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  • Scott Carter

The Ultimate Guide To Sash Windows

Updated: 5 days ago

Sash windows are some of the most iconic, eye-catching, and downright beautiful features of the period and its historical properties. Despite being instantly recognisable, traditional sash windows are still misunderstood by homeowners across the country.

If you’re looking to get your sash windows renovated, or new ones installed, you’ve come to the right place. We’re going to take you through everything you need to know about this window style – from its historical origins right through to its use on brand-new builds.

What is a Sash Window?

The sash window is a classic example of period design. Combining striking looks with practical functionality, sash windows drip with character and charm. A traditional sash window is made from two glass-filled panels. The window is opened by sliding one sash (the moving panel) over the other.

Sash windows were widely used during the Georgian period in England, and their popularity only grew throughout the following Victorian era. At the beginning of the 20th Century, they were the most popular type of window construction across the UK.

It wasn’t until the invention of hinged casement windows that the popularity of sash windows began to decline. By the 1950s, timber sash windows were seen as old-fashioned and overly expensive.

Today, sash windows are becoming more and more sought after, thanks to their totally unique styling and practical features. The addition of modern technology such as double glazing and efficiency improvements have brought the windows right into the 21st Century, and they continue to be a great option for anyone looking to add a ton of character to their home.

newly fitted sash window

How Do Sash Windows Work?

There are various types of sash windows, but they all share the same basic design principle. Either one or both of the window panels can slide across the other, which allows the window to be opened to different degrees.

Typically, sash windows open vertically, but horizontally sliding sash windows have also been popular throughout history. Horizontal sash windows avoid the need for a counterweight system to keep the moving panel raised.

The majority of vertical sash windows use a weighted system to hold the sash open. A cast-iron or lead counterweight is hung inside the frame of the window, which balances against the moving sash. When the sash is lifted, the counterweight ensures that the panel doesn’t crash back down under the force of gravity.

Modern sash windows may use a spring-loaded system in place of the counterweight. This holds up the weight of the sash without the need for a complex system of pulleys and weights.

Benefits Of Sash Windows

Unmatchable looks

One of the biggest advantages of sliding sash windows is their fantastic styling. There’s truly nothing else that screams period property quite like a great sash window. With a range of classic styles to choose from, it’s easy to get a design that blends seamlessly with your property.


Sash windows aren’t just about the looks though. In fact, they are extremely functional and have never really been surpassed when it comes to practicality. Security is a particularly important consideration when it comes to windows and the sash design has always been a safe and secure option.

Thanks to the mechanisms involved in a sliding sash window, incorporating security features such as locks and child safety measures is an absolute breeze. In addition, since there is usually only one sliding panel, it’s very difficult for intruders to clamber through an open sash window.

Low maintenance

Another key benefit of sliding sash windows is their relatively low maintenance requirements. A well-built timber window frame will rarely require any repair work (evidenced by the existence of original sash windows that have lasted for centuries). Occasionally, if water penetrates the paint layer, the window frame joints can expand and loosen. Keeping the paintwork topped up is the best way to avoid this issue.

Great ventilation

Sliding sash windows can be thrown wide open for easy ventilation. Windows with two moving sashes are particularly effective in this regard and can ventilate the largest rooms extremely quickly.

Impressive insulation

Although ventilation is important, it’s essential that a window can offer insulation when the weather takes a turn. Timber window frames have always been super effective insulators and will greatly limit the amount of heat that can leak out from the room.

Recent advancements in glassmaking have led to even better sash window insulation. Double-glazed sash windows are the modern standard and perform extremely well in efficiency and insulation testing.

The Many Styles of Sash Windows

Traditional timber sash windows come in a range of shapes and sizes. The sash window has gone through a range of style changes throughout the centuries, from classic Georgian designs to grand Gothic statements. If you’re looking to renovate or install sash windows in your period property, then it’s important to choose sash windows that match up.


The Georgian design is the most recognisable type of sash window in the UK. Head to towns such as Bath and Cheltenham Spa and you’ll see beautiful examples displayed on many buildings. Lots of Georgian sashes are still original, which goes to show just how well-built and effective these windows can be. The quintessential Georgian style is known as “six over six”, with six pieces of glass filling each of the timber panels. Large slabs of glass were extremely expensive during the Georgian period, which is why the panels were broken up into smaller segments. Manufacturers of new sash windows aren’t faced with this logistical problem, but they still segment their glass to retain that Georgian look and style.


