Wrong windows already in? Enforcement, time limits and selling the house

This page covers England and Wales, which share the Town and Country Planning Act 1990. Scotland and Northern Ireland have their own enforcement statutes and we did not verify their time limits, so nothing below should be applied to them. If you are reading this because a letter has arrived, the first thing to establish is not the time limit but whether there was a breach at all — which is a question about what counts as development and, usually, about whether an Article 4 direction covered your windows. Most people who end up in breach do so because a direction had removed the permitted development right and nobody checked.

The time limit, exactly

The provision is section 171B of the Town and Country Planning Act 1990. As it now stands:

171B(1) Where there has been a breach of planning control consisting in the carrying out without planning permission of building, engineering, mining or other operations in, on, over or under land, no enforcement action may be taken after the end of the period of — (a) in the case of a breach of planning control in England, ten years beginning with the date on which the operations were substantially completed, and (b) in the case of a breach of planning control in Wales, four years beginning with the date on which the operations were substantially completed.

Town and Country Planning Act 1990, s.171B(1) — legislation.gov.uk, latest revised text

Three things about that text matter more than the headline.

It says nothing about conservation areas. The clock is set by the nation and by the date of substantial completion. Designation, an Article 4 direction, a conservation area appraisal naming your window type — none of them alters the period. This is worth stating plainly because the question is almost always asked as though conservation areas had their own rule.

The change was made by an amendment with a commencement date. The England ten-year period was substituted by section 115 of the Levelling-up and Regeneration Act 2023 and brought into force on 25 April 2024.

And there is a transitional saving that most secondary sources omit. Regulation 5 of the commencement regulations provides that the amendments “do not apply where … the operations were substantially completed … before the day on which that section comes into force”. So the old four-year period survives for everything finished before 25 April 2024, and where four years had already run by that date, immunity had already been acquired and was not retrospectively taken away.

Amendment annotation to s.171B: “substituted … (25.4.2024) by Levelling-up and Regeneration Act 2023 (c. 55), ss. 115(1), 255(3)(b); S.I. 2024/452, reg. 3(b) (with reg. 5)”; SI 2024/452 reg.5

A Planning Inspectorate inspector applied exactly that cut-off in a window enforcement appeal decided in March 2026, reciting the four-year period “where substantial completion took place before 25 April 2024”.

Appeal APP/A1530/C/25/3364430, Lexden Lodge Kindergarten, Colchester, decision 6 March 2026, DL23

The condition point, and why we are not pretending it is settled

If your windows were installed under the Class A permitted development right but fail its condition A.3(a) — materials “of a similar appearance” to the existing house — then the work was never permitted development. The awkward question is which limb of section 171B catches that. On one reading it is still the carrying out of operations without permission, so section 171B(1). On another it is “any other breach of planning control” under section 171B(3), which has been ten years in both England and Wales throughout and was untouched by the 2024 change. We could not verify which characterisation is correct against any authority, and we are not going to guess: if your case turns on the difference between four and ten years for a condition breach, that is a question for a planning solicitor, not for a website.

Relevant demolition is not your windows

Section 171B(2A) removes any time limit for enforcement in respect of “relevant demolition” — the demolition of an unlisted building in a conservation area in England, which since 1 October 2013 requires planning permission, and carrying it out without that permission is a criminal offence under section 196D. That sounds alarming until you notice it bites on demolition of a building. The House of Lords held that “the reference to the demolition of a building in a conservation area must be taken to mean the removal of the whole building”; stripping out and replacing windows is alteration, not demolition.

Shimizu (UK) Ltd v Westminster City Council [1997] UKHL 3, Lord Hope. Decided on the pre-2013 wording of ss.27 and 74 P(LBCA)A 1990; we found no post-2013 authority applying it to s.196D, which uses the same phrase.

Two enforcement regimes, and only one of them times out

Keeping these apart is the single most useful thing you can do. They run on different Acts, they use different notices, and they end differently. See also conservation area consent for windows, because the consent people expect to be in breach of does not exist in England.

A breach of planning control is a civil matter. Section 171A(1) defines it as carrying out development without the required permission, or failing to comply with a condition. Nothing in that is criminal. Section 171A(2) also lists what counts as taking enforcement action: an enforcement notice under s.172, a breach of condition notice under s.187A, and — in England since 25 April 2024 — an enforcement warning notice under s.172ZA, a further form of notice introduced by the Levelling-up and Regeneration Act 2023.

