Careful underpinning was needed when restoring a former hospital. Olivia Gagan reports.
In September 2007, Falcon Structural Repairs began work on the Grade II listed Elizabeth Garrett Anderson Hospital building in Bloomsbury, London.
Soon to become part of the headquarters for public services union Unison, the Victorian building was founded by the UK’s first qualified female physician, and was one of the earliest specialist women’s hospitals. The historical importance of the site, and its listed status meant that renovations to restore the site to a contemporary workspace had to be carried out with care.
Furthermore, the building is found in the midst of one of London’s busiest locations: just off Euston Road, trains, Tubes, road traffic and pedestrians all converge in this area to make for a logistically challenging work site.
Falcon’s brief was to temporarily stabilise the existing four-storey building which had distorted by 200mm due to ground movement. They were also contracted to salvage a number of listed features, carefully log and dismantle the bay (including the carved brickwork panel at parapet level) and construct a piled underpinning scheme under the heavy four storey walls.
Buried 19th century constructions and the possibility of unexploded WWII bombs on site created complications
Work was completed nearly two months ahead of schedule in January 2008, despite being complicated by huge amounts of London traffic, difficult and restricted access, buried 19th century constructions and the possibility of unexploded Second World War bombs.
Planning issues created delays when dismantling the bay and the subsequent reconstruction of its foundations and structure. Additional works, including deep mass concrete underpinning, were added during the contract period.
In conjunction with the client’s engineers, AKS Ward, Falcon amended the design of the tendered scheme.
They installed 88 internal and external auger piles, some to a depth of 14m in and around the building, capping these with ring beams before transferring the 400kN/m wall loads to the new scheme via steel encased needles. A new reinforced concrete slab capped the foundation scheme off internally.
More recently, further contracts have been awarded to Falcon; to rebuild the bay, with the majority of the bricks handmade specially to order, assist the demolition contractor with stabilisation works, underpinning to allow construction of a planned basement within the central courtyard area, structural repairs including installation of Cintec Anchors and mass concrete underpinning to an adjacent five-storey tower.
Planning consultant Gerald Eve
Project manager Drivers Jonas
Quantity surveyor Davis Langdon
Structural engineering AKS Ward
Services Foreman Roberts