrofit, this time by John Robertson Architects (JRA) of a 1992 SOM building, the feature wall is onyx with the emphasising lighting coming from behind and other lighting carefully designed into the walls of the new entrance in the centre of the main facade that replaces SOM’s low-key, single-storey corner entrance even at the cost of sacrificing a little of the lettable area above it by making it two-storey (although some lettable space has been recovered in other ways).
The clients, British Land, wanted to reposition the building and one of the ways JRA has done that is by leaving you in no doubt about its gravitas the moment you enter. The height and the onyx feature wall, as well as the two-tone travertine of the floor, play a major part in setting that scene.
John Robertson told NSS that he has always admired the work of Skidmore, Owings & Merrill and their use of stone, and it was because they had so effectively used travertine in buildings nearby that he wanted to use it at 199 Bishopsgate. ”It seemed to me we should bring some sort of sympathetic material into the project,” he says.
He had never used travertine before but had also wanted for some time to work with the Italian stone company Mariotti, which has a travertine quarry and major processing works just outside Rome. The quarry was visited several times by JRA Director Festus Moffat, who worked on the project. ”Festus spent quite a lot of time with them selecting the block,” says John. ”What attracted me to Mariotti is the quality of their stone, it really is that beautiful ochre yellow travertine.”
Both a dark and a light stone were selected and were separated so that bands of the darker shade could be used to decorative effect.
The white onyx of the feature wall was sourced by Putney & Wood from Iran and John Robertson says: ”Putney & Wood did a stunning job of that.”
The stone was carefully selected for the purity of its whiteness but also to maintain the figuring. It is backed by glass for strength and lit from behind with LEDs so there are no pools of light showing through on the viewed side, but rather a uniform illumination. John: ”It’s a very rich glow. It makes a massive impact. British Land are delighted with it.”
There is also LED lighting in the walls, which helps create an overall brand in the foyer.
John Robertson says natural stone is synonymous with headquarters buildings in London. ”I love the richness and beauty of the natural material. It has a corporate feel to it. It smacks of wealth and success. That’s the reason we select it.
”Putney & Wood help us with procurement, but I’m keen to be involved in the stone selection.”
He admits that budgets in the City of London are higher than in many parts of the country but clients still expect value for money. At 199 Bishopsgate ”there wasn’t actually a huge budget”, says John (the construction cost was £21.2million of which the stone package accounted for £1.2million), but the client agreed that travertine and onyx would be a good investment.
”They got the bang for their buck,” says John, although adding: ”Our work is about understatement and simplicity. We tend to shy away from decoration and we also don’t like these overly ostentatious entrances. We want to create a sense of drama and want the building to be noticed but we don’t want to resort to bling. It’s a question of taste.”
