St. Paul’s Cathedral
This was not only a prestigious project but also a very worthwhile cause. The project involved the modification of the existing staircase to the Whispering Gallery in order to facilitate disabled people to gain access.
The spiral staircase to the Whispering Gallery wraps around a brick built circular hollow central core. This originally extended from the Church floor level upwards. The task was twofold. Firstly, it was necessary to increase the internal diameter of the hollow brick built central core to accommodate a disabled lift assembly. Secondly, the central core needed to be extended 2 stories downwards, through the foundations of the Cathedral, to be level with the cafeteria down at Crypt level. In order to form a horizontal corridor between the Cafeteria and the disabled lift, it was necessary to tunnel some 20 metres to connect the two areas.
This is a view looking downwards from the Whispering Gallery through the hollow central core of the spiral staircase. The base of the core at Church floor level can just be seen through centre of the scaffold. In order to increase diameter of the core, the original brick liner was partially removed and progressively replaced with a thinner section of reinforced concrete.
At Church floor level, where the spiral staircase originally started, it was necessary to introduce a circular ‘Pynford’ beam around the base and then to excavate downwards to Church Crypt level. This photograph shows the completed ‘Pynford’ beam and the support columns. These columns were placed progressively as the excavation took place.
At the bottom left of this photograph, one can just observe the blockwork entrance to the horizontal tunnel connecting the new base of the circular stair core to the cafeteria. This enables a person in a wheel chair to travel from the cafeteria on a level line into a disabled lift placed within the enlarged central core. The foundation of the existing Cathedral was apparently constructed using debris from the building that existed prior to the Fire of London in 1666. We were informed that the dark coloured stone was actually the soot stained debris which the original builders incorporated into the weak concrete foundation. We partially broke out this foundation in order to extend the stair core downwards thus revealing the blackened stone.