This project was awarded Highly Commended in the New Modern Style Stone Cladding category at the Natural Stone Awards 2010.
The official guide said, 'The objective was to remove the existing external granite façade to the front of a central London office building entrance and replace it with a new limestone façade while the offices remained operational.
The project was undertaken over an eight week period to February 2009. The area was approximately 200m ² with an overall height of 15m, which included flank walls to adjacent properties. The lower section of the new limestone façade is sloped forward at two different angles, with the steeper stone face shaped to form an arched 'scallop' over the entrance door. The plinths were produced from Portuguese Viseu granite and the cladding above from Bowers Basebed from Portland. To complete the interface elements to the internal office entrance lobby, matching granite paving and Travertine cladding was installed at ground floor level within the enclave of the portico.
Vertical stainless steel channels were bolted to pre-drilled holes in the steelwork frame, with stone support and restraint fixing in turn bolted to the channels. The design process involved close co-ordination between parties to ensure the pre-drilled holes in the steelwork frame suited the positional requirements of the vertical stainless steel channels and the staggered stone joint layout.
The design and manufacture of the curved portico stones, with solid returns to the rim interface with the sloped cladding section was spatially complex and entailed a high level of expertise by the design office and masons in the factory.
Installation of the stonework to the sloping section around the scallop was a particular challenge as the stone faced down as they were positioned.'
The judges commented, 'This truly is a monumental entrance to Cannon Bridge House. It makes a bold statement giving the entrance real presence. The design required the masons to cut curves in several directions.
Setting out is technically difficult with such large stone. Nonetheless, the project is well executed. The identity of the building carved into the stone in bold lettering is perfectly in scale with the building.'
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