700 years of roof cadastre Vienna / City Centre

A pilot project of the Federal Monuments Authority Austria in cooperation with the City of Vienna and the Federal Chancellery.

The Viennese roofscape harbors a previously untapped treasure of century-old wooden structures. This stock has changed significantly in recent decades. From a closed historical texture, a heterogeneous ensemble of roofs transformed by contemporary interventions has developed.

For this reason, the Federal Monuments Authority Austria together with the City of Vienna and the Federal Chancellery launched the research project in 2016 and 2017 to analyse the historic roof structures of the First District.

The roof cadastre records approximately 1,400 objects in the centre of Vienna in terms of construction age, construction and development status. The inventory is enhanced by the scientific survey of 90 individual objects. Above all, the focus is on the roofs of the Wiener Bürgerhaus, which have been exposed to high usage pressure for many years and are therefore threatened by loss.

In the first phase, all roofs were subjected to a preliminary dating process. This happened on the basis of monument inventories as well as archive sources of the Federal Monuments Authority. In the plan archive there were representations of roof structures for around 200 objects. From the photo archive, historical roof views and measurements as well as the documentation of war damage were helpful. The archive provided information on measures to the individual objects since the beginning of the state preservation of monuments in 1850.

The second phase of the study included systematic surveying, photo documentation, technical description and dendrochronological determination of selected individual objects. On the basis of the roof mapping, 90 roof structures were chosen for this purpose, which represent structures that are as unchanged as possible and a good cross-section of the epochs. On average, two system photos were taken per object, granting material for total number of 180 roof constructions. The photographs were taken using reference sheets, which precisely defined the presentation and data entry and should serve as the basis for the systematic evaluation of the catalogue.

Based on the first overall survey and the detailed object photographs, the third phase currently focusses on the typological classification of the roof structures and the reconstruction of their development history.

Why a roof cadastre for Vienna?
The roof cadastre is a supplementary survey of ​​Vienna's city centre. It clarifies the number, variety and distribution of the roof types, helps secure the construction plans by documenting them and is the basis for technical decisions.

The project team consists of employees of the Federal Monuments Authority, involved agencies of the City of Vienna and the Federal Chancellery as well as construction researchers of "DenkMalForscher", the team of "BaukunstConsult" and the team of Dr. Michael Grabner (BOKU, Institute of Wood Technology and Renewable Resources) for dendrochronological dating.

The project was completed in the planned period from 2015 to 2017.

The roof cadastre in numbers

  • Roofs of 1,400 objects in Vienna's 1st district were explored
  • detailed image of 73 objects are available = 73 object files
  • 180 roof construction systems
  • 15,000 photos
  • 1,200 data sheets
  • 1,440 dendro samples for wood age determination
  • 600 drawings

Results

  • Vienna has the only comprehensive roof cataster of a protected old town in Europe.
  • Vienna's rooftops cover a span of 700 years.
  • There are 9 roof forms in Vienna.
  • oldest sacral roof truss: Old Town Hall (1299)
  • oldest profane roof truss: Fleischmarkt (1429)
  • Vienna has a special history of roof structure development: the baroque attic is used here for over 200 years (1613-1837).
  • Vienna has a specific type of roof typology, such as the “Firstgarbendach” (Böhmische Hofkanzlei, 1711 at Judenplatz 11). From some forms exist only single copies, as for example from the Mansard Firstgrabendach.
  • The roof cadastre helped date all roof structures to the nearest decade.
  • For many objects, the history of the building can be rewritten, as the roofs allow conclusions to be drawn about the entire architectural monument.

Further information can be found at: Bundesdenkmalamt