How to Retrofit Double Glazing in Older Homes

How Double Glazing is Retrofitted in Older Homes

These are the typical stages of retrofitting:

1. Survey and Measurement

An installer will visit your home to assess your existing window and discuss their recommendations. They may recommend replacing a frame if it shows damages that are beyond repair.

Once the assessment is done, the installer will give you a quotation and the time needed to complete the retrofit. This may happen on-site or they will contact you after a day or two.

The installer will also discuss the payment terms and interest rates. Many window companies in the UK offer payment terms at no interest.

2. Custom-building Double Glazed Windows

A window company may have sashes readily available for installation. If there’s none, they will give an estimate of the number of days it takes to custom-build sashes that will fit your existing frame.

3. Installation

The window installation company will start by removing the existing sashes, sealants and beads. If needed, they will modify the frame to ensure that the new sash fits properly.

Then, the installer will fill the gaps around the frame with an insulating foam and apply silicone seals. They will also replace the hinges and handles to accommodate the double glazed sash.

4. Site Cleaning

Window professionals can install 4-6 windows in a day. This estimate can vary depending on the type of windows and the complexity of the job.

After the window is installed, the installation company will clean up their work area, discuss the warranty and offer care tips for your windows.

Pros of Retrofitting

Improved energy efficiency
In a poorly insulated home, £1 out of every £3 spent on energy goes to waste. Retrofitting will improve a home’s energy efficiency and reduce heating costs.

Quicker than a new installation
Retrofitting can be faster than a new installation because the old frame gets reused. Additionally, there’s no need to fix damages to the drywall which often occurs when the frame is removed.

Cheaper
It takes fewer materials and fewer labour hours to install a new sash into an old frame.

Reduced waste
Reusing existing window frames significantly reduces waste. Moreover, many window installers in the UK are happy to take in used glasses for recycling.

Maintains the character of a property
With the right skill and materials, a window installer can keep the character of a heritage property while improving its energy performance.

Cons of Retrofitting

Heat can still pass through the existing frame if it’s not thermally broken
You can still lose a significant amount of heat on windows that have aluminium or steel frames that are not thermally broken.

The thickness of the double glazing is limited by the size of the frame
Your choice of sash is limited by what the existing frame can accommodate. This limits the energy performance you can achieve since the type of glass and its thickness affect a window’s thermal efficiency.

May weaken the frame
Sections of wood may need to be cut out to accommodate the double glazed sash which can weaken the frame.

Could devalue heritage
Some timber windows in the UK have been around for 100 years. Any modification on them could remove their heritage features.

Risks of DIY Retrofitting

You can retrofit an old house yourself if you have the tooling and experience. Otherwise, it’s best to work with professionals because retrofitting can be a complex and demanding task.

Installation errors are costly
If you break any component of your existing window or the new sash, you will need to pay for the repairs or the new sash out of pocket.

Installing double glazing is tricky mainly because of the weight. A double glazed sash that measures 4x20x4 mm can weigh 20 kg per square metre. Installing it requires the proper tooling and ideally an extra pair of hands.

Retrofitting is a technical task
Installing a window requires precision every step of the way: from the measurement of the window to the addition of weather seals.

When measuring a window, you need to account for:

• The right amount of gap is needed between the frame and sash to accommodate thermal components.
• The thermal expansion of a window’s components.

Poor installation will negate any benefit of double glazing
Improper installation can leave air leaks and gaps where your home’s heat can quickly escape.

DIY retrofitting may void the warranty
Some window warranties might be void if the window is not installed by a professional.

Window installation requires proper tooling and protective equipment
If you don’t have those already, your costs of acquiring tools will offset your potential savings.

Conclusion

Retrofit double glazing is a cost-effective way to improve the energy efficiency of an older home while retaining its character. Once you have considered its benefits and drawbacks, the next step is to find out what window companies are offering.

Our price comparison tool helps you do that: compare costs and features from multiple window companies to find the best deals. At zero cost and absolutely no obligation, we can also request quotes on your behalf. Simply get in touch with us.