If you have been looking at new windows, you have almost certainly seen the word "casement" and wondered what actually makes a window a casement rather than anything else. Here is the plain-English version, with no jargon.
A casement window is a window that is hinged at the side (or sometimes the top) and swings open like a door, usually outwards. You open it with a handle, and it seals shut against the frame when you close it. That is really all there is to the basic idea. It is the most common style of window in UK homes, and it has been for a very long time, because it is simple, secure and easy to live with.
How a casement window works
A casement has two main parts: the outer frame that is fixed into the wall, and the sash, which is the part that opens. The sash is held on hinges along one edge. Turn the handle, and the sash swings open on those hinges. Because it opens fully, you get plenty of fresh air, and the glass is easy to clean from inside on many designs.
You will often see a few sections in one frame:
- Fixed panes that do not open, used for light.
- Side-hung casements that open like a little door.
- Top-hung casements (sometimes called awning windows) that hinge at the top, handy over a kitchen sink.
The main types you will come across
Not all casements look the same. In 2026 the two you will hear about most are:
- Standard casement: the frame of the opening sash sits slightly proud of the outer frame. Classic, affordable, very common.
- Flush casement: the sash sits flush within the frame when closed, giving a neat, flat face. It suits period and character homes because it echoes the look of old timber windows. If that is the style you are after, our casement windows page shows the finishes we fit.
Casements come in uPVC, aluminium and timber. uPVC is the budget-friendly all-rounder, aluminium gives slimmer frames, and timber suits traditional properties.
The pros and cons
Casement windows are popular for good reason, but they are not the only option, so here is the honest picture.
What is good about them:
- Excellent seal when shut, which helps keep heat in and draughts out.
- Strong security, as modern casements use multi-point locking.
- Great ventilation, because they open wide.
- Lots of styles, colours and glass options.
Worth bearing in mind:
- They open outwards, so you need clear space outside (a problem next to a busy path).
- Very large single casements are heavier, so big openings are often split into sections.
Casement or something else?
If you love the traditional look but want the sliding action of an old sash window, it is worth comparing casements against sash styles before you decide. For most York homes, though, a casement is the sensible, good-value choice that will look right and last for decades.
FAQs
What is the difference between a casement and a sash window?
A casement is hinged at the side or top and swings open like a door. A sash window slides up and down (or side to side). Casements seal more tightly and tend to be cheaper, while sash windows suit certain period properties.
Are casement windows more secure?
Yes, modern casements are among the more secure styles. When the handle is locked, the multi-point locking pulls the sash tight into the frame at several points, which makes them hard to force.
What is a flush casement window?
It is a casement where the opening part sits level with the outer frame when closed, giving a flat, tidy appearance. It is popular for period and conservation-area homes because it mimics old timber windows.
Do casement windows come in different materials?
They do. You can have casement windows in uPVC, aluminium or timber, each with its own look, price and level of upkeep.
Not sure which style suits your home? Download our latest brochure to see casement options in different materials and colours, or request a free quote and we will help you choose.