With the four-story addition, Basel's Matthäusquartier, with its typical workers' housing from the turn of the last century, will gain eight new, sustainable apartments.
In the backyards of the perimeter block buildings in Klein-Basel, many craftsmen's workshops were built towards the end of the 19th century, which are now converted or stacked up. For example, Lukas Raeber Architects stacked four new residential floors on top of an existing tinsmith's workshop that serves as the base floor. Since the utilization did not allow for four full stories of the addition, the building was stepped down to the rear courtyard, allowing for outdoor spaces for the apartments. These are complemented by a communal garden cultivated with useful plants. The economical use of structural and financial resources is exemplified at Efringerstrasse 107, showing how this influences the design and structural realization and results in sustainable architecture.
Eight new residential units for Basel
The new building contains eight residential units and was prefabricated to measure as a deconstructible wooden element building. Towards the street, the addition continues the eaves' height of the neighboring property. In analogy to the pitched roof of the adjacent property, the roof termination is designed as a shed roof with solar panels that power the air- to-air heat pump for heating. A green roof also serves as a habitat for microorganisms.
Made from prefabricated wood elements, the new four-story building sits atop the existing ground-level structure. On the street side, the addition matches the eave height of the neighboring property and reinterprets the adjacent roof edge as a sawtooth roof. Its shape and orientation also make it the ideal location for the building’s solar panels. On the courtyard side, the building is stepped back as required by zoning, creating a spacious balcony for each apartment.
Traces from the past
The residential units are entered at street level, where the mix of new and existing elements feels perfectly natural. The atmosphere in this entrance area is defined by traces of the past, and by the reinforced-concrete and masonry work intrinsic to the building’s structure. From ground level, a staircase made from prefabricated wood elements leads to the warmer atmosphere of the apartments above.
Large metal panels protect the wood structure from the elements and add urban flair. The construction firm that runs the metal shop on the ground floor was extensively involved in the project – they fabricated the street-facing facade, among many other components – and their materials are visible everywhere. The simplicity of the fabrication and construction processes remains visible in the finished building, and the interplay between the different materials contributes significantly to the atmosphere of the space.
Urban Mining for the circular economy
The entire addition and all of its fixtures implement the idea of “urban mining” to the greatest extent possible. This idea is based on the argument that all the resources used to build a building should be reusable, recyclable, or compostable whenever feasible. The building was designed and built with these restrictions in mind. As a result, almost all of its components are attached with screws for easy removal, rather than being glued down. In keeping with this way of thinking, the wood floors are installed with screws, the chrome-steel bathrooms are jointless, and the heating ductwork and electrical conduits are exposed.