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Bexley, London

Basement impact assessment in Bexley

Bexley's planning application checklist has no stand-alone basement impact assessment, which makes it unusual among London boroughs. A basement still triggers other documents, and flood risk can add more. We tell you exactly which ones apply to your address, and quote a fixed price after a free constraints check.

Fixed quote after a free constraints check

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  • LABC Partnered
  • Fixed fees, VAT included

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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 basement impact assessments

    Seven 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.

    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

    What Bexley asks for when a basement is proposed

    The council's list of documents for a planning application reads, in short: no BIA item; FRA in FZ2/3. Put plainly, a basement is named only as a trigger for a demolition methodology and a structural survey, and flood risk assessment is a separate duty in the higher-risk zones.

    That is a shorter list than inner London boroughs publish, and it helps to be honest about what it means. It does not mean the council will ignore ground and water. It means the evidence has to be assembled from the structural survey, the flood assessment and the engineer's design, not from a single borough template.

    Our job is to join those pieces so the officer can see the whole case. The development plan is the Bexley Local Plan, adopted in 2,023, and for the part of a scheme above ground the Design Guide SPD Part 2: Building Alterations and Extensions applies.

    Pencil resting on a dimensioned technical drawing beside a scale rule

    Local figures for Bexley

    Figures with their unit, period and source
    MeasureValuePeriodSource
    No stand-alone Basement Impact Assessment item exists in this list; basement development is named only as a trigger for the demolition methodology and structural survey. A flood risk assessment is required for all new development including minor development in Flood Zones 2 and 3 or critical drainage areas.no BIA item; FRA in FZ2/3—bexley.gov.uk, London Borough of Bexley Planning Application Requirements (reviewed 17 October 2018), pp.14, 17-18
    Conservation areas23 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries114 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Green Belt share of the council area17 % of council area covered by green-belt polygons—planning.data.gov.uk
    Householder applications granted94.6 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time99.4 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Households living in a house75.3 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Domestic gardens share of land (GLUD 2005)25.1 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Local planBexley Local Plan—bexley.gov.uk
    Party Wall etc. Act 1996 s6(1): excavation within 3 m horizontally of an adjoining owner's building or structure and deeper than the bottom of its foundations3 m—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 Bexley
    Which application your project needsLawful Development Certificate decision: 8 weeks. Prior approval decision: 42 days. Householder decision: 8 weeksYour projectWithin permitted development?Lawful Development CertificatePrior approvalHouseholder applicationYesLarger rear extensionNoABC

    Which application your project needs

    The usual route for a house; flats and listed buildings follow other rules.

    A · Lawful Development Certificate decision
    8 weeks
    B · Prior approval decision
    42 days
    C · Householder decision
    8 weeks

    Why Bexley homes suit a basement conversation

    Bexley is a house borough: 75.3 per cent of households live in a house and 68.6 per cent own the home they live in. Domestic gardens cover 25.1 per cent of the land, so there is room to dig down under a rear extension or an outbuilding.

    Constraints are fewer than in the centre of London. The borough has 23 conservation areas and 114 listed entries, and 17 per cent of its area is covered by green-belt polygons, so the edge of the borough needs a separate check against the local plan.

    Heritage at Risk lists 3 entries. If your house is one of them, or sits beside one, we flag it before we draw.

    Fewer constraints do not remove the need for care in the ground. A basement changes where rainwater goes, and drainage and groundwater are the questions a structural engineer will want answered first. We ask for any borehole or trial-pit information you already hold, any previous flooding on the street, and the age of the house, because older foundations are shallower and more sensitive to a neighbouring dig.

    How Bexley decides householder applications

    Bexley decided 877 householder applications in its latest year, granted 94.6 per cent and decided 99.4 per cent in time. Those are strong figures, and they reflect a borough where most schemes are modest and well documented.

    A basement is not modest, and the figures do not separate it out. We would rather over-prepare the structural survey and the flood evidence than rely on a good average.

    In practice we build the submission in a fixed order: the survey of the existing house, the proposed sections showing the excavation against the neighbours' foundations, the flood evidence where a zone applies, and a short covering note that tells the officer where each answer sits. That order saves a round of questions.

    Levy, party wall and Building Regulations

    Two costs catch owners out. The first is the Community Infrastructure Levy. The borough's charging schedule is the London Borough of Bexley Community Infrastructure Levy Charging Schedule April 2015, with residential rates of £40/m² (Zone 1); £60/m² (Zone 2), plus indexation. Nationally, the position is this: No basement-specific CIL exemption. Minor development exemption: no liability where gross internal area of new build is under 100 m2 (reg 42); residential extension and annex exemptions by claim (Forms 8 and 9).

    The second is the Party Wall etc. Act. A notice is needed for excavation within 3 metres of an adjoining building that goes deeper than its foundations, and within 6 metres on the diagonal test, and you must give it at least 1 month before work.

    Building Regulations then check drainage where the water table can rise within 0.25 metres of the lowest floor.

    Next steps and neighbouring boroughs

    A basement scheme in Bexley is an unpriced service because the scope depends on the site. After the free check you receive a fixed quote, and our planning drawings in Bexley carry the plans and sections that the survey and flood documents refer to.

    For the borough overview, see architectural drawings in Bexley. Across the border, Bromley has 47 conservation areas against Bexley's 23, and the national rules sit on the basement impact assessment 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.
    Rows of brick terraced houses and gardens on a residential street
    The street around you
    Move across the plinth — the blocks rise around the pointer.

    Other services in Bexley

    Basement impact assessments nearby

    Questions

    Does Bexley require a basement impact assessment?

    The council's validation list has no stand-alone item, but a basement triggers a demolition methodology and structural survey, and a flood risk assessment is required in the higher-risk flood zones. We confirm what applies to your address.

    Is a flood risk assessment needed for a basement in Bexley?

    It is required for all new development, including minor development, in the two higher-risk flood zones and in critical drainage areas.

    Does a basement attract the Community Infrastructure Levy in Bexley?

    There is no basement-specific exemption nationally, and liability depends on the charging schedule. We flag it in the next-steps pack.

    What does the work cost?

    A fixed quote after a free constraints check, because the scope depends on depth, soil and flood zone.

    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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