In pics: Google's King's Cross HQ plans in

Google has submitted new planning documents for its proposed £1bn headquarters at London’s King’s Cross.

The new 80,819 sq m building has been redesigned by US-Danish architect BIG and Heatherwick Studio after the tech giant parted ways with previous architect AHMM. The executive architect is BDP.

The 11-storey building will sit on a plinth punctuated by office entrances with up to 15 retail units at ground level along King’s Boulevard – totalling 4,376 sq m of space.

It will also feature a three lane, 25m long pool, multi-use games area and gym on its upper floors and an 8,590 sq m landscaped roof garden, while an events centre occupies the lower ground and first and second floors.

The events centre will be used by Google for product launches, talks, presentations and industry events. Google said it also anticipated the space would be used by technology-focused organisations and community groups or charities.

The roof garden will include a 200m “trim trail” – a running or walking track with exercise stations at regular intervals.

Google said its new “stepped” terrace-style HQ would house 4,500 employees, who would be able to access the building via a diagonal staircase running through the building. The staircase will also function as a space for social gatherings with the steps creating seating areas to watch events taking place games area. The building will also be dotted with several cafes and outdoor seating areas.

The web giant has also submittied plans for a triangular shaped area at the southern end of its proposed new HQ and the existing Battle Bridge Place.

Google appointed Lendlease as the main contractor in January on the job, which was revealed by Building. The original project was going to be built by Bam, but the contractor did not pitch second time around.

Building also revealed last week that the first subcontractors will be appointed over the summer to allow a rapid start on site. The job has an estimated construction cost of £350m.

A source close to the project previosuly told Building: “The work carries on in terms of design [once plans are submitted] and they’ll start tendering for subcontractors over the summer. Some clients stop during planning but they won’t.”

The project will fill a 1-hectare hole at the southern end of developer Argent’s wider 27-hectare regeneration scheme, next to King’s Cross station.

A second source said: “Everyone’s delighted it’s moving on. I don’t think there’s any doubt it’ll go ahead. It’s massively important to the overall Argent scheme, it gives two sides to the main boulevard leading up from the station and will help [Argent] attract retailers. It’ll be a terrific addition.”