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An opulent Mayfair apartment scheme features high-strength precast columns and spandrel panels, with a subtle black acid etched finish, supplied by Cornish Concrete Products.

Burlington Gate is a stylish new development of 42 luxury apartments in the exclusive London neighbourhood of Mayfair.

Precast columns, spandrel panels and permanent formwork, supplied by Cornish Concrete Products (CCP), have played a key role in both the structural design and aesthetic considerations of the project.

Developer Native Land selected Rogers Stirk Harbour + Partners as concept architect for the nine-storey scheme, which sits between Old Burlington Street and Cork Street, and comprises two separate linear buildings separated by an internal courtyard. The project involved transforming an existing commercial building into 65,000 sq ft of residential accommodation, along with 25,000 sq ft of retail spaces on the lower floors, and creation of a new arcade, connecting the
two streets.

Multiplex was appointed main contractor and work got underway in June 2015.

The choice of precast components was driven by the architect’s desire for high quality finishes on the exposed concrete, says David Moses, preconstruction director at CCP.

“The vertical columns, and the horizontal spandrel panels which span between the columns, have a black acid-etched finish, and these precast elements are exposed on both elevations of the building,” he explains.

While the vertical columns are structural, the 8m-long spandrels are in fact decorative. The floor slabs were poured in situ, using permanent formwork units, which have a black finish.

“Together with the columns, the spandrels and the formwork create the illusion that the structural frame was created in one seamless pour,” says Moses.

The vertical columns, 900mm by 400mm in cross section, are twostorey height and mostly 7m long, apart from on the upper four floors of the street elevations, where the facade is inclined. The raking columns on these levels are 9m in length, and again two storeys high.

The high level of reinforcement necessary for the columns, coupled with the aesthetic requirements of the finish, meant the casting was a major challenge for CCP.

“There is a considerable amount of rebar in each column, which meant we had to cast in lifting points on top of the columns, instead of fitting the usual concealed connector,” says Moses.

“From an aesthetic viewpoint, we were concerned that the lifting points would be visible. So, after consulting with the architect, we decided to fit stainless steel caps over the top of each lifting point, after the columns had been installed, making a feature out of them.

“We also had to fit bespoke steel plates for the column and spandrel panel connections back to the floor slabs, and steel nodes for external cross bracing which was to be added on the internal courtyard elevations,” adds Moses.

CCP worked closely with Rogers Stirk Harbour + Partners to develop the high strength mix for the precast components. This is a combination of crushed black
basalt coarse and fine aggregates, stent with a high mica content, a CEM II/B-V PFA, plus ordinary Portland cement.

Along with internal columns, CCP supplied over 100 vertical and raking structural columns – 72 double height and 28 single height – for the project,
plus 60 spandrel panels and 45 permanent formwork units.

CCP began its manufacturing process in February 2016 and completed installation of the precast elements on site in October the same year.

On the street elevations, the grid created by CCP’s precast columns and spandrels is infilled with stainless steel-framed windows interspersed with solid panels of handmade bricks, which match the dark finish of the exposed concrete.

The elevations facing the courtyard have steel crossbracing across sections of the
facade, a signature feature of the Rogers Stirk Harbour + Partners practice, with echoes of its Pompidou Centre design in Paris.

The overall project was completed in late 2017.