Common Windows Terminology Explained

Looking for new windows can be hard work, and if you’ve spent any length of time looking them up online you are probably baffled by all the terminology companies use. So, in this article we are going to be clearing up the meaning of some of the most common phrases that window and door specialists use.

Pane

A pane is a single sheet of glass in a window. Most windows are made up of one or more panes held in place by the frame.

Sash Windows

A sash window is a classic window style made up of one or more movable panels, known as “sashes.” These sashes slide up and down or side to side within the window frame to open. Sash windows are popular for their traditional appearance and are often found in older homes.

Sliding Sash Windows

Sliding sash windows is another name used for sash windows. While all sash windows operate by sliding, many windows and doors companies refer to them as sliding sash windows, but there’s no functional difference since all sash windows slide.

Box Sash Windows

A box sash window is a specific type of sash window where the sashes slide vertically within a frame. The box frame holds a hidden weight system that helps balance the sashes, making it easier to open and close the window.

Double-Hung Sash Windows

Double-hung sash windows have two sashes that both move up and down independently of each other. This gives you the flexibility to open the top, bottom, or both sections of the window, allowing for better airflow and more control over ventilation.

Georgian Sash Windows

Georgian sash windows are distinguished by their grid-like appearance. The sashes are divided into smaller panes of glass, separated by glazing bars. This design was popular in the Georgian era, and it adds a traditional, symmetrical look to any property.

Georgian Bars

Georgian bars are decorative bars that divide the glass in a window into smaller panes. They are often used in Georgian sash windows to give them their distinctive grid-like appearance, adding a traditional touch to the window.

Victorian Sash Windows

Victorian sash windows typically feature a larger pane in the lower sash and smaller panes in the upper sash, creating a more ornate look compared to the simpler Georgian style. These windows add elegance and decorative detail, making them a popular choice for period homes.

Edwardian Sash Windows

Edwardian sash windows are known for having larger panes of glass and fewer glazing bars compared to Georgian and Victorian styles. This design lets in more light and provides a cleaner, more open look. They’re often found in homes built during the Edwardian era.

Sash Pulley System

The sash pulley system is the mechanism inside a box sash window that helps the sashes move smoothly. The system uses cords, pulleys, and counterweights to balance the weight of the sash, making it easier to open and close without much effort.

Casement Windows

Casement windows are windows that are hinged at the side and open outwards, like a door. They are usually opened and closed by turning a handle and are known for providing good ventilation and clear views.

Flush Casement Windows

Flush casement windows are a type of casement window where the part of the window that opens sits flush (level) with the frame when closed. This gives the window a sleek, flat appearance that blends in with the rest of the frame, creating a modern and clean look.

Lipped Casement Windows

Lipped casement windows are different from flush casement windows because the part of the window that opens slightly overlaps the frame when closed. This creates a more traditional, layered appearance that adds character to the window.

Fixed Casement Windows

Fixed casement windows are windows that do not open. They are used to let in light and provide a view but remain stationary. Fixed casements are often used alongside other types of windows that open.

Top-Hung Casement

A top-hung casement window is hinged at the top and opens outwards from the bottom. This design is ideal for keeping rain out while allowing ventilation and is often used in kitchens or bathrooms.

Bottom-Hung Casement

A bottom-hung casement window is hinged at the bottom and tilts inwards from the top. It’s often used for ventilation in places like basements, where outward-opening windows might not be practical.

Side-Hung Casement

A side-hung casement window is hinged on the side and opens outward. This is the most common type of casement window and is great for providing a wide opening for ventilation and easy cleaning.

Cottage Windows

Cottage windows are typically smaller windows with multiple panes of glass separated by glazing bars. They are often found in country style homes and add a traditional, cozy look to a property.

Picture Windows

Picture windows are large, fixed windows that do not open. Their main purpose is to provide an unobstructed view of the outdoors and allow in plenty of natural light.

Stormproof Windows

Stormproof windows are designed with a slight overlap between the window frame and the part that opens. This overlap creates a better seal, making the window more resistant to wind and rain. They are called “stormproof” because this design helps keep bad weather from getting inside the house.

Timber Windows

“Timber windows” just means the frame is made from wood, giving them a nice natural look. They are popular for their classic appearance and can be painted or stained in various finishes. Timber windows are great for homes that want a warm, natural feel.

PVCu Windows

PVCu windows are made from unplasticised polyvinyl chloride, a type of plastic that is strong, durable, and low-maintenance. They are one of the most common types of windows because they don’t need much upkeep and are often more affordable than other materials.

Aluminium Windows

Aluminium windows are made from metal frames, which makes them lightweight, strong, and sleek. They are often used in modern homes because of their slim profile and ability to hold large panes of glass without bulky frames.

Steel-Look Windows

Steel-look windows are designed to look like traditional steel windows but are usually made from aluminium. They mimic the thin, industrial-style frames of steel windows, giving a modern look without the weight or cost of real steel.

Astragal Bars

Astragal bars are decorative bars fitted on the outside of the window glass to give the appearance of smaller panes. They are commonly used on traditional-style windows to create a classic, elegant look.

