1-3 Bishopsgate

This beautiful Grade II listed building dating back to 1877 was designed by Thomas Chatfield Clarke. It is comprised of 4 storeys plus basement and garret and was once the offices of the Royal Bank of Scotland. The Swags, Balustrades', Ionic Columns, Dentil Course and Ashlars' were all covered in particulates caused by pollution and in need of refurbishment/redecoration/cleaning. The main challenge was to erect scaffolding in one of London's busiest streets without disruption to local businesses and foot traffic in and around peak hours. 

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Contract Value - £240,000

 

Scope of Works: 


TORC Clean (stone cleaning): 
Cleaning consisted of using The TORC system to remove the Carbon sulphation, on the facade and this system enables the intricate details to be cleaned to high standard. The TORC system used creates a gentle swirling vortex using a mixture of low air pressure, little water and a safe inert fine granulate. 


Lime Mortar Repairs/Pointing: 
In situ mortar repairs were used including the installation of stainless steel reinforcement to repair damage caused by the erosion of the original stone leading ultimately to failure of the existing stone. 


Renew Portland Stone: 
Defective stones identified for repair/ replacement were cut out to a suitable depth measured on bed by adopting such methods necessary to prevent damage to surrounding stone. Following completion of the removal works the void was cleaned out ready to receive the new stone. The void was then dampened and a mortar bed applied, the replacement stone was dampened and eased into their correct position. 


Other works completed were:

  • Repair/Replace Damaged Leadwork

  • Remove/Replace Existing Rooflight
     

Brickwork/Pointing Repairs: 
Defective pointing was removed by using thin necked quirking chisels to rake out the mortar joints to a depth of 10mm - 25mm and remove the existing mortar. Where cementitious based mortar was present, small, mechanical cutters were used to cut through the centre of the mortar joints ensuring no over cutting occurred to the surrounding brick or stonework. Then with the use of chisels, the defective mortar above and below the cut line was removed. The exposed joints were then flushed out with clean water, taking care not to saturate the surrounding stone or brickwork. While the joint was still damp, it was fully filled with the approved mortar mix. Finish to the pointing was completed by using a sponge and soft brush to emulate surrounding jointing. 


Prior to works commencing Minerva Building Restoration Ltd undertook a condition survey to provide accurate records of the condition of the stone masonry identifying the proposed works to be completed for approval by the project design team.
 

 

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