Situated above the future Crossrail station at Canary Wharf, London, Crossrail Place features a distinctive, timber latticed roof which cantilevers out over the waters of the North Dock at both ends. The most prominent feature of the design is the 310-metre long timber lattice roof, which arches 30 metres over the landscaped park and wraps down around the concrete substructure. Together, the galvanized nodes and spruce glulam beams support large triangular ETFE cushions.
To achieve the high level of accuracy demanded by the ETFE structure, the geometry of the nodes had to be very precise and a special jig was developed for construction. In total the roof has 1418 glulam beams connected by 564 nodes, over half of which are unique in geometry. There are 348 types, but are designed as one single family. The node connections are all made from hot dip galvanized steel. Geometrically, the nodes are in fact the most complex component of the roof. This made the hot dip galvanizing process particularly appropriate as it could be batch produced rather than painted, which would have made the process extremely labour intensive.
The axis of each successive diagonal beam twists as it coils around the roof, and this twist is taken up at the nodes. In addition, as the geometry of the building accelerates out over the cantilever, the incoming angles at nodes get successively more acute and asymmetric. Each node connects to a beam plate fixed to the end of each glulam beam via timber screws.
Images © Nigel Young / Foster + Partners
See more examples of galvanized steel used in the: