Secondary Glazing Costs & Buying Guide for 2025

Installing secondary glazing is a cost-efficient way to upgrade your windows to be more energy efficient and soundproof. However, there are different types of secondary glazing and if you want to research the cost for installing new secondary glazing, there are several factors that can impact the price.

To compare costs from different suppliers, make sure that you are comparing like-for-like products. You can DIY install secondary glazing with cheap plastic panels, or have fully glazed bespoke made-to-measure frames.

In this guide, we focus on the cost of quality bespoke secondary glazing that is suitable for a listed building and maintains the architectural integrity of the original design.

How Much Does Secondary Glazing Cost in 2025?

To help you research and budget if you are thinking about adding secondary glazing, we can offer a guide price to manufacture and install quality secondary glazing.

At Everest, our secondary glazing is constructed from an aluminium frame and glass pane with different options for frame style. We make all frames to measure for a perfect fit, so every install is different and we don’t offer list prices for set sizes.

Please note, these are not actual list prices but guide price ranges only.

The cost of secondary glazing is from £500 per window, depending on many options.

A fixed sash style in white is the most cost-effective secondary glazing pane we offer.

Why Install Secondary Glazing?

One of the main reasons for installing secondary glazing is for homes that have restrictions on upgrading their windows to double or triple glazing. Listed buildings and properties in conservation areas can be restricted from changing their single-glazed window and this causes issues with heat loss and condensation.

The main benefit of secondary glazing is its impressive energy efficiency and ability to reduce sound transmission.

The gap created between a window and the secondary glazing creates a thermal barrier that has two main benefits. The gap helps the window to reduce heat loss – this is a huge benefit for period properties that struggle to increase their energy efficiency. The gap is also effective at reducing external noise and can be more effective than specialist noise reduction glass.

Types of Secondary Glazing

Secondary glazing is a glazed panel in a frame that is installed to the inside of your existing window. There are different types of secondary glazing, ranging from a DIY plastic-glazed frame that can be clipped to the inside of a window.

Cheaper secondary glazing will impact the design of the house and interior styling and is not sympathetic to architectural integrity or aesthetic. They also might use plastic panes that have reduced clarity and can scratch easily.

There are three main types of secondary glazing on the market.

Temporary Film

Not unlike cling film, this window film is attached to the window frame with double-sided tape and with a hairdryer is shrunk for a tight fit.

The major drawback of this solution is that you can’t open your window and you might get condensation behind. The film will bend and bulge with drafts and can be easily punctured.

Also, it does look like you applied cling film to your window.

Clip-on and Magnetic Panels

DIY-applied panels use a clip or magnet to hold them in place. They are made from plastic frames and have plastic panes.

To work efficiently, the panels must be a snug fit, but this can be difficult to achieve with window frames that are not square in the corners (which is very common).

They can be useful in situations where double glazing is a seasonal requirement. The panels are easy to remove for cleaning and storage, however, the fixings are not aesthetically pleasing.

Fixed Frame

The most efficient type of double glazing is made from an aluminium frame with glazed panes and made to measure for a perfect fit.

Quality secondary glazing is actually the best way to soundproof your windows as the distance between the window glazing and the secondary glazing reduces the sound transfer. The wider the gap, the better the sound reduction.

Secondary glazing is also highly effective at reducing heat loss to make a room more energy efficient.

A quality secondary glazing frame is made with slim profile frames that don’t distract from the character of the existing window and the glass offers good clarity.

What factors affect the price of secondary glazing?

When researching the cost of secondary glazing, there are several factors to consider to make sure that you get the right price.

• The size of the windows - large picture windows would be much more expensive than a small-sized frame.
• The frame style - a fixed pane, sliding sash or hinged casement are all options to consider.
• The glass used in the panes - cheap secondary glazing uses plastic panes that look cheap. A quality secondary pane will use glazing that can be toughened or has a Low-e coating to make it more energy efficient.
• The number of windows - several windows can be more cost-effective to construct than just one or two. The more windows in one project will reduce the cost per window.

Always use a window installer that is registered with a competent person scheme, such as FENSA or Certass. This means that you have automatic approval for building regulations. Always use a supplier that surveys your property before they give you a final and fixed cost to install your secondary glazing.

What are the benefits of secondary glazing?

As mentioned above, the main reason people install secondary glazing is because of listed building restrictions. However, there are other reasons to consider these windows, such as soundproofing or enhanced heat retention.

Soundproofing

The distance between the window glazing and the secondary glazing reduces the sound transfer. The wider the gap, the better the sound reduction and quality secondary glazing is the best solution to help soundproof windows if noise is an issue where you live.

Thermal insulation

In the same way that the distance between the window and the secondary glazed pane reduces sound transfer, it also helps to cut the transfer of heat. Quality secondary glazing can make a considerable difference to the energy efficiency of a window and is the top reason that most people install them.

Reduced Condensation

When warm, moist air comes into contact with a cold surface, condensation occurs. Secondary glazing helps to eliminate condensation by forming a thermal barrier and stops the moist air from getting to the coldest part of the window.

Retained Character

Another significant reason for installing secondary glazing is when there is a need to retain original features on a property. Quality secondary glazing with slim profiles can retain character and architectural integrity of a historic property.

Enhanced security

Windows are a favourite access option for burglars. Installing another layer of glass makes access harder, and your property more secure.

Financial Savings

Secondary glazing is more cost-effective than installing double or triple glazing but can offer comparable energy efficiency. It will also help to lower your utility bills.

Listed Building Compatibility

If your property is listed, consent for secondary glazing is likely to be readily given as it is an unobtrusive upgrade that won’t substantially alter the character of a historical building.

Do I Need Planning Permission for Secondary Glazing on a Listed Building?

Yes, you do need to obtain listed building consent if you have a listed building.

Secondary glazing is usually an acceptable installation to improve the energy efficiency of listed buildings and recognised as preserving the integrity of any existing heritage windows. Also for properties in conservation areas that might have restrictions on the type of window they can install, secondary glazing is a good solution to improve the energy efficiency.

But, in some exceptional circumstances, there might be a full restriction to any secondary glazing due to the construction of the property. If you are in any doubt, you should check with your local authority and planning office as it is a legal requirement.

The Listed Building Property Owner’s Club LPOC notes that an average of 90% of all listed building planning applications are granted annually.

What You Should Expect from Secondary Glazing

Make sure to compare the cost for secondary glazing as a like-for-like. Ask your potential supplier to provide a full and transparent quote that lists everything that's included and don’t forget any aftercare and warranties they offer.

What should be included in the cost of your secondary glazing:

• A full survey of where the glazing is to be installed
• The sizes, styles and colours of the frames
• The frame material to be used
• Type of glass to be used
• The window energy rating for the glass
• Full installation

Most importantly, make sure you get a certificate to say your installer is registered with a competent person scheme, such as FENSA or Certass. This means that you have automatic approval for building regulations.