PROJECT SPOTLIGHT: Gresham St Paul’s, City of London
Specified by: Wilkinson Eyre
Gresham St Paul’s on Gresham Street in the City of London has undergone a £50 million transformation, delivered by Mace. Designed by leading architectural practice, Wilkinson Eyre, the project has maximised the building’s net internal area with an extensive remodelling programme, and added a three-storey extension at roof level.
Originally constructed just 22 years ago, Gresham St Paul’s has undergone a radical transformation to elevate it to the contemporary standards of Cat A office accommodation expected by corporate occupiers. Effectively, the project has created an entirely new building within the existing shell, delivering a contemporary BREEAM ‘Excellent’ rated development.
The building’s existing Portland stone façade has been retained and simplified with aluminium in-fill panels. The design intent was to carry through the materiality of the existing Portland stone to the three-storey extension, however, the possibility of using Portland stone was discounted early in the specification process.
The architect needed to find a cladding material that would reference the existing building and answer planning requirements, while working within the loading parameters of the original structure and meeting a series of criteria; look and feel, cost, fire safety, weathering, green credentials and mechanical suitability. The design team also considered a number of reference projects, which included Axtell House, where Shackerley’s SureClad® Engineered Stone system was used for the façades of additional storeys to co-ordinate with the original building’s Portland Stone.
Shackerley’s SureClad® Engineered Stone system offered a viable solution for the buildability challenges of working at height on a confined site in the City. Mace’s strategy was to install the façade as a modular system, with each pre-fabricated façade section delivered to site as an installation-ready module that could be craned into position and secured in place. A successful collaboration between Shackerley, and Austrian façade specialist, GIG Fassaden, resulted in a bespoke pre-fabricated module installation scheme to aid speed, ease and safety of installation. The cladding modules were delivered to site on a just-in-time basis and installed aligned to the wider construction programme.
Shackerley’s SureClad® Engineered Stone system was used in a creamy beige Valpolicella colourway and sandblasted finish. The large format panels were 3050 x 1240mm and just 30mm thick, providing the visual impact of large pieces of stone with a lightweight solution.
Thanks to Shackerley’s technical expertise and ISO 9001 certified manufacturing capabilities, both the SureClad® Engineered Stone large format panels and the 400 modular façade units required for the project were produced at one of Shackerley’s Lancashire factories.
The custom-designed modular units utilise Shackerley’s tried and tested under-cut anchor and bolt fixing system, with the panels secured directly onto an aluminium frame, designed and supplied by GIG Fassaden.
Tzi Leung from Wilkinson Eyre comments: “Shackerley’s SureClad® Engineered Stone system scored well against all our assessment criteria. Robust and lightweight, it is fire tested and certified as A2-s1,d0 in line with BS EN 13501-1. The creamy beige Valpolicella engineered stone material with white variegation we selected from Shackerley’s extensive range provided an ideal match for the existing Portland Stone façade and the sandblasted finish created the right aesthetic for the project.”