Applying for windows: drawings, fees and what officers actually look at

This page is about mechanics: what to submit, what it costs, how long it takes, what the officer looks at. It assumes you have established that you need to apply at all — a separate question, often answered the other way: see do you need planning permission to replace windows in a conservation area? and, for the whole subject, the complete guide to conservation area windows. If the building is listed, read windows in a listed building too.

First, be sure you need to apply

Section 55(2)(a) of the Town and Country Planning Act 1990 takes out of the definition of development any works of maintenance, improvement or alteration affecting only the interior or which “do not materially affect the external appearance of the building”. A new sealed unit in an existing sash, nothing visible changed, is the clearest case — Islington: “Improving existing windows (including repair, draft proofing, secondary glazing and replacing glass) does not require planning permission”. An Article 4 direction cannot alter that: a direction withdraws the permission granted by the Order, and cannot turn non-development into development.

TCPA 1990 s.55(2)(a); Islington 2025 window guide §7.2; Brighton & Hove PAN09 to the same effect for slim units in existing frames

Whether it is “like for like” is not your call, though. City of York says it plainly: most unlisted houses have permitted development rights to replace windows “if considered by the planning authority (not the owner) to be a like-for-like replacement”, and checking what that means in detail “is recommended as it is subject to interpretation”.

Which application, and what it costs

Wales charges £585 for one dwellinghouse from 1 December 2025 — the highest of the four nations — but the same fee document records “Exemption from payment” both for listed building and conservation area consents and where the proposal “relates to ‘permitted development’ works that require planning permission only by virtue of an Article 4 direction or condition”. Northern Ireland charges £347 per dwelling from 1 April 2025, cut to £78 on that same basis. Scotland charges £371 from 1 April 2026 with no Article 4 relief at all — so a Welsh homeowner in an Article 4 area pays nothing where a Scot in the identical position pays full price.

Welsh fee document, 1 December 2025 — gov.wales (PDF); Planning (Fees) Regulations (NI) 2015 as substituted by S.R. 2025/49, Article 4 reduction at reg.7; Scottish Circular 1/2026 ¶B.39

For England we publish no single figure, because it is prescribed by regulations uprated annually and council pages go stale. The one authority in our survey that states it on its windows page is Lewisham: £548 for a flat or an Article 4 house, £1,083 for more than one dwelling. Read that wording carefully, because it merges two different things. England, like Wales, exempts an application needed only because permitted development rights were withdrawn by an Article 4 direction or a condition — but a flat never had those rights to withdraw, so a flat owner has nothing to be exempted from. Ask the authority in writing which category and which exemption applies before you pay; we did not verify the English fee regulations at source.

Timing. Wales and Northern Ireland both set eight weeks for a non-major application on the face of their procedure instruments; Scotland sets two months for a planning application and 28 days for the first stage of the prior-approval route, plus two months more if prior approval proves to be required. England’s equivalent Order sets the same eight weeks — we verified the Welsh and Northern Irish articles at source and not the English one, so treat eight weeks as the authority’s published target. The Northern Irish Order adds a point worth carrying everywhere: since 1 April 2025 the clock does not start until any direction specifying “validation particulars or verifying evidence” has been complied with. Validation, not submission, starts the period.

DMP (Wales) Order 2012 art.22(2)(a); GDPO (NI) 2015 art.20(2)–(3)(d); DMP (Scotland) Regs 2013 reg.26(2)

The drawing standard, and why there is no such thing as “the” standard

Torbay is the most explicit about both reason and sanction: details “must be drawn to specified scales so that the planning officer can ascertain the width of visible framework”, and “If the frame width is not shown or if the plan is not drawn to an identified scale then we cannot validate your application.” It also names the failure mode in one line — “a frame cannot be presented as a single line”.

Torbay Council, Details for windows in Conservation Areas or Listed Buildings, January 2015 — torbay.gov.uk (PDF). Dated 2015; check it is still current.

