Three outdoor circular gathering spaces have been erected to enliven an office campus in London. But how were these glulam lattice pavilions made?
What Circular gathering spaces
Where Regent’s Place, London
Inspired by the randomness of a pile of sticks, the design and engineering of Nex-Architecture’s timber lattice pavilions at London’s Regent’s Place has been anything but haphazard.
The three curvilinear structures were conceived as soft, natural organic forms to enliven the public realm at the British Land-developed office campus, and to encourage people to gather. The first pavilion is a simple screen wrapped around a curved bench; a second, larger pavilion surrounds a rotating circular bench; larger still is the third which encloses a circular performance space for use by the local community theatre. ‘Our concept was for three timber lattice pavilions that would sit lightly in the landscape to act like a trail of breadcrumbs to draw people in,’ explains Nex-Architecture director Alan Dempsey.
Nex- developed the early designs through sketches, study models and VR simulation to determine the form, size and location of the pavilions. ‘We didn’t know the exact shape,’ he goes on, ‘but as soon as you move away from a dome you need to form-find and to do that you need good computing skills and a good understanding of how timber behaves.’
Nex- approached Xylotek at Stage 3, having persuaded the client to involve the timber structure specialist in the pre-contract design. ‘Xylotek was great, we had to engage with manufacturers early to avoid creating a standard grid-like product,’ says Dempsey.
Xylotek rationalised the form using an iterative, collaborative process that kept the timber laths slender, and stiff enough to self-support the lattice. He says: ‘They look random but there is an order to them.’
Oak was selected for its strength and durability. Over 400 laths are used to form the three structures. Each lath is assembled from oak lamellas, formed by finger-jointing short lengths of sustainably sourced French oak end-to-end to make 8mm thick, thin 9.5m long strips of timber. Five of these are glue-laminated in Xylotek’s Bristol workshop to create a single, 65mm by 40mm cross-section lath.
Each pavilion is assembled from four concentric rings of laths. Within each layer the laths share the same curved shape, so every lath in that layer could be formed on a single bending jig. The bent laths spiral in opposite directions on alternate layers; the overlaps add rigidity while appearing random. Deliberate variations in the length of the laths add to the structures’ seeming haphazard form.
Laths are bolted together at specific intersections through holes drilled in the centre of each strip. ‘We didn’t throw bolts in everywhere. Our structural sub-consultant Format worked out where they would be most effective,’ says Martin Self, design director at Xylotek.
The structures are bolted to metal baseplates. The bottom edge of each lath is square-cut and incorporates a slot for an angled steel flitch-plate which is welded to the baseplate. ‘In a weird way, there is more complexity to assembling the steel because the angle variation is taken out there, rather than in the laths,’ he explains.
He says segments of the pavilions were pre-assembled by Xylotek ‘to give us something to build off when we got to site’. Assembly of the stick-inspired pavilions was completed late last year.