A striking five-story residential building featuring a distinctive metallic exterior has been completed in Trofa, a municipality in northern Portugal, marking the beginning of a new urban promenade development. The HS Building, designed by local architecture firm NOARQ, combines 15 residential units with a commercial space on the ground floor, serving as the architectural gateway to a planned public walkway that will transform a former 19th-century railway corridor.

Trofa, located approximately 40 minutes by train from Porto, gained significant importance during the 19th century as an industrial hub. Buildings from this industrial era continue to define the outskirts of the city, and a railway line that once ran along the main axis of Alameda da Estação through the old town served as a testament to this industrial heritage for many decades. In 2010, the city removed the railway tracks, and the resulting linear open space is now planned to be developed as a public promenade.

The HS Building, commissioned by a private developer, occupies a sharp trapezoidal plot at the entrance to this future promenade. The surrounding context consists of tree-lined streets with beige-red casas and individual residential blocks made of plastered masonry. Against this backdrop, the currently freestanding new building stands out dramatically with its generously glazed street facades and, most notably, its metallic exterior cladding.

A grid of HEB-180 steel beams forms the outer framework for the street-facing balconies, applied to the building as an additional layer similar to the aluminum panels. Structurally, this does not function as an exoskeleton, as the load-bearing function is handled by reinforced concrete within the interior. To prevent thermal bridging, the architects paid meticulous attention to the routing of insulation and sealing systems. For example, the roof was executed as a conventional flat roof with parapet in the center of the building and as a surface inverted roof on the sides to create the slimmest possible profile.

While the northeastern fire wall invites future construction connections, the building presents a narrow figure with volumetric breaks toward the old town. Due to local building regulations, the structure steps back toward the southeast-facing street and forms roof terraces. Through technically controlled ventilation projections and the sharp building corners, a relatively unorganized elevation emerges.

The interior spaces present a much calmer aesthetic, with the structural elements hidden behind white drywall and plaster, and other built-in elements such as kitchen units and sliding doors designed in neutral colors. Eucalyptus parquet and marble in the kitchen area provide the only natural-finish surfaces visible throughout the units. In total, approximately 1,900 square meters of gross floor area were realized on a footprint of about 305 square meters.

This project represents NOARQ's continued engagement with Trofa's urban development, as the firm has previously designed the city's town hall. The metallic facade of the HS Building serves as both a contemporary architectural statement and a tribute to the area's industrial past, creating a bridge between Trofa's historical identity and its modern urban aspirations.