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How Do Sash Windows Work?

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How Do Sash Windows Work?

Reading Time: 4 Minutes
Published on: January 21st, 2021

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How Do Sash Windows Work?

Sash Windows, also called box sash or vertical sliding sash windows, are unique windows with a vertical opening mechanism that allows you to push the window up when opening it. 

Sash windows enhance homes with the unique beauty of the pulley system they operate on, making it possible to push your window upwards and pull it back downwards. 

Are sash windows more unique than the standard windows, and is there anything special about their workings?

Let’s find out in the following paragraphs. 

Components of a sash window that you should know

Before we move further in this conversation, let us describe the parts of a sash window and where you find them. 

A pair of lead Weights hang on the sash cord and balances each sash that slides up and down.

Weight pockets are made of timber linings and sit at both sides of the window. The lead weights sit in these weight pockets.

Sash Cord: The sash cord holds the weights that balance your sash slides. The sash cord runs across the pulley wheel to maintain the weight correctly. 

The top rail is the top-most horizontal frame of the window, while the meeting rails are horizontal framings that join both sashes in the middle.

A pulley wheel sits at the top of a pulley lining that allows the sash cords to pass above it while maintaining balance.

A Parting bead is a long and narrow seal that creates channels for the lower and upper sashes to run through while also holding the upper sash in place.

Timber linings are hollow sections that house the weights and form the box frame’s casing. 

How do Traditional Sash Windows Work?

A traditional sash window comes with two sliding sections, also called sashes. They slide up and down, using a pulley and weight mechanism inside the window frame. 

When a sash opens, the weight counterbalances with a weight inside the window frame. This weight connects to the opened sash through a cord that runs over a pulley at the top of the window frame. This method is a simple cord, weight, and pulley mechanism.

Generally, sash windows are designed in a manner that you don’t see the intricate functional mechanisms.

For instance, the sash cord that runs above the pulley through the top rail is unseen because it hides in the window frame.

The counterweight, which comes in lead, cast-iron, or steel, connects to the window using the hidden sash cord. 

So, the entire pulley mechanisms by which sash windows operate are hidden within the frames so that you can only see the beautiful window and not the workings behind it.

How do sash windows work - a sash window under construction
A sash window under construction – you can clearly see the cord for the pulley mechanism.

What changes do we see with Sash Windows?

The method of operating slide windows is gradually changing in recent years. The lead and steel weight that counterbalances the sash windows are being replaced by cords and spiral balances.

Spiral balances are a more flexible version when compared to traditional weights. They make it easier to open your windows. Spiral balances hold the weight of each sash and maintain their position while the windows remain open. 

When closing a window, the mid-rail is a point where the sashes at the top and bottom meet and lock. This mid-rail ensures that the window doesn’t slide down again, thereby ensuring that the entire design is secure.

Weighted springs also slow down the process of bringing the windows down to avoid accidents involving your fingers.

uPVC sash windows are also replacing the traditional timber sash windows with more modern functionality.

How do modern sash windows operate?

Modern sash windows have their working mechanisms hidden in a frame like the traditional sash windows. However, some modern systems use a loaded spring mechanism instead of a weight and cord system. These new sash windows also favour a torsion balance over a counterbalance. 

When you move the sash upwards or downwards, the spring loosens or tightens while the window remains open due to the spring’s tension that releases a countering force.

How do sash windows work?

Sash windows work on a time-honored and ingenious system that has stood the test of centuries. These classic windows consist of one or multiple glazed panels (sashes) that move vertically within the frame. The secret behind their smooth functionality lies in a carefully balanced mechanism. Each sash is counterbalanced by a weight concealed within the window frame. Connected by sash cords and pulleys, the counterweights create a perfect balance, allowing you to effortlessly slide the sashes up or down. This user-friendly design not only makes sash windows easy to operate but also provides excellent ventilation control. When properly maintained, sash windows can last for generations, preserving their timeless charm and functionality while enhancing the character of your home.
How do sash windows work? A diagram of an edwardian sash windows

Conclusively, sash windows are a great addition to your home’s aesthetics, functionality, and style. They come with high-security locks, optimal energy efficiency, and long-lasting mechanisms. 

You can’t go wrong with a professionally designed and installed sash window for your home or office.