A listed building turns the usual cost question on its head. The issue is not how many windows you have or what material you prefer, it is whether you are allowed to touch them at all. Inserting double or triple glazing into historic windows usually requires Listed Building Consent, and uPVC replacement is generally refused outright. For most owners the practical, approved and far cheaper answer is secondary glazing, which Historic England actively recommends. This page sets out what each route costs in 2026 and why the cheaper option is often the better one. For the head-to-head, see our secondary versus double glazing comparison.
What the routes cost
The table compares the three options an owner of a listed building realistically faces. The first is the one most councils and Historic England prefer. The others depend entirely on securing consent, which is never guaranteed.
| Route | Per window (fitted) | Consent position |
|---|---|---|
| Secondary glazing | £164 DIY supply, £300 to £900 fitted | Usually no planning permission needed |
| Slimline timber double glazing | £1,330 to £2,850 | Listed Building Consent usually required |
| uPVC replacement | Not applicable | Generally refused on listed homes |
Source: clearviewsg.co.uk (secondary glazing pricing) and historicengland.org.uk (consent position), cross-checked against the DGCC 2026 dataset.
Why secondary glazing is the recommended route
Conservation officers prefer secondary glazing for one reason above all: reversibility. A secondary system sits on the inside of the existing window and is fixed with screws, so it can be removed without leaving a mark on a window that may be two centuries old. It is invisible from the street, which preserves the external appearance the listing protects. Historic England recommends it as best practice, and research commissioned by English Heritage and Historic Scotland found that secondary glazing can outperform replacement double glazing for thermal efficiency in traditional buildings, while also cutting noise by around 80%. You keep the original windows, improve comfort, and usually avoid planning permission altogether.
Worked example: a Grade II terrace, four front windows
Take a Grade II listed home with four original single-glazed sashes on the front. Bespoke fitted secondary glazing on all four, surveyed and installed, typically lands in the low thousands for the set, well below the cost by house size of a consented timber replacement and with no risk of refusal. By contrast, applying for Listed Building Consent to fit slimline timber double glazing on those same four windows could run £5,300 to £11,400 if approved at all, and the application itself can take months. For most owners the maths and the timeline both point the same way.
On a listed building I always start with secondary glazing, and so does any decent conservation officer. You keep the old sashes, you lose the draughts and most of the noise, and you do not need consent to rip out original glass. The owners who fight for double glazing usually spend a year and a fortune to end up worse off.
Tom Bradley, FENSA-registered installer
Best Buy for a listed building
For almost every listed home, secondary glazing Best Buy is the answer: approved, reversible, cheaper and effective. Slimline timber double glazing It depends is worth pursuing only where consent is likely and the original windows are already beyond repair. uPVC It depends is effectively off the table. If your home is in a conservation area as well as listed, our conservation area cost page and Victorian terrace cost page cover the overlapping layers of rules, which our guide to the conservation area rules explains in full.
Frequently asked questions
Sometimes, but inserting double or triple glazing into historic windows usually requires Listed Building Consent, and uPVC replacement is generally not acceptable. Many councils prefer secondary glazing instead, which Historic England actively recommends as best practice because it is reversible and leaves the original windows untouched.
Secondary glazing prices start from around £163.66 per window for a DIY supply order. A professionally surveyed and fitted bespoke aluminium system costs more per window, but it is still usually cheaper and far less disruptive than seeking consent for full replacement.
For most glazing changes to a listed building, yes. Altering or replacing historic windows affects the special character the listing protects, so Listed Building Consent is normally required. Secondary glazing often does not need planning permission because it is reversible and hidden inside the reveal.
For a traditional building, research commissioned by English Heritage and Historic Scotland found secondary glazing can outperform replacement double glazing for thermal efficiency, and it cuts noise by around 80%. It also preserves the original windows, which matters when they are part of why the building is listed.
Possibly for the secondary glazing or repair element if you qualify on income and EPC grounds, but funding for listed properties is tightly tied to conservation approval. Always confirm both the grant eligibility and the consent position before committing.