Butterfly Walk

Split across three blocks, the 25,000 sq m scheme will deliver new and improved public realm, retail spaces, a 102-bedroom hotel, an eye hospital, and 145 new homes with amenity space.

Block A will provide residential accommodation across a 12-storey reinforced concrete tower and a lightweight three-storey build with a basement. The reinforced concrete frame, on continuous flight auger piles, will be stabilised by reinforced concrete shear cores.

Due to planning restrictions on height, the slab depths will be slimmed down to 220mm in conventional reinforced concrete. Precast columns and walls will be installed to speed up the construction process. The basement will be formed using a secant pile wall due to the high water table, and the low rise apartments will likely be constructed using Modern Methods. 

Block B forms Phase 2 and involves creating 100 new residential units adjacent to an existing retail unit, with the new eye hospital built above the store. Internal foundations and columns are to be upgraded to cater for the additional load from the eye hospital while the commercial space remains operational. We developed an outline construction methodology and construction sequence animation to demonstrate to stakeholders how disruption will be kept to a minimum.

We undertook a detailed appraisal to explore the feasibility of the additional storeys, including Vierendeel girders to span over the existing units, and strengthen and build on top of the existing structure while keeping the ground floor commercial units operational. Specialist surveys indicated the capacity of the existing structure had sufficient capacity without expensive or intrusive strengthening works or the need for a heavy transfer structure.

Each Block has been fully modelled in 3D to aid collaboration. Due to the complexities of the build, the 3D model shows each key step throughout the phasing programme and construction sequence will be developed with our augmented reality software.