Subframe for aluminium and steel cassettes

Subframe for aluminium and steel cassettes

Cassettes are trays folded from aluminium or steel sheet, usually 1.5 to 2.0 mm thick in aluminium, and sized to the project. They are the classic choice for architectural ventilated facades, because they give crisp edges, hidden fixings and a controlled joint pattern. The subframe for cassettes must hold them accurately, allow adjustment and let each cassette move as the temperature changes.

Cassette types

• Open type: cassette with return flanges and an open joint of about 10 to 20 mm, giving a strong shadow line.
• Closed type: joints are covered with a flange or a strip, so the cavity is hidden.
• Hook-on type: cassettes hung on rails via slots or hooks, which allows quick installation and removal.

Cassettes can be painted aluminium, anodised aluminium, galvanised painted steel or composite.

Subframe features

• Horizontal or vertical rails with cassette support brackets or slides
• Adjustment of cassette projection by a few tens of millimetres, so the plane can be set exactly
• Thermal breaks under brackets to limit heat loss
• Rail gaps and sliding fixings for expansion
• Special corner rails to hold external corners

Design points

• Cassette height and width are balanced between look, weight and wind loading; very large cassettes may need stiffeners.
• Horizontal joints should drain freely.
• Perforated or open joints reveal the backing, so choose a dark membrane.
• Steel cassettes are heavier than aluminium, so brackets are calculated accordingly.
• Aluminium and steel cassettes are non-combustible, but Georgian rules for buildings above 12 m (Chapter 14 of the Building Safety Rules) are applied to the whole wall build-up.

Pricing is on request. Send us your elevations and we will prepare a cassette and subframe calculation.

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