Anyone who clads an existing building with a metal facade rarely works under ideal conditions. At Augustenstraße 2 in Stuttgart, a renovation project by Altvater GmbH based on plans by Plan 11 GmbH, almost all the factors that make facade planning challenging came together: no complete 3D scan of the building, three fundamentally different substrates, a multitude of special geometric situations and a facade system that requires precise structural requirements.
System selection: Where INVISIO works – and where it doesn’t
The key question at the start of planning was not which system to choose, but where which system would find its limits. BEMO-BOND INVISIO requires a defined suspension geometry, which cannot be achieved in every facade area.
The facade areas were systematically divided into two categories: Areas where INVISIO’s concealed fixing principle is structurally feasible, and areas where a riveted design is technically superior or remains the only option. The decision criteria were:
- Geometry of the installation location: Inclination angle of the cladding surface (inclined forwards, inclined backwards, vertical), accessibility for installation and the hanging direction of the panels.
- Edge formation: Areas with folded edges, closed edges or perforated sheet metal panels each required an individual system approach, as INVISIO’s undercut technology reaches its geometric limits here.
- Panel format and installation depth: The available construction depth in front of the existing facade determined which substructure height was feasible and thus indirectly which fastening system was suitable.
Solid aluminum panels were used wherever solid, dimensionally stable cladding elements were required, especially in areas with an increased risk of wear or where the panel geometry did not allow concealed fastening.
Three substrates, one concept
The existing building has reinforced concrete, steel structures and masonry as substrates – each with its own requirements for fasteners, edge distances and load transfer.
The planning of the steel substructure was awarded to an external engineering firm. This area was the most complex in terms of planning: first of all, it was necessary to define the points at which steel components protrude from the facade level and the minimum distances to be maintained from the façade surface. Only then could the connection situation between the steel profile and the BEMO substructure be detailed – and only after this detailing was a static calculation possible.
System lines as a planning substitute for missing inventory data
The lack of a complete 3D scan was the main planning restriction. The solution: definition of system lines as grid-like reference planes from which all dimensions were derived. This principle decouples the facade planning from the inaccuracy of the existing geometry.
The system lines define the alignment, height differences and inclination planes of the cladding. All brackets, substructure components and panel connections refer to these lines – not to the actual existing surface.
The advantage of this approach is that the façade has a geometrically defined, flat surface, regardless of unevenness and tolerances in the existing structure. The prerequisite is sufficient depth of the substructure for the necessary leveling.
Detailed planning: From 30 to 9 rule details
Theoretically, around 30 individual details would have fully mapped all situations in the project. The planning team reduced this to 9 standard details that bundle the essential connection principles: Vertical cladding between window axes in three inclination variants, balcony cladding on the soffit and parapet, the terrace area with the existing roof including a separate structure for the intermediate areas, corner and edge situations as well as the connection to the window reveal and lintel. Anything that could not be detailed according to the rules was not forced onto the drawings – but handed over to the design team with the clear requirement to check and adapt on site.
Bracket planning and fastening grid
The bracket planning followed the same principle of systematization: all areas with clear planning options were fully worked out, including projection, centre distance and load assumptions. Areas that cannot be clearly planned must be determined on site and executed accordingly.
Results and planning quality
The project shows how methodically structured planning can lead to a technically resilient and economically feasible solution, even with a patchy foundation. The combination of BEMO-BOND INVISIO and solid aluminum panels makes it possible to resolve the different geometric and structural boundary conditions of an existing building in a uniform facade appearance – and the reduction to 9 standard details makes the planning concept transferable to comparable renovation projects.
