What Is a Window Sash?

Dorling Kindersley / Getty Images

A window sash is truly the sum of its parts. If all of the pieces of a window sash were disassembled, it would probably be unrecognizable. Older windows can be disassembled, but newer windows increasingly come with parts that are factory-built and sealed. PVC window frames are welded together. Grilles are sealed behind glass. And the separate sheets of glass are no longer separate; rather, they are built as one unit, called an insulated glass unit (IGU).

What Is a Window Sash?

A window sash is the part of the window that you move up and down when you want to open and close the window. It’s a wooden frame keeping the panes of glass in place.

Glass

Two sheets of glass comprise a double-paned window. Sometimes this is called glazing, as in double-glazed window or triple glazed window. Single-paned windows are less common than in years past, with double-paned windows being more the norm.

Insulated Glass Unit (IGU)

The insulated glass unit is the heart of the modern window. IGU is a window industry term that refers to double- or triple-paned collection of glass, gas, seals, and gaskets. The window frame and peripheral items are not included with an IGU.

Window Frame

Window frame is a convenient term for the wood, fiberglass, vinyl, or metal parts that hold the glass together. In older windows, the window frame is actually composed of rails (horizontal pieces) and stiles (vertical pieces).

Window Grille

Within the window frame may be smaller sections of window that go under different terms but collectively called grillework. Older, single-pane windows may have true mullions, in which panes are separated by wood. Newer double-pane windows may have a mullion look. The industry term for this is GBG or grille-between-glass, in which false mullions are placed between the sheets of glass and serve no structural purpose. GBGs provide aesthetic appeal and allow for easier cleaning of the glass.

Gaskets

Glass must be sealed into the framework. Gaskets made of rubber or TPVs (thermoplastic vulcanizates) serve this purpose.

Argon and krypton are colorless, odorless gasses that are injected between the sheets of gas for its insulating properties. Single-pane windows have no gas. Seals allow for equalization of gas and outside pressure. IGUs come with the gas already inside.

Seals

Because of the difference in pressure between the IGU and the exterior, seals are built into the IGU to equalize pressure.

Double-Hung Windows

Window sashes are typically found in the double-hung window style, in which one sash is positioned above a lower sash. The lower window sash has the capacity to slide up and down until it is nearly parallel with the upper sash.

It is not uncommon in older windows for the upper sash to be fixed in place, while the lower sash remains operable. In this case, it may be referred to as a single-hung window. Newer double-hung windows, though, tend to have upper sashes that move up and down.

One benefit of this action is that it allows for the window to be open, without the hazard of people, namely small children, falling out of the window. An open upper sash is too high for most children to reach.

Fun Fact

Sliding sash windows became prevalent in England after the Great Fire of London, in 1666, when new building regulations stipulated that timber window frames had to be recessed behind stone or brick.

Casement Window Sashes

While mostly associated with double-hung windows, window sashes can be found on any type of window which moves, such as the casement window. Care must be taken with casement windows when they are open. A high wind can move casement window sashes and break them off.

Window Fogging and Leakage

Double-glazed IGUs often come with one problem: fogging. Fogging is the result of improperly installed gaskets or gaskets that have deteriorated over the years. Impaired seals allow gas to escape, greatly impacting the window’s insulating properties. As condensation builds, light and views are obscured.

Window defogging companies can fix this problem by drilling 2mm holes in the glass, injecting cleaning fluids, letting them dry, and then plugging up the holes. Window defogging is not a common practice, since the procedure often does not last for long.

Window Sash Replacement Kits

If the window sash breaks, it is possible to purchase a sash replacement kit. This avoids the cost and mess of total window replacement. Also, because it is designed for homeowners to be able to use, it helps avoid labor costs associated with entire window or individual sash replacement.

Sash windows

GET IN TOUCH

Fill in the form and let us know what service you are interested in, and we will call you back.

We are suppliers and installers of bespoke sash windows, handmade and hand painted in our UK workshop. This means you can choose everything, from the configuration of your windows to the exact colour of your paint. We will create the perfect windows for your property, improving aesthetics, insulation and soundproofing.

Our windows are made from Scandinavian kiln-dried redwood, which is strong and robust, though if you would like to use a different wood type we are always happy to accommodate you – please enquire.

Sash windows are made of moveable panels, also known as sashes, that sit within a frame. There may be one pair of sashes per frame, or one frame may contain multiple sashes. They can be used in many different types of building and can be customised to suit your purpose.

