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What is a casement window?


What is a casement window?

Everything you need to know including how casement windows work and the key benefits they provide for any type of property.

What is a casement window

A casement window is the oldest style of window in the UK and the most popular as the design is so versatile.


A casement window is hinged at the side (unless it’s a top hung window) and is usually fitted in single or double panels. Casement windows have plenty of configurations to make different windows from single, double or more panels.


Casement windows are available in uPVC (the most popular), timber or aluminium for a contemporary building.


Different variations of casement windows will suit most properties and are our best selling window style at Everest.


The different types of casement window

  • Side hung

    The most common type of casement window that is hinged at the side and the window opener will swing outwards.

  • Single casement

    A basic window that has just one panel and is usually side hung.

  • Double frame or french casement

    Two panel windows that are both side hung. The window has a central mullion with the window handles in the centre and opens outwards to create a large aperture opening.

  • Top hung or awning window

    A window that opens from the bottom and is hinged at the top. The window swings outwards so rain doesn’t come into the room in wet climates.

  • Bottom hung or hopper window

    The window opens at the top of the frame with a hinge at the bottom - tilt and turn use a bottom hinge. Ideal for apartments and upper floor rooms to allow safe opening.

  • Flush casement

    A sleek frame where the window sits flush in the frame when closed. A contemporary finish that is becoming more popular, especially for aluminium frames that have a slim profile.

  • Fixed casement

    A casement window that doesn’t open. Usually part of a configuration that has window openers on either side. Popular in bay windows.


What is a casement picture window?

A picture window is a large rectangular casement window that cannot be opened to maximise the area of glass to appreciate views from a window. Usually fitted in living spaces or windows that overlook an attractive aspect. Hence, picture window.

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What are the different parts of a casement window?

parts of a casement window

parts of a casement window

  1. Window Frame
    The window frame holds the casement window in place. It is made up of a head and a sill that runs horizontally along the top and bottom, combined with two jambs that run vertically on either side.
  2. Window Sill
    Forming the bottom of the window frame, window sills (also called cills) are slanted to effectively direct water away from the window frame and the building.
  3. Casement
    The casement is the part of the window that opens, securing the glazing in place.
  4. Mullion
    A window mullion is the vertical strip of supporting uPVC, timber or aluminium that divides separate window units.
  5. Transom
    A window transom is the horizontal strip of supporting uPVC, timber or aluminium that divides separate window units.
  6. Lock Handle
    The casement window's locking mechanism is located on the casement jamb.
  7. Trickle Vent
    Fitted at the top of the window, trickle vents consist of a grill on the outside and a closing vent on the inside.
  8. Georgian Bars
    Fitted inside the sealed unit, Georgian bars are the vertical and horizontal bars that create the classic appearance of the glass being divided up into small squares.
  9. Astragal Bars
    Similar to Georgian bars, Astragal bars are applied to one single piece of glazing; fitted on top of the window, internally and externally.

Are casement windows the best type of window?

  • Limited in size
    A casement window is limited by the size of the opening panel. Due to the weight of the glass, an opening panel hinge would have to support the window so it can only be a certain size. This is why bay windows will have a central picture or fixed window with smaller window openers at the sides.
  • Versatile style
    Even though casement windows are limited in the size of the opener, they are so versatile in configuration that you can have many different styles to suit most needs.
  • Versatile materials
    Casement windows are available in uPVC, timber and aluminium to suit all properties.
  • Energy efficient windows
    The opening panels will close tightly and Everest casement windows are highly energy efficient.

Are casement windows more expensive?

A uPVC casement window in white is the cheapest style of window that you can buy.

Everest window styles

Casement Windows →

  • Thermally efficient
  • 12 colour options
  • Smooth or wood grain
  • Highly secure GrabLock

Tilt & Turn Windows →

  • Opens in for easy cleaning
  • Tilts for secure ventilation
  • Five colour options
  • Smooth or wood grain

Bay Windows →

  • A sense of space and light
  • Panoramic views
  • Four different configurations
  • uPVC, timber or aluminium

Sash Windows →

  • Replica traditional design
  • Smooth running mechanisms
  • Smooth or wood grain
  • Traditional sash furniture

We can help you choose the right windows for your home

We have 1000s of options to make your windows unique to your home. Choose from a selection of stunning colours, beautiful furniture and glass styles, all offering exceptional energy efficiency and security.

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