As you walk into the main entrance of the University of Reading’s new business school the building reveals itself immediately. The striking rise and curve of the glulam beams, the two enormous glulam columns, the spruce curtain walling, the finishes of oak joinery and furniture, and the stairs leading up to two storeys of tutorial rooms and offices which overlook the central hub, are all there to see.
This warmth and openness are important in making students and visitors welcome and apt, as the building brings together the diverse elements of the school, including the Henley Business School, which merged with the university last year, under one unifying roof.
The open space also reflects architect BDP’s philosophy. “We try to avoid corridors and ensure spaces can have many functions,” said architect director Helen Groves. “When you walk into the business school you can see where you’re going; you don’t feel intimidated.”
The patchwork of blue glazing in the curtain wall at the entrance helps to create a soft light, but it is the use of timber that is essential to this welcoming ambience.
The client gave a fairly loose brief when it came to materials, and it was BDP’s decision to use wood
extensively to create warmth. “It’s a tactile, warm material,” said Groves.
And glulam, in particular, was chosen for the structural elements because it provided the engineering solution for the toroid geometry of the roof which requires the beams not only to curve over, but around as well. “Glulam was the natural choice because of its strength, the sizes available and its versatility,” said structural engineering director Stephen Beggs.
This complex concept and its resolution earned BDP this year’s Achievement in Engineered Timber prize, awarded by Timber & Sustainable Building’s sister magazine TTJ. However, while glulam did meet the engineering and aesthetic requirements, the connections between the beams and the rectangular concrete buildings below presented challenges.
“The roof itself is a pretty pure geometrical form, but the interface with it and the rectangular buildings which sit beneath at an angle mean that at every point where the roof touches the building it is unique in its geometry,” said Beggs. “We’ve done glulam roofs over concrete buildings before, but never quite with this complexity of geometry.”
In order to create economies of scale, the solution was to make as many of the connections as uniform as possible. The stresses on the glulam required rigid steel-to-steel moment connections, which are left visible. “Visually, it’s an honest connection. Aesthetically the timber structures are enhanced by the detail at the connections,” said Beggs, who likened the effect to the timber pegs, dowels and joints that are apparent in ancient timber buildings.
All the beams are made from PEFC-certified spruce and finished with a clear varnish, except for the two beams at the front of the building, which extend to the exterior. These are made from unfinished larch, which will weather to grey – complementing the exterior curve and western red cedar cladding of the lecture theatre, which will also weather naturally. This curve is mirrored in the theatre’s interior wall, in the heart of the building, where, protected from the elements, the species’ rich golden colour will be retained.
All the glulam – beams, purlins, and two columns that support the roof in the centre of the building, 120m3 in total – was manufactured by Wiehag at its plant in Altheim, Austria, and transported on six lorries.
The curve of the beams limited the length that could be transported so they were delivered in three sections, complete with steel fixings. This high degree of prefabrication means there are virtually no surprises when the sections are fitted together on site, and no need to build in tolerances in the beams.
“Glulam to glulam doesn’t have any tolerance because it’s all manufactured in the factory,” said Wiehag’s project manager, Jörg Koppelhuber.
Factory manufacture also mitigates the impact of factors outside the control of the project team. “The beams are 99% preassembled so we can be independent from weather conditions, especially wind,” he said. What could have been a problem for the Wiehag erection team was the tight space of the site, which is close to existing buildings. However, Koppelhuber talks about this with a matter of fact manner that reflects Wiehag’s expertise in planning. “On a big site you can lay out over the whole area, but we had a clear sequence programme of where things needed to be stored and where the installation could be done,” said Koppelhuber.
What did tax Wiehag and the design team was the apparent double curve of the roof at the front of the building. As glulam cannot curve and twist at the same time this led to some “interesting” discussions among the project team, said Groves.
The double curve effect was achieved with a single beam and by changing the geometry in the cantilever area. “It was very challenging,” admitted Koppelhuber.
Throughout the project Wiehag also collaborated closely with the German curtain walling company Vereinigte Holzbaubetriebe Memmingen.
Beggs is full of praise for Wiehag’s role in the project. “The glulam members went together beautifully,” he said. “Wiehag deserve the highest commendation for the way they sorted it all out.
|
The glulam is made from Austrian spruce |
|
Two circular glulam beams, or ‘trees’, support the roof |
