co.arch studio Merges Two Milan Apartments Around a Shared Threshold

co.arch studio has transformed two small early 20th-century apartments in Milan's Bovisa district into a single 100 m² home, set for completion in 2026. The intervention turns a shared threshold into its conceptual engine: a spatial device that separates and connects two distinct domestic identities.

The Milan-based practice, led by lead architects Andrea Pezzoli, Giulia Urciuili and Alessandra Negri, organized the entire renovation around that threshold. Rather than erasing the boundary between the two original apartments, the architects amplified it. The device now divides and links the plan at once, and the designers expressed this duality immediately through two contrasting chromatic atmospheres: terra red and matcha green.

Photographers Tiziano Ercoli, Riccardo Giancola and Francesca Iovene documented the completed interiors. Manufacturers One to One object and Rabatto supplied the project's fittings and furnishings.

What does the threshold change for the plan?

The threshold operates as a hinge, not a wall. It separates two domestic identities while physically connecting them, which allowed the architects to preserve the reading of the original two-apartment structure instead of collapsing it into one undifferentiated space. Each side of the home carries its own chromatic register—terra red on one side, matcha green on the other—so occupants register the transition between the two identities the moment they cross the shared threshold.

The contrast is chromatic, not structural. The 100 m² plan keeps the logic of two small early 20th-century apartments, and the color atmospheres do the work of marking where one identity ends and the other begins. For a district like Bovisa, where housing stock often consists of exactly this kind of small paired unit, the project demonstrates how merging apartments can gain space without losing the legibility of the original plan.

The architects described the threshold as the conceptual starting point of the intervention: a spatial device that separates and connects two distinct domestic identities. They expressed that idea directly, through the two contrasting atmospheres, from the first moment of entry.

Who delivered the project?

• Architects: co.arch studio
• Lead architects: Andrea Pezzoli, Giulia Urciuili, Alessandra Negri
• Area: 100 m²
• Year: 2026
• Location: Bovisa district, Milan
• Photographs: Tiziano Ercoli, Riccardo Giancola, Francesca Iovene
• Manufacturers: One to One object, Rabatto

The project joins a growing body of Milanese renovations that treat existing partitions and thresholds as design material rather than obstacles. As compact early 20th-century housing stock across districts like Bovisa continues to absorb new living patterns, the terra-red and matcha-green pairing shows one way architects can merge units while keeping their histories legible.