For architects Carlos Rebolo and Alejandro Caraballo — who co-founded their Madrid-based firm CRAC in 2020 — the purpose of architecture is not simply to build but to investigate and examine how one interacts with and is influenced behaviourally by their surroundings. So when it came to renovating his own apartment (which he shares with his partner), Rebolo naturally experimented by transforming a conventional three-bedroom layout with a closed-off living room and kitchen into a bright, open one-bedroom space centred around a large metal-wrapped cube that contains the bathroom, as well as storage for a study on one end and the bedroom closet on the other.

Dubbed Metalcore, the square volume is clad in a turquoise wavy metal skin that is perforated to play with transparency and privacy. “The perforated sheet allows you to see through the skin, not with a clear view but a mysterious one,” says Rebolo. “[It] subverts the classic concept of a bathroom by transforming its programmatic conception into a playful and hedonistic one.”

Conceived as a geode or hidden gem, Metalcore itself pairs rectangular glazed tiles in the same watery tones as the metal exterior with white dimpled tiles, the two working together to create a calm, spa-like atmosphere. Designed as a “rough subtraction of the wall,” the bathtub can be glimpsed from outside through the hazy veil; mirrors and translucent doors continue the “game of glances and hidden places.”

“The colour of the skin relies on the concept of understanding the core as a strange element that crashed into the domestic space,” says Rebolo of the unexpected structure that now dominates his apartment.