© James Balston
© James Balston

20 Northdown Street

This seven-storey mixed-use scheme in King’s Cross was designed and funded by architects Squire and Partners. A top-lit central lightwell, together with sunken wells and full height glazing to the front and rear elevations allows natural light to flow deep in to the basement and ground floor office plan.

Built on the site of a former three-storey building, the new development is sandwiched between three adjacent properties. Both the excavation of a full basement and complex boundary conditions generated the need for extensive underpinning of party walls, as well as the installation of temporary sheet piles and king post retaining walls. The choice of temporary wall system was driven by restricted site access and the need to minimise loss of internal area.

The presence of the Victoria line beneath the site precluded the use of piles, resulting in the development of a raft foundation to support the reinforced concrete superstructure. The position of a central lightwell and access core divides the upper floor plates into two sections, with each bay consisting of a flat RC slab supported by a single internal column and localised slab thickening. Perimeter support is provided along each boundary by a series of columns that transfer down through the various floor levels and in turn are supported on the permanent perimeter RC retaining wall.

The single penthouse unit, with spectacular views across London from its private terrace, is formed from a simple, economic lightweight steel frame portalised in each direction for stability. Discrete shear walls at each end of the core and the framing action of the perimeter columns provide the overall building stability system.

The inclusion of a feature steel and stone stair which runs between ground and basement, as well as the crisp detailing of the oak timber, natural stone and glass façade, combine to make this a distinct development.

Stylish seven-storey scheme incorporating commercial office space and luxury penthouse apartment

London, UK
Squire and Partners
Squire and Partners
£ 5 million