Sash Windows

Sliding Sash Windows originated in 13th Century Europe; however, they were nothing more than sliding wooden shutters.

They became a large part of the United Kingdom architectural heritage, especially in London, starting with the 16th century. Typically featuring the Georgian, Edwardian, and Victorian eras buildings, the timber Sash Windows are still standing in UK home counties.  

Like many architectural features, different designs and styles have dropped in and out of fashion over the years. Sash Windows are an excellent example of this. It is sporadic to see modern homes featuring Sash Windows.

However, in recent years, timber Sash Windows are again in trend, particularly as part of the broader movement of going back to old-fashioned aesthetics and traditional features—a significant difference in the quality and durability of modern materials used to make the windows and doors.  

So, let’s take a closer look at the Sash Windows and what benefits they might add to our home.

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What are Sash Windows? 

A Sash Window is constructed of one or more movable panels referred to as ‘sashes’ and are held together by glazing bars. The individual windows are traditionally paned windows, with the number of panes depending on the era. However, in modern times, uPVC Sash Windows contain one individual sheet of glass (or sheets, in the case of double glazing). 

What is the Sash Part of the Window?

The sash part of the window is the area inside the frame, which holds the glass or the windowpane. The sash has several components, such as the still (the horizontal part along with the frame), the jamb (the vertical sides of the frame), and the head (the flat aspect from the top of the frame).

The History of Sash Windows

The Sash windows originate from England; however, it is impossible to determine their original inventor. Originally designed during the 17th Century, they became popular after the Great Fire of London in 1666. Many important buildings such as Kensington Palace, Greenwich, or Ham Hall incorporated sliding Sash windows in their design.

As you can see, the London area’s trend in home design was started and its home counties. The classic arrangement of three panes across by two up on each of two sashes, giving a six over the six-panel window, is often found in Georgian and Victorian houses. Many late Victorian and Edwardian suburban homes were built using standard sash window units of approximately 4 feet in width.

Timber Sash Windows’ design changed over the years. The price of glass and different taxes and regulations influenced the windows’ system. When larger panes became available to anyone, a new feature was introduced: the sash horns. The role of these horns was to provide extra support for the more massive window panes. Sash horns are still used in modern design and will make a significant architectural element to be added to your home.

Historic Image of Sash Windows in Englan

Historic Image of Sash Windows in England 1898

How Does a Sash Window Work?

It is important to note that a sash window does not open on a hinge as common windows do. Sash windows open and close with the help of a weight and cord system. The sash weight is connected to the window via a cord, and it is concealed inside the hollow timber linings that form the basic box frame. Nowadays, the weights have been replaced by spiral balances.

When the sash window is closed, the top and bottom sashes lock together, preventing the window from sliding this way, adding security and safety to your home.

A double-hung sash window is opened by sliding the top sash downwards. And this design is perfect for the proper ventilation of your home.

Modern uPVC Sash Windows are designed to tilt in and out for ease of cleaning. The contemporary design also features handles that can be used for opening the new windows.

What is the Difference Between Sash and Casement Windows?

While these window styles are equally popular among homeowners, there are several essential differences between Sash and Casement windows. 

Sash windows generally feature two panels, which are opened by sliding either vertically or occasionally horizontally. The windows can either be double-hung, where both sashes are operational, or single-hung, meaning that only one sash can be moved. The primary benefit of a double-hung Sash window is that it allows better ventilation of the properties.

In contrast, Casement windows are attached by two or more hinges, and they open outwards like a door, although they may also open inside.

The benefit of this style of opening is that these windows can provide better views than Sash windows; however, since they open outwards, this also means that they tend to be more exposed to the elements than Sash windows.

Again, as they have more mechanical parts within, many things can go wrong, and they will need more regular maintenance than uPVC Sash windows.

Sash windows generally have a higher air leakage rate since when closed, they press against the frame. Therefore, it is essential to note that Sash windows require professional draught-proofing.

In terms of security, Casement windows are more challenging to break into than Sash windows. When locked, it is more difficult to force open the window from outside. This is because the lock is held within the frame, and the window opens out.

Are Sash Windows Double Glazed?

Traditional timber sliding sash windows from the Edwardian, Victorian, and Georgian eras were not double glazed. The window panes were thin, and the staff bead did not contain a draught seal. They were simply thermally inefficient and often draughty. The sill was also missing; therefore, the rainwater leaked through and the rot set in. Also, they were well-known for rattling in the wind and not shutting out external noise.

The traditional wooden Sash windows for the home were made of fragile glass (generally about 2mm – 4mm); subsequently, the glazing bars (the pieces of wood that separate each pane of glass) were also very thin and light. In comparison, modern double-glazed uPVC units consist of two panes of glass and an air gap in between, usually filled with an inert gas like Krypton. It is this air gap that produces thermal benefits and lowers your energy bills.

Each pane will typically be 4mm thick, and the air gap anything from 6mm to 20mm. Due to this fact, it is virtually impossible to simply add double glazing to the original sliding Sash windows as it is so much heavier and surely will not fit into the glazing bars. 

The solution to this is to replace your existing sliding Sash windows with new Sash windows that can be crafted to exactly match the existing ones. And energy-efficient double glazing can also be installed into them. You will have new Sash windows with modern uPVC sash windows’ performance while retaining the charm and character of your original timber Sash windows. 

