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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.

01Lambeth, London

Basement conversion drawings in Lambeth

Lambeth caps a residential basement at one storey, will not allow one beneath an existing basement or semi-basement, and requires a Basement Impact Assessment and a draft Construction Management Plan. We draw to those limits, from £1,995 including VAT.

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    02The brief

    The depth rule and the rear-garden test

    Under the Local Plan's basements policy, a residential basement goes no more than 1 storey below ground and not under an existing basement or semi-basement. Where a lower floor already exists the idea stops there, so we check the existing levels before any scheme is proposed.

    A basement beyond the house footprint is supported only at the rear, no larger than the footprint of the house. The garden test reads 70% garden retained. Domestic gardens make up 26% of Lambeth's land (GLA land-use data), so each garden is precious and measured closely.

    Georgian brick terrace with sash windows, arched fanlight doorways, stone steps and iron railings in London
    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline
    Photograph: Ben Hadfield

    03The record

    Local figures for Lambeth

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Residential basements must be no more than one storey below ground and not beneath existing basements or semi-basements.1 storeyNo periodlambeth.gov.uk, Local Plan 2021, Policy Q27, p.224, Q27 F
    Basements beyond the house footprint are only supported at the rear, no larger than the house footprint, with at least 70% of the rear garden left free of basement at original ground level.70% garden retainedNo periodlambeth.gov.uk, Design Guide Part 5, PDF p.13, para 5.50 (Policy Q27 G)
    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
    Party Wall etc. Act 1996 s5, s6(7)A dispute arises if the adjoining owner does not consent within 14 days of the noticeNo periodlegislation.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk
    Conservation areas64 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Article 4 directions12 Article 4 directions published by the councilNo periodplanning.data.gov.uk
    Listed building entries953 list entries (Historic England, within the LPA boundary)No periodplanning.data.gov.uk
    Grade II* listed entries56 list entriesNo periodplanning.data.gov.uk
    Domestic gardens share of land (GLUD 2005)26 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Tree preservation orders339 tree preservation orders published by the councilNo periodplanning.data.gov.uk

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

    Lambeth7 neighbouring councils
    Councils bordering Lambeth

    04The streets

    Householder applications by street in Lambeth

    Streets in Lambeth with the most householder applications, and the share approved
    StreetApplicationsApproved
    Hydethorpe Road2792%
    The Chase2072%
    Haverhill Road1888%
    Rodenhurst Road1775%
    Clive Road1573%
    Shakespeare Road1571%
    Narbonne Avenue12100%
    Fentiman Road1180%
    Ferndene Road1191%
    St Julian's Farm Road1164%
    Abbeville Road1067%
    Downton Avenue1088%
    Knollys Road10100%
    Lancaster Avenue1078%
    Rosedene Avenue1075%

    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, Lambeth: depth and garden share: 70% garden retained. B, Lambeth: excavation depth: 1 storey. C, 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. D, Escape from basement rooms: Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exitABCD

    A basement in section

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

    A Lambeth: depth and garden share
    70% garden retained
    B Lambeth: excavation depth
    1 storey
    C 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
    D 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

    What the Part 5 guidance expects with the application

    The council's Lambeth Design Guide SPD Part 5: Basements sets out the submission. A Basement Impact Assessment and a draft Construction Management Plan are required for all basement development. Specialists write those documents; our drawings supply the plans and sections they work from.

    The Local Plan is the Lambeth Local Plan 2021, with the Lambeth Design Guide SPD Part 2: Advice for All Development as the wider guide. The application itself is a householder one, and the council charges £548 for it.

    Neighbours, trees and shared buildings

    Only 24.8% of Lambeth households live in a house or bungalow, so digging often means working under or beside shared structure. 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. A dispute arises if the adjoining owner does not consent within 14 days of the notice.

    The council publishes 339 tree preservation orders, and our survey records protected trees and roots before an excavation line is set.

    Lambeth's designations before the dig

    The designations stack up: 64 conservation areas, 12 Article 4 directions, and 953 list entries, 56 of them Grade II*. Any of these can sit on the street where you want to dig. A listed house needs consent for the excavation as well as permission: see listed building consent drawings in Lambeth.

    If the same house is also getting a roof storey, the route is in mansard roof drawings in Lambeth. Addresses around the Common are covered in architectural drawings in Clapham, and the general steps sit in the basement conversion drawings hub.

    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

    Brick house being extended, with a wide new opening supported over the ground floorStructural calculations
    Photograph: Brett Jordan
    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

    Can I extend an existing basement in Lambeth?

    Not beneath an existing basement or semi-basement under the Local Plan's basements policy. We survey the existing levels first and tell you whether a scheme is possible.

    How much of my garden must stay free of basement?

    The Part 5 guidance supports basements beyond the house footprint only at the rear, with at least 70% garden retained. We measure the garden in the survey.

    What documents does the council require?

    A Basement Impact Assessment and a draft Construction Management Plan for all basement development. Specialists write them; we draw the plans and sections they use.

    Is the Basement Impact Assessment part of your fixed fee?

    No. Our fee starts at £1,995 including VAT and buys the surveyed and proposed drawings that the assessment's author works from. The specialist quotes for the assessment and the Construction Management Plan.

    Rows of brick terraced houses and gardens on a residential street

    26%

    of land that is domestic garden (GLUD 2005)

    Domestic gardens share of land (GLUD 2005), Lambeth, 2005. Source: data.london.gov.uk

    Photograph: Altaf Shah

    09Further reading

    Other services in Lambeth

    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 Lambeth