Secondary Glazing

Granada logo

At Apollo Windows we are proud to offer Granada Secondary Glazing. Which is specifically designed for heritage properties, those in conservation areas and Grade I & Grade II listed buildings as the external character of the fenestration is maintained.

Secondary glazing is a discreet, internal window that is fitted to an existing window. Therefore the external appearance of the property is maintained, but you benefit from an increase in acoustic insulation, a substantial reduction in heat loss and increased levels of security.

The Benefits…


Just 65dB of noise can be problematic, whilst levels between 70-125dB can be painful, disrupt sleep patterns and increase levels of stress. To put this into perspective, a passing diesel bus may reach up to 85dB. Our secondary glazing can reduce noise levels by up to 54dB. Therefore at only 31dB a noisy bus passing is now the equivalent of a whisper!

Thermal Performance:

Creating a second barrier to the elements – an ideal way to reduce wasteful thermal heat loss. All our secondary glazing is supplied with an FSC approved timber subframe. This timber subframe acts as a thermal barrier preventing cold transference, reducing levels of existing condensation and increase thermal insulation. Installing secondary glazing exceeds Building Regulations’ requirements for thermal control and will save money on energy bills too!


Providing an additional physical barrier against forced entry and is extremely difficult to open from the outside. All frames are made from tough aluminium and are securely fixed to resist any forcing.

Secondary Glazing benefits

Secondary Glazing styles

The Styles…

  • Horizontal and vertical sliders are designed for easy access and cleaning.
  • The hinged units operate on a hinged mechanism that can be placed on the side, top or bottom, depending on your opening requirements.
  • Other styles include fixed or lift outs which can be easily lifted out of the frame.

Installation of secondary glazing is advised by Historic England as it does not change the fabric of the building.

All our secondary glazed units are bespokely manufactured to fit your existing windows. It is available in over 200 RAL colours and with minimal sightlines it is slimline and discreet, making it a popular choice for homeowners. Secondary glazing does not impact on internal windowsills meaning blinds and ornaments can still easily be displayed.

Create a Peaceful, Warm & Secure Home with Apollo Windows.