Town and Country Planning Act 1990, s.171A; s.172ZA inserted by Levelling-up and Regeneration Act 2023 s.117(2)(a), commenced by SI 2024/452

Criminal liability enters only if a notice is ignored. Section 179 makes the owner guilty of an offence where, after the compliance period ends, a required step has not been taken. The penalty is a fine, on summary conviction or on indictment, and the court must have regard to any financial benefit that accrued from the offence. There are two defences worth knowing: that the owner “did everything he could be expected to do to secure compliance with the notice”; and, where he was never served with a copy and the notice is not in the register kept under section 188, that he was unaware of it.

Town and Country Planning Act 1990, s.179(1), (2), (3), (7), (8), (9) — legislation.gov.uk, latest revised text

Enforcement is discretionary, not automatic. Section 172(1) allows a notice where it appears to the authority that there has been a breach “and that it is expedient to issue the notice, having regard to the provisions of the development plan and to any other material considerations”. In practice authorities act on complaints, which produces the inconsistency everyone notices; an inspector recorded exactly that in the decision letter later challenged in the leading uPVC case, observing that the council “evidently tends to take enforcement action only in reaction to complaints, which is bound to cause inconsistency”.

Town and Country Planning Act 1990, s.172(1); inspector’s decision letter as quoted in LB Haringey v SSHCLG & Muir [2019] EWHC 3000 (Admin). That decision was quashed — the inspector had wrongly treated the prevalence of uPVC nearby as relevant to s.55 — so treat the observation as a description of practice, not as law.

For a listed building, none of the reassurance applies. Section 7 prohibits works of alteration affecting the building’s character as a building of special architectural or historic interest unless authorised, section 9 makes contravention an offence, and section 9 contains no time limit on its face. Conviction carries up to six months’ imprisonment or a fine or both summarily, and up to two years or a fine or both on indictment, and the court must have regard to any financial benefit that accrued from the offence. There is a defence, but a narrow one: the works must have been urgently necessary in the interests of safety or health or to preserve the building, no lesser measure would have sufficed, they were the minimum immediately necessary, and written notice justifying them was given to the authority as soon as reasonably practicable. See windows in a listed building.

Planning (Listed Buildings and Conservation Areas) Act 1990, s.7 and s.9. We verified that s.9 states no time limit; we did not verify prosecution practice or summary limitation rules, so we do not state a prosecution deadline either way.

What an enforcement notice actually requires

The common assumption is that the worst case is a retrospective application and a fee. It is not. Notices upheld on appeal in the last two years have required, in terms:

• Colchester — “Permanently remove the UPVC windows and doors from all elevations” and “Install replica painted timber windows and doors to match those removed.” The inspector deleted a subjective “clean and tidy” requirement and extended the compliance period from six to twelve months, then upheld the notice.
• Southend-on-Sea — remove unauthorised uPVC windows from the east and north elevations at first and second floor, remove the uPVC fascia, and remove the resulting materials from site. The notice as issued gave six months; ground (g) succeeded in part and the inspector varied it to nine months for the windows and six for the fascia, then corrected and upheld it.
• Bradford, a listed converted barn — remove unauthorised patio doors; reinstate the previously existing wall in reclaimed stone matching the existing profile and coursing, pointed 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.” Four months. Upheld.

Appeals APP/A1530/C/25/3364430 (6 March 2026), APP/D1590/C/24/3357092 and /3357147 (21 November 2025), APP/W4705/F/25/3362503 (31 October 2025)

The appeal, and the two grounds that decide window cases

An enforcement notice can be appealed to the Secretary of State under section 174, on the grounds in section 174(2). Summarised, they are: (a) permission ought to be granted; (b) the matters alleged have not occurred; (c) the matters do not constitute a breach of planning control; (d) at the date the notice was issued no enforcement action could be taken; (e) copies were not served as required by section 172; (f) the required steps exceed what is necessary; and (g) the compliance period is too short. Ground (a) is not unconditionally available — section 174 itself restricts when it can be used in England — so read the section before assuming it is open to you.

