Black Knight Secondary Glazing
Black Knight Secondary Glazing

Secondary Glazing for listed buildings

Using secondary double glazing in listed buildings

There are many reasons for using secondary glazing for listed buildings in the UK and limitations on how alterations, repairs and improvements can be carried out.


English Heritage define a listed building as having been built before 1919 without a damp proof course, having sash windows which are single glazed.


So many Victorian, Georgian  and Edwardian properties now fall under the listing officers remit.


Other properties which are not of sufficient interest to merit listed status may still have restrictions on what can be done as they fall in a Conservation Area. These areas are created to ensure that inappropriate work is nor carried out thereby ruining the external appearance to the detriment of the area as a whole.  

The good news is that using secondary glazing for listed buildings is considered an acceptable alteration and does not generally need permission for it to be installed.


However we would recommend that you discuss the work with your listing or conservation officer first just to make sure you are not falling foul of any regulations.

By their very nature sash windows are draughty and create uncomfortable living conditions because of draughts and cold spots. By installing secondary glazing you will achieve a  considerable reduction in energy costs, cut CO2 emissions and presperve the important external character of your property.

Secondary double glazing in period properties

Ever since the early 1970’s when aluminium and uPVC windows became a ubiquitous addition to our buildings we have witnessed the appearance of many old buildings being changed radically and, more often than not, totally out of keeping with the original design.


Whilst it is true that modern primary windows are much better at insulating than their earlier counterparts unfortunately our older housing stock was never meant to be sealed up to that extent and the problems associated with reduced ventilation, increased humidity and condensation have escalated as a result.


As a guideline you should be looking to change the air completely in an old building about once an hour.

A common use for secondary glazing for listed buildings and conservation areas Secondary glazing used effectively in a listed building

Reasons for use

There are a few reasons why secondary double glazing should be considered for traditional properties:

  • Generally the only acceptable option allowed by Planning & Conservation Officers
  • Won’t alter the appearance of the exterior of the property
  • No detrimental impact on property values through inapproariate use of materials
  • The cost will be considerably less than full replacement
  • aesthetics – secondary double glazing does not spoil the appearance of an older property
  • greatly reduced heating costs will quickly pay for the initial expenditure
  • improved reduction in noise levels where required

Often windows in period properties are not just rectangular – the huge flexibility of design within the Black Knight range can cater for all kinds of shapes, curves and arches.


And with a full range of hundred’s of RAL colours you can be certain that they will blend discreetly with your existing décor.


Benefits Summary for Listed Buildings

  • improved heat insulation
  • better sound insulation – when correctly installed secondary windows is the most effective way of reducing  noise
  • controlling both the symptoms and effects of condensation
  • improving security particularly in windows that are in vulnerable locations

Our Experience

We have many years of fitting secondary glazing for listed buildings and properties in Conservation Areas for many years. We are always happy to give you whatever advice and guidance you need to ensure that you can carry out the work successfully and compliantly.


If necessary we can attend site to provide consultation and design advice, provide specifications to support your Planning Application and we have a comprehensive guarantee to ensure that you benefit from our products capabilities long after the initial purchase.

About Listed Building Consent

Any alteration to windows and doors needs Listed Building Consent – that includes the fitting of secondary windows.

Conservation Areas

You do not need consent to fit secondary windows to a building located in a Conservation Area unless the building is also Listed (see above).


We recommend that you contact your local authority Planning Department prior to placing an order to ensure that they have no issue with your proposals.  

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