How do sash windows work?
Sash windows work by sliding up and down, one behind the other. To keep them in place when open and to ease movement, they have a traditional cord and weight pulley system or modern spring mechanism. Modern sash windows, like our uPVC sash windows, can also tilt inwards slightly to help with cleaning.
The main types of sash windows explained
When companies talk about sash windows you'll probably hear quite a few types being mentioned. There are four key terms to look out for; single-hung, double-hung, sliding sash and box sash. The first two refer to how the windows open and the last two refer to the opening mechanism, so let's go through what they mean.
Single hung sash windows
The majority of sash windows have two glazed panels, but sometimes only one of them moves. This is called a single hung sash window, usually done when you only want one of the sashes to open for ventilation. A good example would be when you live at street level and you don't feel comfortable having a bottom sash that can be opened.
Double hung sash windows
Double hung sash windows have two movable sashes, meaning both the top and bottom panels can slide. This type of sash window you see most of the time. It's good because you can slide the panels independently or at the same time, giving you more control over airflow.
Sliding sash windows
Sliding sash windows can refer to sash windows generally but normally means the modern opening mechanism. Modern sash windows open by sliding up and down in the frame using springs, as opposed to weights and pulleys. Double glazed sash windows are very heavy and modern springs help make operation effortless.
Box sash windows
A box sash window is the traditional sash window mechanism where the moving panels slide up and down using cords, weights and pulleys. They are still used on some timber sash windows, usually for conservation area rules. The box hides the weights and some of the cord, helping to keep the sashes in place and making opening them easier.
Why are sash windows so popular?
Sash windows have been popular since they first appeared in the Georgian period. They went out of fashion after double glazing became more widely available, because most originals were single glazed, draughty or rotting. People replaced them with casement windows or imitations, but they have really come back into fashion in the past 20 years.
The main reason is that modern versions are double glazed, less draughty and more secure than the old versions. Other than that, they look much better and more stylish than the casement imitations. People have also started renovating their homes to celebrate their original architectural style.
Aside from looks, sash windows are really good at ventilation. Most windows only open one way, but a double hung sash gives you so much flexibility in controlling airflow.
Modern sash windows, like Safestyle’s uPVC sash windows, also offer advantages that older timber designs lacked, including:
- Improved home insulation
- Fewer draughts
- Lower maintenance
- Enhanced security features
- Better energy efficiency
Can you replace casement windows with sash windows?
The simple answer is yes, you can replace casement windows with sash windows. In the 1980s and 1990s, lots of people replaced original sash windows with modern casement windows. Replacing these with new sash windows is a great way to restore your home to its original Victorian or Edwardian glory.
However, it’s worth knowing that it isn't as easy as it sounds. Casement windows are thinner in depth and sit at the front edge of the window opening. Sash windows are much deeper and sit at the back edge of the window opening.
Because of this, you need to remove any plaster that sat behind the casement window in the window opening. You can also lose your internal sill because the sash frame sits further back in the window cavity, often flush with the opening. This usually means adding your own wooden sill and trim to frame the window.
So overall, replacing casement windows with sash windows can be more costly and disruptive, requiring additional construction work. However it is still the best way to bring back period character while still benefiting from modern window performance.
How to choose the right sash windows for your home
One of the main reasons people choose sash windows is to replace existing ones. This usually means replacing like-for-like, so look at your current windows and make sure you choose a design that matches. Glazing bars can be added in almost any design to match what you've got.
People also choose sash windows when they renovate, bringing their home back to its original look. This often means they're replacing newer casement windows, which might not look anything like originals. In that case - look at other houses on the street to get an idea for the right design and look of your new sash windows.
Something else to think about is whether your home is listed or in a conservation area. In this case you'll probably need planning permission, and you'll need to replace like for like. This can often mean having to choose timber over uPVC, but it's a good idea to check with your local authority first.
You should also consider:
- What colour you want
- Window furniture options
- Whether you want internal or external glazing bars
- Whether you want one moving sash or two
- Your overall budget
Sash windows FAQs
Sash windows slide open vertically or horizontally within the frame. Casement windows usually open outwards on side hinges. Sash windows are often chosen for their traditional appearance and flexible ventilation.
Yes, modern sash windows can be fitted with double glazing. This can help improve energy efficiency, reduce outside noise and make your home feel warmer and more comfortable.
Many modern sash windows are designed to tilt inwards, making them easier to clean from inside your home. This is especially useful for upstairs windows or harder-to-reach areas.
Some sash windows open wider than others, depending on the design. Double-hung sash windows allow both the top and bottom sashes to move, giving you more control over ventilation.
High-quality uPVC sash windows are designed to be long-lasting and low maintenance. Their lifespan can depend on the quality of the product, installation and how well they are cared for.
Modern sash windows are designed with security in mind. uPVC sash windows can include strong frames, secure locking systems and tough glazing options to help protect your home.