Cross-laminated timber (CLT) is a compromise between an industrially manufactured element system and craftsmanship. Cross-laminated prefabricated solid wood elements were delivered from Stora Enso’s factories in Austria as raw sheets (16 metres long, 4 metres wide, various thicknesses). The sheets are made of Austrian spruce and glued with emission-free M1 class urethane adhesive. The sheets were machined in Pälkäne, where also other work phases were completed including the installation of heat insulation. The Austrian concept of quality can be seen for example in the mending of holes: instead of using just any piece of wood, holes have been repaired with knot discs.
Austrian wood was used because CLT was not manufactured in Finland before Haltia's construction. However, a CLT production line has been opened in the Lapland University of Applied Sciences in Kemi for training purposes. One of Haltia’s objectives is to promote this trend to support the construction of public buildings made completely of wood.
• Strong structure
• Naturally braced (allowing Haltia to be the first building in Finland with a wooden lift shaft)
• Balances moisture levels inside the building
• Excellent acoustic features
• An aesthetically pleasing working environment
• Creates a structural barrier (moisture soaks 2 cm deep into the intercellular space of the wood and dries out in winter when the air is drier)
• Heat insulation: although a passive-energy building, Haltia is in energy efficiency class B because the exhibition and kitchen premises consume a lot energy. Compared to other similar buildings its consumption is low, however. Fibreglass (made from recycled glass) was used, since wood-based wool is prohibited by fire regulation. Fibreglass has superior heat insulation properties to wood (in the walls, the wool layer is 30 cm thick and in the ceiling, 70 cm thick)
• The building’s fire barrier wall is designed to withstand a 90-minute fire at the minimum.