The steel frames of masonry clad buildings, constructed in the early 20th century, can corrode. The corrosion leads to an expansion in the steel frame which can results in cracking and movement of the external cladding units. Cathodic protection schemes have been installed to address this issue.
The building was located in the centre of a major city and was a grade II listed building. A survey of the cathodic protection system found that it was no longer functioning satisfactorily and needed to be refurbished, although the source of many of the defects in the system were not precisely known. As scaffolding access was available an opportunity was taken to reconfigure the zones to make the new cathodic protection system more effective. The improvement works had to be undertaken during a full refurbishment and alteration of the building involving multiple trades.
Topbond was appointed to carry out the refurbishment of the cathodic protection system which had to be undertaken sympathetically due to the building’s listed status. The work was carried out using Topbond’s cathodic protection technicians and skilled stone masons. Initially an extensive programme of testing and recording was undertaken to locate and repair the damaged anodes, which were embedded along the mortar joints in the cladding panels. External junction boxes and reference electrodes were replaced. The transformer rectifier was also replaced.