© Valerie Bennett
© Valerie Bennett

Sloane Telephone Exchange

In changing the use of the Grade II-listed Sloane Telephone Exchange we faced the issue of maintaining the grandeur of a Georgian-inspired, red-brick façade whilst implementing internal improvements which would add significant value. The 3,205 m² building, completed in 1924, was converted into ground floor office space with residential units above.

We undertook an initial assessment of the existing structure, using this to decide which elements were redundant, as well as where we could feasibly introduce new additions. We removed and infilled both existing stair cores and an existing lift core and provided two new cores and three new lifts. We refreshed the external materials, limiting the provision of new cladding to an area on the rear elevation, where a self-supporting, preassembled masonry panel was installed. Care taken to reuse existing materials meant that the environmental impact of the building was extremely low.

For the most part, the structure of the original building could remain the same; a steel frame was used to support concrete filler joist floors, while a 1970s extension to the building was in-situ concrete. The building benefitted from extremely large floor-to-ceiling heights, particularly in its double-height ground floor. A decorative stone band which wrapped around the building was exploited to mask a new first floor comprising in-situ concrete set onto profiled metal decking which acts as permanent formwork. Where modifications were needed to the floor plates, steel trimmers were pinned to the underside of the existing floors and fixed back to existing steel beams and columns, thus minimising temporary works.

We also introduced an additional top storey; due to planning height restrictions the original roof structure was removed, a steel frame was installed with a floor comprising an in-situ concrete slab with a timber roof overhead.

Retaining a Grade-II listed façade during a conversion into offices and residential units

London, UK
Cadogan Estates
PDP London
£ 8.8 million
3,205 m²