Treehouses Bebelallee

Addition to an existing estate of terraced houses in prefinished wood frame construction. The doubling of living space whilst at the same time halving carbon emissions released from regular use of the building demonstrates wood’s quality as a building material for redensification projects.

address of building



blauraum architekten bda, Hamburg/D, ­  


Robert Vogel GmbH & Co KG, Hamburg/D,

Structural design

IB Dr. Binnewies, Hamburg


June 2010

The housing estate on Bebelallee was built in 1959 and is located in Alsterdorf, about seven kilometres north of Hamburg’s city centre. Five two-storey apartment rows running south-west to north-east and a three-storey block set perpendicular to them house 104 flats, each with forty to seventy square metres of living space. The aim of the redensification feasibility study carried out in 2006 was to double the living space while reducing by half the carbon dioxide emissions from the complex. A solution was reached to add two storeys in timber construction on top of the existing buildings. Forty-seven new, family-friendly flats offering ninety to 140 square metres of living space apiece have now been added to the small existing apartments, whose residents have a high average age.It was possible to carry out the modernisation work without the current residents having to vacate the premises. The facades of the existing storeys were given a layer of heat insulation and then clad in brick typical of the area. To carry the loads added by the new storeys it was necessary to underpin parts of the existing strip foundations. The added storeys were built using a hybrid constructiontechnique: the stairwells and the walls separating apartments are made of concrete and brick, while prefabricated timber elementswere used for the remaining walls, facades and the majority of the ceilings. Wood as a building material can also be found in the shingled facade of untreated Alaskan cedar, which will turn grey over time, blending in with the colour of the brick facade. Fire tests were required before the facade could be approved. With this modernisation, the wide-open spaces typical of 1950s’ housing estates have been replaced by a denser urban layout and a social mix appropriate to the buildings’ central location. In view of the large number of housing estates from the post-war reconstruction era that have yet to be refurbished, this project can be regarded as an exemplary model for the technical and design qualities offered by timber as building material for use in urban redensification.

projekt-aufstockung-hamburg402 K
Category: Dachbodenausbau, Bauen im Bestand, Wohnbauten