30 Gresham Street
Contractor Sir Robert Mc Alpine Ltd
Photos: Charlotte Wood
The project was for a nine-storey building, bounded by four main streets (from North clockwise) Gresham Street, Lawrence Lane, Russia Row/ Trump Street, Milk Street.
The concept of one distinct solution for the curtain walling on each façade did not apply to this project. The three main cladding materials: glass, aluminium and stone are noticeably separate from each other.
On plan the building has an irregular arrangement, with a curved corner and façade that follows the angle at Gresham Street and preserves the urban space in front the Guildhall and Lawrence Jewry Street. The building is partly clad with "punched windows" inserted into the stone clad north elevation. The main curtain walling of the other elevations, consists of glazed and aluminium façades. All the façade types are projecting from the building plan for the first 5 floors and then change their geometry on the 6th, 7th and 8th floors where they are recessed. This solution reduces the visual impact of the building from Lawrence Jewry Street.
Two exciting findings were unearthed during the area redevelopment: Roman water works, the first of their kind to be discovered in Britain, and a 13th-century Jewish ritual bath, having only one similar example in Britain, in Bristol.
Whilst not in a Conservation Area, Gresham Street is nevertheless part of the historic centre of the City of London. That centre has a scale and "grain" that in this location has largely been lost during post war reconstruction. Of particular influence however are the historic buildings forming the Guildhall complex and the church of St Lawrence Jewry.
Flat and curved unitised curtain walling
Flat and curved punched windows
Bolted glazed façades
An average thermal insulation not exceeding 2.0 W/m2 °K.And an acoustic performance to the levels of attenuation requested.
The use of such technology involved a high level of production, which was constantly quality controlled.
The main curtain walling areas include fully prefabricated aluminium spandrel panel units between columns, floor to floor height vision areas, and curved aluminium cladding around the feature columns.
The spandrel panels, which span from column to column, are manufactured in single independent units, each individual element being up to 11 metres long. It’s profile and shape designed to meet the specific architectural requirements. The spandrel panels consist of external aluminium sheets with PPC feature profiles and internal stainless steel sheet. Between the internal and external metal sheets there is insulation which ensures compliance with the specified U-value. The vision units are supported by the slab and are independent from the spandrel panel, this allows for any movement and deflection of the building structure.
The same technique in terms of prefabrication was adopted for the vertical aluminium column cladding to the structural columns. These aluminium column covers have a semi-circular shape, which matches the rounded stone columns at the ground floor. Here the vision areas of the curtain walling consist of fully unitised structural silicone glazed panels.
The main curtain walling has been designed to give an overall appearance of projecting bay windows within vertical and horizontal aluminium feature cladding. The bays have small glazed projections on each side with an aluminium head and soffit.
Between each glass panel there is an external feature glass fin which, if necessary, can be replaced by disconnecting from inside the building and lowering to the ground outside.
"Punched windows": 3000x3250x250mm - 850 kg
The "punched windows" are three-dimensional windows, similar to a large bay window, each window was delivered to site completely prefabricated and then craned into position.
The unusual dimension of the windows (3000 x 3250 x 250 mm) required the design of bespoke equipment both for manufacture, transportation and installation.
Once the installation was completed, feature stone fins were fixed to the front face of the window mullions.
Curved "punched windows"
The same principle as described above was used for the curved punched windows. These windows have a greater dimension at 8000 mm x 3250 mm – 1300kg. The installation of these windows involved the use of one-off equipment that was designed, manufactured and thoroughly tested by Focchi before use.
Brise Soleil Louvres
Aluminium louvres of width 410 mm provide shading at 7th and 8th floor.
Bolted glazed façades
Interesting features of this solution are the glass fins 4500 mm high and 19 mm thick which are fixed to the underside of the floor slab above with substantial stainless steel brackets. The point fixings of the glazing were bespoke designed for this project. The revolving doors were a feature of both main entrances and the automatic pass doors also acted as smoke vents.
Smoke vents windows
The bespoke windows along the two stairwells have dimensions of 1500 mm x 3200 mm, the opening leaf has a weight of 190 kg, and is electrically operated to open to 45° when/if necessary.
Sidell Gibson Partnership
Sidell Gibson Architects is a London and Birmingham based Architects Practice, started in 1973 by Ron Sidell and Paul Gibson partnership. The practice has an established track record in commercial, residential, and several specialist sectors including education, housing and interior design. Sidell Gibson Partnership LLP includes John Miller + Partners with Sidell Gibson Architects and Sidell Gibson Crouch Butler. Sidell Gibson Architects believe that each building should respond to its location not only architecturally, but also in terms of its environmental performance; they are proud members of the UK Green Building Council, The Green Register and the Association of Environment Conscious Builders.