10 Trinity Square

Sep 03, 2013

10 Trinity Square is one of the best known – yet also one of the least known – buildings in London. Standing just behind the Tower of London, this imposing building is a familiar landmark to millions of Londoners and visitors to the capital, yet few have ventured past its doors. Now work is underway to give 10 Trinity Square a new lease of life, with Byrne Looby Partners playing an important role in ensuring the structural integrity of this important building.

10 Trinity Square was designed by Sir Edwin Cooper in a grand neoclassical style, and opened by David Lloyd George, then Prime Minister, in 1922. The building was originally home to the Port of London Authority, and hosted the inaugural reception of the General Assembly of the United Nations in 1946. More recently, the building was used as offices and was even used as a location in the 2012 James Bond film Skyfall. Now it is undergoing a transformation under the ownership of The Reignwood Group, and will re-open as a 120-bedroom hotel with 41 serviced apartments alongside a private members’ club, spa, two bars and a restaurant.

The development of the building includes constructing a basement level below the existing courtyard and the construction of a new zinc panelled roofing structure. Donban Contracting UK are the main contractor on the project with PJ Edwards Hills and Fussey carrying out a variety of piling works. Byrne Looby was employed by both contractors to provide specialist geotechnical and structural design during services the project.

One of the key features of 10 Trinity Square is an imposing 51-metre high tower facing the River Thames. Over the years the building has suffered structural damage – not only because of its proximity to the river and the water table but also thanks to bomb damage sustained during WWII. Byrne Looby were commissioned to carry out a 3D Finite Element analysis of this part of the structure which would assess the suitability of the foundations, establish the existing loading arrangement and analyse how this would change with the new additional loads. Byrne Looby used this analysis to establish the optimum underpinning arrangement to support the tower.

These design elements were complex as they needed to take into account the new loading on the structure and ensure the structural integrity of the Grade II* listed building. The courtyard basement solution included a contiguous micro-piled temporary retaining wall to support a 5.5m deep excavation for the new basement. The permitted movement tolerances for the building were tight (limited to 5mm vertical and horizontal movement) to ensure that the façade did not become damaged during construction. Inclined micropiles were also required to underpin the existing building and support the façade.

Thanks to Byrne Looby Partners’ work, 10 Trinity Square’s new future within the UNESCO Tower of London World Heritage Site is assured, and the building will soon be opening its doors to the public.