The Macallan Distillery and Visitor Experience
The first sight of the new distillery and visitor centre for The Macallan is a row of five meadow-topped domes, rising gently in the Speyside landscape. Closer in, you see that the dome roof is raised above ground, revealing, through a long glazed elevation, glimpses of the giant copper stills of whisky production. Once inside, the roof structure is revealed, a magnificent undulating lattice of timber beams, creating a dramatic enclosure to the distillery production processes. At 207 metres long the roof is one of the largest timber structures ever built, yet the homogeneity and consistency of detailing achieves an economical and efficient design.
The Macallan, the distinguished single malt whisky, has been produced in Speyside since 1824, and its new building is set into the sloping contours of the estate grounds. It will enable whisky production to increase by a third to meet increasing global demand – 90 per cent of The Macallan is exported – but the company also wanted a building which would reflect its global status, be a world-class destination for visitors and give the opportunity to entertain overseas distributors and clients. The architect Rogers Stirk Harbour + Partners with Arup as structural engineer have combined these requirements in a single building.
The design has an extraordinary clarity, its elegance and simplicity the result of a careful analysis of the constraints and processes of distilling. The roof shape was a key decision. The exhaust of hot air above a circular template of equipment required height, so the apex of each dome is located above the hottest part of the process, the stills. The five repeating sets of stills and domes, capped with a covering of meadow grass, create a powerful symmetry, while externally mirroring the rolling hills of Speyside. To build a roof with a form of such complexity, with a clearly visible structure, relatively light in weight to allow it to ‘float’ above the ground, timber was a clear and obvious choice.
The first and highest dome encloses the main entrance and the visitor experience centre, where an exhibition and gallery introduces visitors to The Macallan and its history. The following three domes, arranged in a linear format, each house a circular set of copper stills. The final dome encloses the mash house, containing one of the world’s largest mash tuns. Other parts of the production process are housed in a deep concrete basement with counterfort retaining walls, extending in some parts to ten metres below ground level.
The roof structure
The structure of the grass-covered domes consists of a 3 x 3 metre square grid of hybrid timber beams, faceted to form the complex curved geometry. The structural engineer, Arup, describes the development of the roof structure.
‘The geometry of the roof was defined in an analytical space. A series of five domes were assembled in line, effectively above the array of stills. Over these domes a ‘fabric’ was then ‘draped’ which connected with the boundary elements. The boundary elements were fixed by consideration of roof drainage and a continuous (200m long) glazed wall. Adjusting the analytical properties of the ‘fabric’ resulted in a funicular, form-found surface. Together, the domes and fabric are blended to create a continuous surface. A square grid of 3 metres (on plan), when projected onto this surface, creates tessellated triangles which can be framed in timber.
Under a uniform load of 150mm earth (2000T), broadly symmetrical fields of axial tension and compression develop, plus significant shear. In discreet areas timber alone cannot carry all the forces. So, rather like concrete was first reinforced by François Coignet, timber is reinforced in selected areas by steel. Steel is embedded as required within sections of constant depth and width.
Vertical support to the roof is at the point of inflection of the surfaces, conveniently where each ‘dome’ and ‘fabric’ separate. Here, inclined steel frames provide both lateral and vertical support, meaning the roof is not affected by lateral forces from the retaining walls.’
The grid structure is made up of hybrid timber beams in 27 metre, 12 metre and 3 metre lengths and the orientation and angle of individual beams were determined by the overall roof geometry. Longer beams were pre-faceted at 3 metre intervals and the shorter 3 metre beams were connected to them to form the square grid.
The beams are consistently 200mm thick and in most cases 750mm deep. They consist of a 160mm thick glulam core with a 20mm structural LVL (laminated veneer lumber) cheek structurally glued to each side. The LVL cheeks extend to form a channel at the bottom face of each beam, and the bottom edge of the glulam core is bevelled, creating a neat detail when four beams are connected together. In areas of high shear the beams consist of LVL boxes with steel inserts.
The roof is clad with 200mm thick triangular prefabricated timber cassettes, two to each grid, which are screwed to the tops of the beams. The top 9mm OSB layers of the cassettes extends to cover the tops of the beams. The lower layer of LVL is recessed at the edges to create a shadow gap, and forms the internal ceiling soffit. The cassettes support a waterproof membrane and insulated green roof system.
The five domes are each supported at mid-depth by a four-sided portal frame of tubular steel, octagonal in plan, which is supported by inclined V-shaped tubular steel columns; these in turn rest on the massive concrete basement structure.
The roof is separated from the ground. This separation of the roof from the walls and the basement meant that the timber structure was relieved of lateral earth load and need only to be designed for the minimum required for vertical load and snow load. It also meant that work could start on earthmoving and basement construction while the roof was still being designed.
The Austrian timber construction company Wiehag joined the design team to help complete detailed design and construction drawings. All the timber elements, including the cassettes, were fabricated using advanced CNC machinery in Wiehag’s highly automated facility in Altheim, Austria. The production process gave each individual timber piece a barcode identity so that it could be tracked down and delivered when required. Wiehag started erection in March 2016 and finished the roof structure in September 2016, using 20 installers and two cranes, carrying out 4,245 lifts.
All the Austrian spruce used for the glulam and LVL was sourced to PEFC standards. A total of 1,000 cubic metres of glulam was used, capturing 1000 tonnes of C02. The nature of the design produced large numbers of repetitive and identical timber elements and so most could be prefabricated offsite, reducing the number of vehicle deliveries. Timber waste was fed into Wiehag’s factory power station, which is self-sufficient in heat and electricity.
2018 Wood Awards, shortlisted
2017 Green Roof Award Winner
2018 Scottish Design Awards, Culture and Leisure category Winner
May 2018Building type:
Distillery, visitor centreLocation:
Rogers Stirk Harbour + PartnersStructural and services engineer:
Roof structureTimber species:
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