Pulling together.

A new use of an ancient material, oak, acting as an appropriate, evocative screen to halls for rowing shells, some of the most beautiful wooden artefacts ever made.

The museum at Henley is David Chipperfield's first major building to be realised in his home country. The design itself, in its clarity and simplicity, carries within it the matured experience of the first 10 years of Chipperfield's otherwise international practice. It also exemplifies his beliefs concerning both the design process and the materiality of architecture. In these issues of principle, Chipperfield has said: 'In our work we try to ensure that decisions about material are given priority in the conception of the project ... our development [of design ideas] relies on continuous interaction between programme, space, plan and material, a process which is not a linear one but allows even material decisions to reinform or put into question aspects of the plan'.(1)

In the design of the Henley Museum, these principles are very clearly expressed, especially in the section and the external expression of the programme in the elevated oak-clad boat-halls.

The museum buildings are sited in the water meadows on the south bank of the Thames, close to Henley town centre. The museum will contain a significant collection of rowing boats, long cigar-shaped forms of various types, together with a catalogue of exhibits that convey the history of the sport and of the river itself.

Three decisive factors have influenced the design: the reinterpretation of traditional building forms, the elevation of the ground plane, and the floating wooden boat-halls over a transparent base of glass. First, the architecture is established in the choice of traditional pitched-roof forms that recall the wooden barns of Oxfordshire, the riverside boat houses at Henley, and the temporary tents, erected annually, to house the boats and spectators at the Henley Regatta. This formal decision also proved to be successful in helping the design to fit into the planning constraints of a sensitive, conservative and historic town. Chipperfield considered that 'the architectural strategy could be described as one of adopting a traditional form in principle and redescribing this form in detail. Through the choice of materials and the composition of details the building is given another reading'.(2) Next, the process of reinterpretation is confirmed by raising the ground plane and constructing this anew as an elevated concrete slab on exposed concrete piles, in this case resembling sunken pilotis. Over this, the first floor is lifted up on both circular and slab-form concrete columns.

Finally these upper level boat-halls are expressed as floating, naturally top-lit linear gable forms clad in immaculately detailed green-oak boards, with a transparent glass skin to the raised ground floor public spaces beneath. So the boat-halls are essentially introverted '... spaces of isolation and concentration in contrast to the open and transparent spaces of the ground floor'.(3)

The generous raised ground floor public terraces associated with the main entrance and shop, restaurant and meeting room, are reached by both ramp and stairs, and are all finished with oak decking, which imparts a nautical character to these areas. Chipperfield has also described this as a 'ground plane [that] extends outside the building, forming a raised timber platform rather like those found in Japanese temples'.(4) The floor plan and the section of the museum contain distinct echoes that are reminiscent of the discipline and order of Louis Kahn's Kimball Museum in Texas. The upper level plan of the main building is distinctly characterised by Kahnian zones of served and service spaces related to the structure and to the provision of deep-walls for services and exhibits which line the main boat-halls. Similarly, the section with its shaped extruded cone form and natural light reflector at the apex, recall the principle, if not the profile, of Kahn's cycloid vaults.(5) The roofs, in this case, are also finished in metal - a taut sheathing of terned stainless steel. Boat-hall one, on the north face, is dramatically sliced open at the eastern end, a special event window, giving wonderful views towards the river through the willow trees. The deep wall zones incorporate services, as does the raised floor, and a fit-out zone is clearly determined by this deep section of the boat-hall walls. The discipline of the central 'service' zone is momentarily broken by the secure in-board picture gallery, but the main staircase and lift, with natural top-light, are also appropriately housed in this central spine.

The spine is continued westwards in the form of a dramatic glass and GRC bridge link which leads to a third boat-hall, a second phase of development, with ancillary accommodation and caretaker's flat below. This hall is cubic, with a shallow metal roof and side daylighting, in contrast to the main buildings. Its north wall is a magnificent plane of oak cladding, sliced by a continuous band of glass clerestories.

The green-oak cladding was carefully selected for economy and long-life.(6) The silver-grey weathered layer which forms eventually protects the oak board from the loss of its natural tannin protection.

The oak cladding is essentially a rain screen, open jointed to allow air-flow and to avoid capillary action in rain. The fixing of the oak boards is at close centres, to a sub-frame of Colombian pine. The stainless-steel screws and slotted washers are each precisely located in a circular sinking. The washers, with the slots aligned vertically, allow downward and upward shrinkage of the 160 x 20 boards to be naturally accommodated (shrinkage does not occur in the long dimension). The Colombian pine sub-frame in turn is attached to a softwood stud sub-structure which is secured to a lattice metal portal frame, which occurs at 3.9m centres and is finished within by plastered dry lining. The whole structure is heavily insulated.

The transparent glass walls are held in stainless-steel trims with retractable fabric sun-shades on the southern entrance face. The transparent quality of the raised ground floor, with naturally ventilated entrance, the restaurant, library and committee room, is simple and stunning in its immediacy. This is enhanced by the natural finishes of the exposed concrete structure, white plaster infill and oak floors. Detailing of elements such as toughened glass balustrades in stainless-steel frames is all of the finest quality. But the overall range of materials is almost Spartan in its strictness and this limitation heightens and sharpens the overall forms and the absolute clarity of their programmatic expression.

The functional tradition of boatyards and buildings has also been captured - each boat-hall has direct external access doors at first floor to allow the superb hulls of the eights to be brought in.

The museum is a major addition to the legacy of Henley, and the Trustees of the foundation that has sponsored the project have given a vital opportunity to an emergent British architect who has discharged his task with a precise and beautifully crafted response. Time and weather will only add further to this work in the process of its ageing - a quality embedded in the nature of its principal material - English oak.

1 Theoretical Practice David Chipperfield, Practical Theories pp54 and Projects introduction pp61. Artemis 1994, London.

2 Ibid. The River and Rowing Museum Henley, pp111.

3 Ibid.

4 Ibid.

5 The Kimbell Museum and its cycloid vaults are poetically described by Louis Kahn in Light is the Theme: Louis Kahn and the Kimbell Art Museum compiled by Nell E. Johnson, Kimbell Art Foundation, Fort Worth, Texas 1975.

6 The architects have paid tribute to the excellent advice given on the selection of the green-oak cladding by the Timber Research and Development Association.