Puukuokka is the first eight-story heigh wooden apartment building in Finland. Developed in collaboration with Lakea, it is an energy-efficient trio of multi-story wood-framed flats in the Jyväskylä suburb of Kuokkala, neighboring the Kuokkala church also designed by OOPEAA. The Puukuokka apartment complex is comprised of three 6-8 story buildigns. The first building in the Puukuokka complex is now complete and the other two buildings will be built over the next two years. The complex offers 150 flats with a combined floor area of aprox. 10,000 m2. The buildings are composed of prefabricated cubical modules made of cross laminated timber (CLT) utilizing the Urban MultiStory concept developed by Stora Enso. Planned in collaboration with the Jyväskylä City Planning Department, the project will visually enhance the townscape while offering affordable, eco-efficient housing that is easily adaptable to changing needs over time.
Puukuokka is constructed with prefabricated modules that are fully prepared and finished in controlled indoor conditions. They are then brought to the construction site ready to be simply plugged in much like building a structure out of Lego pieces. Even the façade is made using prefabricated and finished elements that are installed on site in phases corresponding to the progress of the installation of the modular elements. This makes it possible to achieve a higher quality in the end result than would be possible in a traditional construction process. The central hallway is the only part of the building that is constructed on site. This cuts the construction time on site down to six months, a very valuable advantage in the northern climate conditions in Finland. The use of modular prefabricated elements ensures a uniform high standard of quality and minimizes delays and other weather-related problems during the construction process. The modular cubical elements made of cross laminated timber are dry, adaptable, lightweight and ready-to-install. The CLT frame serves both as a loadbearing and stiffening element while also providing vapor barrier and partial heat insulation.
There are fewer joints and less material is needed than in conventional timber buildings. There is also a reduced risk of installation flaws and the modular structure is more dimensionally stable under a moisture attack. On the courtyard side, the façade made of larch wood has been left untreated. On the side facing the street, spruce has been used and it has been treated with a coat of dark paint. On the courtyard side the façade is animated with extruding balconies while the majority of the balconies are recessed and provided with sliding glass doors covering the entire length and height of the interior wall and opening up vistas into the surrounding landscape. A sense of openness and wealth of light is present also in the shared hallways of the apartment building. They are more spacious than usual and offer a rhythmically arranged series of views opening out to the landscape of forest and hills around. The plan of the apartments is efficiently arranged and the presence of wood in the interior surfaces adds an element of warmth and quality to the living spaces. The building is characterized by an overall fine quality of the wooden surfaces and by carefully thought out, yet straightforward detailing.
The prefabricated modules constructed out of CLT are made of spruce. Each apartment is composed of two modules, one housing the living room, the balcony and the bedroom, the other housing the bathroom, the kitchen and the foyer area. The piping for heat, water and electricity for the apartment units is installed in the shared hallway spaces where it is integrated in the wall structure. In that way it is easily accessible for maintenance and repair.
The flooring of the hallway areas is made of bridge-like CLT elements. In the interior spaces, the wooden CLT structure has been left exposed in the ceilings and in the floors and staircases of the hallways. However, the walls have been covered with gypsum board partly to avoid an appearance of too much wood in the interiors as well as to fulfill the regulations mandated by law for fire safety. The apartments have parquet flooring. The town plan has been tailored to meet the needs of the building complex, which has made it possible to count only part of the shared spaces as part of the permitted building volume. In order to preserve the naturally hilly landscape of the site, as much of the bedrock has been left untouched as possible. The building complex is built on a concrete foundation with indoor parking spaces offered on the basement level. Puukuokka pilots a low-cost, low-risk financing model for homebuyers. After renting a flat for 20 years, the occupant becomes its owner. Before moving in, the future owner pays a modest down payment (7% of the total value of the home). The remaining sum is covered by a State-guaranteed bank loan. The occupant pays off the loan in the form of rent over a 20-year period, after which the flat becomes his or her own. The sales price is negotiated and agreed upon when the lease is signed.