What the drawings have to show:

1. A window schedule — each side of the building, each window in situ, individually numbered (Torbay). Gravesham’s appendix is a lettered fill-in template reading “Window B to be replaced, included in application” / “Window A not to be replaced”.
2. Existing and proposed together. Islington wants whole-building elevations “1:50 or larger with a scale bar and unique drawing number clearly shown”, windows to be removed “clearly marked in red on the existing drawings”.
3. Dimensioned sightlines. Torbay: “Exact measurements — including width of the glazing bars, and the total width of mullions and transoms … the inner and outer frame width.” This is the number the officer turns into a judgement, and Historic England’s published comparison shows why it moves: a Georgian glazing bar of 12 mm face width grows to about 18 mm to conceal the edge seal of a 12 mm unit, 24 mm for a 10 mm unit, 26 mm or more for a 6.5 mm vacuum unit with a 10 mm edge seal.
4. The glazing bar in section, integral not applied. Gravesham: “Windows must use solid (through) glazing bars … Glazing bars applied to the surface of a sealed glazing unit will not be acceptable.”
5. The meeting rail. Gravesham publishes the only numeric limit we found anywhere: it “should not exceed 34mm when closed or where an original window survives it should match that window”.
6. Horns, with a reason — and the two published tests contradict each other. Warwick uses a date: “most sash windows before 1870 did not have horns and these should not be included in replacement windows where … they did not previously exist.” Gravesham uses style: avoid horns “where they have not been used historically, for example they would not have been used on a Georgian house with multi-pane windows”. Blackpool wants them “run-through … (as opposed to ‘planted on’)”.
7. Putty or bead, and the spacer. Islington: units “should always be putty mounted in integral glazing bars and the spacer bar inside the double glazed unit should match the colour of the window frame”. Note the trap both statutory advisers flag — ordinary linseed-oil putty damages insulating unit seals, so a unit needs a manufacturer-approved non-setting compound faced to a putty profile. Linseed putty remains correct for single glazing.
8. Cill, reveal and set-back. Camden lists “the depth at which the window is located in the reveal” as a feature that must match; Kensington & Chelsea’s listed building consent order prohibits alteration or removal of “cills, sub cills, jambs, aprons, casings, shutters or shutter boxes”.
9. Photographs to the authority’s rules. Lewisham takes them in place of existing elevations, but “each window to be replaced must be individually identified by a number or letter on the photograph”, and “photographs where elevations are obscured e.g. by trees will not be acceptable”.
10. Location and block plan — the layer nobody thinks about until validation fails.

Lewisham says the quiet part out loud: “The contractor who is making your windows should be able to supply these drawings.” A supplier who cannot produce a dimensioned section has told you something useful. The specification behind the drawings is in timber windows for conservation areas.

If only the glass is changing, the package is different. Islington asks not for scaled joinery sections but for “Product and manufacturer details for the proposed new glazing product”, plus sections showing how the unit or secondary glazing sits in the existing surround and “Details of how this would be fitted in the existing frame (e.g. putty mounted in existing glazing bars)”. Keeping reglazing and replacement apart changes the paperwork as well as the law.

Heritage statements and condition surveys

In England, NPPF paragraph 207 requires an applicant to describe the significance of the heritage assets affected, including any contribution made by setting, at a level of detail “proportionate to the assets’ importance”; paragraph 208 then requires the authority to assess that significance itself. Many authorities make the statement a validation requirement, and Lewisham publishes a heritage statement guide alongside its windows checklist. A competent one for windows is short and specific: the date and type of building, what survives of the original joinery and glass, what the proposal removes and retains, why repair was rejected, and an explicit statement of the harm and of the public benefits said to outweigh it. Vagueness is not neutral — it invites the officer to fill the gap with the conservation area appraisal.

NPPF (December 2024, as amended 7 February 2025) paras 207–208 — gov.uk. England only: Wales uses Planning Policy Wales and TAN 24, Scotland NPF4, Northern Ireland the SPPS.

If you are replacing historic joinery rather than repairing it, the condition survey decides the application. Gravesham requires “a survey report from an architect, surveyor or specialist timber joinery workshop setting out the extent of decay and justification for replacement rather than repair”, and wants it per window, “discussing the options for repair or why such repairs cannot be carried out”. Islington makes it a validation requirement and rules out the easy arguments: “Defects to glass, putty, paintwork and hardware/opening mechanisms can be addressed with routine repairs and renewal and do not necessitate replacement.” Blackpool publishes the only numeric benchmark we found — beyond economical repair at “more than 3/5 rotten” — which is one authority’s yardstick, not a national test. York warns of over-diagnosis: “Often windows look in worse condition than they actually are.”

