In Kuninkaantammi, Helsinki, Koskisen’s Housing Industry has erected a 58-apartment wooden building, which is part of an internationally renowned research project,” explains Hannu Saari, Technical Director for Rakennusliike Reponen, the project’s turnkey contractor. “We built two corresponding houses – one with a wooden frame and the other from concrete. We monitored work efficiency during framing and VTT will perform tenant satisfaction surveys, which reliably compare the impact of the different frames on tenants’ lives and simultaneously rule out environmental impacts as the buildings are adjacent to one another,” Saari says.
“Research is also being carried out on energy consumption, looking into whether the thermal mass of the frame has an impact – wooden houses do not have a thermal mass, while concrete houses have a large one,” Saari adds.
According to the Technical Director of Koskisen’s Housing Industry, Harri Moilanen, happy families live in wooden apartment buildings. “Or at least families that are happy with the building, according to the research,” Moilanen says. According to him, wooden blocks of flats have excellent sound insulation, for example. Saari from Reponen agrees with Moilanen, adding that the completed flats are acoustically pleasant: “There are no hard surfaces anywhere.” Moilanen and Saari are also unanimous in their praise of wooden apartment buildings’ eco-friendliness. “The facts speak for themselves,” Saari says.
“Our employees are happy to work in wooden apartment buildings because the work is much quieter. There is no chipping or drilling holes for plugs or the ever-present fine cloud of dust. These are factors that affect occupational health and work efficiency,” says Saari.
The construction of wooden apartment buildings is also faster. “The external walls are made as ready as possible at the factory, including windows and flashings, and intermediate walls are added as elements. We are thus able to reap the benefits financially because the implementation phase is a third shorter. The elements installed at the frame phase are also larger than in a concrete building,” Saari adds.
Saari’s concern is, however, that wooden apartment buildings cannot hold their own against concrete buildings in price competition. “There are no regulatory changes in sight that would alter the situation. Construction costs are increased, for example, by the mandatory sprinkler systems.” Also the weather protection implemented at the frame phase increases costs but it also brings savings because it speeds up the work. “We have carried out all of our wooden apartment building projects under weather protection: when the installation of the second storey is under way, we can work on the interiors of the first storey.”
Saari says that the wood products industry in Finland is not yet ready for wooden apartment buildings. “The construction industry doesn’t understand the process yet; Koskisen is a pioneer in this respect, however. They have insight into the construction business and are light years ahead, although there is still much to achieve,” says Saari.
Moilanen sees wooden apartment buildings as a growing business that has experienced growth for the past seven years. Koskisen has been focussing on development work in order to support this growth and its standardised wooden apartment buildings include, not only the wall and roof elements, but also intermediate floors and component products such as stairs, glue-laminated timber structures and balconies. The company’s wooden apartment buildings include design and installation. “Koskisen’s wooden apartment building concept has been repackaged, which has attracted the attention of construction companies in the SME sector,” concludes Moilanen.