GRIDSHELLS - A NEW TIMBER FORM IN THE MAKING

It is a sky blue summer open day at the Weald and Downland Museum, in Singleton, West Sussex. Crowds flock around the various traditional craft attractions, which, along with one of the largest collections in the country of renovated historical buildings, comprise the museums stock in trade. Up in the woods in the museums’ southerly corner a sizeable contingent of visitors are clumped together, looking admiringly at the uncovered roof of the latest building at the centre. This is no medieval, Elizabethan or Regency house. It is a great weave of whirling timber laths, making three lattice-shaped shell domes, which will become the roof of this latest, only too contemporary addition to the museum. This is the Weald and Downland Museum’s brand new gridshell building, which in the last year has won praise from press and public alike.

Image Stuart Keegan and Elaine Duigenan

On this summer day the cladding is yet to be added. The structure looks like a beautiful ship’s hull turned reverse side-up, but still naked as you can see the criss-crossing timber laths running in great long curves, some 30 metres, side to side. One year on the building has been completed, the cladding is in place, and after a big launch the gridshell is a stand-out showcase of what can be achieved with the emerging synergies of computer modelling power, related developments in glue and timber technologies, and a dedicated team of expert carpenters and sympathetic architects.

By the gridshell there is a viewing stand and there Cullinan’s project architect, Steve Johnson, and one of the projects engineers, Ollie Kelly, are describing to all comers exactly what they think they have been doing in designing the building. At one of these wall-to-wall tours an elderly man pipes up. He worked with Barnes Wallace during the war, and the wooden lattice design of the skins for the Wellington and Lancaster bombers is exactly the same. The knowledge has been around for decades, but why the transfer to architecture never happened remains something of a mystery.

What are gridshells though? They are, at core, lattice shell structures, shellshapes pocked with diamond lozenge holes. Because of their shell properties they are phenomenally strong, and don't require internal supports. They are usually made out of steel, aluminum and concrete the recent British Museum courtyard roof is a contemporary example of a steel version. Today however a number of gridshells have emerged around the country, all made of wood, and all in a very short period of time. They are very different. The Weald and Downland building has the highest profile, amassing sheafs of press-cuttings, as well as being narrowly pipped at the post for the coveted annual Stirling Architecture Prize.

The history of timber gridshell engineering actually reaches much further back. At the turn of the last century German and French engineers began putting onto paper nascent gridshell plans for agricultural buildings. From there the design was adapted for first World War zeppelins, and in World War ll became the aforementioned body design of Wallace Barnes' famous Lancaster bombers. But the real year zero for gridshell is 1975, when the eminent German Architect, Frei Otto, unveiled the first real gridshell building in Mannheim. Originally a temporary horticultural exhibition hall, today this set piece of wood engineering futurism is a listed building. A member of the Ove Arup's original engineering team described it as one of the most advanced buildings of the twentieth century. Since then? Well, not very much. In the interim years since 1975 two buildings have emerged in Japan, one out of timber, the other from bamboo. Japan's submission at the Hanover 2000 Expo was also a gridshell, very similar in shape to Weald and Downland, but twice the size, constructed from cardboard tubes. Whether it truly constitutes a gridshell building is something of a moot point, since it has already been dismantled.

Image Stuart Keegan and Elaine Duigenan

The history of gridshell building is intimately connected to Frei Otto’s Mannheim building. A generation of engineers, mostly initially connected to Ove Arup’s, received exposure and experience there, which is now, over thirty years later, bearing direct intergenerational fruit, and feeding through to this new wave of timber design. Until Frei Otto and Arup at Mannheim, the Wallace Barnes gridshell knowledge hadn’t effectively jumped tracks into architecture. Originally, Otto had uncovered the possibilities of gridshells by observing the biological structure of double-curved coral, a textbook example of nature as a strategy for design. The entire Arup timber team, including Ted Happold, Michael Dickson, Ian Liddell, and Chris Williams defected to form Buro Happold, bringing with them their timber expertise to Britain.

