Parliamentary Ticket Office, Westminster, London

Introduction

The design of this small pavilion, made of solid wood panels (SWP), points the way towards much wider applications for timber in large-scale buildings. With its pre-fabricated machined connections, rigidity, enhanced fire resistance and unique sustainability credentials, SWP has the potential to challenge steel and concrete in substantial structures where conventional timber frames cannot compete.

The client's immediate need was an attractive, demountable ticket office to replace a portacabin and marquee which were no longer acceptable to Westminster planners or English Heritage. Having stressed the need for any facility here to be of the highest quality, English Heritage embraced the proposed design.

PRS, who were working for the Parliamentary Works Services Directorate at the time, had an established relationship with Finnforest and Alan Baxter and Associates. This ensured a swift response and Finnforest transported the structure from Germany - then erected it in only three days - a mere nine weeks after receiving the order.

The budget for the structure was just £55,000. Parliament used the ticket office for four summers from 2003, until an alternative solution was found within the Palace of Westminster, and then sold it, in 2006, to the German sport club TSV Mühlhausen. It is now a refreshment pavilion in their grounds near Augsburg in Bavaria.

 

Building description

This ticket office for summer visitors to the Westminster Houses of Parliament had to be capable of being dismantled and stored in a flat-pack form ready for re-erection the following year. PRS Architects selected solid wood panel (SWP) because it lent itself to rapid and repeat assembly, had low embodied energy and it looked stunning - all within the tight budget.

Pringle's scheme called for a stiff structure with no internal supports, sloping and curved walls, and a stylish fabric roof. The annual demount meant the building had to be light, with a simple foundation system that could be concealed in the off-season. Security was an obvious problem when dealing with visitors in close proximity to parliament.

The 48m2 pavilion has four ticket points for customers, sheltered under a fabric roof. The form of the building is like a scallop shell with a membrane roof supported on ribs cantilevered from the load bearing walls. The office is naturally ventilated with grilles in the floor and roof cavity.

 

Structure

Mass concrete foundation blocks are covered over with lawn that could be re-laid when the building was in storage. Resistance against wind uplift is needed because of the disproportionately large cantilevered roof.

At the base of the structure, galvanised steel angle perimeter components are attached to the foundations via bolted plate connections. The pre-drilled angle upstand fixes the bases of the wall panels and there are cleats to connect the floor joists. The internal floor is made of plywood planks.

The 81mm thick walls and 65mm thick roof are Finnforest Lenotec SWP, made with three orthogonal layers of spruce. This provides a secure enclosure for cashiers, with good acoustic and thermal insulation. The timber panels were sized for transport by road. The connections are all bolted to allow assembly and dismantling - either timber lap joints for panel-to-panel connections or galvanised steel brackets for beams and connections to foundations.

As well as the short lead time, Finnforest had the further challenge of machining the cut-outs in the panels. Using computer-controlled CAD/CAM technology, they were able to  translate a complicated pattern into the finished product in their German factory. Openings for windows, doors and vents were cut precisely, ready for on-site installation of modular units. Trial assembly ironed out any niggles, such as the tolerance at the interface between the timber structure and foundation.

Slender roof beams of Kerto laminated veneer lumber (LVL) spruce span the office and project over the public area. The translucent PVC-coated polyester roof membrane covers the office and public area, and provides a ventilated cavity above timber panels in the office. Galvanised steel tubes brace the membrane roof.

The splayed layout of the Kerto beams allowed for minimal bracing between them to ensure the fabric roof was properly tensioned.

The deck is non-slip Thermowood, which is heat-treated and rot-resistant when in contact with moisture and the ground.

To meet environmental targets, all timbers were harvested from Finnish or Bavarian forests, with chain-of-custody certification from forest to factory.

Completion Date:

2003

Year Published:

December 2008

Building Type:

Visitor reception

Location:

Westminster, London

Country:

England

Client:

Parliamentary Works Services Directorate

Architect:

Pringle Richards Sharratt

Structural Engineer:

Alan Baxter & Assoc.

Main Contractor:

Finnforest with Eurban

Timber Supplier:

Finnforest

Timber Elements:

Floor, walls, roof beams and external deck

Timber Species:

Spruce. Thermowood decking: heat-treated spruce

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