What makes a Sash Window different from a Casement Window?
“What is the difference between a sash window and a casement window?” is a question we hear a lot at Gowercroft Joinery. To help answer it, we’ve created this post outlining the key differences between the two types of windows — and offering guidance on which might be best for your home.
So, if you’ve ever wondered “What is the difference between a sash window and a casement window?” – read on!
1. How They Open
Sash windows open vertically.
They usually have two window frames, slightly overlapped, within a larger outer frame. The bottom sash slides up to open. If both sashes can move, it’s known as a double-hung sash window. If only the bottom moves, it’s a single-hung sash window.
Casement windows open horizontally.
They’re typically one large window hinged on the side, opening outwards like a door. This design is now common in modern homes but was also popular during Tudor times
2. How Wide They Open
Casement windows tend to open wider, allowing for more air flow.
Although a double-hung sash window can create good ventilation from top and bottom, it still always has at least one sash covering part of the aperture.
3. How Much Light They Let In
Casement windows let in more light.
They can hold a single pane of glass without a dividing rail, offering better lighting and a clearer view. Sash windows always have a horizontal meeting rail.
4. Suitability for Smaller Openings
Casement windows can fit into very small or narrow openings and still offer ventilation.
Sash windows, due to their sliding mechanism, require larger openings—typically no smaller than 2 feet by 4 feet.
5. Draught-Proofing
Casement windows often provide a tighter seal.
Their handle pulls the sash firmly into the frame, improving insulation. While sash windows can be draught-proofed, casements are naturally better insulated. At Gowercroft, both our sash and casement windows achieve top weather test ratings, but our casements exceed the standard by a greater margin.
6. Security
Casement windows are generally more secure.
They fit tightly into the frame, with multi-point locking and concealed hinges. Sash windows can also be made secure, but it takes more design effort. Gowercroft’s sash and casement windows both meet PAS 24 security standards.
7. Simplicity vs. Complexity
Casement windows are simpler.
They swing open on hinges. Sash windows, especially larger ones, rely on a system of hidden weights and pulleys to operate. These mechanisms can be hard to access in older windows, though modern sash windows are much more reliable thanks to updated technology.
Which Is Better: Sash or Casement?
There is no single answer to whether sash or casement windows are better. It depends on your property and your priorities.
If cost is the main concern, casement windows are typically more affordable to manufacture and install.
For period properties or homes aiming to preserve their traditional character, sash windows are often the preferred option, especially in Georgian or Victorian-style buildings.
A helpful way to identify what your property might have had originally is to look at the shape of the openings: sash windows are usually portrait, while casement windows tend to be landscape in proportion.
In listed buildings or conservation areas, local planning authorities often require replacements to match the original design as closely as possible. In these cases, heritage sash windows are usually essential. Gowercroft’s award-winning Heritage Window Range was created specifically for these sensitive settings. For new build properties, your choice will depend on the style you are trying to achieve.