Stiffening a Timber Floor at Somerset House

Abstract

The Portico room at Somerset House, above the main entrance foyer (known as the Seaman's Hall) was built as a large open space with a timber floor spanning over 12 m. Early on in the life of the building, it appears that the floor suffered a significant loss of stiffness, and remedial hangers were introduced to provide additional support to the first floor from the second floor. In the twentieth century, the second floor was replaced and new hangers installed. The hangers were hidden in partition walls that split the Portico room up into small offices. The Somerset House Trust (current owners of the building) wanted to open up the room and remove the hangers to create a function space. Highly interventionist engineering solutions to stiffening up the floor while allowing the hangers to be removed were clearly inappropriate. The solution arrived at involved a careful understanding of the original structural action of the floor and the reasons for its problems. By reversing the original flaws and providing an extra ‘helping hand’, the floor was restored to its original configuration, without hangers. A magnificent function room has been created, and the project has won the Institution of Structural Engineers Heritage Award for Buildings 2006.