The gallery and ateliers at Brunnenstrasse 9 are built on the foundations of a ruin, the result of a bad investment in the 1990’s. This made the plot unattractive for corporate investors who were purchasing empty lots at the time. This opened up an opportunity for the architect, both investor and constructor, to buy the land for the current cost minus the demolition expenses. When the plot was purchased in 2007, only a couple of walls and parts of the basement ceiling remained, alongside the elevator shaft and an entrance passage. Instead of removing this original structure, it was included and developed further in the new design.At the time, Berlin’s City Planning Department promoted a 'critical reconstruction' agenda, in reference to the city’s historical context. Instead of interpreting critical reconstruction as regressive, Brunnenstrasse 9 uses the idea of referencing the site’s context to create a new typology for working and living. Therefore, the basic volume is defined by the eave heights of the two adjacent buildings, with the attic floor shaped accordingly to compromise with the neighbours behind the rear courtyard, ensuring that light reaches their buildings. The continuation of the adjacent building heights into Brunnenstrasse 9 results in a 30cm difference between the two floor levels. This 30cm step divides the floor plate on every storey, a natural division of the space for different uses with different heights. The initially unroofed basement has become a double height room, visible from the street. If desired, this single space can easily be divided into two by inserting the missing ceiling, using the visible anchor bolts already set in the reinforcement.The concrete core, reduced to a minimum, houses the bathrooms and the elevator. It directly connects the different units to the street level via an entrance located in the public passageway. Apart from this central core, there is no other physical connection between the single units. The only way to circulate between them is either through elevator access or the external staircase attached to the rear façade.This exterior circulation layer is offset five meters from the back façade in accordance with the building code and fire regulations. The need for an interior stair is eliminated by shifting the staircase outside, which permits maximum spatial efficiency and complete independence for the users. The platforms connecting the exterior staircase also function well as terraces and public space for the residents.As the tram wires prevent firefighters from using extendible ladders on the street side, a second entrance had to be installed at the rear. In order to comply with regulations for the second fire escape —via the windows— the courtyard ground was raised 72cm on one side and 36cm on the other to match the maximum length of the fire brigade’s 8-metre ladder. This methodology of understanding, using and reacting to the given rules and building code parameters also shaped the facade. The street side, facing the heavily trafficked Brunnenstrasse, is given a closed quality. To allow light to enter the space without opening the façade to the street, every storey has a fixed glazed part, whose length derives from the maximum liftable weight for an average crane, while the rest is in translucent polycarbonate panels. This polycarbonate has a sun protection layer, which generates different colours in the course of the day. Small ventilation flaps set on the facade side provide cross- ventilation for the spaces.In contrast, the rear wall facing onto the courtyard is completely glazed. Ceiling-high sliding doors allow the users to open half the facade overlooking the courtyard. All the facade elements rest on a robust metal sub-structure of L brackets, providing for future changes to the facade, following the same logic of flexibility and adaptability employed on the inside. The concrete slabs were built at the same time as the shell. All interior walls are in cast concrete, without any preconceived system for the formwork and pattern. All the walls and floors were ready by the time the structural work was completed, and were treated afterwards. The electrical system is concealed in ducts embedded in the concrete while the heating pipes are exposed, with no insulation, in order to heat the space. This concrete platform enables users to adapt the rooms to their specific needs while keeping costs to a minimum and ensuring the affordability of the space. The only pre-installed elements are the mechanical connections and oak planks along the street facade, used as a substructure for the polycarbonate elements on one side, while on the other side, they can be used as benches, desks or shelves.