Oslotre . photos: © Kyrre Sundal . + archdaily
“Lumber 4” is a commercial and office building spanning six floors. A recessed ground floor constitutes the commercial level, with the five floors above dedicated to office spaces. The structure is composed of a mass timber construction with columns and beams made of glued laminated timber.
The floors are constructed using a composite structure of CLT and concrete, creating a slim and efficient floor system that spans long distances while also addressing fire and acoustic requirements. Diagonals on the ground floor facilitate better vehicular access around the building. The existing communication core from adjacent building phases contributes to lateral stability and access to the office floors. Between the third and fourth floors, an atrium with an internal staircase made of mass timber has been introduced. Wood elements are prominently displayed in the interior, providing warmth in winter and cooling in summer.
The facade is composed of prefabricated curved wooden elements in pine, treated with green paint. The eaves above the curved elements are straight, creating a curved shadow on the panel. Over time, the paint under the shadow will weather, leading to a changing facade with lighter and darker curved sections. The insulation used throughout is wood fiber. The cladding consists of fire-treated pine. All load-bearing structures are exposed, and exterior walls are clad with white-pigmented spruce panels. Wood wool acoustic panels are used in concealed service areas and meeting rooms. Visible conduits are painted in a light beige color. The large floor-to-ceiling windows open up to the view and provide ample natural light.
The construction of the building was completed in record time, with detailed planning and construction taking only 12 months. “Lumber 4” has demonstrated that it’s possible to construct competitive timber buildings when compared to the same technical standard concrete and steel structures. The building was 90% leased upon completion. Oslotre served as the project’s architect, interior architect, and timber structural engineer.
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