Truly an architectural wonder, the building’s unique perforated brick façade envelopes the structural frame, acting as a rain screen. The corners and creases are column free, emphasising the continuity of the surface, whilst providing “open views” to the exterior.
In total 336,000 bricks in 212 different types were installed between August 2014 and February 2016, using a new system that could be installed in ‘all-weather’.
The architectural intention was for the wall to be ‘movement joint’ free and this was a key consideration in developing the most suitable brickwork system. Accommodation of the relevant tolerances in the façade, manufacture and installation were critical to achieving a successful building envelope. 3D setting out tools were invented for the project, to ensure that tolerances of +/-2mm were maintained over the 65m high façade.
The masonry selected for the façade was carefully specified to ensure its long term behaviour and performance. The brickwork underwent three rounds of testing. The specified bricks are 215mm square and 69mm high engineering bricks and had varying colours in order to be similar to the existing building. The brick pattern is based on a Flemish bond, also similar to the existing building, with bricks stacked in pairs and prebonded with polymerised mortar, creating a block of 215 x 215 x 145mm high, and the header bricks omitted, creating a ‘perforated’ screen of bricks.
Construction of the brick façade is as unique as the structure, with the bricks being used in a way never previously thought possible and acting as a veil over the structure. On site the blocks were connected together using elastomeric joints, stainless steel pins and a resin joint. The façade works in a series of arches to allow the brickwork to move horizontally and vertically and is restrained back to the façade with 11,500 corbels made up of 400 types.
Corbels are an integral part of the scheme. Supported by the internal perimeter structure and floor beams, precast panels provide support for the corbels and brickwork and provide a thermal and moisture barrier to the building. Sitting in empty header spots in the masonry, the corbels support the brickwork skin and offer a mechanism for reducing general frame tolerances as an interface to the more refined brickwork. Solid brickwork is used on the lower levels. The sloping brickwork is achieved by offsetting blocks at each course to create the correct overall slope. In the vertical façades the double courses are also offset in and out of the wall plane to give a texture similar to the sloped façades.
There are 5 distinct ‘types’ of brickwork:
- Vertical perforated – stepped brick
- Sloping perforated – stepped brick
- Sloping solid – flush brick
- Vertical solid – flush brick
- Vertical solid – stepped brick
At the corners and creases additional ‘special’ blocks and site cut standard size blocks were required to suit the interface between adjoining brick elevations. A procedure was developed to maintain a consistent method of support to the brickwork and to also meet the required irregular visual appearance.