Portcullis House, London

Species: American white oak

Architects: Michael Hopkins & Partners

Awards: Timber Industry

Photography: Peter Ross, Arup

Structural beams at Portcullis House The New Parliamentary Building in Westminster, known as Portcullis House, by Michael Hopkins and Partners, was completed in 2000. The six-storey rectangular block occupies one of the most prominent sites in Westminster. It houses accommodation for 210 Members of Parliament and a suite of publicly accessible Select Committee Rooms. Catering facilities and a library open onto a central courtyard which has an innovative glass roof with a diagonal lattice structure of laminated white oak. It is one of the most complex timber roof structures in Europe and was central to the architect's goal of providing a focal point to the building, protected from weather and glare and with maximum use of natural light.

Originally the atrium roof was conceived as a steel structure but the architects chose a traditional material to reflect the character of the nearby Palace of Westminster where oak is extensively used in such structures as the hammer-beam roof of Westminster Hall. The atrium roof of Portcullis House represented one of many challenges presented to structural engineer Arup. It is supported on only six columns and is based on a system of node joints and glass panels with a consistent curvature. American white oak provided the engineers with the strength to weight ratio that satisfied their desire to keep the individual struts to a minimum mass.

The New Parliamentary Building has won numerous engineering and design awards, including the Timber Industry Award in 2001. The judges commended the 'lightness and elegance' of the 'stunning central space'.

By Michael Buckley