During the Victorian period, the Georgian “six over six” arrangement made way for “two over two” designs. Rapid advancements in glass technology propelled this change, and the larger panes were desirable as they allowed more light into a room.

The introduction of heavier glass meant that other innovations and changes had to be made. The most important was the introduction of “sash horns”, which were added to strengthen the joints of the window. Consequently, sash horns became a stylistic feature of Victorian windows and are an easy way to identify sash windows from the period.


With curved sash horns, arched peaks and intricate latticework, Gothic sash windows are immediately recognisable. The Victorian Gothic Revival drew on the incredible European architecture of the medieval period and incorporated it into sash window design.

Gothic sash windows were a popular choice for bay windows, and they can look particularly impressive when grouped in this way. If you’re looking for something unique and eye-catching, then a Gothic design could be the way to go.


Just like Gothic sash windows, Venetian designs draw on the past. Specifically, this style has its origins in the Tripartite window, which was popular in Venice in the mid-16th Century. The modern version consists of three segments of glass – one large pane across the top with two smaller panes below. Venetian sash windows have a more minimalist look when compared to Georgian or Gothic alternatives. This makes them ideal for modern builds that don’t require strong period features.


A fixed design offers the look and character of a classic sash window but without any moving components. These windows are very popular with period property owners who do not require the functionality of a sash, but still want their windows to be in keeping with the rest of the house. A big advantage of fixed sash windows is that they are virtually maintenance-free. With no spring or counterweight systems involved, there’s practically nothing that can break or go wrong. They’re also a super energy-efficient option, especially when installed with double glazing. A fixed window can be installed as a new fixture or retrofitted to a traditional sash window. Many property owners who already have sash windows choose to switch to a fixed design to benefit from the energy efficiency that it provides.

The Best Materials For A Replacement Sash Window

Modern sash windows are built with a range of materials, but it’s still tough to beat the traditional timber design. Timber sash windows offer a range of benefits, including excellent insulation, fantastic durability and of course, a wonderfully classic look.

If you live in a listed building or a conservation area, then timber is likely to be your only option anyway. Thankfully, timber sash windows can be repaired and renovated to an incredibly high standard without breaching any conservation restrictions. Pairing a timber design with modern glass technology is the best way to retain character whilst ensuring high performance. Finding a high-quality, experienced renovation team will guarantee that your windows will be usable for years to come, without losing any of their beautiful styling. Existing designs can also be upgraded to double-glazed sash windows to improve efficiency. In fact, the vast majority of window renovations will require the addition of double glazing to stay in line with modern building regulations.

What Level Of Maintenance Do Sash Windows Require?

A sliding sash window features a range of moving parts. As a result, you should expect your sash windows to require some level of maintenance. That said, a window that has been built or renovated to a high standard will keep this maintenance to an absolute minimum.

Paintwork may require a top-up every few years to prevent moisture from getting to the timber below. It’s also possible for problems to develop with the counterweight system inside the frame of the window, but these are quite rare. In general, you can expect your renovated sliding sash windows to take care of themselves.

Replacing Traditional Sash Windows

Homeowners who are looking to update their windows or are taking on a renovation project may be considering getting their sash windows replaced. Although replacing sash windows is definitely possible, repair and renovation is nearly always a better choice. Unless the timber window frames have completely rotted away, there’s really no reason to lose the period features. Timber can often be saved through a process of restoration, re-conditioning and waterproofing. Maintaining original features also makes it easier to stay on the right side of conservation and listed building regulations. That said, if your windows are beyond repair, then it’s possible to get replacements made to match the originals as closely as possible. Hiring an experienced window and joinery team is the best way to guarantee high-quality sash windows that match your property perfectly.

Can Sash Windows Be Fitted To New Builds?

Absolutely. Even though sash windows are considered to be period features, that definitely doesn’t mean that they can’t be used with a new build. Thanks to the improvements that have been made with double-glazed glass and draught exclusion, sash windows are more than suitable for a new property. Whether you enjoy the classic Georgian design or prefer more unique Gothic arrangements, you can be sure that there’ll be a window design to style you and your new build.

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Why Choose Classic Sash Windows?

Our team of friendly, professionals based in Warwickshire will be able to provide you with all of the information you need when you enquire. At Classic Sash Windows, we can survey your requirements and provide a bespoke itemised quote covering a range of options.

Our sash removal system allows for easy removal and painting of sashes, negating the need for scaffolding.

Whether you need a brand-new sash window or need help with repair and restoration, our team are here to assist. Get in touch today and find out how we can help you.

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