London
54 The Broadway
The renovation and refurbishment of 54 The Broadway for commercial use was commissioned by owners British Land, working in collaboration with main contractor McLaren Construction Group. British Land appointed evolve to provide civil and structural engineering services for these works.
54 The Broadway, previously known as Crystal House, forms part of Ealing Broadway shopping centre which opened in 1985. The centre includes a mix of retail units at ground floor level and commercial office space on the upper floors, with a multi-storey car park at the rear.
The proposed structural works were to include the complete renovation of three floors of office space, ground floor reception area and basement. This was in addition to the installation of new lifts with existing shafts and complete refurbishment of the rear terrace area, including bespoke cantilever frames to support large awnings.
Client: British Land
Location: Ealing Broadway, London
Sector: Offices
Completion Date: Date 2020
Architect: Corstorphine + Wright
Key Evolve Contacts: Ian Craig & Phil Hunter
Project manager: RPP
Main Constractor: McLaren Construction Group
M&E Engineer: Insignis Consulting Engineers
Challenge
This ‘cut and carve’ commercial refurbishment has completely revitalised 54 The Broadway.
An updated external façade designed by architects Corstorphine + Wright and a modern new entrance canopy, supported by the existing structural canopy frame, have fully refreshed the external appearance of the building. The demolition of existing pre-cast façade elements, and the addition of the new façade, enabled the installation of larger windows on the south elevation which introduced significantly more light into existing areas.
The internal fit-out centred around the idea of exposing the existing concrete waffle slab soffits within the office floorplates while exposed services have helped give the space an added urban edge. The existing reception was enhanced to provide a warm, inviting space for users of the building, incorporating the British Land concept of a ‘world class welcome’.
All new structural elements have been designed and specified for life in excess of 50 years. The upgrades and enhancements to the existing façade and overall fabric of the building, alongside new M&E installations, have improved the overall thermal performance. Energy efficient measures were also introduced throughout the scheme including the use of low carbon technology for heating and cooling.
Solution
A number of site constraints were taken into account during the structural design phase. The ground floor retail units and shopping centre entrance were to remain operational for the duration of the works, while the location of the ‘landlocked’ site in the town centre also caused logistical challenges. A temporary gantry was installed above the public footpath just off The Broadway which incorporated a lifting beam and goods hoist to aid material and plant movement into the building, while minimising disruption to pedestrians.
Although built in a similar style to the main centre, 54 The Broadway was originally constructed during a later phase of the Ealing Broadway development. The six-storey building, which includes a part single-storey basement, has a reinforced concrete (RC) frame structure with ribbed slabs at ground and first floors, and waffle slabs at second and third floors.
An analysis of the original RC drawings showed that the waffle floor slabs were not reinforced as two-way spanning flat slabs as one would expect but were instead one-way spanning onto the front-to-back beams which were very heavily reinforced. There were no shear walls or bracing within the building and therefore the structure’s stability was assumed to be provided by frame action.
The existing Broadway-facing façade above the ground floor retail units was formed with brick cladding and precast concrete features to the main structural columns. Glazing and spandrel panels in between the columns were articulated out horizontally at floor levels and vertically at intermediate mullion positions.
As part of the renovation, this façade was replaced between the main brick clad columns with a simpler flat curtain walling system. The intermediate mullions, and the lintels and blockwork they supported over the windows, were also removed. The existing upstands and main structural columns were retained, as was the corresponding cladding.
A tea and coffee station in the newly refurbished reception was formed within the existing stair core. This masonry core was load bearing, providing support to the stair flights and landings. The new opening in the masonry wall was formed largely within the zone of the stair flight, while a new post to support the landing above was introduced to enable the opening to be widened further. The double height reception space was also given a new glazed balustrade.
New lifts were installed in the existing lift shafts, with new lifting eyes fixed into the shaft capping slab which was formed of 200mm thick reinforced concrete. Co-ordination was required with the existing opening in the lift shaft concrete lid.
The basement was reconfigured to provide a stylish washroom area for commuters including showers, lockers, and vanity area, with existing drainage outlets used where possible. An existing masonry wall was reconfigured to assist with access to the basement and to form a new basement lobby. A review of the record drawings indicated that no load bearing masonry walls were present in this area; the walls were therefore able to be reconfigured without adversely affecting the structure.
An enhanced cycle facility with maintenance station was installed externally – another welcome addition to the building’s commuter facilities.
The terrace area was also totally transformed with impressive cantilever frames supporting a 3m awning to create a fantastic outdoor amenity.
