Conservation area window rules in Scotland, Wales and Northern Ireland

Scotland used to be the strictest of the four nations here and is now, on paper, arguably the most permissive. That reversal is why so much published advice — including some council pages and some heritage guidance — is out of date. Start with the complete guide to conservation area windows, and for England in detail, do you need planning permission to replace windows in a conservation area?

Three regimes stay separate in every nation, and an answer to one says nothing about the others: is the work development (planning permission), does it affect a listed building’s special interest (listed building consent), and does it meet the building regulations. And everywhere, the distinction between replacing the window and replacing only the glass does more work than any other fact about your job.

The four nations at a glance

Scotland

Development is defined by section 26 of the Town and Country Planning (Scotland) Act 1997; permitted development comes from the 1992 Scottish order, never replaced, only amended. Note the numbering trap first: Scotland has no plain “Class 1”, and Class 1B is a two-storey ground-floor extension, not windows. Windows are Class 7A of Part 2 of Schedule 1, “Sundry minor operations”.

Section 26(2)(a) takes out of “development” works of maintenance, improvement or alteration which affect only the interior or “do not materially affect the external appearance of the building”. Government guidance applies that to windows in terms: “the installation of like-for-like windows will not require an application for planning permission. This is the case in all locations.” That includes World Heritage Sites — but a listed building still needs listed building consent, which has no external-appearance filter at all.

Planning Circular 1/2024, ¶7.1 — gov.scot, published 28 May 2024; statutory basis s.26(2)(a)

Class 7A and the three tests

Class 7A(1) permits “any alteration or replacement of an existing window”, subject to two absolute limits: Class 7A(2) removes it within a World Heritage Site, and the rights “do not apply to the creation of new windows in an existing building” (¶7.4), so a new opening still needs permission.

In a conservation area, the extra step applies only where the window is on the principal elevation, or a side elevation that fronts a road, and the replacement “would not be the same, or substantially the same” as the existing window as regards (i) the manner in which it is opened and closed, (ii) the number, orientation and colour of the panes, and (iii) the dimensions and colour of the frame or any astragal bars. Then you must, before beginning the development, apply for a determination as to whether the authority’s prior approval is required, with a written description, the materials, a site plan and the fee — and may proceed after 28 days if nothing has been determined. On a rear elevation, or a side elevation not fronting a road, none of it applies: “there are no restrictions on the design or appearance” and no information need be submitted (¶7.7). Consideration is “limited to the design and external appearance”, with no neighbour notification or publicity (¶7.15).

Class 7A, inserted by S.S.I. 2024/102 art.8. “Astragal” is the Scottish term for a glazing bar and appears in the legislation itself — see the glossary

Because Class 7A sits in Part 2 rather than the dwellinghouse Part, it covers “the existing windows of a house or flat” and non-domestic buildings too (¶¶7.2–7.3). A Glasgow tenement flat has window permitted development; a Cardiff or Belfast flat does not — see windows in a flat or maisonette.

The authority’s view of your material only becomes a planning question if a design criterion is also failed. Where a case does reach a decision the arguments in uPVC windows in a conservation area still run: in ENA-230-2159 an enforcement notice over a uPVC tilt-and-turn window replacing a wooden sash-and-case window on a gable in Edinburgh’s Grange Conservation Area was upheld.

DPEA ENA-230-2159, dismissed 9 September 2019, Reporter Mr Don Rankin — dpea.scotland.gov.uk. We verified reference, site, breach, date and outcome, not the reasoning; the decision predates Class 7A

Fees, periods and appeals

Three traps in that table. The circulars disagree on the fee: Circular 1/2024 ¶7.13 still says £100, the May 2024 figure — the fee circular governs, and Scottish fees rise every 1 April. The appeal route differs for the same window, as Edinburgh’s own flowchart shows: prior approval to the Scottish Ministers, householder permission to the council’s Local Review Body under section 43A(8). And Scotland gives no fee relief where an Article 4 direction is the only reason you are applying — England and Wales exempt those applications entirely, Northern Ireland charges £78, Scotland the full £371.

Consents, HES, Edinburgh and Glasgow

Conservation area consent still exists in Scotland, under section 66(1) of the 1997 Act, and it is demolition only: “A building in a conservation area shall not be demolished without the consent of the appropriate authority.” Windows never engage it — see conservation area consent for windows. Listed buildings are untouched by Class 7A (¶7.5), and Historic Environment Scotland is consulted on listed building consent for category A and B buildings; councils alone determine category C consent and unlisted buildings in conservation areas.

HES’s Managing Change in the Historic Environment: Windows is the design authority and the clearest case of stale guidance here: last updated 3 February 2020, four years before Class 7A, its line that “planning permission may be required for replacement windows in conservation areas” now over-states the position for unlisted buildings. Use it for design, not consent thresholds — that in replacing sash windows “materials other than timber, e.g. uPVC, will rarely be acceptable”, that narrow-profile and vacuum glazing have “directly resulted in double-glazing becoming more generally acceptable in historic buildings”, and that astragals sandwiched between panes alone “will be very unlikely to be acceptable”.

