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Conservation area:

Secondary glazing


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Age/Period: 1870’s
Type: 2 storey detached Victorian villa. Grade 2 listed
Years in residence: 20 years
No. Bedrooms: 4
Wall type: Solid wall, Bath stone Ashlar
Area: Combe Down

Key Features

Secondary glazing that conforms to listing and conservation requirements; also, window draughtproofing


Built in the 1870’s this family home retains many of its original features. Motivated by the need to reduce energy losses, homeowners Jacqueline and Simon, sought to improve the thermal performance of the existing sash windows.

In early 2023, south-west-based company Mitchell & Dickinson were employed to restore the original windows, fitting draught excluders and secondary glazing. Their wealth of experience in working with historic buildings helped to satisfy the planning requirements of this listed building in a conservation area.

With work starting in early June 2023 a total of 11 original sash windows were fully restored within a 3-week period. The fully reversible Cosy Glazing secondary glazing system was installed to 7 of the refurbished existing windows. Utilizing magnetic strips, the system can be easily removed for cleaning whilst reducing heat loss over single pane glass by 70%, without significantly altering the integrity and fabric of the original window.



To provide a good balance between ease of operation and thermal efficiency, a mixture of single and double pane secondary glazing has been employed. Windows on the ground floor, were fitted with 2 panes of secondary glazing attached directly to the window frame, allowing full operation of the sash windows. To provide for the extra thickness of the secondary glazing minor alterations to the frame and liner were required.

Two rarely opened windows on the first floor were fitted with a single pane of secondary glazing, requiring removal to open the window. The lightweight nature of the Cosy Glazing system means this process can be completed with ease allowing for flexibility throughout the year.

All major works were completed within the 3-week period. Jacqueline and Simon noted the professional nature of the restoration and installation works, commenting that all aspects the project were completed to a high standard and in keeping with the original features of the windows.


As a summer installation means that it is too soon to see how the secondary glazing has helped to reduce energy demand, other indicators of comfort have been noted by the homeowner, most notably the reduction in draughts and noise transmission.


Mitchell & Dickinson: