London Museum

The 1880s General Market structure had extensive deterioration across its cast iron columns, wrought iron girders and brick vaulting. Introducing new gallery floor loads, exhibition platforms and services penetrations required understanding the existing structure's real behaviour before designing reinforcement schemes. Traditional code-based analysis couldn't reliably predict how these hybrid Victorian construction systems would perform under new loading conditions.

We conducted comprehensive structural assessments using non-destructive testing combined with targeted intrusive investigation to map the condition and capacity of existing elements. Our team developed bespoke connection details between new steel and concrete elements and the existing iron girders, accounting for material degradation and construction tolerances in a140-year-old structure. We specified strengthening schemes that preserved the historic structural fabric while meeting modern loading requirements for museum galleries and circulation spaces.

This detailed assessment gave Keltbray confidence to proceed with the demolition and enabling works, with Sir Robert McAlpine assured that the existing fabric could safely support the new museum functions with targeted reinforcement rather than wholesale replacement.

Converting former goods depots and salt stores into gallery spaces required extensive excavation, underpinning and new slab construction directly adjacent to the live Thameslink corridor. An 800m² network of Victorian vaults was rediscovered, requiring removal of up to 1,800mm of material for new ducting. Ground movements had to meet stringent railway settlement criteria while maintaining construction access. Any instability would have disrupted rail services and compromised the historic vaults above.

We developed integrated temporary works combining wall retention, underpinning and extensive floor propping to control ground movements throughout excavation and construction. Our team created 3D geotechnical models analysing soil-structure interaction at the rail interface, with monitoring regimes tracking actual performance against predicted behaviour. We sequenced underpinning operations and service trench excavations to maintain global stability while protecting Victorian vault geometry above.

These systems enabled Keltbray to safely execute basement remodelling and services installation while maintaining rail operations and protecting the historic structure.

Keltbray's enabling works required simultaneous façade support, roof strengthening, vault conservation and new structural installations across two separate market buildings. The constrained City of London site had limited cranage access, narrow surrounding streets and strict heritage protection requirements. Traditional sequential construction would have extended the programme, but parallel working introduced complex interface risks.

We created detailed construction sequences coordinating façade retention, floor propping and new structural installations across both buildings for Keltbray's enabling phase. Our team designed temporary works interfaces between subcontractor packages, ensuring each system maintained global stability while allowing phased removal as permanent works progressed. We developed bespoke propping providing access for Keltbray's follow-on trades while supporting deteriorated floors and walls during structural alterations.

This enabled Keltbray to maintain high momentum with multiple subcontractors working simultaneously, reducing demolition and enabling phase duration.