A complex temporary works design for the Grade II listed redevelopment of New Zealand House — balancing heritage fabric, buried vaults and an accelerated City programme.

New Zealand House is the redevelopment of a 1960s Grade II listed tower block in Westminster, adjacent to His Majesty’s Theatre — also Grade II listed, constructed in 1897. The £150m landmark retrofit demanded an approach that safeguarded heritage fabric while enabling an ambitious, accelerated programme.

BG&E were engaged to develop a temporary works strategy and design that balanced complex city-centre constraints — buildability, an accelerated programme, utility and infrastructure interfaces, and the need to protect the heritage value of both New Zealand House and the theatre’s historic fabric.

To find the best solution, BG&E applied advanced technical analysis to manage below-ground risk — rigorous assessment of geotechnical conditions, ground movements, impact on adjacent foundations, underground services and LUL assets, and verification of the ground loading on buried historic vaults. This demonstrated the compliant use of a 450-tonne mobile crane, accelerating the programme by releasing multiple concurrent working fronts.

To improve buildability and safety, BG&E designed out temporary works and complex strengthening by demonstrating the adequate capacity of the existing structure, with solutions sensitive to the architectural requirements. Construction risk and proximity to the public were managed through detailed specification of critical temporary propping and clear sequencing requirements. Going further, the temporary works design maximised proprietary systems — enabling reuse and minimising material consumption and carbon.

BG&E’s design enabled the complex landmark retrofit to an accelerated programme, while securing approval from Historic England, Thames Water, Cadent Gas and London Underground (Bakerloo line).