Between the 16th and 18th centuries, Geneva expanded its fortifications, absorbing medieval suburbs. The city center densified while new districts emerged, notably between modern-day Pâquis and Rue de Lausanne. In the Prieuré area, watchmaking, banking, and manufacturing transformed the rural fabric into a dense urban quarter, reinforced by the expansion of Cornavin as Geneva’s principle railway station.

The project involves the vertical extension of buildings 27 and 29 on rue du Prieuré. Lined on both sides with varied structures, the street showed a noticeable visual gap that the project filled by aligning with existing cornices and rooflines, clarifying the urban scale.

Built in 1892 by Gédéon and Louis Dériaz, these adjoining buildings retain their 19th-century coherence despite a later addition built in 1951. The new intervention follows Geneva’s tradition of raising buildings, linked to the reception of Protestant refugees from 1536 and reinforced after the Revocation of the Edict of Nantes.

The project removes the top floor to adds two levels and attic apartments, totaling twelve three-room dual-aspect units. The attic space is maximised to create bright, singular volumes.

Façades are unified with continuous plaster; only existing cornices mark transitions. Original window rhythms are retained, framed with contemporary UHPFRC (ultra-high performance fibre-reinforced concrete) elements. Recessed picture windows, dark metalwork and vertical blinds enhance sobriety. A continuous balcony crowns the top floor, reinterpreted with modern lines.

In the courtyard, plastered elevator shafts extend the façade language. Common areas are upgraded for accessibility and comfort. The wooden structure and UHPFC elements, crafted by Form C, combine technical innovation with artisanal precision.