Edinburgh publishes the clearer decision tree, dominated by the World Heritage Site carve-out: “If you live in the World Heritage Site or a Listed Building, then these changes do not affect you and you should continue to apply for planning permission/listed building consent.” Its Quick Guide to Windows splits the three statutory tests into seven prior-approval matters, separating pane number, orientation and colour and frame and astragal dimensions and colour, and points to a Certificate of Lawfulness for written confirmation that you need nothing. Glasgow publishes the better evidence checklist — nine items including glazing bars, horns and any decorative, stained, coloured or leaded glass existing and proposed, photographs, and the manufacturer’s specification — and is candid that on rear elevations its preference is advisory: “There are no restrictions on materials, colours, proportions, or means of opening, but we would encourage you to replicate the design and appearance of the existing window”.

Scottish building standards

No building warrant is needed to replace a window, including the frame — Schedule 3 paragraph 20 of the Building (Scotland) Regulations 2004 lists “A door, window, or rooflight when the work includes replacing the frame” among work not requiring a warrant. Schedule 3 is conditional on the work meeting “any standards required by the Regulations”, so there is no warrant, no inspection and no self-certification scheme — FENSA and CERTASS operate under the England and Wales regulations and have no statutory function in Scotland — while compliance stays mandatory.

The April 2026 domestic Technical Handbook applies to work commenced on or after 6 April 2026. Table 6.2 sets 1.4 W/(m²·K) for windows, with note 2 allowing “a Window Energy Rating or Doorset Energy Rating of B or better” in an existing building, and clause 6.2.1 adds a floor: “Glazing with a U-value poorer than 3.3 should not be used”. The 1.4 is a rise from 1.6 in the 2022 handbook that most trade content has missed. Two provisions matter for period windows: clause 6.2.11 says that where the work relates only to one or two replacement windows, “the frame may be disregarded for assessment purposes, provided that the centre pane U-value for each glazed unit is 1.2 W/m²K or less” — a centre-pane figure, not a whole-window one — and clause 6.2.7 requires “a flexible approach to improvement” for historic, listed or traditional buildings, while adding that “the ‘do nothing’ approach should not be considered initially”.

Wales

Wales still uses the Town and Country Planning Act 1990 and, for permitted development, the 1995 order: S.I. 1995/418 was revoked for England only in 2015, and Wales’s householder Part 1 was substituted in 2013. Its heritage statute was replaced. From 4 November 2024 the framework is the Historic Environment (Wales) Act 2023, and section 74(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 is recorded as omitted for Wales from that date. Welsh Ministers were explicit that this was consolidation — the Act “makes no changes to the operation of the current management and protection regimes” — but the citations changed, and anything quoting “s.74 of the 1990 Act” for Wales is out of date. The conservation-area duty is now section 160(1), “must have special regard to the desirability of preserving or enhancing the character or appearance of that area”, where section 72(1) says “special attention”.

HE(W)A 2023 s.160, s.161, s.162, in force 4 November 2024 by S.I. 2024/860 art.3(c)

Windows are permitted development — but read condition A.3(a)

Class A permits “The enlargement, improvement or other alteration of a dwellinghouse”. In a conservation area — “article 1(5) land” in the Welsh order’s indirect drafting — paragraph A.2 restricts cladding, external wall insulation, single-storey side extension limits and enlargements of more than one storey. It says nothing about windows. So replacing the windows of a Welsh house in a conservation area is permitted development unless an Article 4 direction, a condition or listed status intervenes.

The condition is where Wales diverges. A.3(a) requires that the appearance of the materials used “must so far as practicable match the appearance of the materials used in the majority of the equivalent element of the existing dwellinghouse”; England asks only for materials “of a similar appearance”. The risk is real: replacing some timber sashes with uPVC on a house whose other windows are timber may breach A.3(a), and a breach of condition means the work was never permitted development at all. We state that as a risk, not a certainty — we found no Welsh appeal decision or judgment on the point. Two further limits catch retrofit work: A.1(k) removes permitted development for external wall insulation projecting more than 16 centimetres, and A.1(l)(vii) for shutters on any part of the principal elevation.

GPDO 1995 Sch.2 Pt.1 A.1, A.2 and A.3, as substituted for Wales — legislation.gov.uk; “article 1(5) land” at article 1(5)

Consent, fees and building regulations in Wales

Conservation area consent survives under section 162 of the 2023 Act and is demolition only. TAN 24 ¶6.10 records that “the courts have ruled that demolition amounts to pulling down a building so that it is destroyed completely or at least to a very significant extent”; ¶6.11 disapplies it for, among other things, buildings not exceeding 115 cubic metres; ¶6.12 requires a heritage impact statement. Planning Policy Wales ¶6.1.17 is explicit that “partial demolition does not require conservation area consent” — the opposite of Northern Ireland, below. Prefer TAN 24 (25 March 2026) over PPW 12, last updated 19 July 2024, which still cites the 1990 Act.

