Windows in a listed building

This page deals with England, with the Welsh statutory position noted where it differs since 4 November 2024. Scotland and Northern Ireland have their own Acts and their own heritage bodies — see Scotland, Wales and Northern Ireland. If your building is not listed but is in a conservation area, the question is a different one and the answer is often more favourable: start with do you need planning permission to replace windows in a conservation area? or with the complete guide.

Why the listed regime is stricter, in the statute’s own words

Section 7 of the Planning (Listed Buildings and Conservation Areas) Act 1990:

Subject to the following provisions of this Act, no person shall execute or cause to be executed any works for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural or historic interest, unless the works are authorised under section 8.

Planning (Listed Buildings and Conservation Areas) Act 1990, s.7(1) — legislation.gov.uk, revised text

Read what is not in that sentence: no reference to external appearance, no visibility requirement, no “materially” and therefore no de minimis threshold on the face of the provision, no distinction between inside and outside, and no mention of the grade.

That is why the reasoning that works on an unlisted building fails here. There, the question is whether the work is development, and section 55(2)(a) of the Town and Country Planning Act 1990 takes out of the planning system any alteration affecting only the interior or not materially affecting external appearance — so a genuinely invisible change is outside the system altogether. Section 7 has no equivalent escape hatch.

Free to apply for, criminal to skip

The asymmetry here is stark, and it is the reason to apply. The Planning Portal states the fee position plainly: “There is no fee for an application for listed building consent.” (If a planning application is needed as well, the planning fee is still payable.) Meanwhile section 9 makes it an offence to contravene section 7 or to breach a condition attached to a consent — on summary conviction, imprisonment for up to six months or a fine, or both; on indictment, up to two years or a fine, or both, with the court required to have regard to any financial benefit accruing from the offence. A narrow defence exists for works urgently necessary for safety, health or the preservation of the building, where no lesser measure would do, the works were the minimum immediately necessary, and written notice justifying them was given to the authority as soon as reasonably practicable.

Planning (Listed Buildings and Conservation Areas) Act 1990, s.9; Planning Portal, Listed building consent

Section 9 contains no time limit, and there is no listed-building equivalent of the section 171B immunity period that eventually protects unauthorised windows on an unlisted building. We are not stating a practical prosecution deadline — charging practice and the limitation rules for summary offences are outside what we could verify from primary sources. What is verifiable is that time does not cure it.

Grade changes the argument, not the requirement

Section 7 does not mention grades. Grade I, Grade II* and Grade II buildings are all simply “listed buildings” for the purposes of the offence and the consent requirement, so the grade makes no difference to whether you need consent.

What the listing actually covers

The listing is of the building, not of the front elevation. Section 1(5) defines a listed building as one included in the list, and provides that “any object or structure fixed to the building” and “any object or structure within the curtilage of the building which, although not fixed to the building, forms part of the land and has done so since before 1st July 1948” are treated as part of the building.

Planning (Listed Buildings and Conservation Areas) Act 1990, s.1(5)

Two practical consequences. First, rear and side elevations are fully within scope — a point confirmed the hard way at 20 The Close, Blandford Forum, where an inspector dismissed the rear uPVC windows and rear uPVC door on a Grade II listed building while allowing other, severable parts of the same appeal. Rear elevations are not a safe harbour on a listed building.

Appeal APP/D1265/Y/24/3341181, Dorset Council, decided 29 November 2024 (DL7)

Second, the coach house, garden wall or outbuilding you assumed was unprotected may be part of the listed building if it was in the curtilage before July 1948, in which case its windows are subject to section 7 as well. The list entry on the National Heritage List for England is the place to start, but the entry description is not a definition of what is protected.

Replacing the window versus replacing only the glass

This is the distinction that runs through the whole of this site, and it is the point at which the listed regime diverges most sharply from the unlisted one. On an unlisted house, putting a new sealed unit into an existing sash without changing anything visible is very likely not development at all. On a listed building, that argument is unavailable: section 7 has no external-appearance filter, and the glass is part of the fabric whose loss can affect character.

The clearest illustration is Champions Place, Kent Hatch Road, Limpsfield — a Grade II listed house by Mervyn Macartney. The works were framed as removing the existing windows in part and replacing the glazing: the existing frames and historic ironmongery were to be reused, with slimline double glazing and applied lead on both faces. The appeal was dismissed, and it was dismissed on the glass:

the proposal would result in the loss of historic fabric through the loss of the existing glass and lead, which makes a positive contribution to the special interest of the listed building

Appeal APP/M3645/Y/25/3367188, Tandridge DC, dismissed 9 October 2025 (DL8)

Retaining the frame did not save it. The inspector also found the slimline profile would be “chunkier” with “different reflective qualities”, and that applied lead “would also fail to be authentic” (DL8). Harm was assessed as less than substantial, at the “mid-to-lower end of the scale” (DL13) — and still fatal.

