Hanover Square

project: Hanover Square Steel Frame Cathodic Protection
client: Jones Lang LaSalle/Scottish Widows
location: London
duration: 4 months
value: £190,000

scope of works:

  • 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 5 no 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
  • clean down entire facade

22 Hanover Square, is a steel framed building constructed in the 1920’s in the style typical of the early 20th Century era. The building would have been constructed in accordance with the LCC building acts 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. 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 to 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 floor.

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 even today 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 partially occupied during the refurbishment.