Can I upgrade my single glazed sash windows to double glazed, without ripping them out?

As timber sash window experts, we always prefer to renovate or upgrade original windows over replacing them. In fact, we go to great lengths to preserve historically-important windows in a range of domestic and commercial properties – whether they require restoration, repairs or energy efficient updates. This can include things like splicing in new timber to bring a sill back to life, replacing broken sash cords and weights, or fitting our innovative Ventrolla Perimeter Sealing System to keep out draughts (you can find out more about VPSS here).

The good news is, that our dedication and expertise in preserving original windows also extends to upgrading glazing, to give you a warmer and more energy-efficient home. So if you’ve ever wondered whether you can double glaze your original sash windows, to avoid having to replace them, the answer is a resounding yes (in most cases!).

Installing slim double glazing: The process

Our process is tried and tested – and ensures your existing windows remain intact. Standard double glazed units are too deep to fit in original sash windows, so we use slim double glazing to achieve the same effect. You’ll enjoy the benefits that you’d get from any double glazing, but ours fits seamlessly into Georgian, Edwardian or Victorian windows.

How does it work? Quite simply, we fit slim double glazing into your existing sash box frame, to protect your home’s heritage and authenticity. These energy-efficient slim double glazed units are installed along with our innovative VPSS, that has been tested to withstand winds up to 71 mph (a category 1 Hurricane starts at 74mph). The result is the same beautiful timber sash windows that you’ve always had – but now with all the modern benefits that uPVC would bring.

When choosing our Double Glazed sashes, our specialised renovation service also includes a full overhaul of your sash box, or window frame, including:

• Sanding down & replacing any rotten timbers in the sash box, taking your windows back to sound & healthy wood.
• Replacing your pulleys & chords
• Weighing your new sashes and installing the correct weights within your sash box, so your windows operate smoothly
• Installing new hardware
• In addition to the above, we also install our unique draught proofing system the Ventrolla Perimeter Sealing System in and around the moving sashes. This system closes the gaps that let heat escape and draughts in, making for a warmer home

Our projects range from small domestic homes to large commercial projects. However diverse the scale of our activities may be, Ventrolla’s principles have never changed, restoring the original beauty of your sash windows, whilst improving their energy performance.

Slim double glazing: The benefits in more detail

Most uPVC units are 24mm or 28mm thick. But the double glazed units we fit measure just 16mm – and thanks to the spec of our glazing, the performance is just as good. Our preferred glass is Planitherm Total+ for the outer pane – a thermally-insulating Low-E glass, that has been designed to help windows meet the highest Window Energy Ratings (WERs). And the cavity between the panes is filled with Krypton – an inert gas that has a lower thermal conductivity than air. This not only keeps your home warmer but also gives your window a lower acoustic conductivity, for better noise insulation.

Ventrolla’s slim double glazing specification:

• Slim 16mm (4/8/4) double-glazed units
• Planitherm Total+ glass (outer pane) and krypton-filled cavity
• Centre Pane U-Value of 1.2 Wm²K
• Total Window U-Value of 1.5 Wm²K

Our particular slim double glazing improves the ‘U’ value of your window, too; this is a measure of thermal insulation. The lower the ‘U’ value, the greater the performance, in terms of how much energy is required to maintain a comfortable temperature in a property. The Energy Saving Trust’s website has more information on this topic.

Window upgrades that won’t disrupt your home

One of the often-overlooked benefits to our process is that by using your existing box frames, we leave your décor untouched. Because we don’t have to remove integral parts of your window, we avoid causing cosmetic damage. It’s no wonder It’s our most popular service.

Find out about double glazing your sash windows

As you can see, upgrading your sash windows to double glazed can be achieved with the minimum of disruption. If you’d like to arrange a free, no-obligation consultation with our team to look at double glazing your sash windows, please get in touch today.