Town and Country Planning Act 1990, s.174

For windows, the two that carry the argument are (c) and (d).

Ground (c) is the “it was never development” argument — the point this site keeps returning to. It can work, but the Colchester decision shows how it is actually tested. The inspector held that “For works to ‘materially affect’ external appearance, the changes must be visible from a number of vantage points and material to the appearance of the building as a whole”, and concluded that “as a matter of fact and degree, I find that the works materially affect the external appearance of the building and are therefore development for the purposes of the Act.” Two arguments were expressly rejected: that the same openings had been reused and the apertures not altered — “the windows and doors clearly form part of the building” — and that the work had been done by a glazing installer rather than a builder, since “section 55(1A) does not mean that development can only constitute works which are carried out by a builder.”

Appeal APP/A1530/C/25/3364430, DL12, DL15, DL16, DL17, DL21

That is the honest calibration for anyone hoping to argue that a like-for-like replacement was not development: the argument is real, and it is harder than the trade suggests. Where it is strongest is reglazing — new units in the existing sashes with nothing visible changed — which is a different factual case from a full frame replacement. See double glazing in a conservation area.

Ground (d) is the time-limit argument, and it is where the 25 April 2024 cut-off is fought.

Winning on a technicality is a delay, not a reprieve

Window enforcement notices are frequently defective, and a defective notice can be a nullity — void, not merely capable of correction. At 16 The Leas, Westcliff-on-Sea, the notice required removal of the uPVC windows but “falls short of telling the appellant what he must then do to replacement windows … As a result, the appellant cannot tell with reasonable clarity what steps must be undertaken.” Applying Miller-Mead and Clive Payne, the inspector held that “where a notice fails to comply with the provisions of section 173, there is no power to vary its terms because the notice is a nullity.”

Two things followed, and they are the reason not to celebrate. The council remained free to re-serve; and the owner lost the substantive section 78 appeal about the same windows on the same day.

Appeals APP/D1590/C/23/3322477 and APP/D1590/W/23/3320541, 4 November 2024, DL1 and DL3

There is also a statutory second bite. Section 171B(4)(b) allows further enforcement action within four years of earlier action taken or purported to be taken in respect of the same breach. In the Colchester case six years had passed since substantial completion, but an earlier 2022 notice — itself held to be a nullity — had stopped the clock: “the fact that the 2022 notice was found to be a nullity does not mean that the second bite provisions do not apply.”

s.171B(4)(b); appeal APP/A1530/C/25/3364430 DL27, applying R (Lambrou) v SSCLG [2013] EWHC 325 (Admin). We verified Lambrou only as applied and quoted in that decision letter; we did not read the judgment.

Retrospective permission, or a certificate — which one you want

These are different instruments answering different questions, and people ask for the wrong one.

The section 191 route is the one that produces a document rather than an argument: a determination the authority is bound by, not a planning judgement. Note the words inside the brackets in section 191(2): the certificate covers lawfulness because the works did not involve development as well as lawfulness by lapse of time. That is precisely how the “it was only reglazing” argument gets onto the record instead of remaining a hope.

Town and Country Planning Act 1990, s.73A, s.191(2), s.192(4)

A retrospective application does not, as a matter of law, waive anything or reset any clock. It also tells the authority exactly what has happened, which is a consideration in its own right.

Building regulations: a third, separate problem

A missing FENSA certificate is a different failure from a planning breach, and it is a separate question again on a sale. Three points, all from the regulations themselves.

What the certificate proves is narrow. Regulation 20(2) authorises the building control authority to accept a competent person’s certificate “as evidence that the requirements of regulations 4 and 7 have been satisfied” — the Building Regulations and materials and workmanship, nothing else. Regulation 20(5) makes it “evidence (but not conclusive evidence)”.

It is not required. The scheme route is an exemption from having to notify, under regulation 12(6)(a). The lawful alternatives are a building notice or full plans application before the work, or, after the event, a regularisation certificate under regulation 18, which the owner may apply for where unauthorised building work was carried out on or after 11 November 1985. Regulation 18(3) lets the authority require the work to be laid open for inspection — which is why regularisation is disruptive and not merely a fee.

