Stone Technical Services Group Ltd were contracted by John Taylor & Co. to design and erect a scaffold to the North West Tower of St Paul’s Cathedral as part of a project to remove, overhaul and re-instate the complete ring of twelve bells which were cast in 1878 by John Taylor & Co. The total weight of the bells is 13 tons, with the heaviest bell weighing just over 3 ton. At the time they were cast, and for many years afterwards, they were the heaviest peal of bells in the country.
This was the first time that the bells had been removed from the North West Tower for maintenance since their initial installation, therefore a safe system of work had to be put together using historic evidence and records, local knowledge and up-to-date methods to safely remove each bell from its position within the timber bell frame, transfer it out of the North West Tower and then lowered approximately 150ft onto waiting transport.
This all needed to be carried out whilst the cathedral was fully operational and open to the general public for religious services and sightseeing.
For security reasons, aesthetics and also cost implications, the scaffold required to carry out the works could not be built from the ground up, therefore this also had to be taken into consideration when designing the scaffold.
St Paul’s Cathedral is Grade l Listed so this had to be taken into account when designing the scaffold so that its erection and final imposed loads did not impact the structure in any way.
Working in partnership with the Clerk of Works, the Architect to St Paul’s Cathedral, John Taylor & Co. Loughborough and structural engineers, Stone Technical Services Group Ltd designed an aluminium tube, frame and fitting cantilever scaffold that could be erected using rope access techniques from within the North West Tower bell chamber. Once constructed an independent company was brought in to load test and certify the scaffold prior to hand over.
Weekly inspections of the scaffold were carried out by STS with each inspection recorded in a register held onsite, along with the industry standard Scaff Tag System displayed at the entry point of the scaffold within the bell chamber.