Retrofitting Double Glazing to Wooden Sash Windows

Retrofitting Double Glazing to Wooden Sash Windows

Wooden sash windows are a charming feature adding an elegant touch to any home. Their practical design and timeless style are definitely appealing. However, the romance of these windows can be frequently overshadowed by draughts, rattles and rising energy bills.

So how do you keep the elegance of your sash windows while also making your home more energy-efficient and cosy? The good news is that the solution can lie in double-glazing. Read on for more information on how retrofitting double glazing to wooden sash windows could be the answer to your heating problem.

Why double-glazing?

Modern homes frequently include double-glazed windows, and for good reason. If your windows have two panes of glass instead of one, it stands to reason that you’ll benefit. But the gap between them isn’t simply an empty space, it works as a thermal barrier between the inside and outside of your property.

Along with the two panes of glazing, that gap of air keeps the heat out during the summer and the warmth in during the colder months. So, your home can become a cosy haven all year round.  

What is retrofitting for sash windows?

If you have classic wooden sash windows, you can use a process called retrofitting. This is a method of installing double glazing without affecting the classic woodwork look. Rather than replacing your original sash windows, a secondary panel is installed on the inside to provide the benefits of secondary glazing without affecting heritage.

In short, secondary glazing is used as way of retrofitting double glazing to wooden windows. It can be a detailed process but worth every step – enhancing the insulation as well as the overall function of your windows. The process can be done in 3 steps:

1.  Assessment

Starting with a thorough assessment, the old windows will be inspected closely. Special attention is taken to check for damage or rot in the wooden areas. If any part of the wood is affected, it could make adding additional glazing difficult. It’s hugely important to ensure that any issues are resolved as soon as they are found, so the new windows work well and are properly secure.

2. Measuring

Next, various elements need to be measured to ensure that your new glazed units fit perfectly. The height, width and depth of the existing window frames are measured and special attention is given to any unique architectural features. This is important as doing this will preserve the window’s original character, in particular, the shape – for example circles, arches and keyholes.

The condition of the windowsill and surrounding wall area will then be checked carefully. It’s important to measure each window accurately to ensure that every unit fits perfectly and meets the unique needs of each specific window. Every detail matters to ensure the best results.

3. Installation

Finally, it’s time to prepare for installation. The secondary units should be installed with precision to make sure they fit perfectly. An important element of installation is ensuring that opening and closing your windows is smooth and remains unaffected. The units are then sealed for insulation, making your home warm and draught-free.

Essentially, the goal is to make your windows more energy-efficient, secure, and attractive.

The benefits of retrofitting

Sash window double glazing retrofits using secondary glazing offer a number of benefits, including:

Improved thermal insulation

Secondary glazing puts an extra layer of insulation on your sash windows, helping keep the inside temperature steady. This means less need for heating in winter and air conditioning in summer, saving energy.

Noise reduction

With an extra layer of glass and a gap in between, noise from busy areas is significantly reduced, making the inside of your home calm and peaceful. This structure makes it difficult for sound waves to penetrate, lowering the amount of noise that gets inside. The space between the two panes disrupts the sound waves, causing them to lose energy and volume, adding an additional layer of quiet to your house.

Enhanced security

Sash windows with secondary glazing can greatly improve house security. Their thicker and more durable twin layers of glass provide a strong deterrent against break-ins, far superior to single-glazed counterparts.

The enhanced locking systems of these windows strengthen your home’s security, adding an extra benefit. The mix of durable glass and advanced locks increase the protective barriers of your home, offering peace of mind.

Reduced condensation

Condensation is less of a problem with sash windows that have secondary glazing. The two layers of glass with a space in between help keep the inside pane warm, stopping moisture from building up. This design keeps the window clear and reduces dampness indoors. A warmer glass surface and less condensation means a healthier living space and a clear view of the outdoors.

Increased property value

Switching to double-glazed windows can increase your home’s value – the same is true for sash windows with secondary glazing. Prospective buyers like them because they help cut down on noise, keep the home at a comfortable temperature and make it safer.

Once they’re installed, your home stays warm without running up the energy bill because your heating works more efficiently. In the summer, it helps keep your house cool without overusing the air conditioning. So, it’s not just comfortable living, but it’s also a smart way to increase your home’s value.

The eco-friendly choice

From an environmental perspective, adding secondary glazing is a step closer to a more eco-friendly lifestyle. The boost in energy efficiency benefits both homeowners and the planet. Lower energy usage means fewer greenhouse gas emissions, so every retrofitted home helps in the worldwide effort to combat climate change.

Get a quote for your sash window double glazing retrofit

If you’re looking to retrofit double glazing for sash windows, secondary glazing provides a practical solution. It will protect the charm of your sash windows while improving performance and reducing your energy bills.

This method of retrofitting double glazing to wooden windows is even permitted for listed buildings, because there’s no impact on the primary window. To find out more or get a no obligation quote, contact Clearview today.


Clearview secondary glazing - the solution to significantly improved acoustic and heat insulation to your property, making your home or offices more comfortable, secure, greener and cost efficient to run. Achieved without the disruption of replacement windows, and without damaging the character of your building.

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