At 57/57bis rue Spontini in Paris’s 16th arrondissement, SO/AP Architects have designed a mixed-use building that reconsiders the structural and urban role of stone within a contemporary infill context. Combining residential and office programs across 1,500 square meters, the project negotiates a complex corner site through calibrated massing, hybrid construction, and a material strategy rooted in regional limestone.
Spontini Technical Information
- Architects: SO/AP Architects
- Location: 57/57bis rue Spontini, 75016 Paris, France
- Gross Area: 1500 m2 | 16146 Sq. Ft.
- Completion Year: 2025
- Photographs: © Hapi Photography
We sought to reinterpret stone not as cladding but as structure, anchoring the building in its Parisian context while engaging contemporary modes of construction.
– SO/AP Architects
Urban Insertion and Volumetric Strategy
The building occupies an atypical corner parcel formed during the early twentieth-century opening of Rue Thiers. This urban modification generated a triangular condition and exposed flanking walls that continue to shape the architectural response. Rather than treating the plot as an opportunity for maximum buildable volume, the project adopts a measured stance, stepping back from the allowable envelope to maintain visibility of the neighboring nineteenth-century gable wall. This decision reinforces the stratified reading of the block and acknowledges the district’s incremental formation.
Curved and folded facades mediate between converging street alignments, allowing the volume to shift subtly as it addresses each frontage. Horizontal datums are referenced to adjacent cornice lines, which vary slightly in height due to the sloping terrain and diverse building periods. Through these calibrated alignments, the project establishes continuity with the post-Haussmannian fabric while expressing its own tectonic logic. The massing articulations are therefore neither mimetic nor autonomous; they operate within the constraints and rhythms of the existing streetscape.
Programmatic Organization and Spatial Distribution
The program comprises five residential units totaling 500 square meters and two office spaces amounting to 1,000 square meters. This combination introduces distinct patterns of occupation within a compact footprint. Offices are positioned to benefit from direct street access and visibility, while residential units occupy upper levels where setbacks provide privacy and expanded outdoor space. Vertical circulation cores are organized to maintain clear separation between domestic and professional uses.
Upper-level recesses temper the perceived mass and generate terraces that extend interior spaces outward. These transitions between enclosed rooms and open-air platforms recalibrate the relationship between inhabitants and the city. Nearly 100 square meters of planted roofs and terraces integrate vegetation into the architectural envelope. Beyond their spatial role, these planted surfaces contribute to stormwater retention and urban biodiversity, aligning environmental performance with the modulation of form.
Hybrid Structural System: Stone, Timber, Steel, Concrete
The structural system departs from conventional stone cladding by assigning the facade a load-bearing function. Massive limestone walls directly support cross-laminated timber floor panels, establishing a dialogue between mineral compression and engineered timber spanning. Transverse steel frames stabilize the assembly and distribute loads across the plan, enabling column-free interiors suited to flexible office layouts and adaptable residential configurations.
Concrete beams and walls are introduced selectively to resolve cantilevers and upper-level setbacks. These elements absorb localized stresses generated by volumetric offsets while maintaining structural clarity. On the courtyard elevation, a timber-framed wall with external insulation offers a lighter, more economical construction method. This hybridization recalls historical construction logic, where material use responded to exposure and hierarchy, yet it is calibrated to contemporary performance criteria.
Material Logic and Tectonic Expression
Two regional limestones establish the facade hierarchy. At ground level, Euville stone forms a dense, compressive base capable of carrying structural loads from the upper floors. Above, the Saint-Maximin stone introduces a lighter tone and smoother finish that harmonizes with the surrounding buildings. The transition is marked by a recessed joint that articulates the shift from base to upper stories, reinforcing the legibility of the facade’s stratification.
Large-format stone blocks, with bed heights ranging from 43 to 60 centimeters and substantial depths, emphasize mass and continuity. Wide openings are spanned by flat-arch lintels, while slender mullions conceal aluminum window frames within the thickness of the stone. At the cantilevered underside, stone panels bonded to a honeycomb backing align precisely with the coursing above, preserving formal coherence despite the change in structural condition. Through these calibrated details, the facade communicates both its structural role and its integration within a historically grounded material palette.
About SO/AP Architects
SO/AP Architects is a Paris-based architecture studio engaged in contemporary urban projects that reinterpret traditional materials and construction techniques. Founded in 2016, the practice explores the structural and spatial potential of architecture through rigorous material research, contextual sensitivity, and hybrid building systems that combine stone, timber, steel, and concrete. Their work emphasizes clarity of form, tectonic legibility, and a dialogue between heritage and contemporary performance standards.
Credits and Additional Notes
- Client: Simvest
- Consultants: Batiserf, Energy Pro, Meta Acoustique, ALP Ingenierie
- Awards and Recognition: Prix de la Construction Pierre 2025 – Catégorie Logement
