Home Office Headquarters, UK
Sector: Buildings - Offices
Cost: £ 150,000,000
Client: PFI Consortium Member, Bouygues
Location: London, UK
Provides 70,000sqm office space with associated sports, restaurant, library facilities and basement car parking It includes 3 residential and mixed-use buildings providing 144 apartments and further basement car parking. By reusing foundations and sustainable design, it achieved BREEAM ‘Excellent’ rating. The building also won three awards in 2005, namely, the RIBA Award, the Concrete Society Award, for ‘Outstanding Merit in the Use of Concrete’ and LEAF Award for ‘Best Public Building’.
The development of the structural design highlights the benefit of close co-operation with the contractor’s team from an early stage. The structural frame utilises the speed of a predominately precast concrete solution with each floor plate being cast in an 11 day cycle. Insitu concrete stitching and careful detailing provides a robust solution which satisfies the requirements for bomb blast resistance.
The substructure design re-uses the existing rafts and retaining walls remaining following the demolition of the three old tower blocks. This design solution has allowed significant savings to be made in terms of both time and cost. The mixture of demolition combined with construction of new foundations on top of the existing foundations has, however, posed a challenge for the geotechnical engineering team. It has been necessary to carry out detailed analyses of the foundation movements to predict likely differential ground movements and ensure that the new structure can accommodate these movements. Large quantities of mass filling have been carried out to compensate for the variation between the historical loads on the underlying soils with the new loads.