The Angel Building.

Velveteen concrete envelops the vast foyer of the Angel Building, the soft grey finish complementing an elegant interior design. An array of impressive features delivered multiple awards for this rejuvenated commercial block in London’s vibrant Islington.

Location

London, UK

Client

Derwent London

Architect

AHMM, Veretec

Project Value

£ 70 million

Floor Area

24,000 m²

Status

completed 2010

Expertise

Structures

Architect AHMM’s objective was to sustainably reinvent the 1980s structure, delivering an efficient, state-of-the-art commercial workspace. The existing building provided considerable potential for extension: our design pushed the sides of the building out to meet the site boundaries and made skilful use of a wasted central courtyard.

Initial calculations demonstrated that the existing foundations had been designed to take a much more substantial load than that imposed. Capitalising on this, we introduced new piles and ground beams only where necessary. We analysed the structure and increased support in weaker areas as well as below the extensions where cantilevering was not possible. Existing tree roots were potentially obstructive, so pile diameters were minimised to allow flexibility. The route of a future sewer also cuts through the site, so liaison with the utility company was crucial in creating a functional design within tight constraints.

We used steel frames for the additional elements, chosen for speed of construction and its minimal load implications. Due to the risk of differential deflection, connection details were carefully reviewed, with innovative bonded fibre strips introduced where strengthening was required and existing movement joints following through into the new structure.

Providing a column-free foyer also required complex analysis. Storey-high Vierendeel trusses span 10 m across the open-plan area, supported on encased steel columns. The atrium rises six floors through the core of the building, capped by 1.8 m cruciform concrete supports and a luminiferous ETFE cushion roof. A new energy efficient glazed façade wraps around the building, replacing dated mirrored glass, and rooftop plant was moved to the basement, offering stunning views to staff and visitors.