Secondary Glazing

There are a lot of houses that cannot have Sealed Unit Double Glazing. Listed Buildings, Some Conservation areas, etc, are not allowed to change the appearance of the home or building and therefore do lose heat, feel draughts and also hear traffic and other noises more easily than more modern homes.


We can help with both noise and heat issue by installing Secondary Glazing to the inside of your window.


Available in nearly any RAL colour to match either your windows or interior decoration.


Toughened glass is used where required under Building Regulations.

We can use Pilkington's K glass secondary glazing to reduce heat loss even further and can nearly match modern double glazed sealed units for heat retention, although not quite as good.


If you would like free advice and/or a quotation for a secondary glazing solution please give us a call and we will be pleased to let you know what there is to offer.


How does sound travel?

Sound travels through the air like ripples on a pond surface when a stone is dropped into it. The sound radiates outwards in all directions from the source, gradually reducing in intensity or until an object stops its progress.

Measuring sound Sound is described in different ways but primarily in terms of intensity and frequency. The sound intensity is described in dB. A low dB indicates a soft sound; a high dB value indicates a loud sound. Frequency describes how high or low pitched the sound is (Hz).

For instance, if a stereo has its initial volume set to 60dB, decreasing that volume by set amounts will produce the following effects:

-3dB — the difference is just perceptible

-5dB — the difference is clearly noticeable

-10dB—the sound from the stereo is halved

Sound reduction

Loud music remains the main source of noise complaints in England, Scotland & Wales. 70% of people admit to feeling harassed by noise. Secondary glazing is an excellent solution for homes, hotels, pubs & clubs or factories situated close to housing, allowing them to keep the noise in.

Recommended sound levels



bedrooms: 30-35dB

living rooms: 30-40dB



private: 35-40dB

open plan: 45-50dB

How can secondary glazing help to reduce sound?

New glass technology to reduce sound...


Acoustic laminated glass (Silence) is the latest product to come onto the market. Two sheets of glass are bonded together with a 0.76mm thick layer of special acoustic polyvinyl butyral (PVB). Solaglas estimate a 20% improvement over standard glass. Taking this increase into account when installed into our secondary glazing a reduction of 44-45dBs should be easily achievable.


Sound reduction test...


A three-panel horizontal-sliding secondary glazing unit (1960mm X 1190mm) was sent to the Building Research Establishment in Watford to be tested for acoustic performance (noise reduction).


How was the test carried out?

A cavity wall was built into an aperture between two rooms in the BRE's transmission suite. The specification of the wall was as follows:


Bock thickness: 100mm

Block density: 1800 kg/m2

Cavity spacing: 75-80mm

Finish: plasterboard on dabs (typical new-build method)


An aperture was left in the wall to house a window. A standard Georgian-style casement window with three openers was sourced from a builder merchant, and fitted into the aperture using standard window installation methods.


Finally, secondary glazing was installed behind the window on timber liners, to provide a minimum pane spacing of 100mm.


The set up was then tested for sound reduction using a range of different options:


4mm secondary glass 65% noise reduction (39db)

6mm secondary glass 65% noise reduction (39db)

6mm secondary laminated 70% noise reduction (40db)