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Westminster, London

Daylight and sunlight report in Westminster

Westminster's validation checklist asks for a daylight and sunlight assessment when a proposal is likely to harm light to neighbouring sensitive uses, and it names the BRE guide as the method. In a borough where only 10.2% of households live in a house, those uses are usually flats. We read the checklist, test the nearest windows and tell you whether the assessment is needed before the application is built around it.

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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 daylight and sunlight reports

    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

    Westminster's checklist item on daylight and sunlight

    The Westminster validation checklist includes a daylight and sunlight assessment where the proposal is likely to harm light to adjoining sensitive land uses, following the BRE guide (BRE 2011 edition cited by the 2021 list). The list we have read cites an older edition of the BRE guide, so the first practical step is to ask the case officer which edition they will read the results against.

    Our reports state the edition and method used, and the model is kept so the tests can be re-run if the officer asks for a different one.

    Pencil resting on a dimensioned technical drawing beside a scale rule

    Local figures for Westminster

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Item L12: a Daylight and Sunlight Assessment is required if the proposal is likely to adversely affect light to adjoining sensitive land uses, following the BRE guide 'Site layout planning for daylight and sunlight: a guide to good practice' (Littlefair, September 2011).BRE 2011 edition cited by the 2021 list—westminster.gov.uk, Westminster Local Planning Applications Validation Requirements Check List (Full List; 2021 version, pre-2026 policy numbering), p.10, item L12
    Supplementary planning documentRoofs: a guide to alterations and extensions on domestic buildings SPG—westminster.gov.uk
    Supplementary planning documentMews: a guide to alterations SPG—westminster.gov.uk
    Listed building entries4,015 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Conservation areas56 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions10 Article 4 directions 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
    Owner-occupied households27.4 % of households owner-occupied (owned outright or with mortgage/loan)Census 2021nomisweb.co.uk
    Householder applications granted82 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Local planCity Plan 2019-2040 (2026)—westminster.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

    Roofs and mews: where Westminster extensions meet light

    Two of Westminster's own guidance documents shape most householder-scale work: Roofs: a guide to alterations and extensions on domestic buildings SPG and Mews: a guide to alterations SPG. A roof extension changes the sky seen from the rear windows of the next terrace; a mews alteration changes the shadow across a narrow service lane. Both are light questions before they are design questions.

    We measure the windows that face the new roof line or the new mews wall, and show the officer the effect on each.

    A borough of flats and neighbours at close range

    Owner-occupation is 27.4% in Westminster, and the house share is 10.2%. A rear or roof addition therefore faces flats in several directions. The council decided 366 householder applications in the year, granting 82% and deciding 79% in time.

    The recently adopted policy base is City Plan 2019-2040 (2026). It is the document the daylight argument rests on, along with the London Plan and the national policy framework.

    Heritage designations and light

    Westminster has 56 conservation areas, 4,015 listed entries, 1 World Heritage Site and 10 Article 4 directions. In most of those settings the design is tightly constrained, so a light report works hand in hand with the heritage argument rather than against it. See our architectural drawings in Westminster page for the constraints picture.

    Tree preservation orders also number 685, which matters when a garden-side addition is near a protected tree that affects the sunlight a window receives.

    Edition, method and the model we keep

    Because the checklist item cites an earlier edition of the BRE guide, we tell you how the two compare for your scheme. The neighbour-impact tests are broadly the same across editions, while the guidance on new rooms changed more. If the case officer asks for the older reading, the model is rerun and the changes in the results are shown in a short note. The quote names the edition we propose to use, so nobody is surprised later.

    We keep the model so it can be reused when the design shifts. Westminster applications often go through several revisions as heritage and design officers comment, and a model that updates in minutes saves a fresh report each time.

    Sunlight, gardens and the courtyard problem

    Many Westminster homes have only a small rear courtyard or a lightwell, and those spaces already receive little sun. A new wall or an extra storey can remove what remains. We run the sunlight test for the courtyard on the guide's chosen date and show before and after patterns, so the officer can see whether the change is a tweak or a loss.

    Where the test fails, the useful question is what could be done. A lower parapet, a set-back top floor or a lighter-coloured wall finish can each recover a little, and we show each option's result before you choose a design.

    Starting a Westminster job

    We combine the report with the drawings: our planning drawings in Westminster work uses the same model. Neighbouring pages for Camden and Kensington and Chelsea show how lists differ. Send the address and a sketch for a fixed quote if a report is worth having.

    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

    Daylight and sunlight reports nearby

    Questions

    Which BRE edition does Westminster expect?

    Its published checklist cites an older edition. We confirm with the case officer and state the edition we used.

    Do mews houses need a report?

    If a new wall or roof could affect light to neighbours' windows along the mews, the checklist item can apply. We test the facing windows first.

    Is there a World Heritage Site effect?

    The borough contains one. It affects design and views, and daylight is assessed separately.

    How are roof extensions tested?

    We model the new roof line and measure its effect on the windows of neighbouring rear elevations.

    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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