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Barnet, London

Dormer loft conversion drawings in Barnet

Dormer loft conversion drawings for a Barnet house start at £695 including VAT. The first test the council applies is the size and position of the box: when the work is not permitted development, Barnet asks for a rear dormer to be inset 0.5 m from the eaves, the ridge and the edges of the original roof.

From £695 (VAT included)

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

    How Barnet judges a dormer on a house roof

    Barnet's guidance for roof work sits in the Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. It is blunt about the street side: a front dormer will generally not be supported unless dormers are already a common feature of that street. A rear dormer is the normal answer, and the same guidance gives it a margin of 0.5 m from the eaves, the ridge and the sides of the original roof.

    That margin shapes the drawing more than people expect. On a narrow semi, three set-backs of that size take up part of the slope, so the dormer can come out smaller than the permitted development volume would allow. We draw the inset first, then fit the room, the stair landing and the window positions inside it. Side windows in the cheek follow their own condition, which is that Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor, so we place them with the neighbour in mind.

    The volume allowance still matters when the house keeps its permitted rights: 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume. If a design needs more than that, or the house has lost its rights, the Barnet margin is the standard the officer will hold the drawing to.

    Converted loft bedroom with roof windows and a Juliet balcony

    Local figures for Barnet

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Where not permitted development, rear dormers should be inset at least 0.5 metres from the eaves, ridge and edges of the original roof.0.5 m—barnet.gov.uk, SDDG SPD Part 4 (extensions), p.22, para 4.87
    Conservation areas16 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions15 Article 4 directions published by the council—planning.data.gov.uk
    Article 4 direction areas48 Article 4 direction area polygons published by the council—planning.data.gov.uk
    Listed building entries651 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Householder decisions1,361 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted80.2 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time95.1 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder appeals decided by the Planning Inspectorate413 householder appeals decideddecision dates 1 Jul 2021 to 30 Jun 2026assets.publishing.service.gov.uk
    Householder appeals allowed50.6 % of householder appeals alloweddecision dates 1 Jul 2021 to 30 Jun 2026assets.publishing.service.gov.uk
    GPDO 2015 Sch 2 Pt 1 Class B, para B.1(d)40 m³ (terrace house) / 50 m³ (any other house) additional roof volume—legislation.gov.uk
    Class B, para B.1(c)No enlargement beyond the plane of a roof slope that forms the principal elevation and fronts a highway—legislation.gov.uk
    Class B, condition B.2(b)(i)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)—legislation.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 Barnet

    Householder applications by street in Barnet

    Streets in Barnet with the most householder applications, and the share approved
    StreetApplicationsApproved
    Wolmer Gardens4282%
    Hampden Way3686%
    Oakleigh Park South3677%
    Marsh Lane3591%
    Millway3493%
    Sturgess Avenue3494%
    Uphill Road3273%
    Chanctonbury Way3190%
    Oakleigh Road North3079%
    Woodlands3076%
    Laurel Way2976%
    Mount Pleasant2880%
    Arlington Road2780%
    Berkeley Crescent27100%
    Longland Drive27100%
    Counts of householder applications by street; no individual applications are shown. Streets with fewer than five applications are left out.Source: GLA Planning London Datahub, householder applications, all years held. Contains public sector information licensed under the Open Government Licence v3.0. Contains OS data © Crown copyright and database right 2026.
    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

    Article 4 directions and conservation areas in Barnet

    Barnet has published 15 Article 4 directions, mapped as 48 separate areas, and 16 conservation areas. Where a direction removes roof rights, or where a conservation area applies, a dormer needs planning permission whatever its size.

    Historic England records 651 listed entries inside the borough. A listed house needs listed building consent for roof alterations on top of any planning route, and that is a separate application with its own drawings.

    Two neighbouring roofs can face different rules, so we check your address against all three before quoting a route. Where the house keeps its rights, a Lawful Development Certificate can confirm the design in writing. Where it does not, the dormer goes through householder planning on the same set of sheets, so nothing is drawn twice.

    What Barnet decisions and appeals show for householder work

    In its latest published year Barnet decided 1,361 householder applications and granted 80.2 per cent of them. 95.1 per cent were decided inside the statutory period or an agreed extension.

    The Planning Inspectorate decided 413 householder appeals for the borough and allowed 50.6 per cent. An appeal can overturn a refusal, but it adds months, so we would rather get the dormer right at the first submission.

    Both sets of figures cover every kind of householder project, not only dormers, and say nothing about your roof. We use them to plan the timetable and to explain the risk, not to forecast a result.

    What the Barnet dormer loft conversion drawings include

    A Barnet dormer set shows the existing and proposed floor plans, the roof in section with the dormer cheek and flat-roof build-up, and all elevations, together with the location and block plans. Building regulations set the stair headroom for a loft as follows: 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). We draw to that from the start, so the layout works before the structural engineer is involved. The new storey also brings a fire rule: 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). Both go on the plans and the specification, which keeps the later building regulations drawings consistent with the planning set.

    The fixed price is £695 including VAT, quoted before you commit. A second MCIAT chartered architectural technologist checks every sheet before it goes to the council, and if the council asks for changes we redraw at no charge until approval.

    If the roof suits a wider form, compare it with L-shaped dormer drawings in Barnet. If you want to see the plain alternative, loft conversion drawings in Barnet cover rooflight-only schemes.

    Dormer drawings across north London

    Neighbouring councils measure a dormer differently. See dormer loft conversion drawings in Haringey, in Enfield or in Hertsmere for their rules. For the borough as a whole, start at architectural drawings in Barnet, or read the national picture on the dormer loft conversion drawings hub.

    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.

    Questions

    Do I need planning permission for a dormer in Barnet?

    Often not, if the house keeps its permitted development rights and the dormer stays on the rear or a side slope within the volume allowance. A conservation area, an Article 4 direction or a listed house changes that, and we check the address first.

    How far must a Barnet rear dormer sit from the roof edge?

    Where the work is not permitted development, Barnet's extension guidance asks for an inset of 0.5 m from the eaves, ridge and edges of the original roof.

    Will Barnet accept a dormer on the front of my house?

    Generally not. The council's guidance supports a front dormer only where dormers are a common feature of the street. A rear dormer with front rooflights is the usual alternative.

    How much do dormer loft conversion drawings cost in Barnet?

    From £695 including VAT, fixed up front. Any council application fee is paid to the council separately.

    Sources and dates

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

    Tell us about your property.

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