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What is the difference between a Sash Window and a Casement Window?

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What is the difference between a Sash Window and a Casement Window?

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Published on: November 4th, 2021

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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. In order to answer the question we’ve created this blog post and noted down the main differences between the two types of windows. We’ve also tried to to help you choose which is best for your home.

So if you have ever asked the question “What is the difference between a Sash Window and a Casement Window?” – read on!

5 Key Differences between a Casement and a Sash Window

1 – How they open

A Sash Windows opens vertically

A sash window usually consists of a wooden frame in the wall aperture with two windows in. Each window is roughly half the size of the opening with a slight overlap, with one window behind the other. The window can be opened by raising the bottom window, which will slide vertically in channels in the outer frame. This more common format is called a ‘Single Hung Sash Window’. When both windows are able to be opened, then this is unsurprisingly called a ‘Double Hung Sash Window’.

Sash windows were popular in Georgian and Victorian times, though the design did vary somewhat. Casement windows were more popular during the Edwardian era, though sash windows were not uncommon.

A Casement Window opens horizontally on a hinge

Casement windows are built with one large window within the outer frame. This is hinged and generally casement windows open outwards, like a door. Popular during Tudor and more recently, the vast majority of modern windows are casement.

Casement windows open outwards on hinges
A Casement Windows opens outwards on hinges
A Sash Window lifts open vertically
A Sash Window lifts open vertically

2 – How wide they open

A casement window will usually have a wider aperture when open than a casement window. It could be argued that a double hung sash window will provide superior ventilation when opened at the top and bottom because it creates an air flow.

A casement window could be opened to the size of the frame, whereas a casement window will always have at least half of the opening filled with glass.

3 – How much light they let in

A casement window will allow more light to enter a room than a sash window. This is because a sash window will always have to have the horizontal frame where the two panes meet. A casement window can allow a single sheet of glass to be fitted. This means that the room receives better lighting. It can also mean that the inhabitants of the room can have an unobstructed view of the outside world.

4 – Casement Windows allow ventilation to even the smallest openings

Because a casement window is hinged, it can be made to fit the smallest of apertures and still open to allow ventilation. Even a long and narrow slit can have a fully opening window fitted. Because of the way a sash window is operated, they are impossible to fit to openings of under a certain size – roughly no smaller than 2 feet by 4 feet.

5 – Draught Proofing

Because a casement window creates a tight seal when closed – the handle can force the window to fit tBecause a casement window creates a tight seal when closed – the handle can force the window to fit the frame very snugly – then they are generally better at insulating that a sash window. That doesn’t mean that a sash can’t be made draught-proof, it’s just that casement windows are naturally better insulated by design. Gowercroft have tested both their casement windows and sliding sash windows in weather-testing rigs and both products achieved the top ratings; however casement windows surpassed the standard by a greater amount.

6 – Security

For the same reason, casement windows are generally more secure that sash windows. Because the window is held tight in the frame, they are difficult to prise open. Hidden hinges and multiple locking mechanisms in modern windows make them very difficult to break into. Again this doesn’t mean that a sash window can’t be made secure, it just takes a little more work to make it so. Gowercroft have test evidence to demonstrate that both their casement window and sliding sash window achieve PAS-24 standards for security, but it is harder to achieve with a sliding sash window.

7 – Simplicity vs Complexity

A casement window is very simple – the window swings open on 2 or more hinges that take the weight. A sash window must be lifted – and as windows got larger and larger, then mechanisms had to be introduced to assist with the opening of them. An ingenious mechanism of weights and pulleys was developed over time that allowed even the frailest of serving girls to open the largest of sash windows with ease. As people became more skilled at building windows, these mechanisms were hidden in hollow recesses in the window frames to create smoother designs. Of course, more moving parts means more maintenance and things that can go wrong, and it can be difficult to access the ropes, pulleys and weights when they have been sealed in the window frame for a few hundred years. A latter day sash window is build with modern technology and materials, making it unlikely to suffer a malfunction during the lifetime of the window.

So which is better – a casement or a sash window?

There isn’t really a straight answer to this question and like everything, it depends on your specific circumstances. 

If you are on a tight budget, then casement windows are typically a less expensive option. In fact, it would have been commonplace to have sliding sash windows in the front of a house and casement in the rear, to get all of the aesthetic impact for a minimal cost. Similarly, a lot of traditional sliding sash windows were replaced with casement windows over the past four decades, particularly with the rise of uPVC windows and the lack of availability for uPVC sash windows. In a lot of these properties, homeowners are now looking to switch back to a more authentic product to improve the look of their property. 

How can you tell if your property would have had sliding sash windows originally? As a general rule, sash windows are portrait in aspect and casement windows are landscape – so often you can tell by looking at the shape of your window openings. 

In a new build property, the style of window you choose will form part of the overall aesthetic you are seeking. Over the past 10 years, there has been a significant rise in the number of new build properties which look to replicate Georgian style mansions, so sliding sashes are the best choice for these types of builds. If you are going for something more contemporary, then casement windows are for you.

There are situations where you absolutely need to match the existing product type in your house. This is usually when the property is either a listed building or is situated within a conservation area. In this case, it would be a requirement of the local planning authority to carry out any renovations to look as close as possible to the original appearance of the building. These types of windows are called heritage windows. Gowercroft have won several awards for our range of heritage windows – you can find out more about them on our heritage windows pages.