Seven Buildings for Thirteen Herbs – Ricola and Herzog & de Meuron
- Jakob Schoof
Six times in the past, the confectionery manufacturer Ricola and the architects Herzog & de Meuron have collaborated to build, most frequently at the sweetmaker’s headquarters in Laufen south of Basle. The present structure, the seventh, is the largest to date, with a length of 111 m, a width of 29 m and a height of 11 m. In 2006, Ricola moved its production plant from the heart of Laufen to the periphery. The planar facades of this new herbal centre consist basically of rammed earth, excavated within a radius of 10 km and worked nearby to create large prefabricated elements. The interior is naturally lit by roof lights and four large circular windows – one in each facade. The 5.50 m diameter of these openings accounts for their unusual form. Since earth cannot resist tension or bending stresses, concrete lintels would have been necessary over windows of this width. With circular openings, however, almost exclusively compression loads occur along the jambs, and the compacted earth is perfectly capable of bearing these. Only the entrance gates were designed with lintels, but these are not visible from the outside. The windows themselves are anchored in the prefabricated earth elements. Nearly 670 of these large-scale units – on average 3.36 m long, 1.30 m high, 45 cm thick and weighing up to five tonnes – were required for the 3,060 m² facade area. In the production and erection of the external walls, Herzog & de Meuron worked closely with the Vorarlberg earth construction specialist Martin Rauch. The facades are self-supporting, but are anchored at the back to a concrete skeleton frame. With its 55 × 55 cm columns, this transmits wind and roof loads to the ground as well as providing earthquake resistance. Centrally behind each of the circular windows stands such a concrete column, where the external walls are least stable.
