Following a report by structural engineers Buro Happold into the impact damage resulting from a mobile crane striking the façade of Cannon Bridge House, appointed architects CBRE contacted Szerelmey Cleaning and Restoration for advice on appropriate fixing and repairs.

The result was a 12 week program which included the removal of the entire granite cladding to the east and west facades so that a thorough inspection of the fixing system could be carried out. Likewise, the individual pieces of granite were subjected to an inspection and a dye test to ascertain whether the granite had fractured. Those pieces found fractured were destroyed and replaced with new material.

The original fixings were found to be prone to rotation and did not facilitate movement. A new fixing system was designed that incorporated the use of the existing stainless steel channels that formed part of the support structure.

Following a detailed survey it was noted that the cavity varied in width. The new fixing system (see detail) accommodates both vertical and horizontal movement caused by vibration which is particularly important given the proximity of the building to Cannon Bridge railway station and the resultant vibration from the trains.