Köln, 1996-1997, b&k+ Arno Brandlhuber & Bernd Kniess + Uwe Schnatz; Astrid Becker, Markus Emde, Andreas Laake; Stefan Polónyi / IPP (Tragwerk)
Inserted in an extremely narrow gap - just 2,56 meters wide - is less a house in the classical four walls and one roof sense than an infill for Cologne's city centre. The office and apartment building uses the existing party walls of the neighboring houses by inserting the concrete floor slabs directly into them, which allows for maximised use of the limited space. At ground level, a narrow corridor passes through the building into the rear courtyard, connecting the sidewalk with the exterior staircase at the back of the building. Relocating the vertical circulation to the outside not only increases the use of interior space but also allows for separate use by the apartment tenants. The one-room units have no partition walls. Instead, the core, comprised of the bathroom and storage space, divides the open floor into zones and permits minimum spatial separation. The apartments are open to the east and west sides of the building. With fully glazed facades this provides an unexpectedly spacious feeling inside which is continued on the roof terrace. In addition to the specific construction requirements of the narrow site, the building’s shape derives primarily from the legal situation. The German building code required each building in a block to an independent construction. This law countered the owner’s arrangement with his neighbors, who asked him to maintain the shared party walls as part of the new structure. This condition was later adopted by the German building code as the so-called “Verweisbaulast” (reference construction encumbrances). The new code allowed for the use of adjacent party walls in new constructions, citing 2,56 as its legal precedent.