Vertbois Building: A Bold Adaptive Reuse by Moussafir Architectes & Inside Outside Architecture

The Vertbois Building in Paris represents a forward-thinking approach to adaptive reuse architecture, designed by Moussafir Architectes in collaboration with Inside Outside Architecture. This 10-level, mixed-use structure has been reimagined to harmonize modernist ideals with brutalist aesthetics, transforming a once-generic 1970s commercial structure into a versatile and expressive building fit for contemporary urban life.

Historical Context & Architectural Significance

Originally designed by the Biro Fernier firm during the economic boom of post-war France, the building stands as a rare 1970s architectural specimen in the Haut Marais district, known primarily for its preserved historic landmarks. Despite its age and presence in a protected zone, local authorities (ABF) determined that the structure held no formal heritage status, allowing a full transformation of both the façade and the interior program.

Constructed using reinforced concrete over a 3-level underground parking structure of prestressed concrete, the building features a Mansard roof with six dormers (lucarnes) and a suspended garden—an innovative solution for its time. The redesign preserves and enhances these structural elements while introducing new functional layers.

Design Concept: Embracing Brutalism and Flexibility

The core of the renovation strategy was to reveal the building’s neutral structural framework—open-plan floors without intermediate columns—that enabled programmatic flexibility. By exposing and celebrating the original load-bearing concrete skeleton, the architects made a conscious decision to blur the lines between residential and office typologies.

The interior spaces, including flats designed like offices, reflect this multi-functionality. From open-plan layouts and visible beams to unified flooring and detailing, the building evokes the rationality of modernist architecture while supporting a hybrid lifestyle.

Façade and Materials: Between Transparency and Structure

The new façade design respects the building’s original modular rhythm while modernizing its expression. On the street side, it follows a strict 1.36m pitch, while the courtyard façade spans 10 meters without intermediate supports. The staircases, railings, and façade systems are treated as “borrowed” elements—lightweight, suspended, and separated from the load-bearing shell to express the structure's solidity and permanence.

Material choices emphasize the brutalist palette—raw concrete, exposed frames, and locksmith-like metallic details—all while embracing a contemporary edge. The transparent glazing on both façades brings in ample daylight and opens up the once-heavy structure to the vibrant cityscape of Paris.

Interior Experience: Spatial Clarity and Openness

The building’s interiors emphasize spatial clarity, natural light, and material honesty. Large windows frame city views, while custom millwork, exposed ceilings, and refined concrete finishes create a sense of balance between roughness and refinement. The choice to design flats like office spaces not only reflects current trends in remote workand flexible living but also supports long-term sustainability in terms of building adaptability.

The Vertbois Building sets a new benchmark in Parisian renovation architecture, showing how a seemingly ordinary 1970s building can be reborn through visionary adaptive reuse. The project is a tribute to modernist legacies, brutalist beauty, and the sustainable reuse of urban infrastructure.

This transformative project is not just about aesthetics—it’s about resilience, flexibility, and redefining architectural relevance in a historic city.

All the photographs are works of Vincent Leroux