That said, do not overcorrect. Historic England’s position is that replacing broken glass with modern float glass “is unlikely to affect special interest and therefore would not need consent either”, while early glass “should be retained if possible”. The consent question bites when you change the kind of glazing, not when you replace a cracked pane like for like. Advice Note 18 puts the reglazing position as: “Listed building consent is likely to be required, unless replacing panes in modern windows.”

Historic England, Modifying Historic Windows as Part of Retrofitting Energy Saving Measures (updated 23 July 2024); Advice Note 18 (HEAG321), paragraph 81

What “affects character” means for windows in practice

Historic England’s five principles, imported into its current windows advice from Traditional Windows (HEAG039), are the closest thing to a decision framework. Three of them decide most cases.

Principle 3 — the retrofit route, with its caveat attached:

Where historic windows or replacement windows of historic pattern survive without historic glass it may be possible to introduce slim-profile double glazing without harming the significance of the listed building. There are compatibility issues to consider as the introduction of double glazing can require the renewal of the window frame to accommodate thicker glazing, thereby harming significance.

Principle 4 — the reason a uPVC scheme can occasionally be allowed:

Where historic windows have been replaced with ones whose design does not follow historic patterns, these are unlikely to contribute to the significance of listed buildings. Replacing such windows with new windows of a sympathetic historic pattern, whether single glazed or incorporating slim-profile double glazing, may cause no additional harm. It also provides an opportunity to enhance the significance of the building, which is the desired outcome under national policy.

Principle 5 — reflectivity:

Where a new window or re-glazing is agreed, the reflective properties of secondary and double glazing as compared to modern, polished single glazing, do not usually harm the significance of the building. But when new multi-paned windows are proposed, the desirability of reproducing broken reflections by individually glazing each pane should be considered.

Historic England, Modifying Historic Windows…, principles 3, 4 and 5

Advice Note 18 then sets out the consent expectations by intervention, and this hierarchy is worth memorising because it is the order in which a conservation officer will think:

Two honest caveats about that table. First, Historic England’s own detailed windows guidance — HEAG039, still published, still downloadable, and flagged on its own page as under review — is markedly more cautious: “the installation of IGUs in historic windows is likely to seriously harm their significance”, and “where slim-profile IGUs are inserted, window sashes often have to be replaced”. Both documents are live. Anyone quoting only paragraph 81 at you is quoting selectively.

Second, and more useful: inspectors have applied reflectivity more restrictively than Principle 5 suggests. Principle 5 says reflectivity does “not usually harm” significance, yet reflectivity was a decisive harm finding in three of the recent appeals we read — Harrogate (DL13), Champions Place (DL8) and Parker’s Lodge (DL11). If you are relying on Principle 5, expect it to be met with a finding of fact about your particular window rather than a concession of principle.

What the decided appeals actually show, both ways

Read Mackworth Green against Parker’s Lodge and the pattern is unmistakable. Both concerned steel windows; both proposed double-glazed steel replacements; six appeals were allowed and the other pair dismissed. The difference was not the material but whether the existing windows were historic fabric. At Mackworth Green: “While the replacement of timber with metal may not be suitable in other listed building cases, I am satisfied that no historic fabric would be lost and the overall effect in design terms would be neutral” (DL19). At Parker’s Lodge the windows, believed to be 1920s, “by reason of their design and use of traditional materials make a positive contribution to the building as a whole and contribute towards its special interest” (DL9). Mackworth Green is also the strongest verified answer to “timber or nothing” — the council wanted slimline double-glazed timber and the inspector allowed steel — though it is not authority that steel is generally acceptable. See timber windows for conservation areas for what officers normally specify.

One detail from Thornhill House is almost never reported. The inspector accepted externally applied astragal bars, but only because they were paired with “back-to-back spacer bars inside the unit”, so that “this would give the appearance of separate panes of glass, rather than the bars appearing tacked on” (DL13). Compare Advice Note 18 paragraph 82: “Stuck-on or applied glazing bars rarely replicate the character of historic windows and are unlikely to be acceptable.” Applied bars are not automatically fatal; unbacked applied bars very nearly are.

The “double glazing test case” is not what it is said to be

What the judgment did decide is more useful than the myth. The court held it had no vehicle for a general review of practice — the case “concerns a challenge to one particular decision by one inspector … and does not offer the opportunity for a general review of the practice adopted by local authority officers and planning inspectors” (§49) — and found “no evidence to support the submission that the inspector displayed bias or prejudice towards any particular means of achieving thermal efficiency” (§50). It also gave the working definition of “preserve” that inspectors still apply: a proposal that “causes no harm to the significance of the heritage asset, can be said to preserve the significance of the asset” (§23).

