The project, commissioned by Pudasjärven Vuokratalot Oy, was carried out under ARA's interest rate support model, with Rakennusliike Lapti Oy as the main contractor.
This intriguing project combines steel, concrete, and wood. The framework is supported by Peikko's DELTABEAM® Green Composite Beams, made from recycled steel, along with concrete pillars. The exterior walls are clad in Kontiotuote's non-settling log cladding. In this innovative construction model, the strongest attributes of different materials are combined with an ecological mindset.
"Concrete and steel possess excellent sound, fire, and strength properties. They form a sort of skeleton for the entire building. In my opinion, wood is best suited for the space between the exterior and interior, which is why the outer shell is made of wood," says Jouko Väänänen, CEO of Pudasjärven Vuokratalot Oy.
Designing a hybrid structure requires a deep understanding of materials and their unique characteristics. In the project designed by Sweco, the best qualities of concrete, wood, and steel are utilized both from a structural and aesthetic perspective. This new concept was inspiring for all parties involved, who collectively have over 300 years of construction experience.
Tuomas Jaakkola, a Structural Engineer at Sweco, elaborates on the demands of the design process: "Designing a hybrid structure requires mastery and understanding of materials, as well as insight into the specific characteristics of each material. Only through this can we identify challenging aspects and resolve issues as they arise. Different materials behave differently depending on factors like weather, and the designer needs to be familiar with their physicochemical properties, as well as the environmental conditions of the construction site."
Jaakkola explains that in this project, they wanted to leave as much of the log structure visible as possible. Hence, Peikko's DELTABEAM® Green was chosen as the composite beam solution because it allowed the detailing on the exterior walls of the building to remain consistent around the entire structure. The choice of DELTABEAM® Green aligns well with the building's ecological principles as it reduces CO2 emissions from conventional steel structures by half.
This innovative concept has also sparked enthusiasm among experienced construction professionals, according to Mikko Lohi, the Northern Finland Regional Manager at Rakennusliike Lapti Oy. While designing a hybrid building has required more time than usual, the project is progressing in the implementation phase much like standard apartment building projects. Lohi emphasizes that having reliable partners and a familiar team ensures the smooth progress of the work.
"It's truly exciting to be part of developing something new because the choices we make now will have an impact on the future. We want to be at the forefront of exploring alternative solutions for conventional apartment buildings," he says.