Sash windows emerged as an innovation due to new legislation after the Great Fire of London in 1666. They have become something of a staple in the UK ever since, especially in London. A lot has changed in 350 years – architecture, house styles, house prices… – but the sash window has remained and stood the test of time.

What do our customers think?

Sash window facts and figures

In a poorly-insulated room with ill-fitting windows, the air is completely changed around three times every hour. This means you are paying to heat air that is then simply lost, driving up the price of your energy bills. Well insulated windows save money.

Sash window technology has improved drastically. It is now possible to use unbreakable cords, and staff beads that will drastically improve insulation with integrated draught proofing. If your windows have not been overhauled in a long time, you could really benefit from new technology that has become available.

The very first sash windows date from the 1670s. They create a typically British, aesthetically pleasing appearance. You can replace or renew your sash windows to highlight the historic charm and appearance of your property.

What are the benefits of retaining period sash windows?

Attractiveness The main reason for having sash windows is the aesthetic value they add to a property. They can be fitted into a variety of properties, from Georgian through to modern day new builds. It is simply a question of finding the right configuration and design for your property. Sash windows can be made of slimmer sections than casement or UPVC windows, allowing in more natural light. This also gives them a subtler appearance, which complements classical styles and becomes a key design feature of buildings from the Queen Anne and Georgian periods.

Practicality Sash windows can be finely adjusted to control ventilation. A narrow gap can be opened at either the top or bottom to allow fresh air into the property without the issue of rain blowing into the room. By adding restrictors, sash windows can be locked open to make them more secure whilst also allowing ventilation.

Longevity Sash windows are hung from each of their top corners, rather than from the side like a hinged window. This makes them less likely to distort under their own weight so they will have a longer lifespan. Many sash windows are still serviceable after 100 years or more. Compare this to uPVC windows, which need to be replaced roughly every 20 years.

Window Sash: History, Styles, Types & Maintenance Tips

Depending on the architecture of the house, windows vary in materials, shape, and design. However, window sash is always an essential part of each of them. Have you ever wondered what it is exactly and why it is a necessary part of the window?

Well, the sash is not an entire window but just window panes with related parts holding the glass and framework around it to keep the whole construction in place. Basically, window sash fits inside a frame attached to the house walls, and we use it to open and close our windows.

History of Window Sash

Sliding sash windows originated in Europe. If the fire at the bakery of Thomas Farriner in 1666 (during Great Fire of London) had never happened, we wouldn’t have sash windows. After the fire, British lawmakers decided to reduce risks of future fires, so building regulations in the city became much stricter.

The first sash windows slid horizontally, and they were glazed. It wasn’t until the mid-17th century when the French modified original design by introducing a vertical sliding sash window.

Styles of the Window Sash

Hand in hand with art, the architecture of window sashes was changing through history so we can distinguish several styles:

1. Georgian sash (late 18th and early 19th century)

Sash windows were specific with a ‘6 x 6 panes’ pattern. Traditionally used bars hold together smaller parts of glass. Both glazing bars and frames were thinner than later in the Victorian era. Nowadays, the entire purpose of this type of window is decoration only.

2. Victorian Windows (late 19th and early 20th century)

Exceptionally distinctive Victorian-era preferred a two-panel grid design on both the top and bottom window panes. They also included larger glass pieces, and the window sashes were often made of only one glass.

3. Edwardian Windows (early 20th century, to the beginning of World War 1)

Presenting a ‘6 over 2 window panes’ design that helps to deliver the best of both worlds, Edwardian windows became an ideal option for properties dating from the early 20th century.

Why Is A Window Sash Crucial?

The window sash holds the glass in place and contributes to the complete stability of the window. It needs to be airtight and prevent airflow and drafts through the window. Plus, it will increase the energy efficiency of your home.

The misshaped window sash will cause problems, including leaking, mold, and drafts. If you notice that this part of the window is hard to open and close, you possibly have an alignment problem, and you need to get it repaired.

Additionally, the functional sash makes lock the window correct thanks to the window locks. Otherwise, it is considered to be unsafe for children.

Types of Window Sashes

Not all windows have the same window sashes. Depending on the type of window in your house, they are constructed differently.

a). Double-hung windows

It is common in the older, single hung window type that the upper sash is fixed in place, while the lower sash remains operable. On the other hand, double-hung windows feature two operating window sashes that slide up and down. Both types are not complicated to use since you can tilt them while operating.

b). Sliding windows

Sliding windows are almost the same as double hung models. The primary difference is that here the sashes open and close horizontally.

c). Casement windows

A casement window sash is a bit different than the traditional one. This type of windows open and close like doors and operate on a crank.