Two further points, both against the myth. The inspector in Guinness expressly did not rule out slim double glazing — “The use of slim double glazed units in replacement windows is not ruled out by any of the advice given by the Council or by English Heritage” — but found that “superficially applied glazing bars, as proposed in this case, lack authenticity” (quoted at §17). And the case was lost substantially on evidence: the inspector could not assess subdivision, casement proportions or sub-frame position “in the absence of scaled measured drawings” (decision letter, quoted at §17), because the claimants “chose to present photomontages, and not scaled drawings” (§34).

The base rates, and their limits

Of 69 listed building consent appeals concerning uPVC windows or doors received by the Planning Inspectorate between 1 January 2014 and 31 January 2024, 48 of the 56 decided on the merits were dismissed — about 86 per cent — with 7 allowed and 1 split.

Planning Inspectorate FOI response 2024003, published on gov.uk

The “allowed” column is thinner than 12 per cent suggests. One of the seven was a change away from uPVC to hardwood; another turned on a factual dispute about whether the windows were uPVC at all; two more were rear or secondary elevations, or driven by health and safety. The only clean, fully reasoned grant of front-elevation uPVC on a listed building in the dataset is Thornhill House.

A second dataset records 11 listed building appeals concerning double-glazed windows that were received after 1 August 2019 and allowed — and, strikingly, “no appeals which concern existing original glazing”. Treat both datasets with the caution the Inspectorate itself asks for: there is no database marker for double glazing, the search was of a free-text field, and “the list/data provided may not be definitive”. The second dataset lists only allowed appeals, so it is not a success rate.

Planning Inspectorate FOI response 2024043, “windows in Listed buildings”, data extracted 19 September 2024

The evidence that wins, and the arguments that lose

Across the appeals, outcomes turned less on the design than on the paperwork.

A condition survey is the single most valuable document. Two of the 2025–26 appeals failed squarely for want of one. At Champions Place: “there is no condition survey before me… no compelling evidence before me that the existing windows are beyond repair” (DL11). At Parker’s Lodge the windows were demonstrably defective — corrosion, rust jacking, distorted casements — and the appeal still failed because there was no compelling evidence they could not be repaired in situ (DL10).

Measured drawings, not photomontages. Guinness is the authority; the practical constraint is the authority’s validation list, and there is no national standard — published requirements range from 1:5 sections to 1:1, so check before anyone draws anything. At Mackworth Green the inspector secured 1:20 to 1:1 sections and elevations by condition. See applying for windows: drawings, fees and what officers look at.

Show why secondary glazing will not do. Inspectors keep returning to it. Harrogate turned in part on secondary glazing not having been shown to be infeasible (DL14), and the same decision records Historic England’s technical position that in multi-paned windows secondary glazing will generally be more thermally efficient than replacing the glass, “because even the most efficient units will not overcome thermal bridging through the frame and glazing bars” (DL11). Parker’s Lodge added the visual point: “secondary glazing is typically set further back, which minimises its impact from public views” (DL11). Full treatment: secondary glazing in conservation areas and listed buildings.

Public benefit, not private benefit. Energy efficiency is accepted as a benefit and given significant weight, then routinely outweighed because it is private. Parker’s Lodge: “Given that the proposal relates to a single property, any environmental benefits which would flow to the public at large are likely to be minimal” (DL17). Harrogate: “the proposed works are essentially a private benefit which would not be sufficient to outweigh the harm that I have identified” (DL17). That follows from the statutory duties: sections 16(2) and 66(1) both require the decision-maker to “have special regard to the desirability of preserving the building or its setting or any features of special architectural or historic interest which it possesses”. In Barnwell Manor the Court of Appeal, dealing with the section 66(1) setting duty and the parallel conservation-area duty in section 72(1), endorsed the formulation that a decision-maker “should accord considerable importance and weight” to that desirability. Inspectors carry the same phrase into listed building consent decisions under section 16(2) — it appears in Champions Place (DL13), Parker’s Lodge (DL15) and Harrogate (DL16). This is not an ordinary material consideration to be balanced freely.

Barnwell Manor Wind Energy Ltd v East Northamptonshire DC [2014] EWCA Civ 137 — BAILII; P(LBCA)A 1990 s.16(2) and s.66(1)

What other people got away with counts for little. At Champions Place the appellant’s citation of similar installations elsewhere was given “limited weight” (DL14).

If the wrong windows are already in

The remedy is not “apply retrospectively and pay a fee”. At Land at 4 Back Shaw Farm, Bradford, a listed building enforcement notice issued under section 38 was upheld on appeal under section 39: remove the unauthorised patio doors, reinstate the previously existing wall in reclaimed stone matching the existing profile and coursing, point it slightly recessed in coarse lime mortar to match, and “install a painted timber window to exactly match the design of that of the remaining ground floor window” — within four months.

