Oslotre studio has completed construction of Lumber 4, an innovative six-story commercial and office building in Kristiansand, Norway, that showcases sustainable timber construction with a distinctive curved green facade. The building features a recessed ground floor dedicated to commercial use, while the five upper floors house modern office spaces designed to meet contemporary workplace standards.
The structure demonstrates advanced mass timber construction techniques, utilizing glued laminated timber for columns and beams throughout the building. The floors incorporate a sophisticated composite system combining cross-laminated timber (CLT) with concrete, creating an efficient and slim floor system capable of spanning long distances while meeting stringent fire safety and acoustic requirements. Strategic diagonal elements on the ground floor enhance vehicular access around the building, while the existing communication core from adjacent building phases provides lateral stability and access to office floors.
A standout feature of the interior design is an atrium positioned between the third and fourth floors, complete with an internal staircase constructed entirely from mass timber. Wood elements are prominently displayed throughout the interior spaces, providing natural temperature regulation that offers warmth during winter months and cooling effects in summer. All load-bearing structures remain exposed as part of the design aesthetic, while exterior walls feature white-pigmented spruce panels.
The building's most striking characteristic is its facade, composed of prefabricated curved wooden elements made from pine and treated with distinctive green paint. The straight eaves positioned above these curved elements create shadowed areas on the panels below. Over time, the paint in these shadowed sections will weather differently, resulting in an evolving facade with contrasting lighter and darker curved sections that change with the seasons.
Sustainability extends throughout the building's construction materials, with Oslotre's design team incorporating wood fiber insulation throughout the structure. The cladding consists of fire-treated pine, while wood wool acoustic panels are strategically placed in concealed service areas and meeting rooms. Visible conduits are painted in a light beige color to maintain the building's cohesive aesthetic. Large floor-to-ceiling windows maximize natural light and provide expansive views of the surrounding landscape.
The project achieved remarkable construction efficiency, with detailed planning and construction completed in just 12 months – a record time for a building of this scale and complexity. Lumber 4 serves as a compelling demonstration that timber buildings can be constructed competitively when compared to concrete and steel structures of equivalent technical standards. The building's success is evidenced by its 90% lease rate upon completion, indicating strong market demand for sustainable office spaces.
Oslotre studio served multiple roles in the project, acting as architect, interior architect, and timber structural engineer, showcasing their comprehensive expertise in sustainable timber construction. The successful completion of Lumber 4 represents a significant advancement in Norwegian sustainable architecture and demonstrates the viability of large-scale timber construction for commercial applications.
