Town planning for the Riera Gasulla sector of Sant Boi de Llobregat stipulated that the closed street block we were to design should be laid out in a 15-meter strip around the edge, parallel to the streets, with just a few gaps to allow access to the inner courtyard. This strip turned on itself, closing off the four corners of the street block. The building heights varied between four or five storeys according to the street in question, and the dwellings, belonging to a cooperative, had to be the same, responding to a four-bedroom social housing model of 90 m2

These starting conditions presented certain contradictions and difficulties that had to be mitigated. First, we grouped the dwellings, two to a landing, and laid out the units in blocks which, as required by planning, enclosed the perimeter of the street block while avoiding the corners. This removed the need to introduce new typologies, and the edge streets could be consolidated by means of built frontages, creating an inner courtyard protected from the exterior. Access to the interior is via the gaps between the blocks, creating a secondary network of passages that connects with those in the neighboring street blocks, giving the whole a mixed typology of closed and open street blocks.

In addition, the maximum building depth of 15 m proposed by planning, ideal for the underground car park, was far from suitable for laying out the built typology. A social housing unit of 90 m has a specifically built volume that requires a depth of between 10 and 11 meters. We worked with 10.80 m, which produced a staggering section between the base, occupied by the car park, and the other floors, giving the lower dwellings a private patio within the building depth of 15 m.

Finally, we worked to resolve the contradiction involved in using a single housing typology to consolidate the urbanistic engagement of a street block while responding positively to the requirements of judicious orientation and sunlighting. To do this we used a typology in which the dining room-living room-terrace sequence provides cross-ventilation, giving onto both the street and the street block interior. This gave the communal spaces of all the homes two orientations and views of both the street and the public space at the center of the block, maintaining the typology and only varying the position of the terrace to adapt it to the optimum orientation.

The underlying principle of typological unity and uniformity of conditions was extended to the image of the development. The openings were unified, using a single 0.90×2.10 m unit that was doubled in the case of the terraces. The openings were given a rather random arrangement in the wall of the façade, with an interplay of displaced elements that accommodates the partition walls inside the apartments. This arrangement gives the façades a degree of dynamism and variation without recourse to different typologies and was also used in the end walls, avoiding the blind party walls that are so familiar in many linear blocks. The inner courtyard was planted with tall straight poplars to emphasize its role as an enclosed garden.