The factory extension is a three-storey rectangular construction of stone masonry, built on the remains of a watermill that provided both foundations and a basement. It comprises three bays, with two rows of cast-iron pillars running parallel to the longest façade. The rows of pillars are tied by timber main beams that support brick vaults. On the top floor, the pillars are replaced by timber trusses that support the roof of flat and pan-and-roll tiling. As the extension is built onto the house-cum-factory, it does not have an independent stairway; once separated for conversion into a library, it had no vertical communication, and the entrance from the steeply sloping street is located on the lowest floor. These problems of accessibility and general mobility were the driving force of the project. The importance of the relationship with the street in a public library, a programme introduced into a factory building, conflicted directly with the obligation of using just the first and second floors. We, therefore, chose to modify the entrance by situating it in the highest part of the street, which considerably reduced the level of entrance to the first floor. This called for the creation of a mezzanine floor between the ground and first floors to house the cloakroom and installations, as well as the main entrance.

This mezzanine coincided with the bay closest to the house-cum-factory, which had to be completely remodelled to house the entrances, lift and stairs, as well as services and offices, creating a space that enables users to surmise the bay in its full dimensions, visually linking the floors and the street and providing immediate contact with the timber roof structures and the building’s general functioning. Since the library programme set aside the first floor for reading and consultations and the second for archives, the respective stairways were given two different treatments; up to the first floor there is a single, relatively wide, low-pitched run, whereas two narrower, steeper runs that double back on themselves leading up to the second floor.

Although the building’s structure was in a good state of repair, it was obsolete according to present-day regulations on supporting behavior and fire protection. We chose a solution that maintained and consolidated the existing structure to bring it into line with regulations. First, the timber trusses and tiles were restored, and the roof was fireproofed. Throughout the rest of the structure, the system of cast-iron pillars was maintained and supplemented with angles connecting them to the new main beams embedded in the vaults to brace the whole. The original timber main beams were supplemented by a metal plate bolted to the new main beam. In this way, the original structure continues, with the help of new elements, to contribute to the statics. Red rubber flooring was chosen to avoid adding unnecessary weight to the building, and damp-proof panel sheeting, painted red, was used to conceal the air conditioning and form partitions.

The treatment of the openings to the outside requires special mention. Because of the industrial nature of the town and its proximity to the river, Sallent is shrouded in mist for much of the year. For this reason, in addition to the building’s north-facing orientation, the daylight received by the factory was generally indirect, ideal both for its original purpose and for its use as a library. In addition, the fact that the bay furthest from the main façade is used for entrances and services ensures that the study spaces are not too large and receive acceptable general lighting. The reading tables are arranged near the windows, perpendicular to the façade, providing improved lighting and allowing readers to raise their heads and look outside. The window frames are laid flush against the façade to capture as much light as possible.

However, the openings on the first floor, larger than those on the second, are divided in two: the lower part, closer to the reader, has its frame on the inside, whereas the frame of the upper part is on the outside, like on the second floor. To address the meeting point, protect the jambs on the outside, and show off the depth of the masonry wall, we used metal casing. A large metal cube was also used for the new entrance, set into the wall to house the double door. Artificial lighting elements were suspended from metal supports in the roof that house the electrical installation. The possibility of changing the position of the lighting makes use of the space more flexible with different possible arrangements of the tables and archives.