System 17 Cassette

Cassette High Rise Curtain Walling

Metal Technology's System 17 Cassette, considered to be a modular system, is based on the tried and tested Metal Technology System 17 High Rise Curtain Walling System. It makes use of all the available mullion and transom profiles to create a structural grid. The structural grid is glazed out with individual cassettes consisting of glazing or panels, which are incorporated within the grid’s framework. This design approach allows the architect to design a modular wall where both panels and glass are easily interchangeable. The vision cassettes are available as fixed panes and opening sashes and are fully glazed and sealed off-site. Gaskets and glazing beads are installed in factory controlled conditions before the complete units are moved to site for fast and easy installation in the structural grid. The opening panes have the same build up as fixed sashes so it is not possible to distinguish the difference between them. Its uniform visual appearance offers the designer a continuous and expansive unitised face to the façade, which is uninterrupted by external face fixed cover caps, but complemented by a light shadow gap between the cassettes. System 17 Cassette complies with the current British Standards and is considered as an appropriate option for expansive high rise glazed applications.

Performance Overview

Weather Performance - The Curtain Walling has been tested for weather tightness in accordance with the CWCT dynamic test for curtain walling and achieved the following results:

Size Limitation

Air Permeability 600Pa Pass
Watertightness 600Pa Pass
Wind Resistance 2400Pa Pass
Dynamic Water Penetration (Aero Engine) 600Pa Pass
Dynamic Water Penetration European Standard (Fan) BS EN 13050 900Pa Pass
Wind Load (safety) 3600Pa Pass
Hose pipe test 22l/min @ 220Pa Pass
Air Permeability 0.035m3/h m2 @ 50Pa Pass

Impact Resistance

BS EN 12600 50Kg

Concealed Opening Sash Size Guidance

Maximum height and width cannot be achieved simultaneously. This table provides basic guidance; please refer to size limitation charts in Metal Technology’s technical literature for further details.

Vent Type Vent Width Vent Height Vent Weight
Watertightness 1500 1500 100kgs
Side Hung N/A N/A N/A

Insulated Panel Sizes

Maximum 3000mm x 1400mm
Minimum 400mm x 300mm

Thermal Performance

Metal Technology's Curtain Walling Range, in conjunction with the correct glass specification, is designed to aid compliance with the latest thermal requirements of the current building regulations. The thermal isolator profile has been specifically designed to minimise heat transfer across the mullion and transom.

System 17 U-Frame Values System 17 Cassette
Mullion 3.41 w/m2k
Transom 3.46 w/m2k

The following U-values for System 17 Cassette are based on 7m (w) x 8m(h) curtain walling screen.

Metal Technology can provide tailored U-value calculations using their dedicated estimating software to calculate overall project average window U-values for their full range of systems.


Aluminium profiles are extruded from aluminium alloy 6060T6, T5 or T4 complying with the recommendations of BS EN 12020-2 / BS EN 755 Parts 1 to 9. Polyamide thermally broken sections within this system are manufactured from glass reinforced nylon sections capable of withstanding temperatures in excess of 200 ºC.


The system is fabricated in “stick” form, is pressure equalised, and self-draining by means of overlapping the transoms onto the mullion members. Water is then channelled to the exterior of the building via the integral drainage chambers within the mullions. Where the transoms connect to the mullions, the joint is sealed by means of a purpose designed transom end seal. The transom members are square cut and fixed securely to the mullions by means of spring cleats designed to fit into integral ports within the cavity of the transom wall.

The system is dry glazed using proprietary, high performance captive gaskets internally. All internal gaskets are bonded and sealed during construction, using Metal Technology’s own waterproof adhesive to ensure that a watertight joint at all cruciform connections is maintained at all times. The system is thermally broken throughout by means of continuous thermal gaskets located between the cassettes and all structural members.

Each cassette unit shall be fastened to the curtain walling grid using purpose designed ‘lugs’ located in proprietary grooves within the outer fame and screw fixed to the mullions and transoms in strict accordance with Metal Technology’s recommendations and guidelines as stated within their technical literature. All cassette units should be positioned centrally and squarely on the structural grid to ensure a consistent 19mm joint is achieved. All horizontal and vertical joints shall be closed over with a purpose made moulded closer gasket.

Carefully designed fixing brackets have been developed for System 17 Cassette to allow a secure and simple fix so that all loads can be transferred back to the building’s main structural form with ease.


The range of sections can be provided in either of the following ranges of finishes:

  • Anodised to BS1615 or BS3987 or BS EN 12373-1
  • Powder organic coated to BS6496 or BS EN 12206-1
  • Metal Technology's powder coating is produced to Qualicoat standards.
  • Metal Technology's powder coating is produced to Qualicoat standards. The System 17 curtain walling can accommodate a different colour/finish internally to that used externally.


The system is externally glazed using 32mm glazing units.

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