sash-window-with-astragal-barsA window sash is a crucial component of traditional window design, particularly in period properties and heritage buildings across the UK. Understanding what a window sash is, its functions and the benefits it offers can greatly enhance your appreciation of these architectural features.


Definition and Components of a Window Sash

A window sash refers to the frame that holds the glass panes in a window. Depending on the type of window, it can move or be fixed. The sash is designed to slide vertically or horizontally in sash windows, facilitating ventilation and ease of cleaning.


The main components of a window sash include

Sash windows come in various styles, each with unique characteristics:

  • Single-Hung Sash Windows: Only the bottom sash is moveable, with the top sash fixed
  • Double-Hung Sash Windows: Both the top and bottom sashes are moveable, providing enhanced ventilation and flexibility
  • Weights and Pulleys (for traditional sash windows): These balance the sash, allowing it to be raised or lowered easily


Some Types of Sash Windows

  • Real Dividing Bars: As the name suggests, these are frames with sash glass panes fitted between each square frame. The sash frame holds the individual pieces of glass
  • Unlike a real dividing bar, the Glazing Bars, is different. It may in some cases look the same, but the construction is what makes it different. Often seen in Georgian and Victorian-style windows, they are usually made up of one singular pane of glass on the inside and outside of the sash one whole glass fitted into a frame, with wooden dividers giving the impression that the glass is divided into two or more panes.  If one pane broke, it just needed to be replaced, as it was much cheaper to produce one single pane of glass, which is why these bars are used instead, to give the appearance without the associated cost


Benefits of Sash Windows

Sash windows offer several advantages, making them a popular choice for both homeowners and architects:

  • Aesthetic Appeal: Sash windows are renowned for their timeless elegance and are often a key feature in preserving the historical character of buildings
  • Ventilation Control: With double-hung sash windows, you can open both the top and bottom sashes, allowing for adequate air circulation
  • Ease of Maintenance: Many modern sash windows are designed with tilt mechanisms that make cleaning the exterior panes simple and safe
  • Energy Efficiency: Advances in glazing technology mean that sash windows can be fitted with double or triple glazing, enhancing thermal performance and reducing energy costs


Sash Windows

Understanding sash windows – the individual parts

Various parts make up a sash window and keep it working as it should. They give this type of window its distinctive appearance, ensure it is thermally efficient, and ensure it will open and close as needed.

These are the main components that make up a traditional, weights and cords sash window:

  • Sash, or sashes. There will usually be two sashes, the frames containing the glass. They are moveable to allow you to open the window
  • Box frame. This is the window frame that includes the sashes
  • Sash cord. The cord is attached to the sash’s side and fed through a pulley. It is also attached to the sash weight inside the box frame
  • Sash weight. The purpose of the weight is to counterbalance the sash to allow the window to open. It will weigh the same as the sash and be made from steel, cast iron or lead
  • Staff bead. A staff bead is an internal trim that sits around the box frame. Its purpose is to keep the sashes in position within their frame. Often, when you have a newer staff bead, it will also contain a draught seal
  • Parting bead. This vertical seal fits into the box frame and creates a channel for the top and bottom sashes. As with the staff bead, when you have a newer parting bead, it will often contain a draught seal

Some window sashes will also have these additional features, which might alter the appearance or improve the functionality in some way:

  • Sill. Most sash windows might use a sill on the inside or outside of the window. This is essentially a decorative feature but may also help to protect the window from moisture and rot
  • Draught-proof strips. These can be fitted to help improve the thermal efficiency of a sash window. Your window might already have them, as they are often included with a parting/staff bead (especially if the parting/staff bead, or the window as a whole, is relatively new)


Common Issues and Maintenance

While sash windows are durable, they require regular maintenance to remain functional. Common issues include:

  • Swelling and Sticking: Wood can swell due to humidity, causing the sash to stick.
  • Rope and Pulley Problems: The cords can fray or break over time in traditional sash windows.
  • Draughts: Older sash windows can suffer from gaps that allow draughts, though modern sealing techniques can mitigate this.


Parsons Joinery: Your Sash Window Specialists

At Parsons Joinery, we understand the importance of maintaining the integrity and functionality of your windows. Our replacement service is tailored to meet the unique needs of each property, ensuring that new sash windows are sympathetic to the original architecture while providing modern performance benefits.


Our Replacement Service

We offer a comprehensive sash window replacement service that includes:

  • Bespoke Design: Our skilled craftsmen create sash windows that match the historic style of your home, whether Georgian, Victorian, or Edwardian
  • Quality Materials: We use high-quality timber and glazing to ensure durability and energy efficiency
  • Expert Installation: Our team of experienced installers ensures that each window fits perfectly, operating smoothly and securely

Whether restoring a period property or enhancing the aesthetic appeal of your home, Parsons Joinery provides a professional, reliable sash window replacement service. Contact us today to learn how we can transform your windows and preserve your property’s charm.  


Is there anything else you want to know about window sashes?

Hopefully, you now understand what a window sash is, and how it works within the sash window as a whole. However, if you have more specific questions about sash windows, please don’t hesitate to let us know. We are here to help.