Composite Cassette Ventilated Facade: Pros and Limitations

Composite facade cassettes are cladding elements folded from aluminium composite material (ACM): two thin aluminium sheets with a core of polymer or mineral filler. Cassettes are fixed to the ventilated facade substructure on hooks or rivets, form a flat plane with crisp joints and put almost no load on the wall.

The key selection criterion is the core type and the confirmed fire hazard class of the system: it determines where composite can be used at all. Composite cassettes are chosen for retail and office buildings, petrol stations, inserts and portals that need light cladding with a bright plain surface, where modelling and stone texture are not required.

Composite's place among other claddings is described in the Ventilated rainscreen facades section.

A composite facade is made of sandwich panels: outer and inner aluminium sheets a fraction of a millimetre thick and a middle layer that provides stiffness and determines fire properties. The face sheet has a factory-applied polymer coating. Total panel thickness for facades is usually 3–4 mm.

Panels with different cores look the same, so the core type is checked by documents and markings, not by eye. Alucobond is a trade mark of one manufacturer that is commonly used as a generic name for ACM; the design specifies the particular product and its properties.

It is fire safety limits that determine where composite is permissible. For rainscreen facades, requirements depend on the building's use, height, fire resistance degree and structural fire hazard class. The key point: it is not an individual material that is assessed but the facade system as a whole — cladding, insulation, membrane, substructure, fire barriers. The system's fire hazard class is confirmed by fire tests on a facade mock-up.

• Panels with a combustible polyethylene core are effectively not used on facades of multi-storey and public buildings.

• FR and A2 panels are used as part of systems that have passed tests and hold a technical certificate stating the scope of application.

• Even with permissible cladding, fire barriers around openings and non-combustible insulation are mandatory.

For the client this means that composite quotes cannot be compared without checking the core class and system documents. The price difference between a polyethylene and a mineral-core panel is noticeable, and saving here may end in failed acceptance.

A cassette is a panel whose edges are folded at 90° to form a return; fixing elements are installed on the returns. It is made by routing a V-groove on the back and folding along it — this can be done in a workshop or on site, but quality is higher with factory fabrication.

• Dimensions are limited by coil or sheet width and by stiffness: a large cassette without stiffeners may flex in the wind.

• Types. Open (with a joint and a visible profile) and closed (hung on hooks with concealed fixing). Closed cassettes give a clean look but require a precise substructure.

• Joints are usually open, 8–20 mm; their width is part of the facade architecture.

Advantages of cassettes: low weight, wide choice of colours, fast installation, and the possibility of complex cutting for logos and lettering. Limitations: a flat plane with no relief, susceptibility to dents, fading of the coating over time, and fire restrictions depending on the core class.

Composite facade installation follows the general rainscreen sequence: setting-out, brackets, insulation, wind barrier, rails, hanging the cassettes. Specifics:

• the substructure is light, most often aluminium, with bracket spacing calculated for wind load, since the cladding weight is small;

• cassettes are hung on runners or pins fixed to the rails, or riveted through the return;

• thermal expansion must be accommodated — aluminium expands noticeably when heated, so fixing holes are slotted or sliding connections are used;

• the protective film is removed immediately after installation: in the sun it bonds to the coating;

• panel direction according to the arrow on the film must be respected — otherwise shade variation shows on the facade.

Maintainability is considered separately. A cassette on concealed fixing is harder to remove than a clip-fixed tile: if one panel is damaged, adjacent ones sometimes have to be taken down. So in risk zones — at entrances, on the ground floor, near car parks — cassettes are designed for individual replacement or replaced with a more impact-resistant material. A reserve of panels from the same batch should be ordered from the start: paint from different batches may differ in shade.

High installation speed is one of the main arguments for composite, but it does not remove the need to check fire barriers and insulation fixing.

Composite and GFRC solve different tasks and are often combined on the same building.

TECHNOFORMA manufactures GFRC and installs rainscreen facades with various claddings; the material is chosen to suit the architecture and fire requirements of the specific project.

Composite cassettes are not TECHNOFORMA's core material; in TECHNOFORMA projects, rainscreen facades are made mainly of GFRC, porcelain stoneware and stone. An illustrative example of a modern office building is RUBLEVO BUSINESS PARK in Moscow: 12 storeys, 2 buildings, 15,000 m² of GFRC and 5,000 m² of FRONTEK cladding, design and installation in 2023–2025. For business centres this combination provides expressive architecture without the fire restrictions typical of polymer cores.

Another lightweight cladding option is "Fibre cement panels for ventilated facades".