Pre-application advice is worth it for design and worthless for certainty. Gravesham advises taking it even where no permission is needed — “In the case of replacing like-for-like, where planning permission is not required, we strongly advise you to apply for Pre-application advice to prevent possible enforcement action at a later date” — and the Planning Portal gives the general version: “you are strongly advised to check with your local planning authority before carrying out any work.” What you buy is an officer’s view on sightlines, materials and detailing before you order joinery. What you do not buy is a decision; for that, see the s.192 certificate above. We found no published data on how often pre-application advice on windows converts into approval, and we will not guess at one.

How officers actually assess it

The duty. Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 requires that, in exercising planning functions in a conservation area, “special attention shall be paid to the desirability of preserving or enhancing the character or appearance of that area”. Read it precisely: attention, not an obligation to achieve enhancement; “preserving or enhancing”, “character or appearance”, both disjunctive. It is routinely misquoted as a duty to preserve and enhance. For a listed building the parallel duties are s.66(1) for planning permission and s.16(2) for listed building consent, each requiring “special regard” to the desirability of preserving the building or its features of special interest.

s.72(1), s.66(1), s.16(2), P(LBCA)A 1990 — England. Each nation has its own wording: in Wales the conservation area duty is restated as “special regard” by s.160(1) of the Historic Environment (Wales) Act 2023; in Scotland it is s.64(1) of the P(LBCA)(Scotland) Act 1997; in Northern Ireland s.104(11) of the Planning Act (NI) 2011.

The weight it carries. Not an ordinary material consideration to be balanced freely: in Barnwell Manor the Court of Appeal endorsed the formulation that a decision-maker must give “considerable importance and weight” to the desirability of preservation, and recorded at [65] as common ground that despite the “slight difference in wording” between s.66 and s.72(1) “the nature of the duty is the same under both enactments”.

Then policy. NPPF paragraph 212 requires “great weight” to a designated asset’s conservation “irrespective of whether any potential harm amounts to substantial harm, total loss or less than substantial harm” — and a conservation area is itself a designated asset. Paragraph 215 is where most window cases land: less than substantial harm weighed against public benefits. Paragraph 216 sets a lower bar, “a balanced judgement”, where the building is an unlisted non-designated asset. Alongside sit the local plan, any windows SPD, and the conservation area appraisal — if the appraisal names your window type as characteristic, expect it quoted back at you.

What a refusal looks like

Refusal reasons here are formulaic, which means they can be pre-empted: loss of original joinery and its detailing; materially different material, opening method, frame thickness or glazing pattern; the statutory formula; conflict with named local plan policies and any SPD; then the NPPF balance.

27 Cobham Street, Gravesend, dismissed 13 October 2025, tracks the drawing list above almost item by item. On sightlines: “The UPVC frames are markedly thicker which contrasts negatively with the properties which have retained the traditional timber framed sliding sash windows. Also, the windows have a lack of architectural detailing compared to the original windows typical to the area.” Then the formula — “fails to preserve or enhance the character or appearance of the Conservation Area and causes harm to its significance” — with harm at “the lower end of less than substantial” but still given “great weight in line with paragraph 212 of the Framework”. The energy case was answered rather than ignored: “all these attributes can be incorporated into well designed windows that would safeguard the characteristic style of fenestration”.

APP/K2230/W/25/3366705, 27 Cobham Street, Gravesend, 13 October 2025 — decision letter

And the argument that never works, at 16 The Leas, Westcliff-on-Sea: “Unsympathetic and harmful alterations do not justify further works which may be harmful to the character and appearance of the area” — the inspector’s task is the effect on the host property and the wider area “rather than comparing them with other unsympathetic development that has occurred locally, which may, in fact, be unauthorised”.

Settle the trickle vents before you submit

This is the commonest late collision between the planning file and the building control file, and it is avoidable. Gravesham: “Visible trickle vents are not acceptable on un-listed historic buildings. Trickle vents are not acceptable on listed buildings.” Islington: “Visible trickle vents and rubber seals should be avoided.” Brighton & Hove: “Where trickle vents are required these must be concealed.”

Installers routinely say the Regulations compel them. Blackpool publishes the actual test: “Building Regulations only require a trickle vent in a new replacement window if there was trickle ventilation within the window being replaced.” The statutory basis is regulation 4(3) of the Building Regulations 2010, requiring the building after the work to comply or, where it did not comply before, to be “no more unsatisfactory in relation to that requirement than before the work was carried out” — with regulations 4(4)–(5), inserted for England from 15 June 2022, tying the Part F duty to work engaging Part L. Gravesham notes the alternative: “in many cases this type of ventilation is not needed as ventilation can be achieved by a ventilation latch on the window itself.” Get it answered in writing by joiner and authority before submission; the wider regime is in building regulations for replacement windows.