Appeal APP/W4705/F/25/3362503, City of Bradford MDC, dismissed 31 October 2025

Because there is no immunity period, this exposure does not expire, and it is materially worse at sale than an unauthorised window on a merely unlisted building in a conservation area. See enforcement, time limits and selling the house.

What to do, in order

1. Read the list entry on the National Heritage List for England. Note the grade and what else the entry names, and ask the authority whether curtilage structures are treated as included.
2. Record what you have before touching anything. Photograph each window inside and out with a rule in shot; note glazing bar and meeting rail sections; identify any historic glass by its distortion and bubbles. If early glass survives, the reglazing route is largely closed and secondary glazing is the realistic answer.
3. Commission a condition survey, window by window, from someone competent in historic joinery, and have it say in terms which members can be repaired and which cannot. This is the document that decides appeals.
4. Work down the AN18 hierarchy, and say that you have. Repair, then draughtproofing, then secondary glazing, then reglazing within retained frames, then replacement. An application that starts at replacement without disposing of the earlier steps invites refusal.
5. Check for a Local Listed Building Consent Order. Kensington and Chelsea made one on 18 May 2023 granting consent by Order for secondary glazing (Class A) and for replacing a single-glazed pane with an insulated or vacuum unit (Classes B and C). The reglazing classes apply only to windows “installed in a listed building after the date of listing and with the benefit of listed building consent” — original and historic windows are excluded, and the Order says in terms that replacing them “must remain the subject of full consideration under the process of a listed building consent application”. Conditions include units no greater than 20 mm, integral rather than applied glazing bars, spacer bars coloured to match the frame, and “UPVC is not to be used”.
6. Get measured drawings to the authority’s stated scale, specifying the unit, the sightline, the bedding compound and the sash weights. Standard linseed oil putty can damage insulated unit seals, and heavier glass usually needs the weights rebalancing.
7. Ask for pre-application advice in writing, then apply. The listed building consent application itself is free, though many authorities charge for pre-application advice — check the fee schedule before you ask. The consent is the only thing that makes the works lawful. Listed building consent is not planning permission, and neither is a FENSA or CERTASS certificate — see building regulations for replacement windows.

The two most-discussed technical routes have their own guides: vacuum insulated glazing in conservation areas and listed buildings and slim-profile double glazing in period windows. For the material argument, see uPVC windows in a conservation area.

The other nations

Wales. Since 4 November 2024 the 1990 Act is effectively replaced in relation to Wales by the Historic Environment (Wales) Act 2023. The equivalent of section 7 is now section 88: works for the alteration or extension of a listed building “in any way that would affect its character as a building of special architectural or historic interest” must be authorised under section 89. The Welsh Government’s position is that the new legislation “makes no changes to the operation of the current management and protection regimes”, so English case law on the substance remains persuasive — but the statutory references are wrong for Wales after that date. Cadw on material: “UPVC windows, for example, will not normally be acceptable.”

Historic Environment (Wales) Act 2023, s.88; Cadw, Managing Change to Listed Buildings in Wales (May 2017)

Scotland. A separate Act — the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997 — with its own consent regime, its own decision-maker duty in section 14(2), and appeals to the Planning and Environmental Appeals Division. Scottish guidance is markedly more permissive than England’s about window replacement on unlisted buildings, and explicit that this changes nothing for listed ones: “Irrespective of whether planning permission is needed, listed building consent will need to be obtained if a building is listed.”

Scottish Government Planning Circular 1/2024, §7.5 (28 May 2024)

Northern Ireland. The Historic Environment Division publishes a numerical threshold no other UK heritage body offers: “HED will generally consider acceptable slim profile units with an overall thickness of less than 10mm. However, Listed Building Consent will be required for all forms of replacement double glazing. Please note this does not apply to windows with historic glass as these should be retained in their original profile.” Councils must consult HED.

DfC Historic Environment Division, Guidance for Historic Windows, March 2024

Full per-nation treatment: Scotland, Wales and Northern Ireland. Sources are listed at /sources.

Five things to stop believing about listed windows

1. “If it is not development, no consent is needed.” Section 7 operates independently of section 55. Interior work and invisible work can both require listed building consent.
2. “Replacing only the glass avoids consent.” Not on a listed building. The glass can itself be historic fabric, and Champions Place was dismissed on precisely that.
3. “It is only Grade II.” The grade appears nowhere in section 7. It affects the justification threshold under NPPF paragraph 213, not the requirement.
4. “They cannot do anything after ten years.” There is no immunity period for listed building control, and no time limit in section 9.
5. “The test case settled that double glazing is allowed.” Guinness was dismissed, concerned timber replacements for Crittall windows, and turned on applied glazing bars and the absence of scaled drawings.