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

01Bromley, London

Mansard roof drawings for Bromley houses

Bromley's design guide treats a roof in a conservation area as a heritage question before it is a design one, and that decides what goes on the first sheet. Our chartered architectural technologists (MCIAT) draw the roof against its neighbours and the street, from £845 including VAT.

From £845 (VAT included)

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    02The brief

    The heritage case comes first

    The council's Urban Design Guide SPD is qualitative for householders. For a roof in a conservation area or in the setting of a listed building its requirement is short: Heritage Impact Assessment required.

    So the assessment is where a mansard in one of those places is argued, and the drawings feed it. We show the existing roof, the proposed profile and the neighbouring roofs on one datum, so the assessment has something exact to describe.

    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 Bromley

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Applications in conservation areas or listed building settings need a Heritage Impact Assessment; listed works need LBC.Heritage Impact Assessment requiredNo periodbromley.gov.uk, Urban Design Guide SPD (adopted July 2023), section 2, before para 2.25
    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 areas47 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Article 4 directions108 Article 4 directions published by the councilNo periodplanning.data.gov.uk
    Green Belt share of the council area51 % of council area covered by green-belt polygonsNo periodplanning.data.gov.uk
    Listed building entries412 list entries (Historic England, within the LPA boundary)No periodplanning.data.gov.uk
    Householder decisions (PS2)1,538 decisions2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026)assets.publishing.service.gov.uk
    Householder applications granted (PS2)79 % of householder decisions2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026)assets.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.

    Bromley8 neighbouring councils
    Councils bordering Bromley

    04The streets

    Householder applications by street in Bromley

    Streets in Bromley with the most householder applications, and the share approved
    StreetApplicationsApproved
    Petts Wood Road3981%
    Hayes Way3667%
    Crescent Drive3472%
    Village Way3281%
    Pickhurst Rise3187%
    Hayes Chase3083%
    Charterhouse Road2788%
    Farnaby Road2788%
    Kings Hall Road2591%
    St Paul's Wood Hill2588%
    Eden Park Avenue2477%
    Kent House Road2490%
    Broxbourne Road2391%
    Clock House Road2386%
    Elmstead Lane2381%

    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

    Prominent slopes and dormers

    On roof form, the council's clearest written test sits in its Local Plan, and it is for dormers. They must suit the roofscape in size and design, and they should stay off prominent slopes unless dormers are a feature of the area. A mansard rises across the whole slope, so the same prominence question applies to it, and the street elevation is drawn to answer it.

    National rules narrow things further. Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. Class AA excludes older houses (Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018) and Class AA is not available on article 2(3) land, which leaves householder planning permission as the route.

    Article 4 directions and the Green Belt

    Article 4 directions number 108 in Bromley, set against 47 conservation areas, so the question of whether permitted development survives at your address is a real one here. Green Belt covers 51% of the council area, which matters for houses near its edge.

    Within Bromley the Historic England list has 412 entries, and one entry can cover more than one building. A mansard on a listed house needs consent as well as permission, set out in listed building consent drawings in Bromley.

    Decisions, appeals and fees

    In the four most recent quarterly returns Bromley decided 1,538 householder applications and granted 79%, with 88.6% decided on time. Of the 502 householder appeals decided, inspectors allowed 37.6%.

    A householder application costs £548 at the council, and a shared roof structure brings a notice to the neighbour: Party structure notice at least 2 months before work. A lower floor is a separate application, covered in basement conversion drawings in Bromley, and the mansard roof drawings hub compares how other councils write their roof rules.

    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

    Does Bromley ask for a Heritage Impact Assessment with a roof extension?

    For applications in a conservation area or the setting of a listed building, yes: the guidance records Heritage Impact Assessment required. We prepare the drawings that assessment relies on.

    Where does Bromley want dormers on a roof?

    Away from prominent roof pitches, unless dormers are already a feature of the area, and sized to suit the roofscape. That is the council's written test, and we apply it to the street elevation.

    Is permitted development ever enough for a Bromley mansard?

    Seldom. Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes, and Class AA is not available on article 2(3) land. The address check tells you which side of that line your house falls.

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

    51%

    of council area covered by green-belt polygons

    Green Belt share of the council area, Bromley. Source: planning.data.gov.uk

    Photograph: Lorenc Memaga

    09Further reading

    Other services in Bromley

    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 Bromley