Creative silo

The owners could have easily demolished theformer silo building in Basel, as the interior seemed difficult to use with its numerous old bulk hoppers. Nevertheless, they decided to convert the original building from 1912 and created a striking meeting place for the entire area.

Erlenmatt is the name of the largest conversion area in Basel, namely the former Badischer Güterbahnhof in the north-east of the city. In 2015, the buildings erected by total contractors on the west side of the site had already been completed, while the owner, the Habitat Foundation, took more time in the east: the aim was to create smaller parcels of land and allow residents to participate in the process, and the foundation also decided not to develop all of the 13 plots itself, as defined in a master plan submitted by Atelier 5, but to hand over some of them to cooperatives or socially responsible developers under building law; this includes the residential studio building erected by Degelo Architekten (see Baumeister 10/19).

This directly adjoins the only existing building, a silo building of the Basler Lagerhausgesellschaft from 1912. Bulk goods such as grain and cocoa beans were brought here from the North Sea ports, stored and filled into sacks for onward transportation. The locally renowned architect Rudolf Preiswerk built one of Switzerland’s early reinforced concrete buildings here – Basel also has him to thank for an Art Nouveau building at the fish market and a number of restaurants that oscillate between historicism and Heimatschutz style. Behind the gable-roofed shell, which is structured by pilasters and thus restrainedly classical, he lined up a battery of two by ten silo cells, each of which led into two square hoppers at the bottom.

Although the property was listed in the inventory of buildings worthy of protection, the owner could have insisted that it be demolished. However, the Habitat Foundation recognized the qualities of the building and decided otherwise. In 2015, it announced two competitions: one for a viable operating concept with regard to cultural and gastronomic use and – based on this – a second for the conversion: structural framework, building services, architecture. The young Tohuwabohu team won the first competition with a combination of bistro, event venue, hostel and studios; Harry Gugger (together with Schnetzer Puskas and Waldhauser + Hermann) was awarded the contract for the architectural concept in 2016.

… and preserved

Previously recognizable as a solitary building with its striking gable fronts, the silo building now fits into a row, framed by the studio apartment building to the north and a student apartment building by Duplex Architekten to the south. Gugger’s idea was to preserve the core of the building with its concrete silo cells and supporting structure as far as possible. The hoppers surrounded by ring lights give rhythm to the first floor zone with the restaurant facing the courtyard to the west, the corridor and the seminar rooms on the street side; glass walls framed by wooden profiles divide the different room areas. A new ceiling was installed above the hoppers, some of which were filled with concrete for earthquake safety.

The transverse chamber of raw exposed concrete walls was retained and only had to be provided with passages. Walls made of hollow perforated bricks, which are clearly recognizable as additions, separate the corridors above the central pouring funnels from the room cells. Today, the courtyard side houses studios for permanent rental and the street side houses the hostel’s four-bed rooms.

A further concrete ceiling was installed above the silo cells and below the concreted roof truss; however, it does not rest on the walls of the silos, but on the grid of the concrete supporting structure. On this level, there are again studios to the west – and the second bed rooms of the accommodation facility opposite. The gallery below the ridge, where the conveyor belts once ran, has been preserved, as have the sequence of metal chutes for feeding the silos and their historic license plates. The preservation of the historical structure, which is divided into a delicate concrete structure, is not an end in itself: it lends the newly used rooms a spaciousness that contemporary, spatially optimized construction could hardly achieve.

Portholes as a signal

While Gugger’s interventions in the core area of the building are serving in the best sense of the word, the two newly created stairwells, which replace the northernmost and southernmost rows of silo cells, set their own accents with their organically shaped concrete design; in a sense, the repetitive structure of the room cells is given a sculptural abutment here – quite literally, as they serve not only to provide access (and as an escape route), but also to reinforce the structure. The concreting posed a particular challenge, as all the work had to be carried out from below due to the concrete roof.

Read the entire article in B8: Repair culture