Wood built residential block Puukuokka 1

Puukuokka, built at Kuokkala in Jyväskylä, is the first example of an eight-storey, woodbuilt residential block to be built in Finland since they were permitted, in 2011. The first of this group of three apartment blocks, housing 58 flats, has now been completed. Puukuokka won the 2015 architecture Finlandia -award.

On the western edge of the site is a protected area of rock and a small stand of forest, so that the buildings have been located on the eastern side of the site. When completed, the whole scheme will consist of a total of around 150 apartments. Completely beneath the flats is a concrete-built area housing car parking, stores and plant rooms, so that it has been possible to use the slope of the site to advantage, while the car parking area is serviced with natural ventilation and smoke extraction.

The buildings are assembled from spatial elements which are prefabricated under factory conditions. The frame of the spatial elements is of cross laminated timber, CLT. The aim of the prefabrication is to achieve an even, high standard of quality. The rapid fixing schedule for the spatial elements aims to avoid the site problems which are part of the normal building process. The CLT slabs form a frame of loadbearing and stiffening components. Windows and thermal insulation are fixed to the elements. The facades are prefabricated, and fixed on site with secret fixings at the same rate as the storeys are constructed. The street elevation is in painted spruce and the courtyard side is in untreated larch. The method of construction aims for reductions in the amount of installation work on site and cuts in the quantity of material wasted. It also delivers high quality and durability.

The structural frame of the building consists of modular, container-like spatial elements which offer new potential for building in wood at a large scale. One individual apartment is made up of two spatial elements constructed of CLT. One of the spatial elements is made up of entrance hall, bathroom and kitchen, while the other consists of living room and bedroom, plus the balcony. The spatial elements are completely ready in terms of interior finishes and equipment. Wood is visible in the suspended ceilings and the floors, and also in the windows. Elsewhere, the wood finishes of the loadbearing components are clad in plasterboard to give fire protection in accordance with the regulations.

Services connections, ventilation and other technology are integrated into the wall construction of the stairwell which is built and finished in situ. The end result is a light and airy stairwell where wood is present in the solid CLT floor construction. The floor of the stairwell is constructed of bridge-like beams, with their upper surface forming the floor. The staircase itself is made of the same material. The project was built in cooperation between Lakea, Stora Enso and the City of Jyväskylä town planners. The apartments are affordable, ecological and easily altered to meet the changing needs of residents. As one of the pilot projects, Puukuokka Lakea offers a new kind of alternative for home-buyers. Apartments are paid for in the form of rent over a period of twenty years.