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Brent, London

L-shaped dormer drawings in Brent

Brent's guidance says L-shaped dormers are generally acceptable, within a stated limit: 0.2 m; 50% of outrigger depth. We draw L-shaped dormers for Brent houses for a fixed quote after a free constraints check, VAT included, and set every figure out on the elevation so the officer can check 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 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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    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline

    Brent rule for an L-shaped dormer

    The council's Residential Extensions and Alterations Supplementary Planning Document says L-shaped dormers are generally acceptable. They must be set up from the eaves on all sides and must not cover more than half the depth of the two-storey extension or outrigger, and the council's figures are 0.2 m; 50% of outrigger depth.

    "Generally acceptable" is a real opening for an applicant. The conditions are measurable, so we draw them as dimensions: the distance from the eaves on each side and the proportion of the outrigger covered, both on the roof plan and the section.

    The design guidance behind the rule is the Brent Design Guide Supplementary Planning Document (SPD1), and the Brent Local Plan 2019-2041 supplies the general tests.

    The half-depth limit has a practical effect on layout. Over a long outrigger, the permitted length may suit a shower room or a small bedroom, though rarely both, so we sketch the floor plan against the limit before you decide what the extra space is for. Where the outrigger is short, the limit can leave too little roof to be worth building, and we say so before you pay for a full set.

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

    Local figures for Brent

    Figures with their unit, period and source
    MeasureValuePeriodSource
    L-shaped dormers are generally acceptable, must be set up 0.2 metres from the eaves on all sides and must not cover more than 50% of the depth of the two-storey extension or outrigger.0.2 m; 50% of outrigger depth—brent.gov.uk, Residential Extensions and Alterations SPD 2025, p.34, paras 3.6.9-3.6.10
    Conservation areas23 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions39 Article 4 directions published by the council—planning.data.gov.uk
    Listed building entries93 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Householder decisions879 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted86.6 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time97.2 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Households living in a house43.3 % of households living in a house or bungalow (detached, semi-detached or terraced)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 Brent
    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

    A borough of many designations

    Brent publishes 39 Article 4 directions, mapped as 162 areas, plus 23 conservation areas. Both can take permitted development away, so the address check decides whether your L can go ahead under a certificate or needs a planning application.

    Historic England lists 93 entries, and 1,229 tree preservation orders protect trees in gardens and streets. A protected tree behind the house may not affect the roof, but it can affect where scaffolding stands.

    How Brent has decided householder applications

    In its latest year Brent decided 879 householder applications and granted 86.6 per cent, with 97.2 per cent decided within eight weeks or an agreed extension. That is a fast, fairly generous council, and the written rule means you know the target before you start.

    Only 43.3 per cent of households live in a house or bungalow, and 38.4 per cent are owner-occupiers, so a house with a loft to convert is the less common home in this borough.

    National limits behind the council rule

    If permitted development applies, the roof volume is limited by: 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume. The roof must also satisfy this: No part higher than the highest part of the existing roof. The L-shape depends on the junction rule: Eaves-retention and 0.2 m set-back do not apply where the enlargement joins the original roof to the roof of a rear or side extension.

    In a conservation area the position is: Class B roof enlargements are not permitted development on article 2(3) land. A Brent L-shaped dormer in a protected area therefore becomes a planning application, and the council's own limit is the measure that officer will apply.

    Shared roofs, stairs and fire

    Terraces and semis share roof structure, so the notice rule applies: Party structure notice at least 2 months before work. The stair allowance is: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width). For a taller conversion: New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30).

    The building regulations drawings in Brent cover these, and the party wall notices service prepares the notices.

    On a semi the stair often lands under the new main dormer, which is where the fullest headroom is, and we test that position first.

    Cost, checking and where to go next

    For a fixed quote after a free constraints check, VAT included, you receive plans, the roof section, elevations and location and block plans. Each sheet passes a chartered technologist who did not draw it, and any redraw the council requests is free until approval.

    A simpler roof may suit you better, so compare dormer loft conversion drawings in Brent. The overview is architectural drawings in Brent, and Ealing and Harrow are 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.
    Converted loft bedroom with roof windows and a Juliet balcony
    Storey by storey
    Move up and down — the car travels between floors.

    Other services in Brent

    L-shaped dormer drawings nearby

    Questions

    What is the Brent limit for an L-shaped dormer?

    The council guidance gives 0.2 m; 50% of outrigger depth, and describes L-shaped dormers as generally acceptable.

    Does Brent allow an L-shaped dormer in a conservation area?

    It becomes a planning application, since the borough has 23 conservation areas and national rights do not apply there. The council limit is the test.

    How quick are Brent householder decisions?

    It decided 97.2 per cent in eight weeks or an agreed extension in its latest year.

    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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