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What Glazing (glass) is Available in Sash Windows?

Generally, modern sliding Sash Windows will contain standard double glazing. Still, it is possible to choose from other glazing options such as safety or acoustic glass, according to the nature of the home or workplace. Other factors that may influence the type of windowpane that can be used within a Sash Window include:

The space within the Sash – glazing will need to fit into the sash. If you need to install acoustic glass, this can only be done if complete new uPVC sash windows are included. You might need to check if the existing sliding sash windows can be double glazed.

Listed building status - fitting double glazed windows into a listed building can be challenging as the right permission will need to be obtained before work can commence. It may be necessary to install single glazed windows or to include a very thin double glazing.

Budget – installing additional features will add to the cost of your replacement sash windows. We recommend discussing your requirements so we could advise on the best options regarding details such as safety glass and other products.

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What are The Benefits of Sash Windows?

Comfort:  Double-glazed Sash Windows have been proved to reduce up to 40 decibels of noise. This reduction in noise and disturbance will provide you with a calmer and quieter environment to live in or work in. In terms of energy efficiency, the uPVC Sash Windows are also known to provide excellent insulation properties as the sealed element locks the heat into a room and provides you with a warm and cosy home environment. During the warmer summer months, they offer a fantastic means of ventilation.

Easy to maintain: Sash Windows are widely acknowledged as being easy to maintain due to the features of the sashes tilting either upward or being able to be lowered to facilitate easy and thorough cleaning which of course helps to keep Sash Windows looking like new for longer.

Easy to maintain: Double-glazed Sash Windows are widely acknowledged to require low maintenance. Just clean them regularly, and your windows and doors will look like new.

Security and durability: Locks can be installed on a Sash window that will allow it to be secure and safe while still opening it for ventilation. Double-glazed Sash Windows are highly durable and hard to break. However, for maximum security, a triple-glazed Sash Window offers the benefits of extreme strength and durability. The majority of manufacturers provide a 10-year guarantee.

Money-saving: Although this depends on the property or/and the area you live in, Sash Windows can also help save money. For example, uPVC Sash Windows are the best alternative to timber in terms of cost efficiency, high quality, equal sight lines, and, why not, a better user experience. 

A touch of style: As technology has improved manufacturers' abilities to manipulate materials, the design of Sash Windows has become more and more aesthetically pleasing. These can be easily customized to match your home style. They provide a very sophisticated look that combines traditional with modern - woodgrain finishes that can be added to a uPVC sash window. They also come with a wide range of glass options, and they are at least 10-year guarantee products.

What are The Disadvantages of Sash Windows?

The traditional reliable wooden sash windows do suffer from such issues as rot, swelling and/or distortion of the woodwork, and rattling in high winds due to wood shrinkage.

However, regular maintenance, expert repair and the introduction of draught stripping resolve these issues, keeping your uPVC window beautiful. Installing a box sash will also help.

Another issue that needs to be watched out for is the common problem of painting the sash stuck.

Additionally, the sliding mechanism makes Sash Windows more vulnerable to these problems than a traditional casement window. Having said all this, well-maintained sash windows should stand the test of time without needing replacement parts changed.

Sash windows are built to slide one behind another, similar to sliding doors, and there is a high chance to increase condensation on the inside of the uPVC window.

How do I Ensure that My Sash Windows Keep Working as They Should?

As with all things, Sash Windows require regular and careful maintenance to keep them working they should be. If your property has older Windows, they may require more maintenance to keep them in good condition.

Simultaneously, newer sashes will need some degree of care, such as regular cleaning and the occasional lick of paint. Much of the appeal of Sash Windows is in their appearance, so it’s essential to keep them looking at their very best.

If your Sash Windows need more expert maintenance repair or even replacement, the team here at Welbeck Windows in London are happy to assist; just get in touch with us on 0203 583 3525 to discuss the best option for you.

We bring you a wide range of products such as timber casement windows, uPVC sash windows, window furniture, French doors, and many more. Call us for expert advice!

Are Sash Windows Expensive?

The cost of timber Sash windows depends on the size, glazing options, and type of frame that is required for your home. Timber sash windows' prices range between £700 and £1,500, depending on the size and window furniture.

New Sash windows are available at higher prices than other products due to the extra work required when the windows are made. However, some buildings require replacement sash windows as they are listed properties from conservation areas.

Suppose you are interested in the installation of replacement double-glazed uPVC sash windows. Why not ask us for a free no-obligation quote? We can discuss your option in detail, just call our customer service on 0203 583 3525 or contact us via email:

We offer a wide range of products such as uPVC sash windows or doors. And a 10-year guarantee. All you need is to get in touch with us.

Are Sash Windows Double Glazed?

Sash timber windows or the uPVC ones are double-glazed, and you can also double glaze your old windows. The experts' recommendation is to opt for new double-glazed sash windows that cost less than glazing the old ones.

How Much is a uPVC Sash Window?

The costs for installing uPVC sash windows range between £300 and £550 and depend on several variables such as the uPVC sash window designs, uPVC sash window range of colours, or window company labour fee.

Can I Replace Only the Window Sash?

Installing new windows is an expensive job and sometimes not really needed. You can buy and install a sash replacement kit. This option is less pricey and equally long-lasting. Your home will still have the same window colours and architectural style.