Page D1.2 . 14 February 2001                     
ArchitectureWeek - Design Department



Foster and Partners Roof the Great Court


When the new British Library facility opened in Kings Cross, north London, in 1998, the Reading Room and courtyard were relieved of their storage duties, leaving them in need of a new role.

As if in reward for their loyal service and to ask forgiveness for the years of neglect, the Reading Room and its courtyard were handed to British architects, Foster and Partners for renovation. As Dr. Robert Anderson, Director of the British Museum said, "Norman Foster has elegantly blended his unique brand of contemporary architecture with Sir Robert Smirke's 19th century neo-Grecian building."

The Great Court Project

Foster and Partners' concept was to clear out the bookshelves of the Reading Room and turn the surrounding quadrangle into an inviting public space. The British Museum is a protected building; therefore, any work on this scale would have to be technically demanding as well as sensitive to modern design.

The building facades facing the courtyard were to be cleaned and restored; a new glazed roof would cover the courtyard. The south portico, which had been demolished in the 1870s to enlarge the museum's entrance hall, was to be rebuilt enabling visitors to walk directly into the new space. The idea of the enclosed court was, ironically, to open up the museum to the public.

The £100 million project opened in December 2000, taking just two and a half years to complete. The Great Court, the largest covered courtyard in Europe, fundamentally transforms the nature of the entire British Museum building.

The Reading Room

The Reading Room was originally built of brick because it was never intended to be seen from the outside. Foster and Partners' solution was to clad the circular drum with limestone to match the courtyard walls.

The interior has been restored to its original Victorian splendor and opened to the public as a reference library. The original azure, cream, and gold decorative scheme, discovered beneath several layers of paint, has been fully restored.

The north side of the cylindrical building now houses a shop, a restaurant, and two galleries on four floors in an elliptical extension, accessible via two grand stone staircases.

The Reading Room, with its broad encircling staircases, appears somewhat out of proportion, lessening the impact of the porticos in the courtyard, which are grand in their own right but diminutive by comparison.

The Roof

However, the eyes of any visitor soon transcend the Reading Room to the magnificent steel-lattice roof that covers the quadrangle.

The idea was to produce a canopy that was delicate and unobtrusive, avoiding the need for columns within the courtyard. The result is a stunningly unique geometrical form. Although it looks simple and delicate, it represents a feat of modern engineering.

The fine steel lattice is constructed from custom-made steel box beams joined at six-way nodes. According to Stephen Brown, Buro Happold’s principal engineer on the project, the geometry of the roof’s toroidal framing was defined using a customized form-generating computer program.

The roof shape is curved to a tight radius of approximately 165 feet (50 meters), which means it can act much like a dome, while imposing minimal loads onto the existing surrounding structures.

The junction of the roof and the Reading Room uses a ring of 20 composite steel-and-concrete columns, which align with the room's original cast-iron frame.

These columns are concealed by the new limestone cladding surrounding the entire drum of the Reading Room. The room's domed roof remains external and is used as the hub for the courtyard's roof.

The roof's connection to the original load-bearing walls of the courtyard is through a slide bearing carried by a concrete ring beam on top of the existing wall. The outer edge of the roof rests on a new concrete ring beam at the cornice level of the original Great Court walls.

The roof seems to float effortlessly above the space providing an ethereal presence, which is a tribute to modern design innovation and technology.

The Windows

A series of Venetian windows, previously filled in to obstruct the public gaze, have been restored with new capitals and columns on the outside and newly glazed with reverse-frit glass panels.

The columns are enclosed within a wall of Cabra limestone panels fixed to an I-section steel subframe. The enclosed spaces between them are used for building services: smoke and air exhaust from the basement, electrical conduit for lights fixed to the roof ring beam, vent pipes, and downspouts from siphonic drainage outlets, which drain rainwater from the dome and the glass roof.

Environmental Control

The designers' aim, using advanced engineering and construction techniques, was to create an environmentally controlled area.

Environmentally sensitive areas like the Reading Room, with some 25,000 reference books, the Great Court Gallery housed in the ellipse at the north side of the drum, and the ethnography galleries located north of the Great Court, due for completion in 2003, all needed a controlled atmosphere.

In the basement of the older building, at each corner of the courtyard, four new service rooms have been installed to filter incoming air before it is passed to four further rooms beneath the courtyard. There, the air is fully conditioned before it is distributed to the education center, gallery spaces, and the restored Reading Room.

The glazed roof is also an environmental controller. The canopy combines neutral-tint glass with a fritting pattern, which provides a high-performance shading effect. It reduces the solar heat gain while transmitting a high proportion of the available light. The court is also mechanically ventilated by exhaust fans at the roof level to prevent hot air build-up.

The Stone Story

In a classic quote, Spencer de Grey, Foster's partner-in-charge of the project, described the Great Court as "a symphony in European limestones."

The one aspect, however, that mars the Great Court is the controversy surrounding the use of the wrong stone. Both the Reading Room cladding and the south portico structure were to have been built from Portland stone, the original stone used for the courtyard.

Instead, a less expensive French substitute was used, Anstrude Roche Claire, which has a more uniform and whiter look compared to the mellow and roguish Portland stone.

The general impression is that, although the stone looks noticeably new, this is understandable at this early stage of its life, so it does not diminish the overall result. The cladding surrounding the Reading Room, for example, is pristine and does nothing but enhance the epic surrealism of the Great Court.

The new south portico, however, has caused the most controversy mainly because the differences are more noticeable to the critical eye, with the bright new stone contrasting less subtly with the original mellowness of the aged Portland stone.

Despite the difficulty in establishing new stone with the weathered effect of 150 years, the environmentally controlled arena in which the stone now finds itself will ensure that the weathering will be limited to age rather than acidity. Therefore the new stone will always remain relatively pristine.

The dispute over why this happened rages on between the British Museum, Easton Masonry, Foster and Partners, English Heritage, Camden Council, and others. Still, the episode will eventually pass and turn to folklore. These are, after all, the stories history is made of.

The Foster and Partners design is an inspiring success despite some physical flaws, but beauty was never meant to be perfect. Covered with a spectacular skylight of glass and steel, the courtyard has become a beautiful arena demanding admiration.

As Lord Foster says, "The Great Court has become a living space in the center of the building."

Don Barker is a freelance writer and photographer in London, UK, who has lived and worked in Europe, Australia, Thailand, Sri Lanka, Hong Kong, and Singapore.



ArchWeek Photo

Aerial view of the completed Great Court roof taken from the top of Centrepoint, a skyscraper to the west of the Museum.
Photo: British Museum

ArchWeek Photo

Computer simulation of the Great Court.
Image: Foster and Partners

ArchWeek Photo

Detail from the Great Court roof seen from within.
Photo: British Museum

ArchWeek Photo

With the demolition of the book stacks and outbuildings that cluttered the courtyard almost complete, the exterior of the Reading Room stands exposed for the first time in nearly 150 years.
Photo: British Museum

ArchWeek Photo

The contrast between the old and new stone is visible under the cornice.
Photo: Don Barker

ArchWeek Photo

A Venetian window on the east side of the quadrangle which had been previously filled in, has been restored with new columns.
Photo: Don Barker

ArchWeek Photo

The fine steel lattice is constructed from custom-made steel box beams joined at six-way nodes.
Photo: Don Barker

ArchWeek Photo

One of two staircases that envelop the Reading Room.
Photo: Don Barker


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