TERRELL’s role: Consultant to investor on all aspects of Building Engineering.
Renovation of the CB31 Tower is part of a major programme to modernise La Défense in order to ensure that the business district continues to appeal to users and investors. It is a world first in terms of scale and technical complexity. The building, which used to comprise three wings and stood 155 metres tall with 40 storeys above ground, has been raised 10 storeys to reach a total height of 218 metres and become the tallest building in La Défense. The works also included a 10-storey “levelling” of the upper floors. The office floor space has been increased by nearly 10% to 87.000 sq. metres. The entire structure has been reinforced and the building envelope totally rebuilt with close to 50.000 sq. metres of sloping glass and curtain walling, including 30.000 sq. metres of naturally ventilated double-skin façade. The scale and technical complexity of the renovation project required Terrell to pool its broad range of skills in special foundations, structural design of high-rise buildings, structural steelwork, façades, pre-stressing and renovation. The tower has been awarded High Environmental Quality (HQE) certification and has been chosen to represent France at the Sustainable Building Challenge in Melbourne, Australia.