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AJ SPECIFICATION CASE STUDY

30 Cannon Street by Delvendahl Martin Architects

Delvendahl martin architects index
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Delvendahl Martin Architects explains how the practice refurbished a Grade II-listed 1970s office in the City of London. Photography by Tim Crocker

SPECIFICATION STATEMENTPROJECT DATA

Number 30 Cannon Street is a Grade II-listed office building occupying a prominent, wedge-shaped site near St Paul’s Cathedral in the City of London. It was designed in 1977 as the London headquarters of Crédit Lyonnais by Whinney Son & Austen Hall. The building was the first construction in the UK to use glass reinforced concrete (GRC) panels (developed by Pilkington and Arup) on its façade. In 2015, 30 Cannon Street was added to the National Heritage List in recognition of its architectural value and contribution to the built environment.

In 2013 Delvendahl Martin carried out a feasibility study. Our brief was to determine the redevelopment potential of the building in response to current market conditions. We were subsequently appointed to undertake a comprehensive refurbishment that included the reconstruction of the fifth floor to incorporate additional space, refurbishment of the entrance lobby and a new roof terrace. In addition, we carried out the upgrade and relocation of the existing building services and reglazed the main façades. 

Delvendahl martin architects2

Delvendahl martin architects2

Our aim was to preserve the architectural integrity of the building, which required extensive research to identify the original elements, modifications and later additions. This research helped to establish three main design principles that our new elements adhered to geometry, materiality and colour.

Eric Martin, director, Delvendahl Martin Architects

Site plan

Site plan

Ground floor plan

Ground floor plan

Third floor plan

Third floor plan

Fifth floor plan

Fifth floor plan

Roof floor plan

Roof floor plan

Specification statement 

As with any refurbishment project, most of the decisions regarding the selection of products were made to achieve a balance between the existing and the new elements. In this case since the building is listed, attention had to be paid to make sure the integrity of the original design was not only maintained, but enhanced.

This was achieved by establishing a clear set of principles from the outset, where new components not only had to match the quality and robustness of the existing, but also either follow the colour palette or the geometrical principles of the building. The aim was to create a continuity of the spatial sensibility while avoiding pastiche. This approach becomes clear in the design and rhythm of the new curtain wall façade, which is based on the building’s 1.5m structural grid. The white vertical fins have the same slope as the GRC, which makes the façade read, from certain angles, as a seamless continuation of the existing. 

Sectionaa

Sectionaa

Another example is the geometry of the new roof garden planter and bench, which were generated from a delineation of the building’s footprint with its characteristic rounded corners. Short timber slats were chosen for their flexibility to follow different radii and absorb tolerances.

Eric Martin, director, Delvendahl Martin Architects

Detail

Detail

Project data

Start on site March 2015
Completion September 2016
Gross internal floor area 2,500m2
Form of contract Bespoke
Construction cost £5 million
Architect Delvendahl Martin Architects
Client Romulus Construction
Structural engineer Arup
M&E consultant Hoare Lea
Quantity surveyor and cost consultant AECOM
Glazing consultant NET Project Management Consultancy
Landscape architect (roof terrace) Applied Landscape Design and Willerby Landscapes
Lighting Supplier for the lobby: The Light Lab
Project manager Romulus Construction
CDM co-ordinator Bernard Williams Associates
Approved building inspector HCD
Main contractor Capel
CAD software used Vectorworks and AutoCAD

Free event

Eric Martin of Delvendahl Martin Architects will be speaking at AJ Specification Live: Retrofit on 18 October at 6.30pm – click here for more details

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