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Leaden hall building:
The Leaden hall Building at 122 Leaden hall Street, is popularly known as ‘The Cheese grater’ because of its distinctive slanting profile, created to respect a protected sight line of St Paul’s Cathedral from Fleet Street. It was designed by architects Rogers Stirk Harbour + Partners “RSHP” for The British Land Company plc and Oxford Properties.
The building comprises a number of architectural elements that provide clarity to the composition both as a whole and as a legible expression of its constituent parts. These elements include:
The primary stability structure.
The ladder frame.
The office floor plates.
The northern support core.
The external envelope.
The public realm.
The structure aims to reinforce the geometry defined by the development envelope, which in turn creates the distinctive tapering form, and takes the form of a perimeter braced ‘tube’ that defines the extent of the floor plates. The ladder frame contributes to the vertical emphasis of the building, and encloses the fire-fighting cores that serve the office floors. The frame also visually anchors the building to the ground.
The office floors take the form of simple rectangular floor plates which progressively diminish in depth by 750 millimeters towards the apex. Office floors are connected to the structural ‘tube’ at every floor level without the need for secondary vertical columns at the perimeter.
The northern support core is conceived as a detached tower containing all passenger and goods lifts, service risers, on-floor plant and WCs. Three groups of passenger lifts serve the low, mid and high rise sections of the building, and are connected by two transfer lobbies at levels 10 and 24.
The position of the northern support core relative to the office areas means that the structure is not required to be over-clad with fire protection, allowing the whole to be designed and expressed as visible steel work. This articulated steel frame provides clarity to the whole assemblage.
The highly transparent glazed enclosure makes manifest the structure and movement systems within. The building is designed to express all the constituent elements behind a single glazed envelope. Facades to the office areas require the highest comfort criteria in relation to heat loss, daylight, glare control and solar gain. Here, the facade is supplemented with an internal layer of double-glazing, forming a cavity which incorporates the structural frame. The external glazing incorporates vents at node levels to allow outside air to enter and discharge from the cavity. Controlled blinds in the cavity automatically adjust to limit unwanted solar gain and glare.
The lower levels of the building are recessed on a raking diagonal to create a large public space that opens up to the south. The spectacular scale of the semi-enclosed, cathedral-like space is without precedent in London and will create a major new meeting place and a unique destination in itself. Overlooking the space are generous terrace areas within a bar and restaurant that provide animation and views into the public space and beyond. This enclosure is open at ground level to give access from all directions. The public space is fully accessible by means of a large, gently raked surface connecting St Helen’s Square with Leadenhall Street.
In November 2014, two bolts fractured at the Leaden hall Building, and a third bolt then fractured but and was captured by precautionary tethering. Investigations undertaken by contractor Laing O’Rourke and structural engineers Arup confirmed that the problem was limited to certain bolts. The tests concluded that the bolts had failed due to Hydrogen Embrittlement. This is a crack growth mechanism within the bolt material. Arup also confirmed that there is no adverse effect on the structural integrity of the building. A programme to replace a number of bolts will take place as a precautionary measure.
In January 2015, Rogers Stirk Harbour + Partners “RSHP”, announced that they had taken a 15-year lease on level 14 of the Leadenhall Building and would move out of their long-term home by the river in Hammersmith. They moved on 14 December 2015.
Construction period: 2002-2014
Client: The British Land Company plc and Oxford Properties
Site Area: 3,500 m²
Lettable Area: 56,670 m²
Gross Internal Area: 84,424 m²
Structural & Services Engineer: Arup
Main Contractor: Laing O’Rourke
Landscape Architect: Edco Design London
City of London Building of the Year 2015.
Working (Unbuilt category): NLA Awards
Pre-certified BREEAM Excellent Rating
The Leadenhall Building was officially opened by the Duke of Cambridge and Prince Harry on 19 Octeober 2015. See Leadenhall building opening ceremony for more information.