project: Hanover Square Cathodic Protection

client: Jones Lang LaSalle/Scottish Widows
location: 22 Hanover Square, London
duration: 2 phases over 4 months
value: £190,000

scope of works:

Supply and installation of a cathodic protection system
Locate steel frame, check for continuity and make connections
Drill into joints and install 1204 discrete anodes & make good finishes
Supply and install 16no reference cells
Supply and install 5no distribution out stations
Supply and install main control unit & computer
All associated wiring to complete Cathodic Protection system
Make good defects/repair areas of spalling to Portland stone on building facade  

22 Hanover Square, is a steel framed building constructed in the 1920’s in the style typical of the early 20th Century era, such that the steel frame carries all loads and the thick concrete/Portland stone cladding, which is tightly packed against the steel frame, acts as only as a decorative weatherproof cladding material.

As a result of this form of steel framed construction the building displayed numerous signs of distress typical of those caused by steel frame corrosion ie: Regent Street disease, including cracking and displacement of the Portland Stone façade due to the structural steel sections corroding. In 2008, in conjunction with a full internal refurbishment, it was decided to install an impressed current cathodic protection system to stop the corrosion of the structural steel elements. After carrying out on-site trials, a design incorporating discrete anodes fitted into the joints between the Portland Stone panels was agreed upon. CRL tendered for, and were awarded the work in early 2009. Due to the works being carried out at the same time as the internal refurbishment, and the building being completely scaffolded and sheeted for noise and Health & Safety reasons, it was necessary for the external works to be carried out in 2 phases. Phase 1 consisted of all works from floors 2 to 8, and once the scaffolding had been removed, Phase 2 was carried out on the ground and first floors. 

CRL also carried out the repairs to the Portland stone in various areas where cracking, spalling and displacement had occurred due to the expansive properties of the corrosion material. The repairs had to be carefully matched to blend in with the existing material and it is a testament to the skill and experience of the operatives that it is virtually impossible to see where repairs were carried out!

Programming of the works was difficult due to the proximity of the building to nearby residential apartments and the fact that the building was still occupied during the refurbishment.

CRL are happy to say that the works were carried out on budget, on time and to the clients satisfaction!