The planning of an additional storey for an apartment block designed by Eino Tuompo and completed in 1959 in the Munkkiniemi district of Helsinki was initiated by the housing company. Considerations were the need to finance pipe repairs as well as a synergy benefit in timing.
Planning began in the spring of 2012 and construction was completed in the spring of 2015. The process was quite long, as the project required a special zoning exception because it exceeded both the permitted building volume and number of storeys allowed.
Rakuunantie is located in a culturally and historically valuable area of stylistically coherent architecture built in the 1950s and 1960s. Apartment blocks along the street have been classified as culturally and historically valuable, but the area’s buildings and urban environment have not been protected. The city’s stance on further construction was favourable, following its strategy of more compact housing. While preparing the exception decision the city planning office also drafted a report on possibilities for raising the height of other buildings in the area. Rakuunantie 1 became a kind of test and pilot site.
The existing building did not have an actual attic space, and the space between the upper and lower roof structures was too low to allow for building lofts. Instead, expansion was achieved by adding a storey. In the solution chosen, the floor area of the flats is retracted from the long facade lines and there is a long, open terrace at the front of the flats.
The old mansard roof was demolished, and its edges around the additional storey and eaves were built according to the old model. Existing stairwells were extended to the floor level of the new flats. Lifts were not extended to the top storey, so the new flats have no disabled access. In this respect the additional storey was considered comparable to loft construction in the permit process.
The additional storey has six new flats, two off each stairwell. The new flats are two-room floor-through flats, with larger three-room flats at the ends that have views in three directions. Structural planning of the additional storey followed National Building Code E1 section 6.2.3, which allows an additional storey for a class P1 building of no more than 7 storeys to be constructed from wood. The structures must be protected from fire with cladding.
The wooden walls and roof were constructed using wood elements from Koskisen Oy. The additional storey’s long facades have white, low-profile steel cladding and the ends are smooth facade board. Windows and doors are wood-aluminium and the same colour as the facade. Dividing walls on the south terrace have board cladding. Railings are blued steel. Marquis were designed to top the large window surfaces. The Facade materials repeat the old building’s material world and are logical for a light-frame structure, which is how, based on a construction assessment, the building had to be realised. The floor structure is a steel beam grid and a steel plate and concrete structure installed on top of the old concrete slab.
The old chimneys in existing flats were extended to the roof. Some of the old chimneys were moved horizontally in the floor structure. Hydronic floor heating was installed in the new flats. The ventilation system is a mechanical supply-exhaust system with a heat capture device, and is specific to each flat.