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Kensington and Chelsea, London

L-shaped dormer drawings in Kensington and Chelsea

L-shaped dormer drawings in Kensington and Chelsea are almost always a planning conversation. The borough has 39 conservation areas, 84 Article 4 directions and 1,350 listed entries, so we start by finding out what protects your street.

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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 l-shaped dormer drawings

    Nine 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.

    8. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    9. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

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

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    Slate-clad roof extension on a yellow-brick London terraced house

    A borough of designations before it is a borough of roofs

    In most places the first question about a dormer is how big it can be. Here the first question is whether the right exists at all. The council data gives 39 conservation areas, with 84 Article 4 directions sitting alongside them. Where either applies, the national rule is clear: Class B roof enlargements are not permitted development on article 2(3) land.

    Historic England adds 1,350 list entries and 16 registered parks and gardens, whose settings can touch a roof seen from across a square. The council also records 4,560 tree preservation orders, which matter when scaffolding must reach a rear roof over a mature garden.

    We map all of this against your address before design time is spent, using the council constraints map and the national heritage list side by side, and we send you the screenshots so you can see what we saw. The result is usually one of three answers: a householder application, a lawful development certificate for the few houses outside the protected areas, or advice that the L is not worth pursuing and a smaller roof change is.

    Converted loft bedroom with roof windows and a Juliet balcony

    Local figures for Kensington and Chelsea

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Conservation areas39 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions84 Article 4 directions published by the council—planning.data.gov.uk
    Listed building entries1,350 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Registered parks and gardens16 registered parks and gardens intersecting the LPA boundary (Historic England)—planning.data.gov.uk
    Tree preservation orders4,560 tree preservation orders published by the council—planning.data.gov.uk
    Householder decisions664 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted93.7 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time91.9 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Households living in a house17 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Owner-occupied households31.7 % of households owner-occupied (owned outright or with mortgage/loan)Census 2021nomisweb.co.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 Kensington and Chelsea
    Loft enlargement in section: the permitted development limitsExtra roof volume allowed: 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume. Set-back from the eaves: Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension). Height limit: No part higher than the highest part of the existing roofABC

    Loft enlargement in section: the permitted development limits

    A dormer on the rear slope, with the limits that decide whether it needs planning permission.

    A · Extra roof volume allowed
    40 m³ (terrace house) / 50 m³ (any other house) additional roof volume
    B · Set-back from the eaves
    Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension)
    C · Height limit
    No part higher than the highest part of the existing roof

    Terraces, tenure and what an L-shaped dormer has to prove

    Only 17% of households here live in a house, and 31.7% own their home. Where a house has a rear wing, it has the plan form an L-shaped dormer is built for. Where a house has been divided into flats, the roof belongs to the freeholder and permitted development does not apply to flats, so we ask about tenure first.

    On a protected terrace, an L-shaped dormer has to prove it is subordinate: it should look like a considered addition to the roof, not a second storey placed on top. We draw the L pulled back from the eaves, lower than the ridge and with a visible slope of the original roof around it, then show the view from the street and the view from neighbouring gardens.

    The council works from the Local Plan 2024 (New Local Plan Review), adopted in 2,024. Its one supplementary document in our data is the Basements SPD, which covers basements rather than roofs, so for a roof we read the plan's design policies directly and state which ones we rely on in the application.

    What the council figures tell us

    In the latest year the council decided 664 householder applications and granted 93.7%. That is a high grant rate, and it fits what we see when applicants bring careful drawings: the case is read on its merits.

    Speed is the weaker figure: 91.9% were decided inside eight weeks or an agreed extension. Allow time for questions from the conservation officer, and do not book a builder before the decision.

    Our planning drawings in Kensington and Chelsea page lists the sheets, including the design and access note that explains the roof against the street.

    The levy and the cost of floorspace

    Kensington and Chelsea charges its own borough levy, which we read from the council schedule for the address, and the Mayor of London adds 96.97 pounds per square metre for permissions granted this year. Both apply to new floorspace, and a roof conversion inside the existing building envelope may avoid them or may not, depending on how the council counts the added area.

    We tell you what the drawings add in area before you commit, because on a large addition the levy can be a significant cost. Where a smaller L avoids the charge, we show both options. We also note on the quote which year the levy figure applies to, since a delayed permission can fall under a different rate.

    Alternatives and related drawings

    If the L is too large for a protected terrace, dormer loft conversion drawings in Kensington and Chelsea cover a single rear dormer. The wider loft conversion drawings in Kensington and Chelsea page covers stairs and fire safety. For the whole borough see architectural drawings in Kensington and Chelsea, or compare L-shaped dormer drawings in Westminster next door.

    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.
    Brick cottage with a tiled roof, chimneys and a front dormer window
    Storey by storey
    Move up and down — the car travels between floors.

    Other services in Kensington and Chelsea

    L-shaped dormer drawings nearby

    Questions

    Is an L-shaped dormer permitted development in Kensington and Chelsea?

    Rarely. The borough has 39 conservation areas and 84 Article 4 directions, and a roof enlargement is not permitted development inside a conservation area.

    How many Kensington and Chelsea householder applications are granted?

    The council granted 93.7% of its householder decisions in the latest year. It is a borough figure, not a forecast for your roof.

    Can I add an L-shaped dormer to a flat in Kensington and Chelsea?

    Not normally without the freeholder's consent. Only 17% of households here live in a house, and permitted development rights apply to houses, not flats.

    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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