Structural components of the VCW facade system

System VHF

The typical construction of the facade system is shown in the illustration.

  1. Wall brackets
  2. Facade anchors
  3. Facade dowels
  4. Vertical profiles
  5. Thermal insulation
  6. Ventilated substructures
  7. Fastening elements for the cladding (rivets, ceramic clips, polymer adhesives etc.)
  8. Cladding panels (ceramic, metal, fibre cement, composite)

Anchoring

Facade anchors approved by the building authorities must be used to anchor the VCW to the supporting external wall. The optimum anchors are selected for use in each project based on considerations such as the materials used in the construction of the supporting external wall and the prevailing loads. For VCWs, the most commonly used anchors are plastic anchors with galvanised screws. Generally, a distinction is made between the following types of anchor:

Insulation

Suitable insulation materials:

Only mineral wool materials may be used for the insulation of VCW. These must comply with DIN 18516 and hence be non-flammable and absorb very little moisture. Standard insulation thicknesses in Central Europe are in the range 120 - 200 mm, or even higher where thermal insulation requirements are greater.

Installation:

The insulation materials must be stored dry and then laid and joined together in a single layer on the supporting wall. The insulation panels must be installed in such a way that there is no gap between the surface of the wall and the insulating layer. This ensures that no current of cold outdoor air can circulate behind the insulation. The joints between the insulation panels must be pushed firmly together to ensure a tight seal. Connections to the substructure, e.g. brackets, must be installed with no gaps. The fleece lamination must always be to the outside.

Fastening:

Mineral wool insulation panels are always fixed in place mechanically. They are fastened using insulation brackets, which have a limiter to ensure the insulating material retains its full thickness at the fastening point.

Substructure

The substructure transmits the load of the cladding itself and the wind load to the enclosing external wall. Metal substructures are generally used as these can compensate for tolerances in the shell construction. Most systems consist of a two-part construction, which is fastened to the supporting external wall using anchors. This base construction is aligned plumb and flush and acts as a support for installing a variety of facade cladding materials.

The substructure system must be designed in such a way that materials used can expand due to temperature changes without creating stresses in the structure. For example, when using aluminium profiles with a length of approx. 3 m, an expansion of 5mm must be taken into account (temperature range -20° C to 80° C).

So-called fix point / sliding point structures are often used for this purpose.

The bracket used has the following functions:

  • acts as a fix point for screwing the profiles into position in the round hole – the profile is fixed, transmission of own weight and wind loads
  • acts as a sliding point for screwing the profiles into position in the slot hole – the profile slides in the slot holes, transmission of wind loads only
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