Wales holds both the best and the worst fee position of the four nations. Conservation area consent is exempt from payment, and so is a planning application for works needing permission “only by virtue of an Article 4 direction or condition” — so a Welsh reader in an Article 4 area pays £0 where a Scottish reader pays £371. But the ordinary householder fee rose to £585 on 1 December 2025, the highest of the four nations by a wide margin. The period is eight weeks (art.22(2)(a), Development Management Procedure (Wales) Order 2012), and appeals go to Planning and Environment Decisions Wales.

One sentence in Wales’s Approved Document L is more generous than England’s: “Windows and doors refer to the whole units, i.e. including the frames. Consequently replacing just the glazing or door leaf while retaining an existing frame is not building work and so does not have to meet the energy efficiency requirements.”

AD L Wales Vol 1, para 10.24 (2022 edition) / 11.39 (2026 edition) — gov.wales. England says only that such work is not the provision of a controlled fitting, which is narrower — do not transplant the Welsh sentence into England

Welsh Table 10.1 uses three columns England does not: (a) 1.4 W/(m²·K) or WER Band B for new and replacement units, (b) an alternative maximum of 1.2 centre pane or low-e secondary glazing, and (c) a 3.3 threshold for retained windows. Wales also keeps the explicit “special considerations” heading for historic and traditional dwellings at paragraphs 0.10–0.11 that England has dropped, and its timber transitional cut-off was 23 November 2023, a different date from England’s June 2023. See building regulations for replacement windows.

Cadw is the Welsh Government’s historic environment service, not a separate statutory body — functions are exercised by the Welsh Ministers — and it is not a statutory consultee on ordinary conservation-area window work. How to Improve Energy Efficiency in Historic Buildings in Wales (April 2022) grades measures by risk: draughtproofing and refurbishing or replacing lost shutters green, adding secondary glazing or new shutters amber, and both replacing glass and replacing windows red. On listed buildings, Managing Change to Listed Buildings in Wales (May 2017) says “UPVC windows, for example, will not normally be acceptable”. Cadw has no windows-specific technical note comparable to Historic England’s or Northern Ireland’s, and we found no Cadw position on vacuum glazing beyond one sentence about cost and safety film.

Northern Ireland

Development is defined by section 23 of the Planning Act (Northern Ireland) 2011, with the same not-materially-affecting-appearance exclusion at s.23(3)(a); conservation areas are designated under section 104 and conservation area consent runs under section 105. Permitted development is the Planning (General Permitted Development) Order (Northern Ireland) 2015, and windows sit in Class A of Part 1, as in Wales and England. Paragraph A.2 covers cladding and extension geometry and says nothing about windows. Condition A.3(a) requires materials “of similar appearance”, and A.1(j) removes Class A entirely where the dwellinghouse is within the curtilage of a listed building unless listed building consent has already been granted. Part 1 has not been amended since 2015.

Conservation area consent catches partial demolition

Northern Ireland’s is the broadest conservation area consent in the UK. Section 105(2) is the familiar demolition control, but section 105(8) adds that demolition “includes a reference to any structural alteration of that building where the alteration consists of demolishing part of the building”. Taking a sash out of an existing opening is neither, so ordinary window replacement is not caught. But enlarging or blocking up an opening, or removing a bay, an oriel or masonry surrounds, is a live conservation area consent question in Northern Ireland where it would not be elsewhere in the UK. That is a reasoned reading of section 105(8): we found no Departmental guidance and no Northern Ireland case law applying it to windows. If your job involves structural work around an opening, ask the council first.

Article 4, townscape areas, fees and appeals

Northern Ireland has an Article 4 equivalent, literally called Article 4, with one structural difference: under article 4(2) a council direction “shall require the approval of the Department”, except where it relates only to a listed building or development within its curtilage. Councils cannot unilaterally strip conservation-area window permitted development, which makes Northern Irish rights more reliable in practice than English ones.

There is also a designation with no counterpart in Great Britain: the Area of Townscape Character, at paragraphs 6.21–6.23 of the Strategic Planning Policy Statement, Edition 2 (December 2025). Because the order’s restrictions are keyed to “conservation area”, permitted development is not curtailed in an ATC — but ATC policy still bites on any application that is needed. If you have been told “you’re in a townscape area”, you are not necessarily in a conservation area.