The sash is connected to the crank system as opposed to being in the frame along a track. However, you need to be careful when opening the sash since strong wind can break it.

d). Awning and hopper windows

Both types of windows have one movable sash. The difference is that awning windows are hinged at the top, and the sash opens outwards with a crank. On the other hand, hopper windows are hinged at the bottom, and the sash tilts open inwards.

Window Sash Components

In the past, window sashes were exclusively composed of wood and glass. Nowadays, manufacturers use different materials to make them, including:

No matter what type of windows they are built-in, window sashes need to have certain parts, including:

• IGU (insulated glass unit)
• Glass (glazing)
• Gaskets
• Gas
• Seals
• Window sash frame
• Applied glazing bars

Some window sashes will also have some additional features. They can alter the appearance or improve the functionality of the window:

The insulated glass unit is the primary feature of every modern window. It is actually an industry term implying a double- or triple-pane collection of glass, seals, gas, and gaskets.

Glass

Term glazing refers to the glass itself within the frame. The double-paned window contains two sheets of glass. While single-paned windows were more common in the past, double-paned windows are a standard for modern windows.

Most contemporary windows are filled with argon or krypton. They are gasses with neither color nor smell. The best option for the window is krypton, but manufacturers use argon more often. Filling windows with gas is a standard now since it increases their insulation properties.

Gaskets

The glass needs to be sealed into the framework. For that purpose, manufacturers produce highly sealed windows by inserting gaskets made of rubber or TPV (thermoplastic vulcanizates) between window panes and frames.

Seals

Seals ensure an airtight fit between the window panes filled with gas. That way, they help in creating a barrier between the interior of the house and outside low temperatures and keep your home warm.

Window frame

The window frame is a part of the window made of wood, fiberglass, vinyl, or metal. It holds the glass in place. In older windows, the window frame was composed of horizontally positioned rails and vertically placed stiles.

Mullion

Newer double-pane windows often have a mullion. The industry term for this is GBG (grille-between-glass), describing false mullions installed between the sheets of glass. That procedure provides an aesthetically pleasing window and allows more comfortable cleaning.

Glazing bars

If you want to make the window look like it has smaller panes, it is possible to place bars across the panes of glass. In a modern window, manufacturers attach them to the internal and external of the window sash.

However, traditionally, glass panes between the bars were sold separately. The reason was the price of the glass in the past. Once a pane broke, it was cheaper replacing just one its part.

Most sash windows use a sill on their inside or outside sides. It is mostly a decorative feature. However, the sill can help to protect the window from moisture and rot, as well.

You can also install window boxes or place flower pots and some decorative items on your sill. Plus, if it is large enough, it will be a favorite place for your cat to take a nap there.

Draught-proof strips

If your window doesn’t already have draught-proof strips, you should install them to increase the thermal efficiency of the window sashes in your home. That way, you will prevent cold from coming inside and keep your rooms warm and comfortable.

How to Maintain the Window Sash and When to Replace It?

As with other devices in your home, you need to take care of your window sashes to keep them working. If you have some stylish and old-fashioned ones in your property, they might require more maintenance to stay in good condition.

Newer models of window sashes will need some level of attention as well, including painting and regular repairs. The charm of this part of windows is in its appearance, so you should make some effort and highlight their beauty.

When the window sash breaks, you can purchase a sash replacement kit and repair it. That way, you can save labor costs and avoid a mess in your living room, for example.

Sometimes though, there is no hope to save it. In this instance, you can try to change a single-window sash without replacing the whole window if it is possible. That is also the way to make your windows become much more energy-efficient by investing in the double-glazing glass in your new window sashes.

Many owners of older homes with wooden windows often have problems since wooden frames can rot, swell, or shrink. Therefore, the window sash may become hard for opening, closing, as well as drafting.

If you are one of them and have never replaced your windows by now, then you may consider purchasing replacement windows for your home. You can now use vinyl windows for your home. That is the way to enjoy the look of traditional wood windows without the problems associated with the wood itself.

However, some traditional homes still have aluminum windows, which were popular during the 1960s. The problem is that the aluminum oxidized over time and promotes condensation inside the panes of glass.

Therefore, installing new vinyl energy-efficient window sashes will offer the best quality to your home, although it requires more significant financial investment.