Steel Top-Hung Windows


Operated with a handle at the bottom, attached to the window frame at the top with hinges or friction stays, top-hung steel windows offer saved space inside, maximum daylight, enough ventilation, and easy operation. Also known as top-guided or awning windows, top-hung steel windows are suitable for any type of residential or commercial buildings.

With their slim sightlines, steel top-hung windows offer a sleek and modern aesthetic in buildings. Their versatility makes them suitable for various architectural styles,  from classic to contemporary homes.

Design and Aesthetic


  • Thermally broken profiles as standard 
  • A basic depth for thermally broken steel windows is between 50-70mm.
  • Slim sightlines

Materials and Surface Finishes


  • Strip galvanised steel (Allowing full range of standard powder coated RAL colour options)
  • Corten steel
  • Stainless steel
  • Marine grade powder coated for for use in marine and coastal environments

Size Limitations


  • Standard sash sizes for steel top-hung window are up to 1.8 metres in width and 1.8 metres in height.
  • A steel top-hung window sash may weigh up to 150kg. 

Opening options


  • Top-hung: Equipped with visible butt hinges, enabling the designing of large size top-hung windows.
  • Top-guided: Equipped with concealed friction stays located in the vertical jambs. Upon opening, the top of the sash moves downwards, providing increased ventilation.

Safety & Security Options


  • Steel top-hung windows come usually with multi-point locking systems as standard.
  • Burglar resistance classes of RC2, RC3 or PAS24 are available as security options,
  • Restrictor can be used to limit the amount of opening of the top-hung windows for safety.

Glass Options


  • Double glass option for a standard size top-hung window: 4-20-4, toughened glass, 20mm argon filled cavity, Ug-value of 1.0 W/m2K, low-e coating, warm edge spacers, light transmission over 70%) 
  • Triple glass option to achieve better thermal performance.
  • One pane of glass unit can be built with laminated glass for additional security or safety for preventing fall through, overhead glazing and full height glazing.

Thermal Performance


  • Thermal performance of a steel top-hung window depends on its frame and glass combinations.
  • A typical steel top-hung window can achieve a U-value less than 1.4 W/m2K with a double glass (Ug=1.0 W/m2K).
  • For better U-values, triple glass must be choosen.

Weather-tightness Performance


A typical outward opening steel top-hung window should meet the following minimum weather-tightness performance values:

  • Air tightness: Class 4 (600 Pa)
  • Water tightness Class 9A (900 Pa)
  • Wind load resistance: Class C4 (1600 Pa)

Regulations and Standards


Any steel window to be installed in residential properties is subject to building regulations and certain standards:

  • Windows to be installed on the ground floor of new residential buildings must have PAS24 securilty level. (Part Q, Read More >> )
  • Windows to be installed on residential properties must comply with Approved Document L in terms of thermal performance ( Read More >> )
  • Windows must comply trickle vent requirements specified in Approved Document F (Read More >>)

Buyer’s Guide to Steel Windows


Steel top-hung window allows wide opening with slim profiles

Steel top-hung window allows wide opening windows

Common applications of top-hung steel windows

  • They are traditional window types in the UK and are used in all types of building including historic or modern buildings.
  • As they can be easily opened and closed, they can be used any locations in the buildings. 
  • As they do not occupy any interior space when opened, they are an ideal solution for tight spaces, such as narrow corridors or small rooms. 
  • They are ideal for rainy climates as they prevent water ingress during rain  compared to inward-opening windows.