Client: Alphatower GmbH & Co KG, Wien
Location: Hafnerriegel 53, 8010 Graz
Start of planning: 2013
Start of construction: 09/2013
Completion: 12/2014
Total area: 8.742 m²
Built-in area: 24.700 m3

Conversion of the existing dormitory into residential property. Comprehensive rehabilitation of the existing 19-storey property from the 1960s, addition of another 2 - 3 stories of penthouse flats and addition of a 1-storey auxiliary building.

Residential high-rise, 21 upper floors
The existing property at Hafnerriegel 53, which used to be used as a dormitory (completed in 1964 as the first residential high-rise of that height), was converted into a residential building. The building was rehabilitated and converted according to a modern, technical standard.

The planning was carried out with the greatest possible preservation of the characteristics of the building in order to do justice to the historic monument status of the building. The original window and facade division was restored after the thermal rehabilitation. The added stories were designed to be offset and the building structure was mainly preserved.
The unusual building typology (quarter-storey flats placed around a central staircase) required extensive fire protection related measures in order to not disfigure the building with several additional staircase towers. Besides pressure ventilation systems, which had to be accommodated in a very tight space, the building had to be equipped with a high-pressure water spray system.
The lift core and the utility centres including the technical equipment had to be completely redesigned. The basement levels and flats were given new room partitioning with modern room sizes. In several floors, the flats were connected across floors in order to create an acceptable mix of flats. Altogether, 73 flats were completed in the existing building. The existing facade was thermally rehabilitated and designed as a back-vented facade with an appearance that essentially corresponds to the original stone slab facade.
In addition, additional storeys were constructed on the roof of the existing building, which were constructed using lightweight construction due to static limitations. This added another 4 flats.

Beside the existing building at Hafnerriegel 53, a one-storey auxiliary building was constructed that protects the garden area from the street and creates space for general areas (rubbish room and covered bicycle parking areas) for which there was no space in the existing basement rooms. The access area and garden area were redesigned and are handicapped accessible.

Photos: Paul Ott, Graz