Award of Excellence: Special Projects Category
Historic Preservation of Hoare's Bank
Submitted by C-Probe Systems, Ltd.
C. Hoare & Company
Tooley & Foster Partnership
Paye Stonework & Restoration
GB Geotechnics, Ltd.
C-Probe Systems, Ltd.
The project at Hoare’s Bank on Fleet Street in London was a challenge involving the ingenuity of the design team, the ability, care, and attention of the contracting team and the technological ability of the suppliers to achieve a long-term corrosion managed solution to the owner’s problems.
Hoare’s bank is situated on Fleet Street, London, which for centuries has been the center of both England’s legal profession and national press. As a Grade 2 listed building (in England’s Historical Building rating system), all repair measures taken were the subject of scrutiny by the conservation specialists at the City of London.
The problem the owner faced was corrosion of wrought iron cramps and pins fixing sandstone blockwork of the load-bearing masonry façade. They expected piece-meal replacement/removal of the ironwork over time without the comfort of knowing the end aesthetic appearance.
All the iron components were discreet, which meant that impressed current cathodic protection was not the obvious choice. However, in the absence of many choices, a method for development was the subject of a feasibility study. To do this, a façade and component assessment was undertaken involving a multiple cross correlative approach using different techniques to assess moisture retention, component quantification, and component condition.
The final installation of the impressed current cathodic protection system interlinked over 500 discreet iron components to form a single cathode being protected by 400 interlinked discrete anodes—all of which were installed externally with the conservation specialist insisting on no change to the aesthetic appearance of the building.
The façade also had to retain its bronze (honey) color after any repairs! Despite all these challenges the project was a resounding success.