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Close up of single glazed timber window fitted with secondary glazing

Choosing secondary glazing for warmth and energy savings


Improve energy efficiency and keep the style of your home

Improving the energy efficiency of our homes has never been more important. If you live in a listed building or period property with draughty windows, building regulations often prevent changes being made to the original windows, which is why our bespoke secondary glazing is the ideal way to transform the comfort of your home.

Discreet and made to measure, there is no compromise to the appearance or charm of your home with our secondary glazing system, and you’ll instantly feel the difference.

Historic Environment Scotland advise that installing secondary glazing to traditional sash and case windows can reduce heat loss by 63%, saying: “it (is) one of the most cost-effective ways to improve thermal performance”.

In other home environments, that reduction of heat loss through the glass and through draughts rises to as much as 65%[1]. This is why secondary glazing also works for modern homes, and especially those in busy urban settings or large neighbourhoods. Using only high-spec, durable secondary glazing, customised to match the style of the existing windows, we know that our customers not only benefit from greater warmth, but also from reduced noise levels and greater security. It’s why many more customers are now choosing to fit secondary glazing.

Kitchen window fitted with secondary glazing

Why choose secondary glazing?

The three key benefits of secondary glazed windows are warmth, sound insulation and security. They cut out draughts, reduce noise levels and add an extra layer of protection against would-be intruders.


Installing secondary glazing creates a gap between your existing external windows and the new unit that acts as a layer of insulation and keeps the cold air out. The use of low emissivity glass will maximise the retention of heat, while tight internal seals work to make draughts from existing windows a thing of the past. Custom-made and fitted by our own fully qualified installers, our secondary glazing provides exceptional long-term energy efficiency, helping to lower heating costs.

Sound insulation

The state-of-the-art manufacture of our secondary glazing, with its tightly sealed frame, helps preserve and enhance your home’s peace and quiet, by reducing noise levels by up to 80%[2]. A more effective sound proofing measure than even double glazing, secondary glazing with acoustic noise reduction glass is a favourite with people who live near airports, busy roads and in city centres.


A secondary glazed window adds an additional deterrent as it is incredibly difficult to open from the outside. Our frames are made from the most durable, high-quality aluminium and are securely fixed to resist forcing. And on selected models, we can offer increased security with our “Secured by Design” locking systems and laminated glass.

Old timber window fitted with secondary glazing
Bedroom windows fitted with secondary glazing
Bedroom window fitted with secondary glazing

Secondary glazing for a period property

Period properties are always packed with character and one of the great benefits of secondary glazing is that it can be installed without compromising on your home’s aesthetic charm, and still provide the advantages of modern engineering.

Mr Hunter, who lives in a period property, is completely sold on his new window, and said:

“(CR Smith is a) great company to work with. We had some secondary glazing put on our bedroom window to combat noise from the main road our flat is on.

First and foremost the secondary glazing itself is excellent and has made a phenomenal difference to the noise. We live in a Georgian new town flat so we were concerned about how it would look however the frame is so slimline and blended into the original window sills so well you hardly notice it.
The customer service from the team was also top notch. From the original visit to the final follow up from the office, they were in touch throughout the process.

Highly recommend the product & company and would not think twice about using them again.”

Living room bay window fitted with secondary glazing

Product Range

We have a huge range of styles available and will work with you to find the most suitable option for your home. When choosing, we will guide you through the different looks so that the new window matches your interiors, as well as how the various styles of secondary glazing operate for ease of use and easy cleaning.

Horizontal sliders

These are perhaps most customers’ favourite. Easy to operate with a smooth horizontal gliding action, they fit all styles of home and are compatible with all kinds of existing windows.

Vertical sliders

These are most often paired with existing vertical sliding sash windows. Supported by robust spring balances for easy opening and closing, vertical sliders also provide a unique tilt-in facility which allows each sash to be released from the outer frame and pivoted inwards through 180°, allowing for additional cleaning access.

Tilt and Turn windows

Just like our double glazed windows, this style of secondary glazing system allows you to open the window inwards like a door and tilt it for additional ventilation.

A Discreet Fit for a Perfect Finish

A distinct feature of CR Smith’s secondary glazing is what we call “Discreet Fit”. The slim line frames are designed to ensure that the original look of your window is preserved. When our designer visits your home, we will plan how the secondary glazing will cover as little as possible of your existing windows, while ensuring a seamless fit with existing sills or facings. It is all about achieving a perfect finish.

[1] Historic Scotland. Sash windows: how to reduce heat loss

[2] Noise reduction