Applications go to the district council through the NI Planning Portal. The householder fee is £347 for each dwelling under category 4 of the Planning (Fees) Regulations (NI) 2015 as substituted with effect from 1 April 2025, reduced to £78 where the only reason permission is needed is an Article 4 direction or a condition. The period is eight weeks under article 20(2) of the General Development Procedure Order (NI) 2015, and the clock does not start until any validation direction has been complied with. Refusals go to the Planning Appeals Commission under section 58 of the 2011 Act.

Building regulations, and the Historic Environment Division

Northern Ireland has the least demanding replacement-window standard in the UK: Technical Booklet F1, June 2022 edition, Table 3.1 sets “WER Band C or better … or U-value = 1.6 W/m².K”, against 1.4 or Band B in England, Wales and now Scotland. Where appearance prevents that, ¶3.45 allows a centre pane U-value of not more than 1.2 W/m².K, or single glazing with low-e secondary glazing, and ¶3.43 confirms that “the replacement of a broken window pane is not the provision of a controlled fitting.” The statutory heritage disapplication is regulation 38(2)(a) of the Building Regulations (Northern Ireland) 2012, and it is conditional in the same way as England’s: the energy efficiency requirements do not apply to protected buildings “where compliance with the energy efficiency requirements would unacceptably alter their character or appearance”. “Protected building” is defined in the Building Regulations (Northern Ireland) Order 1979 and expressly includes buildings in conservation areas as well as listed buildings. Northern Ireland states the evidential burden more clearly than any other UK guidance: the case for exemption “must be supported by evidence e.g. by restrictions imposed by the relevant planning authority, advice from the Department for Communities Historic Environment Division, or advice from a qualified conservation specialist” (TBF1 ¶3.3).

Two departments are involved and neither decides your conservation area: planning policy sits with the Department for Infrastructure, heritage advice with the Historic Environment Division of the Department for Communities, and designation and determination with the district council. HED’s remit is listed buildings, scheduled monuments and industrial and defence heritage; it does not routinely comment on unlisted conservation-area window work. Its Guidance for Historic Windows (March 2024) is nevertheless the most quantitative heritage-body treatment of thin glazing in the UK, and the only one publishing a numerical threshold: “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.” It reproduces, from Historic Scotland Technical Paper 20, a vacuum unit at 0.9 W/m²K at 7.2 mm — a centre-of-glass figure, not a whole-window one — and warns that “traditional putty may cause some deterioration of the units’ edge seals”. See vacuum insulated glazing and slim-profile double glazing.

Which English rules do not apply outside England

What we could not verify

Saying so is part of the point of this site. As at 28 July 2026 we could not source the following:

• The enforcement immunity periods in Scotland and Northern Ireland. Do not assume England’s ten years or Wales’s four.
• Any decision on the meaning of “substantially the same” in Class 7A. There is also an apparent drafting slip at Class 7A(4)(e)(ii), which cross-refers to paragraph (3)(b) where it appears to mean (4)(b); Circular 1/2024 ¶7.17 reads the three-year period as running from receipt of the prior approval application, but no amending instrument or judicial consideration was found.
• Whether a partial uPVC replacement breaches Wales’s condition A.3(a).
• The boundary of “structural alteration … demolishing part of the building” under section 105(8) in Northern Ireland, applied to windows.
• Whether a building warrant is needed in Scotland for glazing-only work with the frame retained.
• Whether a fee is prescribed for conservation area consent in Northern Ireland. It does not appear in the fees regulations, which implies none — but with no affirmative statement we do not say it is free.
• Whether any competent-person scheme exists for window installers in Northern Ireland, and the name or code of the NI householder application form. The route is the NI Planning Portal; the form designation is not confirmed.

What this means in practice

1. Establish the nation first, then the designation. Conservation area, World Heritage Site, Area of Townscape Character in Northern Ireland and listed status are four different things with four different consequences.
2. Ask the council the right question. In Scotland: is this the principal elevation or a road-facing side elevation, and would the proposal fail any of the three Class 7A tests? In Wales and Northern Ireland: is there an Article 4 direction, and does the proposal satisfy A.3(a)?
3. Photograph and measure before you order. Frame and astragal dimensions, pane count and orientation, colours, opening mechanism. In Scotland those are the statutory tests; elsewhere they are the evidence for the materials condition. Glasgow’s checklist is the best template published anywhere in the UK.
4. Consider reglazing before replacement. Work that does not materially affect external appearance is not development under s.26(2)(a) in Scotland, s.55(2)(a) in Wales or s.23(3)(a) in Northern Ireland. A thin unit in an existing sash with unchanged astragal sections is the strongest case for needing nothing — see double glazing in a conservation area. If the unit forces thicker astragals you are back inside Scotland’s notification gate, and back into the materials-condition argument elsewhere.
5. Get it in writing where the money matters, and treat listed buildings as a separate problem — none of the above touches listed building consent in any nation. See windows in a listed building. Every figure and date here is traceable through the sources block below.