Y139 is a renovation project that transforms an aging commercial building into a dynamic hub for startups. Through a redefined façade and improved vertical circulation, the project gives new identity and function to the structure. Situated within START-TRACK—Gangnam District’s designated startup innovation corridor—this renewed presence responds to its context of 1970–80s low-rise buildings while introducing a new character to the neighborhood. Drawing inspiration from the contrast between the area’s outdated buildings and the creative energy of startups, the design embraces heterogeneity—a juxtaposition of materials and expressions. The building’s renewed identity is articulated through a double-skin façade system that reflects the tension and synergy between the old and the new. The base layer of the facade reconfigures the existing inefficient window placements to align with the building’s structural grid. Iconic ceramic tiles, widely used in Korean façades of the 70s and 80s, are reintroduced to establish continuity with the local context. Over this tiled surface, a layer of curtain metal mesh forms a secondary skin. The curtain mesh introduces rhythm across the wide facade, enhancing street presence while creating a visual interplay between solidity and permeability. Through this layered strategy, Y139 not only restores spatial efficiency but also embodies the innovative and creative spirit of the startups it may house.