Institute of Physics

Balfe Street

In 2016 CDS were appointed by Murphy Ltd. to design the façade retention system for this project, as well as providing a design for lowering the basement by two levels and support for the party wall. A particular challenge on this project was that the main façade on Caledonian Road was to have its entire ground floor section removed.

The façade retention system was split into two elements. On Balfe Street, a scaffold system was used and on Caledonian Road a steel frame was used. Both façade retention systems were installed externally, so as not to disrupt the basement works that would follow. For the Caledonian Road steel frame, the inner leg was installed into plunge piles and the outer leg was fixed into concrete kentledge blocks. Cantilever needle beams picked up the vertical weight of the façade. From these façade retention towers, support to the party walls were also added via flying shores.

In the basement, all of the walls were underpinned which included the vaults under the pavement on Caledonian Road and the party walls on both sides. On Balfe Street, there were no existing vaults or basements, meaning that the full height of soil needed support. In addition, there were architectural details, such as visual structural concrete, which limited the position in which the steel frames could be placed. The result was a complex, two-level raking prop system with walers that were placed on stubs, to allow the concrete behind to be cast easily. Further works included needling schemes to the vault walls to allow the permanent works to be installed.