Glazing Bars

Glazing bars are the bars inside or outside a window that divide the glass into smaller sections, creating the look of multiple panes. These are often found on sash or Georgian-style windows and add character to the design.

Double Glazed Units

Double glazed units are windows that have two layers of glass with a gap between them. This gap helps to insulate the window, keeping your home warmer and reducing noise from outside.

Triple Glazing

Triple glazing means the window has three layers of glass, with gaps between each layer to provide better insulation. This design helps keep your home warmer and reduces outside noise. Triple glazing is a step up from double glazing, offering even more energy efficiency.

Acoustic Glazing

Acoustic glazing is designed to reduce noise from outside. It has thicker glass and special layers that help block out sound, making it ideal for homes near busy roads or noisy areas. If you want a quieter home, acoustic glazing is a good option.

Thermal Efficiency

Thermal efficiency refers to how well a window can keep heat inside your home. Windows that are thermally efficient help lower your energy bills by reducing the amount of heat that escapes. It’s an important feature to look for if you want a more energy efficient home.

Low U-Value

A low U-value means a window is very good at keeping heat inside. The U value measures how much heat passes through the window. The lower the number, the better the window is at insulation. If you’re looking for energy efficient windows, you’ll want ones with a low U-value.

Tilt and Turn Windows

Tilt and turn windows are windows that can open in two ways. You can tilt the top of the window inwards for ventilation, or you can open it fully like a door by turning the handle. This makes them practical for both fresh air and easy cleaning.

Concealed Hinges

Concealed hinges are hidden inside the window or door frame, so you don’t see them when the window or door is closed. This gives a nice clean look because the hinges are out of sight.

Solar Neutral Glazing

Solar neutral glazing is a type of glass that reduces heat from the sun coming into your home, while still letting in plenty of natural light. It helps keep your home cooler without making the glass look tinted or dark.

Thermally Broken Frames

Thermally broken frames are window frames designed to stop heat from passing through. There’s a special material inside the frame that acts as a barrier, helping to keep heat inside your home and making the window more energy-efficient.

Low-E Glass

Low-E (low-emissivity) glass has a special coating that reflects heat back into your home while still letting light in. This helps keep your home warmer in winter and cooler in summer, making the windows more energy efficient.

Leaded Glass

Leaded glass refers to windows that have thin strips of lead separating the glass into decorative patterns. It’s often used in traditional style windows to add character and detail.

Sandblasted Glass

Sandblasted glass is glass that has been treated to give it a frosted, textured look. This process makes the glass more private because it’s harder to see through, but it still lets light in.

Slim Sightlines

Slim sightlines refer to windows with thinner frames, allowing for more glass and a clearer view. These types of windows let in more light and make your home feel more open and modern.

Full-Length Glazing

Full length glazing means that the window or glass panel runs from the top to the bottom of the frame. These are often used to create large, floor-to-ceiling windows that let in lots of natural light and provide an unobstructed view.

Marine Grade Aluminium

Marine grade aluminium is a type of aluminium that is highly resistant to corrosion, especially in salty, coastal areas. Windows and doors made from marine grade aluminium are ideal for homes near the sea, where regular aluminium might corrode more quickly.

Argon Filled Glass

Argon filled glass refers to double or triple glazed windows where the gap between the panes is filled with argon gas. Argon is a gas that helps improve the insulation of the window, keeping heat inside your home more effectively.

Trickle Vent

A trickle vent is a small vent at the top of a window frame that allows fresh air to flow into the room, even when the window is closed. It helps with ventilation without needing to fully open the window.

Window Sill

A window sill is the flat part at the bottom of the window frame, inside or outside the house. It provides support for the window and helps keep water from coming in through the window by sloping away from the frame.

Mullion

A mullion is the vertical bar that divides two or more window panes or sections within a larger window. It helps support the structure and separates different sections of the window.

Transom

A transom is a small window positioned above a door or larger window, often used to let in more light or for ventilation. In some cases, it can also refer to the horizontal bar that separates the transom window from the door or window below it.

Jamb

A jamb is the vertical part of the window frame on the sides. It helps hold the window or door in place and is part of the main structure of the frame.

FAQs

What is the difference between a window sash and a window frame?

A window sash is the part of the window that holds the glass panes in place. It can either be movable or fixed, depending on the window type. In sash windows, for example, the sash slides up and down or side to side. The window frame, on the other hand, is the outer structure that holds the sash in place. The frame is fixed to the walls of the building and supports the entire window system, including the sash.

To put it simply, the sash is the part that moves and holds the glass, while the frame is what keeps everything together.

What is a window stile?

A window stile is the vertical part of the window sash. It forms the sides of the sash, helping to hold the glass in place and providing structure to the window. In other words, it’s one of the upright sections of the sash that connects the top rail to the bottom rail, giving the sash its shape and allowing it to move or stay in place within the window frame.

Need help navigating all this in real life? Visit one of our showrooms and get expert advice from our team. You can see how different materials, styles, and glazing options actually look and feel: something most window suppliers don’t offer.