Building Regulations 2010 reg.4(3)–(5); 4(4)–(5) inserted for England by S.I. 2021/1391 reg.4, in force 15 June 2022

If it is refused

Appeals go to the Planning Inspectorate in England, Planning and Environment Decisions Wales, and the Planning Appeals Commission in Northern Ireland. Scotland splits the route: a refused Class 7A prior approval goes to the Scottish Ministers through the DPEA, a refused householder planning permission to the council’s own Local Review Body under s.43A(8) of the 1997 Act — two destinations for the same window. The deadline for lodging is on your decision notice; work from that, because we did not verify the statutory appeal periods at source.

What an appeal needs is evidence, and the cautionary tale is Guinness — the case often called the double-glazing “test case”, which was in fact dismissed, concerned timber replacements for Crittall windows, and failed on evidence rather than principle. The inspector could not assess subdivision, casement proportions or sub-frame position “In the absence of scaled measured drawings”, because the claimants “chose to present photomontages, and not scaled drawings”. Measured drawings, not photomontages.

Guinness v SSCLG [2014] EWHC 4114 (Admin) at [17], [34], [47] — Find Case Law

Go in with a realistic view of the odds. The Planning Inspectorate’s published data on uPVC window appeals for listed buildings received between January 2014 and January 2024 records 69 appeals, of which 48 of the 56 determined on the merits were dismissed — about 86% — and the few allowed turn overwhelmingly on the windows being replaced already being modern and of low evidential value. For unlisted buildings in conservation areas we found three dismissals and could verify no allowed decision at all, which is not the same as saying none exists.

The practical checklist

1. Establish whether it is development at all. If nothing visible changes, consider a s.192 certificate rather than an application.
2. Ask for the validation list and any windows SPD before anything is drawn.
3. Ask specifically about Article 4 — whether one covers your address, which classes it withdraws, and whether it reaches all elevations or only the principal one.
4. Photograph everything first, with a rule in shot. Historic England’s repair advice works for applications too: record windows “at least with photographs and some basic measurements” before anything is removed, and record “Any historic glass and its characteristics”.
5. Number every window, consistently across photographs, schedule, elevations and covering letter.
6. Commission a measured section of the existing window, on site, at your authority’s scale, with part of the surrounding wall where asked for.
7. Dimension every visible face width: frame, mullions, transoms, glazing bars, meeting rail. No single lines.
8. Get a per-window condition survey addressing repair options and why they were rejected.
9. Resolve trickle vents, spacer colour, putty-or-bead and horns before submission, not by amendment.
10. Check the fee on the day and ask whether an exemption applies. Never trust a figure printed on a page of uncertain date — including this one.

Where the authorities disagree

Report the contradictions rather than inventing a national rule. Scale of a joinery section: irreconcilable — 1:1 Torbay, 1:2 West Suffolk’s draft, 1:5 Lewisham and Islington. Draw to the strictest scale named; 1:1 satisfies everyone. Slim unit thickness: published figures run from Camden’s “up to 9mm depth” to Kensington & Chelsea’s “no greater than 20mm” — and note they are doing different jobs, Camden’s in conservation area guidance, Kensington & Chelsea’s as a condition in a listed building consent order. Get the figure in writing before ordering glass. Units in original frames at all: Brighton & Hove, Gravesham and Islington are supportive, Warwick says flatly that “double glazed units shouldn’t be inserted into original frames”. Horns: Warwick’s date test and Gravesham’s style test can give opposite answers on the same house, so justify from the building. And Gravesham’s own SPD says both that slim units in existing frames need no permission and that like-for-like means matching “including glazing type” — which single-to-double glazing is not. A contradiction inside one adopted document is precisely why the section 192 certificate exists.

If the building is in Scotland, Wales or Northern Ireland the process differs before any of this applies, including a prior-notification step found nowhere else in the UK: see Scotland, Wales and Northern Ireland. For what the exercise costs, see what it costs; if the windows are already in, enforcement, time limits and selling the house. Sources are listed below and on our sources page; terms of art are in the glossary.