A related stream of influence has been the work of Florian Beigel, who today runs the Architectural Research Unit at North London University School of Architecture. Beigel moved to Britain in the early seventies, who also worked with Frei Otto on another of the renowned German's gridshells, the Munich tent structure. The tent structure was a cable grid structure, in contrast to Mannheim's compression structure. When he came to Britain in 1970, Beigel brought the gridshell concept with him. In 1974, along with his students, he constructed a series of four gridshell structures on Highbury Fields as experimental exercises. From there he tried to get funding support from Arup's and then Happold's to continue the research, just when the two big engineering companies were first beginning to research tension structures, but to no avail. The Highbury Fields' gridshells are documented in one booklet publication by the Stuttgart Institute for Lightweight Structures (document IL13). Beigel, in conversation, though not directly involved in gridshell design for a number of years, remains absorbed by its simple elegance to this day. Despite being double-curvature in form, the use of laths makes for a very simple element. Usually the use of the double-curvature form is difficult and the manufacturing expensive. "I still find the elegance of the idea very fascinating", Beigel says. With wood there was, for the first time, a way of making the square of the form into a parallelogram. His last direct involvement in the form was in 1992 when he was centrally involved in plans for a gridshell theatre and arts centre in Brentwood, Essex, It never got any further however, unfortunately. Were it to have, the beginnings of this gridshell movement might have been earlier off the starting block. By this time, the mid nineties, the influence of the Mannheim building on the two Ted's, Cullinan and Happold, was already water under the bridge. Today, Beigel points out the Weald and Downland gridshell is exactly the same shape as the structures he and his students were playing around with on the playing fields near-on thirty years ago. (see, www.aru.unl.ac.uk)

To some extent it is the influence of all Frei Otto’s architectural and engineering colleagues settling in Britain, which has been a primary inspiration for the different gridshells, which have emerged during this millennium time. This summer, the opening of Weald and Downland gridshell became a springboard, so to speak, for other buildings with unusually singular development in wood construction. The Weald and Downland gridshell makes a geographic midpoint in a short triadic necklace of related buildings; Frei Otto's '90's Hooke Park Workshop to the west in Dorset, and to the east, the smaller adapted Flimwell Woodland Centre chestnut modular gridshell. Even if Hooke Park is not a gridshell, there are similarities which make it persuasively belonginning to the same family. There is also a fourth family member - a northern relative – the hand built completely low tech Pishwanton or Lothian gridshell, designed by the Anthroposophical architect Christopher Day. Pishwanton brings another, accessibly small-scale dimension to the growing band of wood grid dings, (should read gridshell buildings) suggesting that gridshells can also come in many varieties, small and perfectly formed, as well as large-scale.Both the Weald and Downland, and Flimwell structures provide something a testament to a new 'hands-on/hi tech' building paradigm; the convergence of developments in wood and related materials technology, and the new capacity for modeling which have been inaugurated by computers, and also incorporating the skills of the crafts tradition. Add to this the shell properties of the building and the lightweight properties of the material, and it all dovetails into the emergent tradition of 'lightness': becoming a fitting example of how wood can be a suitable candidate in the search for extra-light materials and structures.

As to the future, how will this putative gridshell movement look a dozen years down the line? There are hopeful signs that these buildings are the forerunners of a larger emergent movement with the possibility that a number of further timber gridshells will be constrcuted. Cambridge Botanical Gardens are considering an ambitious gridshell project, while not far away, in Chelmsford, a chestnut modular gridshell is on an architectural practices computers’ screens for a park and ride project. What could be happening is this growing band of buildings, are, bit by bit, pulling a genuinely exciting, elegantly ecological and twenty-first century form into material existence. With a public tuned towards the curvatures of organic form, partially by way of the grand millennium projects, alongside an ongoing and growing research and knowledge base, a possible critical mass may be on the cusp. So, the next steps in a very specific strand of an architecture with organic form, using organic materials, is, at the beginning of the new century, in the early stages of development, as this specific gridshell example demonstrates, examples which will hopefully multiply. That the Weald and Downland gridshell is kickstarting an interest in the double-curvature rectilinear forms which comprise their skeleton, and is building an ongoing momentum as described above. The sections below outline the three principal gridshell examples in this country, albeit one is an adapted modular gridshell. All of these were under construction at approximately the same time, the millennium years between 1998 and 2002.

 

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