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Slate-clad roof extension on a yellow-brick London terraced house
Photograph: Daniel Sikpi

01Barnet, London

Mansard roof drawings for Barnet's suburban streets

A mansard in Barnet meets two kinds of constraint: Article 4 direction areas inside the streets, and Green Belt policy on the borough's edge. We check both before a line is drawn, then produce the set from £845 including VAT.

From £845 (VAT included)

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    02The brief

    Where the controls sit

    Barnet publishes 16 conservation areas and 15 Article 4 directions, and the directions map to 48 separate areas. A house inside one has lost permitted development rights it would otherwise have, so the address check comes first.

    Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. Class AA, the national route for an extra storey, carries its own conditions: Class AA is not available on article 2(3) land, and Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018.

    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline
    Brick cottage with a tiled roof, chimneys and a front dormer window
    Photograph: Tanya Barrow

    03The record

    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 mNo periodbarnet.gov.uk, SDDG SPD Part 4 (extensions), p.22, para 4.87
    Class B, condition B.2(b)(i)(aa)Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removesNo periodlegislation.gov.uk
    Class AA, para AA.1(c)Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018No periodlegislation.gov.uk
    Class AA, para AA.1(b)Class AA is not available on article 2(3) landNo periodlegislation.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk
    Party Wall etc. Act 1996 s3(2)(a)Party structure notice at least 2 months before workNo periodlegislation.gov.uk
    Conservation areas16 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Article 4 directions15 Article 4 directions published by the councilNo periodplanning.data.gov.uk
    Green Belt share of the council area28 % of council area covered by green-belt polygonsNo periodplanning.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 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

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

    Barnet6 neighbouring councils
    Councils bordering Barnet

    04The streets

    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.

    GLA Planning London Datahub, householder applications

    05The drawing

    A mansard roof in sectionA, Permitted development and the eaves: Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. B, Additional storeys under permitted development: Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018. C, Fire protection to the stair: 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)ABC

    A mansard roof in section

    A London terrace with a mansard behind the parapet. The lettered marks show the limits the legend gives.

    A Permitted development and the eaves
    Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes
    B Additional storeys under permitted development
    Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018
    C Fire protection to the stair
    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 mansard in three dimensions3D
    Scroll the page: the model turns with it.

    06The detail

    What the extensions guidance asks of a roof

    The Barnet Local Plan 2021-2036 was adopted in 2025, and the householder detail sits in the Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. Its written tests are for dormers. Where a rear dormer needs permission it should be inset at least 0.5 m from the eaves, the ridge and the edges of the original roof, and front dormers are generally not supported unless they are a common feature of the street.

    A mansard is not a dormer, so we hold no numbered mansard rule for the borough and do not pretend to. What carries over is the idea behind those tests: the new roof has to sit comfortably against the original house and the pair it belongs to. Each set shows the roof against both neighbours, with the existing ridge and eaves marked.

    Green Belt on the borough's edge

    Green Belt covers 28% of Barnet by area. A roof change adds no footprint, but houses near that edge are the ones where we read the address against the Green Belt map as well as the heritage layers.

    A listed house needs consent for a roof change as well as planning permission, and the borough holds 651 list entries. Listed building consent drawings in Barnet covers that second application.

    Council decisions and appeal outcomes

    The council granted 80.2% of 1,361 householder decisions, 95.1% of them on time. Planning Inspectorate casework records 413 householder appeals decided in the borough, with 50.6% allowed, which shows a refusal here is sometimes overturned.

    Barnet takes £548 to receive a householder application, billed by the council and not by us. For the wider picture on period streets read mansard roof drawings, and for a lower floor under the same house see basement conversion drawings in Barnet.

    Planning sheet for a single-storey rear extension: proposed ground floor plan and rear elevation, with the Property Architecture title block
    Sample drawing. Proposed plan and rear elevation from a planning application set, sheet 03 at 1:50.

    07The papers

    What the drawings rest on

    Converted loft bedroom with roof windows and a Juliet balconyLoft conversions
    Photograph: Imad Clicks
    Loft floor plan marked up in an independent review, with three critical issues clouded and explained
    Sample drawing. A loft plan with the reviewer’s mark-up: stair pitch, dormer cheeks and roof ventilation.

    08Correspondence

    Questions

    Can I build a mansard on a Barnet house inside an Article 4 area?

    An Article 4 direction removes permitted development rights the house would otherwise have, so the work needs a planning application. We read your address against the direction maps before we quote.

    How far must a Barnet rear dormer sit from the eaves and ridge?

    Where the dormer is not permitted development, the guidance asks for an inset of at least 0.5 m from the eaves, the ridge and the edges of the original roof. We draw that gap on the section.

    Does a Barnet mansard on a semi-detached house need a notice to the neighbour?

    Where the new roof touches a shared structure, yes. The Party Wall etc. Act 1996 sets the period: Party structure notice at least 2 months before work.

    Upper floors of a large yellow-brick Victorian house in London with chimney pots

    80.2%

    Householder applications granted, Barnet, 1 July 2025 - 30 June 2026. Source: assets.publishing.service.gov.uk

    Photograph: Lorenc Memaga

    09Further reading

    Other services in Barnet

    Mansard roof drawings nearby

    10Sources

    Sources and dates

    Licences

    Kensington street lined with brick townhouses and lit streetlamps beneath an orange dusk sky

    Send us the address of your house.

    We look up the conservation area, listing and Article 4 position, then reply with a fixed fee. A message before 3pm is answered the same working day.

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    Mansard roof drawings in Barnet