Set in the outskirts of Lisbon, the 41SA building is a representation of the development of habitation in the metropolitan area. Despite its proximity to the highway, the seeks to turn potential constraints into singular advantages like bigger balconies, terraces and creation of duplexes.

Volumetrically the building is composed in four parts: a semi-buried floor, a retreated ground floor, a larger main body, and the light structure of the pitched roof. The vertical displacement body of the building regulates this organization defined as a key structural element, as it organizes the different apartments per floor and the common areas.

The north–south double façade orientation allows every living unit to benefit from natural cross-ventilation and abundant daylight. This orientation also defines the spatial layout: private areas are positioned on the north side, while social spaces face south.

The skin facing north works as element of spatial illusion, offering a sense of depth from within, while ensuring privacy from the street. In contrast, the south-facing façade is more discreet. It aligns with a grid found in the surroundings buildings, yet distinguishes itself through generous openings, freeing itself from the urban constraints that define the northern side.