It says nothing about planning. Regulations 4 and 7 do not mention the Town and Country Planning Act 1990 or the listed buildings Act. A FENSA or CERTASS certificate has never been evidence that planning permission or listed building consent was obtained or unnecessary. Note too that Schedule 3 items 10 and 11 cover “installation, as a replacement, of a window” — so reglazing is outside the competent person schemes altogether, and there is no certificate to be missing.

Building Regulations 2010, reg.20(2), (5), reg.12(6)(a), reg.18, Sch.3 items 10–11. Full detail in building regulations for replacement windows.

Selling the house: what is verifiable, and what is merely repeated

This is the part of the subject with the most confident advice and the least sourcing, so we have separated the two.

Verifiable. An enforcement notice is a local land charge and so shows on a local land charges search; HM Land Registry’s Practice Guide 79 lists planning and enforcement notices, conservation areas, listed buildings and tree preservation orders among the common types. Enforcement notices must also be entered on the register kept under section 188 of the 1990 Act — a duty real enough that an inspector who found a notice to be a nullity told the council it “should consider reviewing” that register. Searching costs nothing on the GOV.UK service, £15 for an official certificate, and the service warns that “Not all data is on this service yet”, so in many areas the search must still be made with the local authority. PG79 adds two points a buyer needs: an unregistered charge “will still affect a purchaser in just the same way as it affected the original owner”, but a purchaser who searched first is generally entitled to compensation for loss caused by a search that failed to reveal an existing charge.

HM Land Registry Practice Guide 79; GOV.UK: Search for local land charges; TCPA 1990 s.188; appeal APP/D1590/C/23/3322477, decision para 1

Also verifiable, and the point most often missed. For a listed building an unauthorised window is a criminal matter with no immunity period, which is materially worse at sale than the same window on an unlisted house in a conservation area, where immunity under section 171B eventually arrives. “We have had them twelve years, we are fine” is a defensible position on an unlisted house and no position at all on a listed one.

Not verified — and we are saying so rather than filling the gap. We could not obtain the current official CON29 form, so we do not publish CON29 question numbers. The CON29 Enquiries of Local Authority is the Law Society’s standard set of enquiries used alongside the local land charges search, and it covers conservation area status and enforcement matters including matters not yet registered; but if you need to know which numbered enquiry captures what, get the current form from the Law Society or Land Data rather than from any website, including this one.

We also could not find a primary source for any of the following, all of which are widely asserted: the availability, scope, cost or insurer appetite for planning indemnity or lack-of-consent insurance for unauthorised windows; the common claim that such a policy becomes unavailable once the local planning authority has been contacted; and the conveyancing consequences of having made a retrospective application. Treat all of that as your solicitor’s or broker’s territory, and treat confident numbers about it as unsourced.

If you have just had a letter

1. Establish what the letter is. An informal enquiry from a planning enforcement officer, an enforcement warning notice (s.172ZA in England, s.173ZA in Wales), a breach of condition notice under s.187A and a formal enforcement notice under s.172 have completely different consequences and deadlines. Only the last carries the 28-day machinery in s.172(3) and the appeal route in s.174.
2. Diary the appeal deadline immediately. An enforcement notice specifies the date it takes effect, and the right of appeal is lost if it is not exercised in time. Nothing else you do matters as much as this.
3. Fix the date of substantial completion, with evidence: invoices, the installer’s paperwork, dated photographs, card statements. Whether you are before or after 25 April 2024 in England is worth six years.
4. Establish whether it is listed, and whether an Article 4 direction applied to your elevation. Ask for the direction itself, not a summary of it — see Article 4 directions and your windows.
5. Assemble the “it was not development” evidence, if it exists. Photographs of the previous windows, the joinery drawings, the specification, and anything showing that sightlines, glazing pattern, opening arrangement and external profile were unchanged. In the decided cases, the absence of that material is what loses appeals.
6. Decide between a certificate and an application, using the table above, before you write to the authority. They are not interchangeable and the choice frames everything afterwards.
7. Take advice if the building is listed. This is the one place on this site where we would say that plainly. The exposure is criminal, has no time limit, and the remedy can include rebuilding.

Terms of art are defined in the glossary; every source relied on is listed below and on the sources page. The legal content of this page was checked against primary sources on 28 July 2026. We do not sell windows and there is nothing to buy here.