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Westminster, London

Retrospective planning applications in Westminster

Westminster contains 56 conservation areas and a World Heritage Site, so work built without permission is rarely a small matter here. The council can grant it afterwards, judged as if proposed. We survey the property, draw the as-built condition and prepare the application. Fixed quote after a free constraints check.

Fixed quote after a free constraints check

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  • LABC Partnered
  • Fixed fees, VAT included

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We use it to check conservation areas and constraints.
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    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on retrospective planning applications

    Seven steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Design options

      We model the house in Revit and show you options in 3D and plan, with the planning strategy and the precedents in your street.

    4. Design frozen

      You choose an option in writing. Nothing changes after this without your say.

    5. Independent check

      A second chartered technologist checks every sheet against the council's validation checklist and the policy. A senior review signs it off before anything is submitted.

    6. Submission

      We prepare the forms, certificates, fee and documents and submit through the Planning Portal.

    7. Officer liaison

      We answer the planning officer and make any amendments within five working days, at no charge until approval.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

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    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline

    The guidance Westminster applies to as-built work

    We found no Westminster rule written only for retrospective cases. Officers apply the City Plan 2019-2040 (2026) and two supplementary guides that matter for houses: Roofs: a guide to alterations and extensions on domestic buildings SPG and Mews: a guide to alterations SPG. The roof guide governs extra storeys, terraces and dormers, and the mews guide governs the doors, windows and rooflines of mews houses.

    Even a small change to a mews front, such as a new garage door pattern or a replaced entrance, is read against the mews guide. If your house is in a mews, we photograph the whole row so the officer sees your change in context.

    Roof alterations are where retrospective cases cluster in this borough, because a terrace or extra storey is easy to build and easy to see from the street. The roof guide sets the principle: rooflines in a terrace are judged as a group, not house by house. If your neighbours have not altered theirs, the council will weigh the harm to the group.

    We draw the roof as built, show it against the neighbouring roofs in a street elevation and cite the guide on the first page of the statement.

    Pencil resting on a dimensioned technical drawing beside a scale rule

    Local figures for Westminster

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Conservation areas56 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries4,015 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Tree preservation orders685 tree preservation orders published by the council—planning.data.gov.uk
    Households living in a house10.2 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Householder decisions366 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted82 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time79 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Lawful development certificate applications (PS1)138 certificates2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026)assets.publishing.service.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBP—ribblevalley.gov.uk

    A blank value means the figure has not been published, not that there are none. Check your own address with the council.

    Councils bordering Westminster
    Which application your project needsLawful Development Certificate decision: 8 weeks. Prior approval decision: 42 days. Householder decision: 8 weeksYour projectWithin permitted development?Lawful Development CertificatePrior approvalHouseholder applicationYesLarger rear extensionNoABC

    Which application your project needs

    The usual route for a house; flats and listed buildings follow other rules.

    A · Lawful Development Certificate decision
    8 weeks
    B · Prior approval decision
    42 days
    C · Householder decision
    8 weeks

    Trees, parks and the setting of heritage

    Westminster protects 685 tree preservation orders and holds 28 registered parks and gardens. Cutting down or damaging a protected or conservation-area tree without notice is a separate offence from building without planning permission. If your work involved tree removal, tell us.

    The borough has 4,015 listed building entries, 205 at Grade I, and the council has recorded 23 Heritage at Risk entries. A listed house altered without consent needs a separate listed building consent, not only planning permission.

    A roof terrace carries its own questions: privacy, noise, and the view from the street. We draw screens, balustrade heights and sight lines as built, and we describe the use of the terrace plainly so that an officer is not left to imagine it.

    How the council has treated householder cases

    The council decided 366 householder applications in its latest year, granting 82 per cent, with 79 per cent decided in time. Homes here are mostly flats, since only 10.2 per cent of households live in a house, so flats go through full applications. The wider total was 4,802 planning decisions, and 85.8 per cent of minor ones were granted.

    Westminster owners also ask us whether a high house price changes the fee. It does not. The householder fee is fixed nationally, and the council cannot charge more because the property is valuable.

    None of that predicts your outcome. A retrospective case is judged on its facts and on heritage impact, which weighs more in Westminster than in most boroughs.

    The council recorded 138 certificates of lawfulness in the government return, a reminder that older works may prove lawful without a planning application.

    Community Infrastructure Levy and permission after the fact

    A retrospective permission can bring Community Infrastructure Levy into play for new floorspace, and the Westminster charging schedule is Westminster CIL Charging Schedule, with a mayoral levy on top. Failing to assume liability or to notify the council before starting work can bring surcharges, so we flag the levy in the first conversation and suggest you take advice on how it applies to your case.

    We do not calculate levy ourselves, but we measure the new floor area accurately, since that area is what a calculation uses.

    Route, fee and delivery

    If the work is older than 10 years, a lawful development certificate in Westminster may be enough. Otherwise a retrospective application is decided within 8 weeks, with a householder fee of £548 where it applies.

    We provide the survey, as-built drawings, a heritage-aware statement and the submission, with a second MCIAT chartered architectural technologist checking the set. Our planning drawings in Westminster cover the remaining proposed work, and the Westminster hub lists every service we offer there.

    Send us the address, the dates of the work and any letter from the council. If the property is listed or in a mews, say so, and we will confirm the route and a fixed quote after a free constraints check.

    What you receive

    Planning drawing sheet for a rear extension with plans, elevations and sections
    Sample drawing. Planning drawings for a rear extension: plans, elevations and sections on one sheet set.
    Rows of brick terraced houses and gardens on a residential street
    The street around you
    Move across the plinth — the blocks rise around the pointer.

    Other services in Westminster

    Retrospective planning applications nearby

    Questions

    Is my Westminster mews house treated differently?

    Yes. The council has a dedicated guide to mews alterations, and doors, windows and roofs are judged against it. We draw the mews elevation as built.

    Can the council ask me to remove a roof terrace?

    If permission is refused and the use or structure remains, the council can take enforcement action within the time limit. You can appeal within 12 weeks of a refusal.

    Does listing change the process?

    It does. Listed buildings need listed building consent for most alterations, and altering without it can be a criminal offence. We check the listing first.

    Sources and dates

    City of London skyline glowing at dusk across the Thames under a dramatic orange sky

    Tell us about your property.

    We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.

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