New Double Glazed Sashes or Double Glazing Retrofit to Existing Sashes?

If your home still has single-glazed windows, you may be wondering whether to go for new double-glazed sashes or a double-glazing retrofit service. Both options work and will give you all benefits of having double-glazed sashes, but one will replace your original sashes while another will preserve them.

Here are some thoughts that may help you decide which double glazing option works better for you.

What is wrong with single glazed windows? 

Single glazed sash windows are not very energy efficient, as they allow heat to escape from your home and access to solar energy to enter your room during hot summers. Draught-proofing can definitely help a bit, but it will not resolve issues such as condensation. It will also not reduce the UV, which can cause your furniture and wooden floors to fade over time.

Single glazed sash windows can also be quite noisy, as they don’t do a great job blocking out external noise.

The single-pane glass is easier to break so the security of your windows is also compromised with this type of glazing.

 Can you just replace the window sash? 

In some cases, you may be able to replace just the window sash. This is usually only possible if the box sash window frame of your window is still in good condition. If the frame of your timber window is badly rotten, you’ll likely need to replace the entire window or restore the sash window frame.

Replacing just the window sash is typically less expensive than replacing the entire box sash window.

Can you convert a single pane window to a double?

Yes, you can convert a single pane window to a double-glazed window. This is typically done by removing an old glass, rebating the sashes and fitting new slimline double-glazed units. Then re-puttying is done, and after paying, the sashes will look as original but with better thermal performance glass.

This can make your window more energy-efficient and help reduce noise, energy bills, condensation and improve security.

Retrofit double glazing

Sash window double glazing retrofit is the process of adding double glazing to your existing windows without replacing the existing sashes.

This option can be a great way to upgrade your period timber sash or casement windows and make them more energy-efficient.

One of the main benefits of this option is that it preserves the original look and feel of your windows and costs less then a full sash window replacement.

The best double glazing unit for this task is vacuum insulated units. This VIG glazing is thin and efficient as triple-glazed units.

Restore sash windows before retrofitting 

If your sash windows are in bad condition, repairing window sashes is essential step before retrofitting, as rotten sashes will not be able to hold the additional weight of the double-glazed units.

Restoring sash windows is less expensive than getting new windows, and with proper refurbishment and regular maintenance, your sash window will last as many years as new timber windows.

Replace existing sashes with new double-glazed ones 

New sashes can be fitted to frames of original box sash windows, but if your windows are in a listed building, you will need a permit for this. Also, it’s important to check the properties of double glazing installed into sash replacement. The glass should be low emissivity and vacuum sealed for the best possible energy efficiency.

What are the benefits of converting single-glazed sash windows to double-glazed windows? 

Converting your old, single-glazed sash windows to double-glazed windows offers many benefits. Here are some of the main ones:

1. Improved energy efficiency. This can help you reduce energy bills and make your home more eco-friendly.
2. External noise reduction: Double-glazed sash windows also do a better job of reducing noise pollution from outside, making your home more peaceful and quiet.
3. Improved security: The extra layer of glass in double-glazed windows makes them more difficult to break, deterring potential burglars and making your home more secure.
4. Condensation reduction: Double-glazing can also help reduce condensation in your home, as the extra layer of glass prevents moisture from building up.
5. Improved value: Double-glazed windows can also add value to your home, making it more attractive to potential buyers if you ever decide to sell.

Energy-efficient replacement double glazing units.

As mentioned above, knowing which double glazing will be retrofitted to your original sashes or installed on new replacement sashes is important.

The most energy-efficient double glazing is vacuum-sealed VIG low-emissivity (Low-E) glass. This special type of glass has a vacuum inside, which does not transmit any energy, making it a perfect insulation barrier. VIG glass is also low-emissivity, reflecting heat into the room and preventing heat loss.

Vacuum glazing glass is usually 6-12 mm, but has a U-Value of 0.55-0.7.

Is retrofit double glazing worth it?

Double glazing retrofitting is worth the effort and money and should be the first choice when considering double glazing sash windows. It is cheaper and environmentally friendly as it reses existing sashes. If current double glazing is used, retrofitting beats new triple-glazed sash windows.