Four Pancras Square
As part of the regeneration of King’s Cross in London, Four Pancras Square is the last of six new commercial buildings in the area known as the ‘B Zone’; a commercial zone centred on the new Pancras Square. Comprised of ten-storeys, an open landscaped roof terrace and two levels of basement, the project provides high specification office space, with various amenities and retail units at the ground floor.
The structure adopts both steel and concrete primary structural elements, with an exposed external frame of weathering steel providing support to the slab edges. The internal grid of 9×9 m utilises a post-tensioned flat slab solution, whilst stability is provided by the central reinforced concrete core. This is positioned symmetrically between the north and south edges, allowing 10 m of space between it and the façades.
An exposed Vierendeel truss runs around the perimeter of the building between the first and second floor slab levels, providing the necessary transfer to create a more open column grid at ground floor. Steel balconies are provided at intermittent floors on the north and south to give outdoor amenity, supported by steel rods hung from the slab soffit above.
Plant areas are divided between the basement, level 1 and level 10, where thicker slabs were required, with the latter level also containing office space and an external terrace. Level 11 comprises a landscaped terrace with a mixture of planting beds, raised timber decking, water pools and rocks. The position of large boulders also had to be agreed due to the significant load.
The substructure comprises bored concrete piles, taking support from the London clay and Lambeth group soils below, and is coordinated with the wider B zone basement, creating a service link; whilst the northern boundary to the basement is formed by piled retaining walls that were installed in 2011 as a part of the zones’ enabling works package.
Ten-storey office building with exposed frame of weathering steel in Pancras Square
Eric Parry Architects