A concrete and wood cage for the reinforcement of Cal Fuster. A new life and new function for a building from the 1400s

Cal Fuster, a late 15th-century building in the fortified square that was the origin of the town, is being transformed into a single-family dwelling. In addition to the restoration of the original facades, an interesting system of consolidation from the inside brings it back to life by restoring efficiency to the existing materials and interior distribution

Declared a cultural asset of local interest (BCIL), the Cal Fuster building is made habitable again thanks to Arqbag's design, which proposes a minimal and simple structural system to feed the shortcomings of the pre-existing building in order to prolong its life. It consists of a lightweight reinforced concrete box that is supported directly on the load-bearing stone walls of the basement, avoiding the need for a new foundation. These reinforced concrete nerves connect the four existing facades from the inside, reabsorbing existing collapses and reducing the deformation of the walls by fixing them from their midpoint

Once the facades are supported by this box, the existing walls work together structurally again, also supporting the weight of the new roof. To reduce the weight of the reinforced concrete, the slabs are lightened using a site-built system of solid wood combined with reinforced concrete beams. The structural wood functions both as a disposable formwork for the beams and as an exposed interior finish. With the same load-reducing criteria, the roof is built with a wooden structure, resting on the existing walls

While respecting both the openings and the original façade composition, the architects understand that the element to be exploited to give new and wider light and ventilation to the building is the new roof. One of the 6 squares of the structural grid is kept empty generating a large three-level vertical patio. This patio provides access to the three levels of the building, lighting for all interior spaces, and natural ventilation for the basement, which has pathologies from soil moisture

The patio also functions as a bioclimatic mechanism: in winter it remains closed and provides lighting, while in summer it remains open when fresh air from the basement is desirable.
The restoration of the original stone walls is done with lime mortar and a mixture of aggregates with specific local colors extracted from two local quarries