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Bright finished basement room with a glass-balustrade staircase, high windows and a built-in desk
Photograph: Point3D Commercial Imaging Ltd.

01Bromley, London

Basement conversion drawings for Bromley houses

We have not found basement limits in Bromley's Local Plan or Urban Design Guide, so a basement here is argued from regional policy, the Building Regulations and the neighbours' interests. We draw it from £1,995 including VAT and confirm in our free constraints check whether anything local applies.

From £1,995 (VAT included)

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    02The brief

    No local basement limits found, so what applies

    Bromley's Bromley Local Plan and its Urban Design Guide SPD are the documents we read, and we found no basement-specific limit on depth, garden share or lightwells in either. Regional policy fills the gap: Boroughs should set policies on large-scale basements where this is a local issue.

    The plan was adopted in 2019, and policy can move on after a page like this is written, so whether a basement policy applies to your address is a question for the constraints check, not an assumption. Until it is answered, we design to the practical limits of the site: the garden, the neighbours' foundations and the way out.

    Brick house being extended, with a wide new opening supported over the ground floor
    Georgian brick terrace with sash windows, arched fanlight doorways, stone steps and iron railings in London
    Photograph: Lorenc Memaga

    03The record

    Local figures for Bromley

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Local planBromley Local PlanNo periodbromley.gov.uk
    Supplementary planning documentUrban Design Guide SPD2023bromley.gov.uk
    Households living in a house68.6 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Owner-occupied households68.5 % of households owner-occupied (owned outright or with mortgage/loan)Census 2021nomisweb.co.uk
    Domestic gardens share of land (GLUD 2005)23.4 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Green Belt share of the council area51 % of council area covered by green-belt polygonsNo periodplanning.data.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
    Listed building entries412 list entries (Historic England, within the LPA boundary)No periodplanning.data.gov.uk
    Scheduled monuments9 scheduled monuments intersecting the LPA boundary (Historic England)No periodplanning.data.gov.uk
    Householder applications granted78.6 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder decisions1,609 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    London Plan 2021 Policy D10(A)Boroughs should set policies on large-scale basements where this is a local issueNo periodlondon.gov.uk
    Party Wall etc. Act 1996 s6(1), s6(2), s6(5)Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundationsNo periodlegislation.gov.uk
    Approved Document B Vol 1, para 2.16Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exitNo periodgov.uk
    Approved Document B Vol 1, paras 1.1-1.2All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604No periodgov.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 basement in sectionA, Party wall notice for excavation: Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. B, Escape from basement rooms: Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exitAB

    A basement in section

    A house and garden over a single-storey basement. The lettered marks show the limits the legend gives.

    A Party wall notice for excavation
    Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations
    B Escape from basement rooms
    Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit
    The basement in three dimensions3D
    Scroll the page: the model turns with it.

    06The detail

    Houses, gardens and the ground above

    68.6% of Bromley households live in a house or bungalow and 68.5% own their home. Domestic gardens cover 23.4% of the borough's land in the GLUD land-use dataset.

    The garden is what a basement leaves above it. Our survey records its depth, levels and trees before the design is fixed, because they decide how far the slab can extend.

    Green belt edges, Article 4 directions and listed houses

    Bromley is a large borough with 51% of its area mapped as green belt, so the first thing we check for a plot on the edge of a settlement is whether it falls inside. The designation changes what planning will accept above ground, and a lightwell or a new door to the garden is above ground.

    The council also publishes 47 conservation areas and 108 Article 4 directions, and Historic England lists 412 entries and records 9 scheduled monuments in the borough. For a listed house the consent route is in listed building consent drawings in Bromley.

    Alarms, exits and the wall next door

    A basement bedroom or playroom changes the fire picture. The exit rule reads: Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit. The alarm standard for the whole house reads: All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604. We show both on the sheets from the first issue.

    Excavating beside a neighbour brings in the Party Wall etc. Act 1996, which sets the trigger: Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. If the roof is also on your list, mansard roof drawings in Bromley covers that application, and the basement conversion drawings hub shows how other councils frame their 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

    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared rooflineParty wall services
    Photograph: Ben Hadfield
    Structural calculation sheet for a steel beam over a new rear opening, with the load diagram, loading table and section checks
    Sample drawing. Beam B1 over a new rear opening: loading, bending moment and section checks.

    08Correspondence

    Questions

    Does Bromley restrict how large a basement can be?

    We have not found a size limit in its Local Plan or Urban Design Guide. That can change with a new plan, so we confirm at the free constraints check and not from this page alone.

    Does the green belt stop a basement in Bromley?

    The designation covers 51% of the borough and affects what can be built, so we check whether your plot lies inside it before we quote. If it does, we tell you what that means for the lightwell and any new openings.

    How likely is a Bromley householder application to be granted?

    The council granted 78.6% of the 1,609 householder decisions in its latest year. We draw so that the officer's likely questions are already answered on the sheets.

    Rows of brick terraced houses and gardens on a residential street

    78.6%

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

    Photograph: Altaf Shah

    09Further reading

    Other services in Bromley

    Basement conversion 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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    Basement conversion drawings in Bromley