sculptural ovals shape seismic retrofit of 50-year-old building in japan by C+A

the architects' team gives the building a new identity with a seismic upgrade using asymmetric oval-shaped structural elements.

thomai tsimpou July 4, 2025 4 min

C+A gives seismic upgrade to 50-year-old building in Japan

C+A – Coelacanth and Associates renovates KUBO-BLDG, a small four-story tenant building in downtown Nagoya, Japan. The architects’ team gives the building a new identity, more than fifty years after it was first built, with a seismic upgrade using asymmetric oval-shaped structural elements and a new concrete column-beam frame. The project transforms the aging structure into something that is at once safer, more expressive, and in tune with its urban context.

Instead of hiding the building’s new structural components, C+A chooses to highlight them by embedding oval-shaped seismic elements on the facade. These large, asymmetrical ‘icons’ visibly wrap around a triangular bracing system and frame, reinforcing the building while helping it stand out in the dense, often chaotic streetscape. The ovals are carefully arranged to strengthen the structure while still allowing generous openings throughout the facade.

sculptural ovals shape seismic retrofit of 50-year-old building in japan by C+A - 1 — all images by ToLoLo studio

Asymmetric Oval-Shaped Elements define KUBO-BLDG facade

Japanese architecture firm C+A – Coelacanth and Associates reimagines the facade of KUBO-BLDG with function in mind. The new structure creates space for balconies on each floor, semi-outdoor zones that encourage natural ventilation, and support airflow throughout the building. These additions speak directly to lessons learned from the pandemic, offering better air quality and a stronger connection to the outside. The balconies also animate the street, adding a more social and open layer to the building’s edge.

Inside, the renovation refreshes the common areas and upgrades outdated systems, while in the tenant spaces, the architects keep things intentionally raw. They preserve as much of the existing structure as possible, exposing utility lines and simplifying the layout so that future tenants can shape their spaces as needed.

With a total floor area of just over 350 square meters, C+A’s retrofit shows how seismic safety can also drive creativity, turning technical requirements into forms of expression.