Black Knight Secondary Glazing
Black Knight Secondary Glazing

What are Secondary Windows?

Although they are made of modern materials, they are not a new concept.

During the Victorian era properties were often built with internal secondary windows as part of the original structure. This was usually another entire sash window with counterbalanced lead weights which was fitted behind the existing external window.


The purpose of these windows were was to reduce heat loss as most external sash windows were very draughty and also to give some protection against the ever increasing road noise.



Modern secondary windows are available in a number of complimentary designs to sympathetically suit the existing window configuration: 

  • horizontal sliders where the secondary panels slide from side to side and are removable for cleaning.
  • vertical sliders where the panels of the window slide up and down and are removable for cleaning.
  • lift outs secondary glazing for use over windows that either do not open or where access to the primary window is only need infrequently.
  • hinged units which give unimpeded access to the primary window.

The units are designed to create an effective internal double glazing and to be robust yet discreet. They will reduce heat loss, eliminate draughts and, where required, to greatly reduce noise from external sources such as road traffic and aircraft. 

In many cases the performance of secondary windows will be better than changing the primary windows and will also result in less inconvenience with little or no redecoration works required after fitting.


To read more click here - information provided by English Heritage.


Secondary window prices vary depending on design, size and specification. If you would like to get an idea of costs please click below


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What secondary windows specification do I need?

If you are experiencing heat loss or draughts through your existing windows then there is a range of specialist glass which can be incorporated into your new secondary windows to give the maximum impact. In particular using a low emissivity glass such as Pilkington LowE, which has an invisible reflective surface to direct heat back into the room, is advisable.


If your main concern is to prevent noise then we recommend using SGG Stadip Silence glass which is an acoustic control glass - combined with the optimum gap between the glass in your primary window and the secondary window you can expect a substantial reduction in noise levels.


Finally if you are looking for a high level of security then we recommend using a laminated glass in the secondary glazing.


As always we are pleased to provide as much advice as you need to come to an informed decision - please contact us for more information.