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Double glazing existing sash windows – Reglazing

Our sash window double glazing service has a number of benefits:

Reglazing existing frames
Improve energy efficiency
Reduce external noise

If you’re thinking of replacing your period sash windows, we have a better solution for you.

Reglazing your existing single-glazed windows with double-glazed units can achieve even better energy efficiency than triple glazing without changing the appearance of traditional wooden windows.

This keeps the beautiful charm of your property alive while adding 21st-century window vacuum glazing to your home.

reglazing sash windows with double glazing

The benefits of reglazing your windows and replacing original single-glazing with double-glazed units

During the reglazing process, single glazing is replaced with vacuum-insulated, double-glazed units that offer superior energy efficiency properties, some of which are highlighted and listed below.

As indicated in the thermal photo below, after reglazing, sash windows become highly effective at retaining heat.

Our team works with and installs products from all leading brands and manufacturers of vacuum double glazing, including FINEO Glass and LandVac.

Below are some benefits of vacuum-insulated double glazing.

Single glazed windows vs double glazing.

Can I convert single glazed windows wooden windows to double-glazed?

Yes, single-glazed wooden windows can be simply reglazed with double-glazed units.

Changing glass in period windows is a great way of bringing your home’s insulation into the 21st century without changing the classic look of your property at all.

Vacuum double glazing is only 7 mm, so with some work, it can be fitted into the rebate initially designed for 4-5 mm single glazing.

Why would you retrofit your original sashes?

The biggest reason that many people retrofit their original sash windows with double glazing is to preserve the look of their property.

Any modern equivalent is going to change the look of your home. UPVC glazed windows, even in a traditional style, greatly change the look of your property, and in many cases, they cannot be installed in listed properties anyway.

You are then left with secondary glazing. Secondary glazing doesn’t change the look of your property from the outside but does change the inside of your home. Suddenly opening your window is a two-step process, and you lose the space on your window sill too.

So, simply put, retrofitting sash windows with vacuum-sealed double glazing is the best way to go. It adds modern window technology to your home, saving you energy and money, but it doesn’t change the look of your windows from the outside or inside.

Your windows will look the same as they always have but have up-to-date glass and draught-proofing within. This is why most people are now retrofitting their windows in a period property.

Glazing that does not change the appearance of original sash windows

A sash window that has been retrofitted with double glazing will look exactly the same as it did before. Well, actually, in most cases, it will look even better.

You see, we offer wooden window restoration and retrofitting services. So, in most cases, we have to repair the windows before retrofitting can begin.

This means that the windows we commonly work on are a bit worse for wear when we arrive at the property.

Once we’re finished restoring the windows and adding the energy-efficient glazing, though, the sash windows look as they did when they were first installed into the building.

The property is transformed into the beautiful home it once was, but its thermal performance and thermal efficiency have been greatly improved.

There is some additional weight added when the new glass is added. However, we adjust the sash cords and weights accordingly.

So, the additional weight doesn’t affect how the windows operate, and you’ll likely find they operate better than they ever have before.

Retrofitting original sash windows with double-glazed units

By adding double glazing to your wooden sash windows, you can dramatically improve the energy efficiency of your home while keeping the style of your home intact.

A lot of our customers have been told that they need to replace their original sash windows with modern uPVC glazing units because that is the only way of saving money on their energy bills.

But doing so changes the look of your property forever.

However, this isn’t the case. By retrofitting ultra-thin vacuum-sealed double glazing into your existing windows, your windows look and work the same.

But you can enjoy all the benefits of modern double glazing. In fact, the vacuum-sealed double glazing that we use in our sash window restoration projects is just as effective as triple-glazed uPVC units.

Best double glazing for sash windows retrofitting

If you want to keep your original sash window frame but only change the glass, you don’t have too many options when it comes to retrofitting, as not all glazing is suitable for this job.

There are only a few double-glazed units that can be retrofitted into existing sash windows currently due to the thickness, and only one glass is more likely to get permission from the conservation officer in case you are lining in the Listed property where you would like to change the glazing.

Glazing options completed by heat retention and thickness

The single glazing (simple one pane of glass) is the most inefficient but, as you would expect, the thinnest glazing option.

FINEO glass is eight times more efficient than single glazing and is the second thinnest option, making it an optimal choice for reglazing tasks.

If your property isn’t listed, we can also offer you the option of installing LandVac glass. It is even more energy-efficient than FINEO glass, boasting an efficiency that’s 12 times greater than single glazing.

Both types of vacuum glazing will enable your windows to meet and surpass the A* energy efficiency benchmark.

Best double glazing for sash windows retrofitting

Vacuum-insulated glass (VIG)

Vacuum-insulated glass, or vacuum-sealed glass, is what we use in our reglazing projects.

We use VIG double-glazing because it outperforms all standard double and triple-glazing units on the market.

Below is the comparison table of VIG double glazing to standard triple glazing at the given temperature conditions:

The secret to such a high insulation performance in such a thin profile is the vacuum, which almost does not transmit heat compared to inert gases or air.

Vacuum glazing is not easy to make and, as you would rightly suspect, is not cheap.

Still, it does a perfect job for Listed buildings, which is the preservation of period frames and energy efficiency improvements.

Below is the photo of FINEO glass and how it is delivered from Belgium, where it is manufactured.

It comes in the pallet to our premises or client’s address, and our team reglaze the windows onside.

Before VIG: Slim-profile double-glazing

Before the vacuum double glazing, there was another type of double glazing available for reglazing projects.

Slimline double glazing filled with inert gases is the same as normal double glazing you’ll find in modern homes, but the gap between the panes of glass is smaller.

Slimline glazing is around 14mm thick and offers a U-value of as low as 1.2 with a 6mm gap between the pieces of glass.

This type of glazing has a number of disadvantages, including its service life as insulated units start to fail in just three years.

Double-glazing windows in listed properties

We have many homeowners of Listed buildings amongst our clients.

Their first question is usually about permission; if it is required for double glazing windows in a listed building and our answer is yes, the permission is required.

However, homeowners have a higher chance of receiving permission to reglaze glass to double glazing than for full window frame replacement.

Our windows reglazing service fits the best needs of listed properties as it offers all the benefits of double glazing but preserves the original window frames.

Reglazing windows in Grade 2 listed properties

How much does it cost to retrofit double glazing?

Prices for retrofitting sash windows with double glazing start from £1579 per window. This includes all timber frame repairs, reglazing works, glass, draught-proofing and painting.

All of our work is guaranteed because we trust our services and materials.

The paintwork is guaranteed for eight years. All window repairs are guaranteed for 20 years. FINEO and LandVac offer a 15-year manufacture guarantee for their glass, too.

FAQs

Will you fit the double-glazed units into existing window frames?

Yes, we reuse the existing original frames and only change the glazing from single to vacuum-insulated double glazing.

Can you reglaze casement windows or french door?

Yes, we can reglaze any type of original wooden window and doors. Whether it is a casement window or a sash window, we install double glazing to improve the thermal insulation and sound insulation, which will save you money on your heating bills.

Can I reglaze the original single-glazed windows in the Listed property with double-glazed units?

Yes, they can, but you must seek planning permission in most cases.

For more information about our double-glazing services for sash windows, please get in touch. We can provide a quote for all retrofitting and repair work needed to make your windows beautiful and efficient.