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System 4-20Hi+ Thermally Enhanced Polyamide Casement Window

Metal Technology's System 4-20Hi+ offers the designer a wide and diverse range of profiles that provide structural integrity, weather performance, thermal enhancement and security. It is a highly cost-effective glazing solution complying with and in many cases exceeding current Building Regulations. The polyamide thermal break profiles have been specifically designed to minimize heat transfer across the window profiles. Thermal performance is further improved through the introduction of specially designed thermal gaskets and foam profiles. These reduce radiation heat loss across the air cavities within the window profiles to provide additional thermal enhancement.

Secured by Design:

  • All glazed curtain walling screens, windows, and doors within the ground floor and vulnerable areas are secure by design.
  • All systems installed are tested in line with PAS 24 security standards and certified by a UKAS accredited certification body.

General information

As drawing

As schedule

Uniclass 2015
Pr_30_59_98_02 Aluminium window unitsPrimary

L10/25 Aluminium windows

L10/330 Aluminium windows

Specification data - Aluminium window units
Product Reference

System 4-20Hi+ Thermally Enhanced Polyamide Casement Window


Side hung open out

Top hung open out


As drawing

As schedule

Finish/ Colour -

Insert requirement.


Insert requirement.

Glazing -

24 mm insulating glass units

26 mm insulating glass units

28 mm insulating glass units

30 mm insulating glass units

32 mm insulating glass units




Background ventilation -

Not required

Glazed-In Ventilator

Finish/ colour

Insert requirement or 'not applicable'.

Louvres -
Blade pitch

Not required

33 mm

50 mm


Insert requirement or 'not applicable'.


Not applicable

Bird mesh

Fly screen mesh


Lug fixings

Frame anchor fixings

Ironmongery/ Accessories

Butt hinges

Friction hinges

Special order

Insert requirement.

Standard product features


Extruded aluminium alloy (6060 T6, T5 or T4 to BS EN 12020-2; BS 755-9; 2001).


Frame members are mitre cut at 45°, corners are reinforced with extruded aluminium crimping cleats and corner braces, and a secure joint is formed by pneumatically crimping into the extruded crimping cleat. Mullion and transom bars are square cut shaped and fixed securely to the frame by means of stainless steel screws and fixing cleats. All frame joints are sealed during construction against entry of water using Metal Technology’s two-part adhesive. Metal Technology recommend that only A2 or A4 Austenitic (300 series/class 70) stainless steel fixing screws are used in the assembly of their products.

Sill Liners:

All windows incorporate a sill liner profile to accommodate made to measure bespoke push fit aluminium sill pressing.


Windows can accommodate a range of insulating glass units, and are dry glazed using ‘snap-in’ extruded aluminium beads with colour coded, co-extruded, PVC nitrile, captive ‘E’ gaskets externally and ‘wedge’ gaskets internally. Consult Metal Technology for recommendation and details.

Air tightness:

All windows have a continuous EPDM seal fitted to their perimeter.

Technical properties:

  • Air infiltration (to BS EN 1026): Class 4.
  • Watertightness (to BS EN 1027): Class E900.
  • Wind resistance (to BS EN 12211): E2400.

Product Options


Maximum opening vent size:

– Top hung:

  • Height: 1800 mm.
  • Width: 2000 mm.
  • Weight: 100 kg.

– Side hung:

  • Height: 1800 mm.
  • Width: 1000 mm.
  • Weight: 47 kg.


The finish is generally polyester powder coated to BS EN 12206 or BS 6496 in a standard RAL colour to satisfy a corrosion classification as defined by Akzo Nobel. Can also be anodized to BS 1615, BS 3987 or BS EN 12373-1. The system can accommodate a different colour finish internally to that used externally.

Background ventilation:

The window can incorporate a Glazed-In Ventilator which is polyester powder coated to match the window profiles.

Ironmongery/ Accessories:

Opening vents are hung on a pair of friction hinges or butt hinges, sized to the manufacturer's recommendations, and are fitted with standard push-to-release, lockable, cockspur handles (CA12). Opening vents are fitted with friction restrictors to limit opening depth to 100 mm. Consult with Metal Technology for recommendations and details of additional ironmongery options.

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