Listed buildings, conservation areas and double glazing in Scotland.

First, check what your building is

The rules depend on whether your building is listed (Category A, B or C) or sits in a conservation area, or both. You can search every listed building in Scotland on the Historic Environment Scotland portal. Your council's website has maps of its conservation areas. If you are in a tenement, the listing covers the whole building, including your flat's windows.

Repair comes first

Every authority starts from the same place: keep the original window if it can be saved. Historic Environment Scotland's guidance, Managing Change: Windows, says repair is the preferred option. Glasgow City Council puts it plainly: repairs to original windows using the original materials do not need planning permission or listed building consent.

That covers most of what a restoration involves: splicing out rot, new cords and weights, draught proofing, reglazing broken panes like for like, new single glazed sashes made to match where the originals are beyond repair, pointing and painting. See sash window restoration.

Listed buildings

Replacing a whole window in a listed building, or fitting new sashes that differ from the originals, for example double glazed sashes, changes its character, so it needs listed building consent from the council. A new single glazed sash made to match the original exactly, as part of a refurbishment, is generally treated as like for like repair. If in doubt, ask the council's conservation officer before work starts.

• Glasgow: "Listed Building Consent and Planning Permission are required for the removal and/or replacement of an existing window."
• Category A and B: Historic Environment Scotland is consulted. For Category C, the council decides alone.
• uPVC: Glasgow says it is "not considered an acceptable window frame material for Listed Buildings", and Edinburgh says it "will not be acceptable in listed buildings".

Can you double glaze a listed building?

Often, yes, when it is done carefully. The City of Edinburgh Council's guidance on listed buildings and conservation areas (September 2025) lists the options it considers before a window is replaced, in this order:

1. Repair
2. Shutters, roller blinds, curtains
3. Draught proofing
4. Internal secondary glazing
5. New glass in existing sashes
6. New sashes in existing cases

The last of these is our double glazing upgrade: the original case stays in the wall, and we make new slim double glazed sashes to match its sections and sight lines. Edinburgh describes the narrow profile units it has in mind as 14 mm thick (two 4 mm panes with a 6 mm gap). It also asks that every application for narrow profile glazing includes a cross-section drawing of the existing and proposed windows, showing the cavity and the pane sizes. We help with the application, drawings included.

Complete replacement of original windows is only approved in Edinburgh where they have "clearly deteriorated beyond practicable repair", shown by a professional survey with photographs.

Secondary glazing

An internal secondary window, fitted behind the original, is the least intrusive upgrade. Edinburgh "encourages" it and notes that, depending on the interior and the design, listed building consent may not be required. Historic Environment Scotland's guidance says secondary glazing can cut heat loss through a window by over 60%. If you would rather not have a second window on the inside, our double glazing upgrade puts the insulation into new sashes in your original case instead. We will talk you through both at the free survey.

Conservation areas (buildings that are not listed)

Since 2024, changing windows in a conservation area has been simpler:

• Rear windows, and side windows that do not face a road, can be altered or replaced without planning permission.
• Front windows (and side windows facing a road): in Glasgow, no permission is needed if the new window is the same or substantially the same, meaning the same way of opening, the same number, orientation and colour of panes, and the same frame and astragal sizes and colour. Otherwise you apply to the council for prior approval of the design. In Edinburgh, front and road-facing windows go through a prior approval application.
• These changes do not apply to listed buildings, and in Edinburgh they do not apply inside the World Heritage Site either, where you still apply for planning permission.

Because rear windows on unlisted buildings in a conservation area can be changed without planning permission, this is where a uPVC sash window can be an option. We fit both timber and uPVC sash windows, and will tell you which the rules allow for each of your windows.

Building standards

In Scotland, replacing windows does not need a building warrant, but the new windows must still meet the building standards. For a full replacement that means a U-value of 1.6 W/m²K or a Window Energy Rating of band C or better, with flexibility for historic and listed buildings where that would harm their character.

How we help

We have worked with conservation officers and listed building authorities across Scotland for more than thirty years, from tenement flats to Edinburgh City Chambers. We survey every window individually, recommend the route that suits the building (restore, upgrade or renew), and help with the consent application, drawings included.

Arrange a free survey →