Across six floors and nearly 33,500 square feet, Lumber 4 serves as a bastion of mass timber construction in Kristiansand, Norway. Beyond its sustainable construction, the commercial office structure is conceived to embody comfort and openness in a design from Norwegian architecture firm Oslotre, which served as architect, interior architect, and timber structural engineer for the project. “The inspiration derived from exploring light shadows and dignified aging. The design plays with change over time, during the day and during aging,” says Oslotre architect Christoffer Imislund.
Panels of prefabricated curved pine punctuates the facade, creating sinewy shadows across the exterior. Pine is treated with green paint chosen for how it will weather over time. “Straight eaves create shadows over curved green-painted pine elements,” Imislund adds. “As the paint weathers differently in the shadowed areas versus the exposed areas, the facade will evolve, creating a dynamic visual of lighter and darker sections.” Wood fiber insulation and cladding composed of fire-treated pine is also installed.
Glued laminate timber beams and columns line interiors outfitted with wood to level humidity, imbuing warmth in the winter and cooling the summer. The recessed ground floor is animated with diagonal lines on the floor to facilitate smoother vehicular access, while the existing communication core from adjacent building phases contributes to lateral stability and access to office floors. Floors constructed using a composite structure of CLT and concrete establish a slim and efficient flooring system across all five levels. Floor-to-ceiling windows invite abundant natural light throughout the interior, including service areas and meeting rooms wrapped in wood wool acoustic panels. A timber staircase serves as a sculptural focal point in the internal atrium as it contextualizes scale. White-pigmented spruce panels adorn exterior walls while visible conduits are painted light beige as well. “The use of mass timber in Lumber 4 achieved a 53-percent reduction in greenhouse gas emissions compared to standard buildings,” Imislund says. “The project proves that mass timber can compete directly with conventional steel and concrete buildings in terms of cost.”
