Lumber 4 Building / Oslotre

Architects: Oslotre
Area: 3106 m²
Year: 2023
Photography: Kyrre Sundal
Manufacturers: Splitkon
Lead Architects: Christoffer Imislund, Jørgen Tycho
Interior Architect: Amanda Skadeberg
Entrepreneur: VEF Entreprenør AS
Engineering Company: Bravida Norge AS, Rambøll, Rivcco AS, Sweco AS, Multiconsult AS, Vianova
Wood Company: Splitkon Massivtre
City: Kristiansand
Country: Norway

Architectural firm Oslotre completed a pioneering project in Kristiansand, Norway, known as “Lumber 4,” this structure spans six floors, with a commercial level and five office floors above. The building erected in 2023 is notable for its sustainable design, utilizing mass timber for structural and aesthetic purposes. This summary explores the architectural innovations and environmental strategies employed in Lumber 4, emphasizing its contribution to modern timber architecture.

“Lumber 4” is a commercial and office building with six floors. The ground floor, recessed from the upper levels, is designated for commercial use, while offices occupy the upper floors. This building features a mass timber framework, with columns and beams of glued laminated timber enhancing the structure.

The flooring combines cross-laminated timber (CLT) and concrete in a composite structure that spans wide areas efficiently. This design meets fire safety and acoustic performance standards and contributes to the building’s slim profile. The ground floor includes diagonals to improve vehicle access around the property. The building’s existing communication core, linked with earlier construction phases, enhances lateral stability and access to the office spaces. A notable architectural feature is the atrium between the third and fourth floors, which includes an internal staircase constructed from mass timber, contributing to the interior’s open and inviting atmosphere. The wood inside the building ensures thermal comfort, providing warmth in the winter and coolness in the summer.

The exterior of “Lumber 4” showcases a facade of prefabricated curved wooden elements painted green. The eaves above these elements are straight, casting curved shadows on the panels below. As the paint ages, it will weather differently under these shadows, giving the facade a dynamic appearance. The building utilizes wood fiber insulation and fire-treated pine cladding. All structural elements are visibly exposed, and the external walls are clad with white-pigmented spruce panels. Wood wool acoustic panels enhance the acoustics in concealed service areas and meeting rooms, while visible conduits are painted light beige to blend with the wooden aesthetic. The design includes large floor-to-ceiling windows that offer expansive views and flood the interiors with natural light.

The project’s swift construction, completed in 12 months, showcases efficient planning and execution. Upon completion, “Lumber 4” was 90% leased, demonstrating the market’s readiness for timber constructions that match the technical standards of concrete and steel buildings. Through this project, Oslotre has reinforced its expertise in timber construction, serving not only as the architect but also as the interior and structural engineer for the building.